pki_gcrypt.c

/*
 * pki_gcrypt.c private and public key handling using gcrypt.
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2003-2009 Aris Adamantiadis
 * Copyright (c) 2009-2011 Andreas Schneider <asn@cryptomilk.org>
 * Copyright (C) 2016 g10 Code GmbH
 *
 * The SSH Library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The SSH Library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the SSH Library; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#include "config.h"

#ifdef HAVE_LIBGCRYPT

#include <assert.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <gcrypt.h>
#include <stdio.h>

#include "libssh/priv.h"
#include "libssh/buffer.h"
#include "libssh/session.h"
#include "libssh/wrapper.h"
#include "libssh/misc.h"
#include "libssh/pki.h"
#include "libssh/pki_priv.h"

#define MAXLINESIZE 80
#define RSA_HEADER_BEGIN "-----BEGIN RSA PRIVATE KEY-----"
#define RSA_HEADER_END "-----END RSA PRIVATE KEY-----"
#define ECDSA_HEADER_BEGIN "-----BEGIN EC PRIVATE KEY-----"
#define ECDSA_HEADER_END "-----END EC PRIVATE KEY-----"

#define MAX_KEY_SIZE 32
#define MAX_PASSPHRASE_SIZE 1024
#define ASN1_INTEGER 2
#define ASN1_BIT_STRING 3
#define ASN1_OCTET_STRING 4
#define ASN1_OBJECT_IDENTIFIER 6
#define ASN1_SEQUENCE 48
#define PKCS5_SALT_LEN 8

static int load_iv(const char *header, unsigned char *iv, int iv_len) {
  int i;
  int j;
  int k;

  memset(iv, 0, iv_len);
  for (i = 0; i < iv_len; i++) {
    if ((header[2*i] >= '0') && (header[2*i] <= '9'))
      j = header[2*i] - '0';
    else if ((header[2*i] >= 'A') && (header[2*i] <= 'F'))
      j = header[2*i] - 'A' + 10;
    else if ((header[2*i] >= 'a') && (header[2*i] <= 'f'))
      j = header[2*i] - 'a' + 10;
    else
      return -1;
    if ((header[2*i+1] >= '0') && (header[2*i+1] <= '9'))
      k = header[2*i+1] - '0';
    else if ((header[2*i+1] >= 'A') && (header[2*i+1] <= 'F'))
      k = header[2*i+1] - 'A' + 10;
    else if ((header[2*i+1] >= 'a') && (header[2*i+1] <= 'f'))
      k = header[2*i+1] - 'a' + 10;
    else
      return -1;
    iv[i] = (j << 4) + k;
  }
  return 0;
}

static uint32_t char_to_u32(unsigned char *data, uint32_t size) {
  uint32_t ret;
  uint32_t i;

  for (i = 0, ret = 0; i < size; ret = ret << 8, ret += data[i++])
    ;
  return ret;
}

static uint32_t asn1_get_len(ssh_buffer buffer) {
  uint32_t len;
  unsigned char tmp[4];

  if (ssh_buffer_get_data(buffer,tmp,1) == 0) {
    return 0;
  }

  if (tmp[0] > 127) {
    len = tmp[0] & 127;
    if (len > 4) {
      return 0; /* Length doesn't fit in u32. Can this really happen? */
    }
    if (ssh_buffer_get_data(buffer,tmp,len) == 0) {
      return 0;
    }
    len = char_to_u32(tmp, len);
  } else {
    len = char_to_u32(tmp, 1);
  }

  return len;
}

static ssh_string asn1_get(ssh_buffer buffer, unsigned char want) {
  ssh_string str;
  unsigned char type;
  uint32_t size;

  if (ssh_buffer_get_data(buffer, &type, 1) == 0 || type != want) {
    return NULL;
  }
  size = asn1_get_len(buffer);
  if (size == 0) {
    return NULL;
  }

  str = ssh_string_new(size);
  if (str == NULL) {
    return NULL;
  }

  if (ssh_buffer_get_data(buffer, ssh_string_data(str), size) == 0) {
    SSH_STRING_FREE(str);
    return NULL;
  }

  return str;
}

static ssh_string asn1_get_int(ssh_buffer buffer) {
  return asn1_get(buffer, ASN1_INTEGER);
}

static ssh_string asn1_get_bit_string(ssh_buffer buffer)
{
    ssh_string str;
    unsigned char type;
    uint32_t size;
    unsigned char unused, last, *p = NULL;
    uint32_t len;

    len = ssh_buffer_get_data(buffer, &type, 1);
    if (len == 0 || type != ASN1_BIT_STRING) {
        return NULL;
    }
    size = asn1_get_len(buffer);
    if (size == 0) {
        return NULL;
    }

    /* The first octet encodes the number of unused bits.  */
    size -= 1;

    str = ssh_string_new(size);
    if (str == NULL) {
        return NULL;
    }

    len = ssh_buffer_get_data(buffer, &unused, 1);
    if (len == 0) {
        SSH_STRING_FREE(str);
        return NULL;
    }

    if (unused == 0) {
        len = ssh_buffer_get_data(buffer, ssh_string_data(str), size);
        if (len == 0) {
            SSH_STRING_FREE(str);
            return NULL;
        }
        return str;
    }

    /* The bit string is padded at the end, we must shift the whole
       string by UNUSED bits.  */
    for (p = ssh_string_data(str), last = 0; size; size--, p++) {
        unsigned char c;

        len = ssh_buffer_get_data(buffer, &c, 1);
        if (len == 0) {
            SSH_STRING_FREE(str);
            return NULL;
        }
        *p = last | (c >> unused);
        last = c << (8 - unused);
    }

    return str;
}

static int asn1_check_sequence(ssh_buffer buffer) {
  unsigned char *j = NULL;
  unsigned char tmp;
  int i;
  uint32_t size;
  uint32_t padding;

  if (ssh_buffer_get_data(buffer, &tmp, 1) == 0 || tmp != ASN1_SEQUENCE) {
    return 0;
  }

  size = asn1_get_len(buffer);
  if ((padding = ssh_buffer_get_len(buffer) - size) > 0) {
    for (i = ssh_buffer_get_len(buffer) - size,
         j = (unsigned char*)ssh_buffer_get(buffer) + size;
         i;
         i--, j++)
    {
      if (*j != padding) {                   /* padding is allowed */
        return 0;                            /* but nothing else */
      }
    }
  }

  return 1;
}

static int asn1_check_tag(ssh_buffer buffer, unsigned char tag) {
    unsigned char tmp;
    uint32_t len;

    len = ssh_buffer_get_data(buffer, &tmp, 1);
    if (len == 0 || tmp != tag) {
        return 0;
    }

    (void) asn1_get_len(buffer);
    return 1;
}

static int passphrase_to_key(char *data, unsigned int datalen,
    unsigned char *salt, unsigned char *key, unsigned int keylen) {
  MD5CTX md;
  unsigned char digest[MD5_DIGEST_LEN] = {0};
  unsigned int i;
  unsigned int j;
  unsigned int md_not_empty;

  for (j = 0, md_not_empty = 0; j < keylen; ) {
    md = md5_init();
    if (md == NULL) {
      return -1;
    }

    if (md_not_empty) {
      md5_update(md, digest, MD5_DIGEST_LEN);
    } else {
      md_not_empty = 1;
    }

    md5_update(md, data, datalen);
    if (salt) {
      md5_update(md, salt, PKCS5_SALT_LEN);
    }
    md5_final(digest, md);

    for (i = 0; j < keylen && i < MD5_DIGEST_LEN; j++, i++) {
      if (key) {
        key[j] = digest[i];
      }
    }
  }

  return 0;
}

void pki_key_clean(ssh_key key)
{
    if (key == NULL)
        return;

    if (key->rsa)
        gcry_sexp_release(key->rsa);
    if (key->ecdsa)
        gcry_sexp_release(key->ecdsa);

    key->rsa = NULL;
    key->ecdsa = NULL;
}

static int privatekey_decrypt(int algo, int mode, unsigned int key_len,
                       unsigned char *iv, unsigned int iv_len,
                       ssh_buffer data, ssh_auth_callback cb,
                       void *userdata,
                       const char *desc)
{
  char passphrase[MAX_PASSPHRASE_SIZE] = {0};
  unsigned char key[MAX_KEY_SIZE] = {0};
  unsigned char *tmp = NULL;
  gcry_cipher_hd_t cipher;
  int rc = -1;

  if (!algo) {
    return -1;
  }

  if (cb) {
    rc = (*cb)(desc, passphrase, MAX_PASSPHRASE_SIZE, 0, 0, userdata);
    if (rc < 0) {
      return -1;
    }
  } else if (cb == NULL && userdata != NULL) {
    snprintf(passphrase, MAX_PASSPHRASE_SIZE, "%s", (char *) userdata);
  }

  if (passphrase_to_key(passphrase, strlen(passphrase), iv, key, key_len) < 0) {
    return -1;
  }

  if (gcry_cipher_open(&cipher, algo, mode, 0)
      || gcry_cipher_setkey(cipher, key, key_len)
      || gcry_cipher_setiv(cipher, iv, iv_len)
      || (tmp = calloc(ssh_buffer_get_len(data), sizeof(unsigned char))) == NULL
      || gcry_cipher_decrypt(cipher, tmp, ssh_buffer_get_len(data),
                       ssh_buffer_get(data), ssh_buffer_get_len(data))) {
    gcry_cipher_close(cipher);
    return -1;
  }

  memcpy(ssh_buffer_get(data), tmp, ssh_buffer_get_len(data));

  SAFE_FREE(tmp);
  gcry_cipher_close(cipher);

  return 0;
}

static int privatekey_dek_header(const char *header, unsigned int header_len,
    int *algo, int *mode, unsigned int *key_len, unsigned char **iv,
    unsigned int *iv_len) {
  unsigned int iv_pos;

  if (header_len > 13 && !strncmp("DES-EDE3-CBC", header, 12))
  {
    *algo = GCRY_CIPHER_3DES;
    iv_pos = 13;
    *mode = GCRY_CIPHER_MODE_CBC;
    *key_len = 24;
    *iv_len = 8;
  }
  else if (header_len > 8 && !strncmp("DES-CBC", header, 7))
  {
    *algo = GCRY_CIPHER_DES;
    iv_pos = 8;
    *mode = GCRY_CIPHER_MODE_CBC;
    *key_len = 8;
    *iv_len = 8;
  }
  else if (header_len > 12 && !strncmp("AES-128-CBC", header, 11))
  {
    *algo = GCRY_CIPHER_AES128;
    iv_pos = 12;
    *mode = GCRY_CIPHER_MODE_CBC;
    *key_len = 16;
    *iv_len = 16;
  }
  else if (header_len > 12 && !strncmp("AES-192-CBC", header, 11))
  {
    *algo = GCRY_CIPHER_AES192;
    iv_pos = 12;
    *mode = GCRY_CIPHER_MODE_CBC;
    *key_len = 24;
    *iv_len = 16;
  }
  else if (header_len > 12 && !strncmp("AES-256-CBC", header, 11))
  {
    *algo = GCRY_CIPHER_AES256;
    iv_pos = 12;
    *mode = GCRY_CIPHER_MODE_CBC;
    *key_len = 32;
    *iv_len = 16;
  } else {
    return -1;
  }

  *iv = malloc(*iv_len);
  if (*iv == NULL) {
    return -1;
  }

  return load_iv(header + iv_pos, *iv, *iv_len);
}

#define get_next_line(p, len) {                                         \
        while(p[len] == '\n' || p[len] == '\r') /* skip empty lines */  \
            len++;                                                      \
        if(p[len] == '\0')    /* EOL */                                 \
            eol = true;                                                 \
        else                  /* calculate length */                    \
            for(p += len, len = 0; p[len] && p[len] != '\n'             \
                                          && p[len] != '\r'; len++);    \
    }

static ssh_buffer privatekey_string_to_buffer(const char *pkey, int type,
                ssh_auth_callback cb, void *userdata, const char *desc) {
    ssh_buffer buffer = NULL;
    ssh_buffer out = NULL;
    const char *p = NULL;
    unsigned char *iv = NULL;
    const char *header_begin = NULL;
    const char *header_end = NULL;
    unsigned int header_begin_size;
    unsigned int header_end_size;
    unsigned int key_len = 0;
    unsigned int iv_len = 0;
    int algo = 0;
    int mode = 0;
    bool eol = false;
    size_t len;

    buffer = ssh_buffer_new();
    if (buffer == NULL) {
        return NULL;
    }

    switch(type) {
        case SSH_KEYTYPE_RSA:
            header_begin = RSA_HEADER_BEGIN;
            header_end = RSA_HEADER_END;
            break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
            header_begin = ECDSA_HEADER_BEGIN;
            header_end = ECDSA_HEADER_END;
            break;
        default:
            SSH_BUFFER_FREE(buffer);
            return NULL;
    }

    header_begin_size = strlen(header_begin);
    header_end_size = strlen(header_end);

    p = pkey;
    len = 0;
    get_next_line(p, len);

    while(!eol && strncmp(p, header_begin, header_begin_size)) {
        /* skip line */
        get_next_line(p, len);
    }
    if (eol) {
        SSH_BUFFER_FREE(buffer);
        return NULL;
    }

    /* skip header line */
    get_next_line(p, len);
    if (eol) {
        SSH_BUFFER_FREE(buffer);
        return NULL;
    }

    if (len > 11 && strncmp("Proc-Type: 4,ENCRYPTED", p, 11) == 0) {
        /* skip line */
        get_next_line(p, len);
        if (eol) {
            SSH_BUFFER_FREE(buffer);
            return NULL;
        }

        if (len > 10 && strncmp("DEK-Info: ", p, 10) == 0) {
            p += 10;
            len = 0;
            get_next_line(p, len);
            if (eol) {
                SSH_BUFFER_FREE(buffer);
                return NULL;
            }
            if (privatekey_dek_header(p, len, &algo, &mode, &key_len,
                        &iv, &iv_len) < 0) {
                SSH_BUFFER_FREE(buffer);
                SAFE_FREE(iv);
                return NULL;
            }
        } else {
            SSH_BUFFER_FREE(buffer);
            SAFE_FREE(iv);
            return NULL;
        }
    } else {
        if(len > 0) {
            if (ssh_buffer_add_data(buffer, p, len) < 0) {
                SSH_BUFFER_FREE(buffer);
                SAFE_FREE(iv);
                return NULL;
            }
        }
    }

    get_next_line(p, len);
    while(!eol && strncmp(p, header_end, header_end_size) != 0) {
        if (ssh_buffer_add_data(buffer, p, len) < 0) {
            SSH_BUFFER_FREE(buffer);
            SAFE_FREE(iv);
            return NULL;
        }
        get_next_line(p, len);
    }

    if (eol || strncmp(p, header_end, header_end_size) != 0) {
        SSH_BUFFER_FREE(buffer);
        SAFE_FREE(iv);
        return NULL;
    }

    if (ssh_buffer_add_data(buffer, "\0", 1) < 0) {
        SSH_BUFFER_FREE(buffer);
        SAFE_FREE(iv);
        return NULL;
    }

    out = base64_to_bin(ssh_buffer_get(buffer));
    SSH_BUFFER_FREE(buffer);
    if (out == NULL) {
        SAFE_FREE(iv);
        return NULL;
    }

    if (algo) {
        if (privatekey_decrypt(algo, mode, key_len, iv, iv_len, out,
                    cb, userdata, desc) < 0) {
            SSH_BUFFER_FREE(out);
            SAFE_FREE(iv);
            return NULL;
        }
    }
    SAFE_FREE(iv);

    return out;
}

static int
b64decode_rsa_privatekey(const char *pkey,
                         gcry_sexp_t *r,
                         ssh_auth_callback cb,
                         void *userdata,
                         const char *desc)
{
    const unsigned char *data = NULL;
    ssh_string n = NULL;
    ssh_string e = NULL;
    ssh_string d = NULL;
    ssh_string p = NULL;
    ssh_string q = NULL;
    ssh_string unused1 = NULL;
    ssh_string unused2 = NULL;
    ssh_string u = NULL;
    ssh_string v = NULL;
    ssh_buffer buffer = NULL;
    int rc = 1;
    gcry_error_t rv = 0;

    buffer = privatekey_string_to_buffer(pkey,
                                         SSH_KEYTYPE_RSA,
                                         cb,
                                         userdata,
                                         desc);
    if (buffer == NULL) {
        return 0;
    }

    if (!asn1_check_sequence(buffer)) {
        SSH_BUFFER_FREE(buffer);
        return 0;
    }

    v = asn1_get_int(buffer);
    if (v == NULL) {
        SSH_BUFFER_FREE(buffer);
        return 0;
    }

    data = ssh_string_data(v);
    if (ssh_string_len(v) != 1 || data[0] != 0) {
        SSH_STRING_FREE(v);
        SSH_BUFFER_FREE(buffer);
        return 0;
    }

    n = asn1_get_int(buffer);
    e = asn1_get_int(buffer);
    d = asn1_get_int(buffer);
    q = asn1_get_int(buffer);
    p = asn1_get_int(buffer);
    unused1 = asn1_get_int(buffer);
    unused2 = asn1_get_int(buffer);
    u = asn1_get_int(buffer);

    SSH_BUFFER_FREE(buffer);

    if (n == NULL || e == NULL || d == NULL || p == NULL || q == NULL ||
        unused1 == NULL || unused2 == NULL || u == NULL) {
        rc = 0;
        goto error;
    }

    rv = gcry_sexp_build(
        r,
        NULL,
        "(private-key(rsa(n %b)(e %b)(d %b)(p %b)(q %b)(u %b)))",
        ssh_string_len(n),
        ssh_string_data(n),
        ssh_string_len(e),
        ssh_string_data(e),
        ssh_string_len(d),
        ssh_string_data(d),
        ssh_string_len(p),
        ssh_string_data(p),
        ssh_string_len(q),
        ssh_string_data(q),
        ssh_string_len(u),
        ssh_string_data(u));
    if (rv) {
        rc = 0;
    }

error:
    ssh_string_burn(n);
    SSH_STRING_FREE(n);
    ssh_string_burn(e);
    SSH_STRING_FREE(e);
    ssh_string_burn(d);
    SSH_STRING_FREE(d);
    ssh_string_burn(p);
    SSH_STRING_FREE(p);
    ssh_string_burn(q);
    SSH_STRING_FREE(q);
    SSH_STRING_FREE(unused1);
    SSH_STRING_FREE(unused2);
    ssh_string_burn(u);
    SSH_STRING_FREE(u);
    SSH_STRING_FREE(v);

    return rc;
}

#ifdef HAVE_GCRYPT_ECC
static int pki_key_ecdsa_to_nid(gcry_sexp_t k)
{
    gcry_sexp_t sexp = NULL;
    const char *tmp = NULL;
    size_t size;

    sexp = gcry_sexp_find_token(k, "curve", 0);
    if (sexp == NULL) {
        return -1;
    }

    tmp = gcry_sexp_nth_data(sexp, 1, &size);

    if (size == 10) {
        int cmp;

        cmp = memcmp("NIST P-256", tmp, size);
        if (cmp == 0) {
            gcry_sexp_release(sexp);
            return NID_gcrypt_nistp256;
        }

        cmp = memcmp("NIST P-384", tmp, size);
        if (cmp == 0) {
            gcry_sexp_release(sexp);
            return NID_gcrypt_nistp384;
        }

        cmp = memcmp("NIST P-521", tmp, size);
        if (cmp == 0) {
            gcry_sexp_release(sexp);
            return NID_gcrypt_nistp521;
        }
    }

    gcry_sexp_release(sexp);
    return -1;
}

static enum ssh_keytypes_e pki_key_ecdsa_to_key_type(gcry_sexp_t k)
{
    int nid;

    nid = pki_key_ecdsa_to_nid(k);

    switch (nid) {
        case NID_gcrypt_nistp256:
            return SSH_KEYTYPE_ECDSA_P256;
        case NID_gcrypt_nistp384:
            return SSH_KEYTYPE_ECDSA_P384;
        case NID_gcrypt_nistp521:
            return SSH_KEYTYPE_ECDSA_P521;
        default:
            return SSH_KEYTYPE_UNKNOWN;
    }
}

static const char *pki_key_ecdsa_nid_to_gcrypt_name(int nid)
{
    switch (nid) {
    case NID_gcrypt_nistp256:
        return "NIST P-256";
    case NID_gcrypt_nistp384:
        return "NIST P-384";
    case NID_gcrypt_nistp521:
        return "NIST P-521";
    }

    return "unknown";
}


const char *pki_key_ecdsa_nid_to_name(int nid)
{
    switch (nid) {
    case NID_gcrypt_nistp256:
        return "ecdsa-sha2-nistp256";
    case NID_gcrypt_nistp384:
        return "ecdsa-sha2-nistp384";
    case NID_gcrypt_nistp521:
        return "ecdsa-sha2-nistp521";
    }

    return "unknown";
}

static const char *pki_key_ecdsa_nid_to_char(int nid)
{
    switch (nid) {
    case NID_gcrypt_nistp256:
        return "nistp256";
    case NID_gcrypt_nistp384:
        return "nistp384";
    case NID_gcrypt_nistp521:
        return "nistp521";
    default:
        break;
    }

    return "unknown";
}

int pki_key_ecdsa_nid_from_name(const char *name)
{
    int cmp;

    cmp = strcmp(name, "nistp256");
    if (cmp == 0) {
        return NID_gcrypt_nistp256;
    }

    cmp = strcmp(name, "nistp384");
    if (cmp == 0) {
        return NID_gcrypt_nistp384;
    }

    cmp = strcmp(name, "nistp521");
    if (cmp == 0) {
        return NID_gcrypt_nistp521;
    }

    return -1;
}

static int asn1_oi_to_nid(const ssh_string oi)
{
    static const struct {
        int nid;
        size_t length;
        const char *identifier;
    } *e, mapping[] = {
        {NID_gcrypt_nistp256, 8, "\x2a\x86\x48\xce\x3d\x03\x01\x07"},
        {NID_gcrypt_nistp384, 5, "\x2b\x81\x04\x00\x22"},
        {NID_gcrypt_nistp521, 5, "\x2b\x81\x04\x00\x23"},
        {0},
    };
    size_t len = ssh_string_len(oi);
    for (e = mapping; e->length; e++) {
        if (len == e->length
            && memcmp(ssh_string_data(oi), e->identifier, len) == 0) {
            return e->nid;
        }
    }
    return -1;
}

static int b64decode_ecdsa_privatekey(const char *pkey, gcry_sexp_t *r,
                                      ssh_auth_callback cb,
                                      void *userdata,
                                      const char *desc)
{
    const unsigned char *data = NULL;
    ssh_buffer buffer = NULL;
    gcry_error_t err = 0;
    ssh_string v = NULL;
    ssh_string d = NULL;
    ssh_string oi = NULL;
    int nid;
    ssh_string q = NULL;
    int valid = 0;
    int ok;

    buffer = privatekey_string_to_buffer(pkey,
                                         SSH_KEYTYPE_ECDSA_P256,
                                         cb,
                                         userdata,
                                         desc);
    if (buffer == NULL) {
        goto error;
    }

    ok = asn1_check_sequence(buffer);
    if (!ok) {
        goto error;
    }

    /* RFC5915 specifies version 1.  */
    v = asn1_get_int(buffer);
    if (v == NULL) {
        goto error;
    }

    data = ssh_string_data(v);
    if (ssh_string_len(v) != 1 || data[0] != 1) {
        goto error;
    }

    d = asn1_get(buffer, ASN1_OCTET_STRING);
    if (!asn1_check_tag(buffer, 0xa0)) {
        goto error;
    }
    oi = asn1_get(buffer, ASN1_OBJECT_IDENTIFIER);
    nid = asn1_oi_to_nid(oi);
    ok = asn1_check_tag(buffer, 0xa1);
    if (!ok) {
        goto error;
    }
    q = asn1_get_bit_string(buffer);

    if (d == NULL || oi == NULL || nid == -1 || q == NULL) {
        goto error;
    }

    err = gcry_sexp_build(r,
                          NULL,
                          "(private-key(ecdsa(curve %s)(d %b)(q %b)))",
                          pki_key_ecdsa_nid_to_gcrypt_name(nid),
                          ssh_string_len(d),
                          ssh_string_data(d),
                          ssh_string_len(q),
                          ssh_string_data(q));
    if (err == 0) {
        valid = 1;
    }

 error:
    SSH_BUFFER_FREE(buffer);
    SSH_STRING_FREE(v);
    ssh_string_burn(d);
    SSH_STRING_FREE(d);
    SSH_STRING_FREE(oi);
    ssh_string_burn(q);
    SSH_STRING_FREE(q);

    return valid;
}
#endif

ssh_string pki_private_key_to_pem(const ssh_key key,
                                  const char *passphrase,
                                  ssh_auth_callback auth_fn,
                                  void *auth_data)
{
    (void) key;
    (void) passphrase;
    (void) auth_fn;
    (void) auth_data;

    SSH_LOG(SSH_LOG_TRACE, "PEM export not supported by gcrypt backend!");

    return NULL;
}

ssh_key pki_private_key_from_base64(const char *b64_key,
                                    const char *passphrase,
                                    ssh_auth_callback auth_fn,
                                    void *auth_data)
{
    gcry_sexp_t rsa = NULL;
    gcry_sexp_t ecdsa = NULL;
    ssh_key key = NULL;
    enum ssh_keytypes_e type;
    int valid;

    type = pki_privatekey_type_from_string(b64_key);
    if (type == SSH_KEYTYPE_UNKNOWN) {
        SSH_LOG(SSH_LOG_TRACE, "Unknown or invalid private key.");
        return NULL;
    }

    switch (type) {
        case SSH_KEYTYPE_RSA:
            if (passphrase == NULL) {
                if (auth_fn) {
                    valid = b64decode_rsa_privatekey(b64_key, &rsa, auth_fn,
                            auth_data, "Passphrase for private key:");
                } else {
                    valid = b64decode_rsa_privatekey(b64_key, &rsa, NULL, NULL,
                            NULL);
                }
            } else {
                valid = b64decode_rsa_privatekey(b64_key, &rsa, NULL,
                        (void *)passphrase, NULL);
            }

            if (!valid) {
                SSH_LOG(SSH_LOG_TRACE, "Error parsing private key");
                goto fail;
            }
            break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
#if HAVE_GCRYPT_ECC
            if (passphrase == NULL) {
                if (auth_fn != NULL) {
                    valid = b64decode_ecdsa_privatekey(b64_key,
                                                       &ecdsa,
                                                       auth_fn,
                                                       auth_data,
                                                       "Passphrase for private key:");
                } else {
                    valid = b64decode_ecdsa_privatekey(b64_key,
                                                       &ecdsa,
                                                       NULL,
                                                       NULL,
                                                       NULL);
                }
            } else {
                valid = b64decode_ecdsa_privatekey(b64_key,
                                                   &ecdsa,
                                                   NULL,
                                                   (void *)passphrase,
                                                   NULL);
            }

            if (!valid) {
                SSH_LOG(SSH_LOG_TRACE, "Error parsing private key");
                goto fail;
            }

            /* pki_privatekey_type_from_string always returns P256 for ECDSA
             * keys, so we need to figure out the correct type here */
            type = pki_key_ecdsa_to_key_type(ecdsa);
            if (type == SSH_KEYTYPE_UNKNOWN) {
                SSH_LOG(SSH_LOG_TRACE, "Invalid private key.");
                goto fail;
            }
            break;
#endif
        case SSH_KEYTYPE_ED25519:
            /* Cannot open ed25519 keys with libgcrypt */
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            SSH_LOG(SSH_LOG_TRACE, "Unknown or invalid private key type %d", type);
            return NULL;
    }

    key = ssh_key_new();
    if (key == NULL) {
        goto fail;
    }

    key->type = type;
    key->type_c = ssh_key_type_to_char(type);
    key->flags = SSH_KEY_FLAG_PRIVATE | SSH_KEY_FLAG_PUBLIC;
    key->rsa = rsa;
    key->ecdsa = ecdsa;
#ifdef HAVE_GCRYPT_ECC
    if (is_ecdsa_key_type(key->type)) {
        key->ecdsa_nid = pki_key_ecdsa_to_nid(key->ecdsa);
    }
#endif

    return key;
fail:
    ssh_key_free(key);
    gcry_sexp_release(rsa);
    gcry_sexp_release(ecdsa);

    return NULL;
}

int pki_privkey_build_rsa(ssh_key key,
                          ssh_string n,
                          ssh_string e,
                          ssh_string d,
                          ssh_string iqmp,
                          ssh_string p,
                          ssh_string q)
{
    /* in gcrypt, there is no iqmp (inverse of q mod p) argument,
     * but it is ipmq (inverse of p mod q) so we need to swap
     * the p and q arguments */
    gcry_sexp_build(&key->rsa, NULL,
            "(private-key(rsa(n %b)(e %b)(d %b)(p %b)(q %b)(u %b)))",
            ssh_string_len(n), ssh_string_data(n),
            ssh_string_len(e), ssh_string_data(e),
            ssh_string_len(d), ssh_string_data(d),
            ssh_string_len(q), ssh_string_data(q),
            ssh_string_len(p), ssh_string_data(p),
            ssh_string_len(iqmp), ssh_string_data(iqmp));
    if (key->rsa == NULL) {
        return SSH_ERROR;
    }

    return SSH_OK;
}

int pki_pubkey_build_rsa(ssh_key key,
                         ssh_string e,
                         ssh_string n) {
    gcry_sexp_build(&key->rsa, NULL,
            "(public-key(rsa(n %b)(e %b)))",
            ssh_string_len(n), ssh_string_data(n),
            ssh_string_len(e),ssh_string_data(e));
    if (key->rsa == NULL) {
        return SSH_ERROR;
    }

    return SSH_OK;
}

#ifdef HAVE_GCRYPT_ECC
int pki_privkey_build_ecdsa(ssh_key key, int nid, ssh_string e, ssh_string exp)
{
    gpg_error_t err;

    key->ecdsa_nid = nid;
    key->type_c = pki_key_ecdsa_nid_to_name(nid);

    err = gcry_sexp_build(&key->ecdsa, NULL,
                          "(private-key(ecdsa(curve %s)(d %b)(q %b)))",
                          pki_key_ecdsa_nid_to_gcrypt_name(nid),
                          ssh_string_len(exp), ssh_string_data(exp),
                          ssh_string_len(e), ssh_string_data(e));
    if (err) {
        return SSH_ERROR;
    }

    return SSH_OK;
}

int pki_pubkey_build_ecdsa(ssh_key key, int nid, ssh_string e)
{
    gpg_error_t err;

    key->ecdsa_nid = nid;
    key->type_c = pki_key_ecdsa_nid_to_name(nid);

    err = gcry_sexp_build(&key->ecdsa, NULL,
                          "(public-key(ecdsa(curve %s)(q %b)))",
                          pki_key_ecdsa_nid_to_gcrypt_name(nid),
                          ssh_string_len(e), ssh_string_data(e));
    if (err) {
        return SSH_ERROR;
    }

    return SSH_OK;
}
#endif

ssh_key pki_key_dup(const ssh_key key, int demote)
{
    ssh_key new = NULL;
    gcry_error_t err = 0;
    int rc;

    gcry_mpi_t p = NULL;
    gcry_mpi_t q = NULL;
    gcry_mpi_t g = NULL;
    gcry_mpi_t y = NULL;
    gcry_mpi_t x = NULL;

    gcry_mpi_t e = NULL;
    gcry_mpi_t n = NULL;
    gcry_mpi_t d = NULL;
    gcry_mpi_t u = NULL;

    gcry_sexp_t curve = NULL;

    new = ssh_key_new();
    if (new == NULL) {
        return NULL;
    }
    new->type = key->type;
    new->type_c = key->type_c;
    if (demote) {
        new->flags = SSH_KEY_FLAG_PUBLIC;
    } else {
        new->flags = key->flags;
    }

    switch(key->type) {
        case SSH_KEYTYPE_RSA:
            err = gcry_sexp_extract_param(key->rsa,
                                          NULL,
                                          "ned?p?q?u?",
                                          &n,
                                          &e,
                                          &d,
                                          &p,
                                          &q,
                                          &u,
                                          NULL);
            if (err != 0) {
                break;
            }

            if (!demote && (key->flags & SSH_KEY_FLAG_PRIVATE)) {
                err = gcry_sexp_build(&new->rsa,
                        NULL,
                        "(private-key(rsa(n %m)(e %m)(d %m)(p %m)(q %m)(u %m)))",
                        n, e, d, p, q, u);
            } else {
                err = gcry_sexp_build(&new->rsa,
                                      NULL,
                                      "(public-key(rsa(n %m)(e %m)))",
                                      n, e);
            }
            break;
        case SSH_KEYTYPE_ED25519:
		rc = pki_ed25519_key_dup(new, key);
		if (rc != SSH_OK) {
                    ssh_key_free(new);
                    return NULL;
		}
		break;

        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
#ifdef HAVE_GCRYPT_ECC
            new->ecdsa_nid = key->ecdsa_nid;

            err = gcry_sexp_extract_param(key->ecdsa,
                                          NULL,
                                          "qd?",
                                          &q,
                                          &d,
                                          NULL);
            if (err) {
                break;
            }

            curve = gcry_sexp_find_token(key->ecdsa, "curve", 0);
            if (curve == NULL) {
              break;
            }

            if (!demote && (key->flags & SSH_KEY_FLAG_PRIVATE)) {
                err = gcry_sexp_build(&new->ecdsa,
                                      NULL,
                                      "(private-key(ecdsa %S (d %m)(q %m)))",
                                      curve,
                                      d,
                                      q);
            } else {
                err = gcry_sexp_build(&new->ecdsa,
                                      NULL,
                                      "(private-key(ecdsa %S (q %m)))",
                                      curve,
                                      q);
            }
            break;
#endif
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            ssh_key_free(new);
            return NULL;
    }

    if (err) {
        ssh_key_free(new);
        new = NULL;
    }

    gcry_mpi_release(p);
    gcry_mpi_release(q);
    gcry_mpi_release(g);
    gcry_mpi_release(y);
    gcry_mpi_release(x);

    gcry_mpi_release(e);
    gcry_mpi_release(n);
    gcry_mpi_release(d);
    gcry_mpi_release(u);

    gcry_sexp_release(curve);

    return new;
}

static int
pki_key_generate(ssh_key key, int parameter, const char *type_s, int type)
{
    gcry_sexp_t params = NULL;
    int rc;
    rc = gcry_sexp_build(&params,
                         NULL,
                         "(genkey(%s(nbits %d)(transient-key)))",
                         type_s,
                         parameter);
    if (rc != 0) {
        return SSH_ERROR;
    }

    switch (type) {
    case SSH_KEYTYPE_RSA:
        rc = gcry_pk_genkey(&key->rsa, params);
        break;
    case SSH_KEYTYPE_ECDSA_P256:
    case SSH_KEYTYPE_ECDSA_P384:
    case SSH_KEYTYPE_ECDSA_P521:
        rc = gcry_pk_genkey(&key->ecdsa, params);
        break;
    default:
        assert (! "reached");
    }
    gcry_sexp_release(params);
    if (rc != 0)
        return SSH_ERROR;
    return SSH_OK;
}

int
pki_key_generate_rsa(ssh_key key, int parameter)
{
    return pki_key_generate(key, parameter, "rsa", SSH_KEYTYPE_RSA);
}

#ifdef HAVE_GCRYPT_ECC
int pki_key_generate_ecdsa(ssh_key key, int parameter) {
    switch (parameter) {
        case 384:
            key->ecdsa_nid = NID_gcrypt_nistp384;
            key->type = SSH_KEYTYPE_ECDSA_P384;
            return pki_key_generate(key, parameter, "ecdsa",
                                    SSH_KEYTYPE_ECDSA_P384);
        case 521:
            key->ecdsa_nid = NID_gcrypt_nistp521;
            key->type = SSH_KEYTYPE_ECDSA_P521;
            return pki_key_generate(key, parameter, "ecdsa",
                                    SSH_KEYTYPE_ECDSA_P521);
        case 256:
        default:
            key->ecdsa_nid = NID_gcrypt_nistp256;
            key->type = SSH_KEYTYPE_ECDSA_P256;
            return pki_key_generate(key, parameter, "ecdsa",
                                    SSH_KEYTYPE_ECDSA_P256);
    }
}
#endif

static int _bignum_cmp(const gcry_sexp_t s1,
                       const gcry_sexp_t s2,
                       const char *what)
{
    gcry_sexp_t sexp = NULL;
    bignum b1 = NULL;
    bignum b2 = NULL;
    int result;

    sexp = gcry_sexp_find_token(s1, what, 0);
    if (sexp == NULL) {
        return 1;
    }
    b1 = gcry_sexp_nth_mpi(sexp, 1, GCRYMPI_FMT_USG);
    gcry_sexp_release(sexp);
    if (b1 == NULL) {
        return 1;
    }

    sexp = gcry_sexp_find_token(s2, what, 0);
    if (sexp == NULL) {
        bignum_safe_free(b1);
        return 1;
    }
    b2 = gcry_sexp_nth_mpi(sexp, 1, GCRYMPI_FMT_USG);
    gcry_sexp_release(sexp);
    if (b2 == NULL) {
        bignum_safe_free(b1);
        return 1;
    }

    result = !! bignum_cmp(b1, b2);
    bignum_safe_free(b1);
    bignum_safe_free(b2);
    return result;
}

int pki_key_compare(const ssh_key k1,
                    const ssh_key k2,
                    enum ssh_keycmp_e what)
{
    switch (k1->type) {
        case SSH_KEYTYPE_RSA:
        case SSH_KEYTYPE_RSA_CERT01:
            if (_bignum_cmp(k1->rsa, k2->rsa, "e") != 0) {
                return 1;
            }

            if (_bignum_cmp(k1->rsa, k2->rsa, "n") != 0) {
                return 1;
            }

            if (what == SSH_KEY_CMP_PRIVATE) {
                if (_bignum_cmp(k1->rsa, k2->rsa, "d") != 0) {
                    return 1;
                }

                if (_bignum_cmp(k1->rsa, k2->rsa, "p") != 0) {
                    return 1;
                }

                if (_bignum_cmp(k1->rsa, k2->rsa, "q") != 0) {
                    return 1;
                }

                if (_bignum_cmp(k1->rsa, k2->rsa, "u") != 0) {
                    return 1;
                }
            }
            break;
        case SSH_KEYTYPE_ED25519:
        case SSH_KEYTYPE_ED25519_CERT01:
        case SSH_KEYTYPE_SK_ED25519:
        case SSH_KEYTYPE_SK_ED25519_CERT01:
            /* ed25519 keys handled globally */
            return 0;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P256_CERT01:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P384_CERT01:
        case SSH_KEYTYPE_ECDSA_P521:
        case SSH_KEYTYPE_ECDSA_P521_CERT01:
        case SSH_KEYTYPE_SK_ECDSA:
        case SSH_KEYTYPE_SK_ECDSA_CERT01:
#ifdef HAVE_GCRYPT_ECC
            if (k1->ecdsa_nid != k2->ecdsa_nid) {
                return 1;
            }

            if (_bignum_cmp(k1->ecdsa, k2->ecdsa, "q") != 0) {
                return 1;
            }

            if (what == SSH_KEY_CMP_PRIVATE) {
                if (_bignum_cmp(k1->ecdsa, k2->ecdsa, "d") != 0) {
                    return 1;
                }
            }
            break;
#endif
        case SSH_KEYTYPE_DSS:        /* deprecated */
        case SSH_KEYTYPE_DSS_CERT01: /* deprecated */
        case SSH_KEYTYPE_ECDSA:      /* deprecated */
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
            return 1;
    }

    return 0;
}

ssh_string pki_key_to_blob(const ssh_key key, enum ssh_key_e type)
{
    ssh_buffer buffer = NULL;
    ssh_string type_s = NULL;
    ssh_string str = NULL;
    ssh_string e = NULL;
    ssh_string n = NULL;
    ssh_string d = NULL;
    ssh_string p = NULL;
    ssh_string g = NULL;
    ssh_string q = NULL;
    ssh_string u = NULL;
    int rc;

    buffer = ssh_buffer_new();
    if (buffer == NULL) {
        return NULL;
    }

    if (key->cert != NULL) {
        rc = ssh_buffer_add_buffer(buffer, key->cert);
        if (rc < 0) {
            SSH_BUFFER_FREE(buffer);
            return NULL;
        }
        goto makestring;
    }

    type_s = ssh_string_from_char(key->type_c);
    if (type_s == NULL) {
        SSH_BUFFER_FREE(buffer);
        return NULL;
    }

    rc = ssh_buffer_add_ssh_string(buffer, type_s);
    SSH_STRING_FREE(type_s);
    if (rc < 0) {
        SSH_BUFFER_FREE(buffer);
        return NULL;
    }

    switch (key->type) {
        case SSH_KEYTYPE_RSA:
            e = ssh_sexp_extract_mpi(key->rsa,
                                     "e",
                                     GCRYMPI_FMT_USG,
                                     GCRYMPI_FMT_STD);
            if (e == NULL) {
                goto fail;
            }

            n = ssh_sexp_extract_mpi(key->rsa,
                                     "n",
                                     GCRYMPI_FMT_USG,
                                     GCRYMPI_FMT_STD);
            if (n == NULL) {
                goto fail;
            }

            if (type == SSH_KEY_PUBLIC) {
                /* The N and E parts are swapped in the public key export ! */
                rc = ssh_buffer_add_ssh_string(buffer, e);
                if (rc < 0) {
                    goto fail;
                }
                rc = ssh_buffer_add_ssh_string(buffer, n);
                if (rc < 0) {
                    goto fail;
                }
            } else if (type == SSH_KEY_PRIVATE) {
                rc = ssh_buffer_add_ssh_string(buffer, n);
                if (rc < 0) {
                    goto fail;
                }
                rc = ssh_buffer_add_ssh_string(buffer, e);
                if (rc < 0) {
                    goto fail;
                }

                d = ssh_sexp_extract_mpi(key->rsa,
                                        "d",
                                        GCRYMPI_FMT_USG,
                                        GCRYMPI_FMT_STD);
                if (d == NULL) {
                    goto fail;
                }

                p = ssh_sexp_extract_mpi(key->rsa,
                                        "p",
                                        GCRYMPI_FMT_USG,
                                        GCRYMPI_FMT_STD);
                if (p == NULL) {
                    goto fail;
                }

                q = ssh_sexp_extract_mpi(key->rsa,
                                        "q",
                                        GCRYMPI_FMT_USG,
                                        GCRYMPI_FMT_STD);
                if (q == NULL) {
                    goto fail;
                }

                u = ssh_sexp_extract_mpi(key->rsa,
                                         "u",
                                         GCRYMPI_FMT_USG,
                                         GCRYMPI_FMT_STD);
                if (u == NULL) {
                    goto fail;
                }

                rc = ssh_buffer_add_ssh_string(buffer, d);
                if (rc < 0) {
                    goto fail;
                }
                rc = ssh_buffer_add_ssh_string(buffer, u);
                if (rc < 0) {
                    goto fail;
                }
                /* Swap the P and Q as the iqmp in gcrypt is ipmq ... */
                rc = ssh_buffer_add_ssh_string(buffer, q);
                if (rc < 0) {
                    goto fail;
                }
                rc = ssh_buffer_add_ssh_string(buffer, p);
                if (rc < 0) {
                    goto fail;
                }
                ssh_string_burn(d);
                SSH_STRING_FREE(d);
                ssh_string_burn(p);
                SSH_STRING_FREE(p);
                ssh_string_burn(q);
                SSH_STRING_FREE(q);
                ssh_string_burn(u);
                SSH_STRING_FREE(u);
            }
            ssh_string_burn(e);
            SSH_STRING_FREE(e);
            ssh_string_burn(n);
            SSH_STRING_FREE(n);
            break;
        case SSH_KEYTYPE_ED25519:
        case SSH_KEYTYPE_SK_ED25519:
            if (type == SSH_KEY_PUBLIC) {
                rc = pki_ed25519_public_key_to_blob(buffer, key);
                if (rc == SSH_ERROR) {
                    goto fail;
                }
                /* public key can contain certificate sk information */
                if (key->type == SSH_KEYTYPE_SK_ED25519) {
                    rc = ssh_buffer_add_ssh_string(buffer, key->sk_application);
                    if (rc < 0) {
                        goto fail;
                    }
                }
            } else {
                rc = pki_ed25519_private_key_to_blob(buffer, key);
                if (rc == SSH_ERROR) {
                    goto fail;
                }
            }
            break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
        case SSH_KEYTYPE_SK_ECDSA:
#ifdef HAVE_GCRYPT_ECC
            type_s = ssh_string_from_char(
                       pki_key_ecdsa_nid_to_char(key->ecdsa_nid));
            if (type_s == NULL) {
                goto fail;
            }

            rc = ssh_buffer_add_ssh_string(buffer, type_s);
            SSH_STRING_FREE(type_s);
            if (rc < 0) {
                goto fail;
            }

            e = ssh_sexp_extract_mpi(key->ecdsa, "q", GCRYMPI_FMT_STD,
                                     GCRYMPI_FMT_STD);
            if (e == NULL) {
                goto fail;
            }

            rc = ssh_buffer_add_ssh_string(buffer, e);
            if (rc < 0) {
                goto fail;
            }

            ssh_string_burn(e);
            SSH_STRING_FREE(e);
            e = NULL;

            if (type == SSH_KEY_PRIVATE) {
                d = ssh_sexp_extract_mpi(key->ecdsa, "d", GCRYMPI_FMT_STD,
                                         GCRYMPI_FMT_STD);
                if (d == NULL) {
                    goto fail;
                }

                rc = ssh_buffer_add_ssh_string(buffer, d);
                if (rc < 0) {
                    goto fail;
                }

                ssh_string_burn(d);
                SSH_STRING_FREE(d);
                d = NULL;
            } else if (key->type == SSH_KEYTYPE_SK_ECDSA) {
                /* public key can contain certificate sk information */
                rc = ssh_buffer_add_ssh_string(buffer, key->sk_application);
                if (rc < 0) {
                    goto fail;
                }
            }

            break;
#endif
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            goto fail;
    }

makestring:
    str = ssh_string_new(ssh_buffer_get_len(buffer));
    if (str == NULL) {
        goto fail;
    }

    rc = ssh_string_fill(str, ssh_buffer_get(buffer), ssh_buffer_get_len(buffer));
    if (rc < 0) {
        goto fail;
    }
    SSH_BUFFER_FREE(buffer);

    return str;
fail:
    SSH_BUFFER_FREE(buffer);
    ssh_string_burn(str);
    SSH_STRING_FREE(str);
    ssh_string_burn(e);
    SSH_STRING_FREE(e);
    ssh_string_burn(p);
    SSH_STRING_FREE(p);
    ssh_string_burn(g);
    SSH_STRING_FREE(g);
    ssh_string_burn(q);
    SSH_STRING_FREE(q);
    ssh_string_burn(n);
    SSH_STRING_FREE(n);

    return NULL;
}

ssh_string pki_signature_to_blob(const ssh_signature sig)
{
    const char *s = NULL;  /* used in RSA */

    gcry_sexp_t sexp = NULL;
    size_t size = 0;
    ssh_string sig_blob = NULL;
    int rc;

    switch(sig->type) {
        case SSH_KEYTYPE_RSA:
            sexp = gcry_sexp_find_token(sig->rsa_sig, "s", 0);
            if (sexp == NULL) {
                return NULL;
            }
            s = gcry_sexp_nth_data(sexp, 1, &size);

            /*
             * Remove leading zeroes, but only the ones that do not make the MPI
             * representation look like a negative value (first bit is one),
             * which might confuse some implementations.
             */
            while (size > 1 && s[0] == 0 && (s[1] & 0x80) == 0) {
                size--;
                s++;
            }

            sig_blob = ssh_string_new(size);
            if (sig_blob == NULL) {
                return NULL;
            }
            rc = ssh_string_fill(sig_blob, discard_const_p(char, s), size);
            gcry_sexp_release(sexp);
            if (rc < 0) {
                SSH_STRING_FREE(sig_blob);
                return NULL;
            }
            break;
        case SSH_KEYTYPE_ED25519:
            sig_blob = pki_ed25519_signature_to_blob(sig);
            break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
#ifdef HAVE_GCRYPT_ECC
            {
                ssh_string R;
                ssh_string S;
                ssh_buffer b;

                b = ssh_buffer_new();
                if (b == NULL) {
                    return NULL;
                }

                R = ssh_sexp_extract_mpi(sig->ecdsa_sig, "r",
                                         GCRYMPI_FMT_USG, GCRYMPI_FMT_STD);
                if (R == NULL) {
                    SSH_BUFFER_FREE(b);
                    return NULL;
                }

                rc = ssh_buffer_add_ssh_string(b, R);
                SSH_STRING_FREE(R);
                if (rc < 0) {
                    SSH_BUFFER_FREE(b);
                    return NULL;
                }

                S = ssh_sexp_extract_mpi(sig->ecdsa_sig, "s",
                                         GCRYMPI_FMT_USG, GCRYMPI_FMT_STD);
                if (S == NULL) {
                    SSH_BUFFER_FREE(b);
                    return NULL;
                }

                rc = ssh_buffer_add_ssh_string(b, S);
                SSH_STRING_FREE(S);
                if (rc < 0) {
                    SSH_BUFFER_FREE(b);
                    return NULL;
                }

                sig_blob = ssh_string_new(ssh_buffer_get_len(b));
                if (sig_blob == NULL) {
                    SSH_BUFFER_FREE(b);
                    return NULL;
                }

                rc = ssh_string_fill(sig_blob,
                                ssh_buffer_get(b), ssh_buffer_get_len(b));
                SSH_BUFFER_FREE(b);
                if (rc < 0) {
                    SSH_STRING_FREE(sig_blob);
                    return NULL;
                }
                break;
            }
#endif
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            SSH_LOG(SSH_LOG_TRACE, "Unknown signature key type: %d", sig->type);
            return NULL;
            break;
    }

    return sig_blob;
}

ssh_signature pki_signature_from_blob(const ssh_key pubkey,
                                      const ssh_string sig_blob,
                                      enum ssh_keytypes_e type,
                                      enum ssh_digest_e hash_type)
{
    ssh_signature sig = NULL;
    gcry_error_t err;
    size_t len;
    size_t rsalen;
    int rc;

    if (ssh_key_type_plain(pubkey->type) != type) {
        SSH_LOG(SSH_LOG_TRACE,
                "Incompatible public key provided (%d) expecting (%d)",
                type,
                pubkey->type);
        return NULL;
    }

    sig = ssh_signature_new();
    if (sig == NULL) {
        return NULL;
    }

    sig->type = type;
    sig->type_c = ssh_key_signature_to_char(type, hash_type);
    sig->hash_type = hash_type;

    len = ssh_string_len(sig_blob);

    switch(type) {
        case SSH_KEYTYPE_RSA:
            rsalen = (gcry_pk_get_nbits(pubkey->rsa) + 7) / 8;

            if (len > rsalen) {
                SSH_LOG(SSH_LOG_TRACE,
                        "Signature is too big: %lu > %lu",
                        (unsigned long)len,
                        (unsigned long)rsalen);
                ssh_signature_free(sig);
                return NULL;
            }

            if (len < rsalen) {
                SSH_LOG(SSH_LOG_DEBUG,
                        "RSA signature len %lu < %lu",
                        (unsigned long)len,
                        (unsigned long)rsalen);
            }

#ifdef DEBUG_CRYPTO
            SSH_LOG(SSH_LOG_DEBUG, "RSA signature len: %lu", (unsigned long)len);
            ssh_log_hexdump("RSA signature", ssh_string_data(sig_blob), len);
#endif

            err = gcry_sexp_build(&sig->rsa_sig,
                                  NULL,
                                  "(sig-val(rsa(s %b)))",
                                  ssh_string_len(sig_blob),
                                  ssh_string_data(sig_blob));
            if (err) {
                ssh_signature_free(sig);
                return NULL;
            }
            break;
        case SSH_KEYTYPE_ED25519:
        case SSH_KEYTYPE_SK_ED25519:
		rc = pki_signature_from_ed25519_blob(sig, sig_blob);
		if (rc != SSH_OK){
			ssh_signature_free(sig);
			return NULL;
		}
		break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
        case SSH_KEYTYPE_SK_ECDSA:
#ifdef HAVE_GCRYPT_ECC
            { /* build ecdsa siganature */
                ssh_buffer b;
                ssh_string r, s;
                uint32_t rlen;

                b = ssh_buffer_new();
                if (b == NULL) {
                    ssh_signature_free(sig);
                    return NULL;
                }

                rc = ssh_buffer_add_data(b,
                                         ssh_string_data(sig_blob),
                                         ssh_string_len(sig_blob));
                if (rc < 0) {
                    SSH_BUFFER_FREE(b);
                    ssh_signature_free(sig);
                    return NULL;
                }

                r = ssh_buffer_get_ssh_string(b);
                if (r == NULL) {
                    SSH_BUFFER_FREE(b);
                    ssh_signature_free(sig);
                    return NULL;
                }

                s = ssh_buffer_get_ssh_string(b);
                rlen = ssh_buffer_get_len(b);
                SSH_BUFFER_FREE(b);
                if (s == NULL) {
                    ssh_string_burn(r);
                    SSH_STRING_FREE(r);
                    ssh_signature_free(sig);
                    return NULL;
                }

                if (rlen != 0) {
                    SSH_LOG(SSH_LOG_TRACE,
                            "Signature has remaining bytes in inner "
                            "sigblob: %lu",
                            (unsigned long)rlen);
                    ssh_string_burn(r);
                    SSH_STRING_FREE(r);
                    ssh_string_burn(s);
                    SSH_STRING_FREE(s);
                    ssh_signature_free(sig);
                    return NULL;
                }

#ifdef DEBUG_CRYPTO
                ssh_log_hexdump("r", ssh_string_data(r), ssh_string_len(r));
                ssh_log_hexdump("s", ssh_string_data(s), ssh_string_len(s));
#endif

                err = gcry_sexp_build(&sig->ecdsa_sig,
                                      NULL,
                                      "(sig-val(ecdsa(r %b)(s %b)))",
                                      ssh_string_len(r),
                                      ssh_string_data(r),
                                      ssh_string_len(s),
                                      ssh_string_data(s));
                ssh_string_burn(r);
                SSH_STRING_FREE(r);
                ssh_string_burn(s);
                SSH_STRING_FREE(s);
                if (err) {
                    ssh_signature_free(sig);
                    return NULL;
                }
            }
            break;
#endif
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            SSH_LOG(SSH_LOG_TRACE, "Unknown signature type");
            return NULL;
    }

    return sig;
}

ssh_signature pki_do_sign_hash(const ssh_key privkey,
                               const unsigned char *hash,
                               size_t hlen,
                               enum ssh_digest_e hash_type)
{
    const char *hash_c = NULL;
    ssh_signature sig = NULL;
    gcry_sexp_t sexp = NULL;
    gcry_error_t err;

    sig = ssh_signature_new();
    if (sig == NULL) {
        return NULL;
    }
    sig->type = privkey->type;
    sig->type_c = ssh_key_signature_to_char(privkey->type, hash_type);
    sig->hash_type = hash_type;
    switch (privkey->type) {
        case SSH_KEYTYPE_RSA:
            switch (hash_type) {
            case SSH_DIGEST_SHA1:
                hash_c = "sha1";
                break;
            case SSH_DIGEST_SHA256:
                hash_c = "sha256";
                break;
            case SSH_DIGEST_SHA512:
                hash_c = "sha512";
                break;
            case SSH_DIGEST_AUTO:
            default:
                SSH_LOG(SSH_LOG_TRACE, "Incompatible key algorithm");
                return NULL;
            }
            err = gcry_sexp_build(&sexp,
                                  NULL,
                                  "(data(flags pkcs1)(hash %s %b))",
                                  hash_c,
                                  hlen,
                                  hash);
            if (err) {
                ssh_signature_free(sig);
                return NULL;
            }

            err = gcry_pk_sign(&sig->rsa_sig, sexp, privkey->rsa);
            gcry_sexp_release(sexp);
            if (err) {
                ssh_signature_free(sig);
                return NULL;
            }
            break;
        case SSH_KEYTYPE_ED25519:
		err = pki_ed25519_sign(privkey, sig, hash, hlen);
		if (err != SSH_OK){
			ssh_signature_free(sig);
			return NULL;
		}
		break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
#ifdef HAVE_GCRYPT_ECC
            err = gcry_sexp_build(&sexp,
                                  NULL,
                                  "(data(flags raw)(value %b))",
                                  hlen,
                                  hash);
            if (err) {
                ssh_signature_free(sig);
                return NULL;
            }

            err = gcry_pk_sign(&sig->ecdsa_sig, sexp, privkey->ecdsa);
            gcry_sexp_release(sexp);
            if (err) {
                ssh_signature_free(sig);
                return NULL;
            }
            break;
#endif
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            ssh_signature_free(sig);
            return NULL;
    }

    return sig;
}

/**
 * @internal
 *
 * @brief Sign the given input data. The digest of to be signed is calculated
 * internally as necessary.
 *
 * @param[in]   privkey     The private key to be used for signing.
 * @param[in]   hash_type   The digest algorithm to be used.
 * @param[in]   input       The data to be signed.
 * @param[in]   input_len   The length of the data to be signed.
 *
 * @return  a newly allocated ssh_signature or NULL on error.
 */
ssh_signature pki_sign_data(const ssh_key privkey,
                            enum ssh_digest_e hash_type,
                            const unsigned char *input,
                            size_t input_len)
{
    unsigned char hash[SHA512_DIGEST_LEN] = {0};
    const unsigned char *sign_input = NULL;
    uint32_t hlen = 0;
    int rc;

    if (privkey == NULL || !ssh_key_is_private(privkey) || input == NULL) {
        SSH_LOG(SSH_LOG_TRACE, "Bad parameter provided to "
                               "pki_sign_data()");
        return NULL;
    }

    /* Check if public key and hash type are compatible */
    rc = pki_key_check_hash_compatible(privkey, hash_type);
    if (rc != SSH_OK) {
        return NULL;
    }

    switch (hash_type) {
    case SSH_DIGEST_SHA256:
        sha256(input, input_len, hash);
        hlen = SHA256_DIGEST_LEN;
        sign_input = hash;
        break;
    case SSH_DIGEST_SHA384:
        sha384(input, input_len, hash);
        hlen = SHA384_DIGEST_LEN;
        sign_input = hash;
        break;
    case SSH_DIGEST_SHA512:
        sha512(input, input_len, hash);
        hlen = SHA512_DIGEST_LEN;
        sign_input = hash;
        break;
    case SSH_DIGEST_SHA1:
        sha1(input, input_len, hash);
        hlen = SHA_DIGEST_LEN;
        sign_input = hash;
        break;
    case SSH_DIGEST_AUTO:
        if (privkey->type == SSH_KEYTYPE_ED25519) {
            /* SSH_DIGEST_AUTO should only be used with ed25519 */
            sign_input = input;
            hlen = input_len;
            break;
        }
        FALL_THROUGH;
    default:
        SSH_LOG(SSH_LOG_TRACE, "Unknown hash algorithm for type: %d",
                hash_type);
        return NULL;
    }

    return pki_do_sign_hash(privkey, sign_input, hlen, hash_type);
}

/**
 * @internal
 *
 * @brief Verify the signature of a given input. The digest of the input is
 * calculated internally as necessary.
 *
 * @param[in]   signature   The signature to be verified.
 * @param[in]   pubkey      The public key used to verify the signature.
 * @param[in]   input       The signed data.
 * @param[in]   input_len   The length of the signed data.
 *
 * @return  SSH_OK if the signature is valid; SSH_ERROR otherwise.
 */
int pki_verify_data_signature(ssh_signature signature,
                              const ssh_key pubkey,
                              const unsigned char *input,
                              size_t input_len)
{
    const char *hash_type = NULL;
    gcry_sexp_t sexp = NULL;
    gcry_error_t err;

    unsigned char ghash[SHA512_DIGEST_LEN + 1] = {0};
    unsigned char *hash = ghash + 1;
    uint32_t hlen = 0;

    const unsigned char *verify_input = NULL;

    int rc;

    if (pubkey == NULL || ssh_key_is_private(pubkey) || input == NULL ||
        signature == NULL)
    {
        SSH_LOG(SSH_LOG_TRACE, "Bad parameter provided to "
                               "pki_verify_data_signature()");
        return SSH_ERROR;
    }

    /* Check if public key and hash type are compatible */
    rc = pki_key_check_hash_compatible(pubkey, signature->hash_type);
    if (rc != SSH_OK) {
        return SSH_ERROR;
    }

    switch (signature->hash_type) {
    case SSH_DIGEST_SHA256:
        sha256(input, input_len, hash);
        hlen = SHA256_DIGEST_LEN;
        hash_type = "sha256";
        verify_input = hash;
        break;
    case SSH_DIGEST_SHA384:
        sha384(input, input_len, hash);
        hlen = SHA384_DIGEST_LEN;
        hash_type = "sha384";
        verify_input = hash;
        break;
    case SSH_DIGEST_SHA512:
        sha512(input, input_len, hash);
        hlen = SHA512_DIGEST_LEN;
        hash_type = "sha512";
        verify_input = hash;
        break;
    case SSH_DIGEST_SHA1:
        sha1(input, input_len, hash);
        hlen = SHA_DIGEST_LEN;
        hash_type = "sha1";
        verify_input = hash;
        break;
    case SSH_DIGEST_AUTO:
        if (pubkey->type == SSH_KEYTYPE_ED25519 ||
            pubkey->type == SSH_KEYTYPE_ED25519_CERT01 ||
            pubkey->type == SSH_KEYTYPE_SK_ED25519 ||
            pubkey->type == SSH_KEYTYPE_SK_ED25519_CERT01)
        {
            verify_input = input;
            hlen = input_len;
            break;
        }
        FALL_THROUGH;
    default:
        SSH_LOG(SSH_LOG_TRACE, "Unknown sig->hash_type: %d", signature->hash_type);
        return SSH_ERROR;
    }

    switch(pubkey->type) {
        case SSH_KEYTYPE_RSA:
        case SSH_KEYTYPE_RSA_CERT01:
            err = gcry_sexp_build(&sexp,
                                  NULL,
                                  "(data(flags pkcs1)(hash %s %b))",
                                  hash_type, hlen, hash);
            if (err) {
                SSH_LOG(SSH_LOG_TRACE,
                              "RSA hash error: %s",
                              gcry_strerror(err));
                return SSH_ERROR;
            }
            err = gcry_pk_verify(signature->rsa_sig, sexp, pubkey->rsa);
            gcry_sexp_release(sexp);
            if (err) {
                SSH_LOG(SSH_LOG_TRACE, "Invalid RSA signature");
                if (gcry_err_code(err) != GPG_ERR_BAD_SIGNATURE) {
                    SSH_LOG(SSH_LOG_TRACE,
                            "RSA verify error: %s",
                            gcry_strerror(err));
                }
                return SSH_ERROR;
            }
            break;
        case SSH_KEYTYPE_ECDSA_P256:
        case SSH_KEYTYPE_ECDSA_P384:
        case SSH_KEYTYPE_ECDSA_P521:
        case SSH_KEYTYPE_ECDSA_P256_CERT01:
        case SSH_KEYTYPE_ECDSA_P384_CERT01:
        case SSH_KEYTYPE_ECDSA_P521_CERT01:
        case SSH_KEYTYPE_SK_ECDSA:
        case SSH_KEYTYPE_SK_ECDSA_CERT01:
#ifdef HAVE_GCRYPT_ECC
            err = gcry_sexp_build(&sexp,
                                  NULL,
                                  "(data(flags raw)(value %b))",
                                  hlen,
                                  hash);
            if (err) {
                SSH_LOG(SSH_LOG_TRACE,
                        "ECDSA hash error: %s",
                        gcry_strerror(err));
                return SSH_ERROR;
            }
            err = gcry_pk_verify(signature->ecdsa_sig, sexp, pubkey->ecdsa);
            gcry_sexp_release(sexp);
            if (err) {
                SSH_LOG(SSH_LOG_TRACE, "Invalid ECDSA signature");
                if (gcry_err_code(err) != GPG_ERR_BAD_SIGNATURE) {
                    SSH_LOG(SSH_LOG_TRACE,
                            "ECDSA verify error: %s",
                            gcry_strerror(err));
                }
                return SSH_ERROR;
            }
            break;
#endif
        case SSH_KEYTYPE_ED25519:
        case SSH_KEYTYPE_ED25519_CERT01:
        case SSH_KEYTYPE_SK_ED25519:
        case SSH_KEYTYPE_SK_ED25519_CERT01:
            rc = pki_ed25519_verify(pubkey, signature, verify_input, hlen);
            if (rc != SSH_OK) {
                SSH_LOG(SSH_LOG_TRACE, "ED25519 error: Signature invalid");
                return SSH_ERROR;
            }
            break;
        case SSH_KEYTYPE_RSA1:
        case SSH_KEYTYPE_UNKNOWN:
        default:
            SSH_LOG(SSH_LOG_TRACE, "Unknown public key type");
            return SSH_ERROR;
    }

    return SSH_OK;
}

int ssh_key_size(ssh_key key)
{
    switch (key->type) {
    case SSH_KEYTYPE_RSA:
    case SSH_KEYTYPE_RSA_CERT01:
    case SSH_KEYTYPE_RSA1:
        return gcry_pk_get_nbits(key->rsa);
    case SSH_KEYTYPE_ECDSA_P256:
    case SSH_KEYTYPE_ECDSA_P256_CERT01:
    case SSH_KEYTYPE_ECDSA_P384:
    case SSH_KEYTYPE_ECDSA_P384_CERT01:
    case SSH_KEYTYPE_ECDSA_P521:
    case SSH_KEYTYPE_ECDSA_P521_CERT01:
    case SSH_KEYTYPE_SK_ECDSA:
    case SSH_KEYTYPE_SK_ECDSA_CERT01:
        return gcry_pk_get_nbits(key->ecdsa);
    case SSH_KEYTYPE_ED25519:
    case SSH_KEYTYPE_ED25519_CERT01:
    case SSH_KEYTYPE_SK_ED25519:
    case SSH_KEYTYPE_SK_ED25519_CERT01:
        /* ed25519 keys have fixed size */
        return 255;
    case SSH_KEYTYPE_DSS:   /* deprecated */
    case SSH_KEYTYPE_DSS_CERT01:    /* deprecated */
    case SSH_KEYTYPE_UNKNOWN:
    default:
        return SSH_ERROR;
    }
}

#ifdef WITH_PKCS11_URI
int pki_uri_import(const char *uri_name, ssh_key *key, enum ssh_key_e key_type)
{
    (void) uri_name;
    (void) key;
    (void) key_type;
    SSH_LOG(SSH_LOG_TRACE,
            "gcrypt does not support PKCS #11");
    return SSH_ERROR;
}
#endif /* WITH_PKCS11_URI */
#endif /* HAVE_LIBGCRYPT */