/
nasl_crypto2.c
1879 lines (1661 loc) · 48.3 KB
/
nasl_crypto2.c
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/* Based on work Copyright (C) 2002 - 2004 Tenable Network Security
*
* SPDX-License-Identifier: GPL-2.0-only
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file nasl_crypto2.c
* @brief This file contains all the crypto functionality needed by the SSH
* protocol
*/
#include "nasl_crypto2.h"
#include "../misc/strutils.h"
#include "nasl_debug.h"
#include "nasl_func.h"
#include "nasl_global_ctxt.h"
#include "nasl_lex_ctxt.h"
#include "nasl_misc_funcs.h"
#include "nasl_packet_forgery.h"
#include "nasl_tree.h"
#include "nasl_var.h"
#include <gcrypt.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include <gvm/base/logging.h>
#define INTBLOB_LEN 20
#define SIGBLOB_LEN (2 * INTBLOB_LEN)
#define MAX_CIPHER_ID 32
#undef G_LOG_DOMAIN
/**
* @brief GLib logging domain.
*/
#define G_LOG_DOMAIN "lib nasl"
/**
* @brief List of open cipher handler.
*/
static GList *cipher_table = NULL;
/**
* @brief Struct holding a cipher handler.
*/
struct cipher_table_item
{
gcry_cipher_hd_t hd;
int id;
};
/* Type definitions */
typedef struct cipher_table_item cipher_table_item_t;
/**
* @brief Prints a GnuTLS error.
*
* The parameter err should be the GnuTLS error code
*/
void
print_tls_error (lex_ctxt *lexic, char *txt, int err)
{
nasl_perror (lexic, "%s: %s (%d)\n", txt, gnutls_strerror (err), err);
}
/**
* @brief Prints a libgcrypt error.
*
* The parameter err should be the libgcrypt error code
*/
void
print_gcrypt_error (lex_ctxt *lexic, char *function, int err)
{
nasl_perror (lexic, "%s failed: %s/%s\n", function, gcry_strsource (err),
gcry_strerror (err));
}
/**
* @brief Helper function to find cipher id in the table
*
* @return 0 if the cipher id exits/is in used. -1 otherwise.
*/
static int
find_cipher_hd (cipher_table_item_t *cipher_elem, int *id)
{
if (cipher_elem->id == *id)
return 0;
return -1;
}
/**
* @brief Helper function to get a free id for a new cipher.
*
* @return Id for the new cipher.
*/
static int
get_new_cipher_id (void)
{
int cipher_id;
for (cipher_id = 0; cipher_id < MAX_CIPHER_ID; cipher_id++)
{
if (g_list_find_custom (cipher_table, &cipher_id,
(GCompareFunc) find_cipher_hd)
== NULL)
return cipher_id;
}
return -1;
}
/**
* @brief Helper function to validate the cipher id.
*
* @param[in] cipher_id The cipher ID to validate.
* @return Handler on success, Null on error.
*/
static gcry_cipher_hd_t
verify_cipher_id (lex_ctxt *lexic, int cipher_id)
{
cipher_table_item_t *hd;
GList *hd_aux;
hd_aux = g_list_find_custom (cipher_table, &cipher_id,
(GCompareFunc) find_cipher_hd);
if (!hd_aux)
{
nasl_perror (lexic, "Cipher handle %d not found.\n", cipher_id);
return NULL;
}
hd = (cipher_table_item_t *) hd_aux->data;
return hd->hd;
}
/**
* @brief Create a new cipher handler item parameter.
*
* @return New cipher handler item.
*/
static cipher_table_item_t *
cipher_table_item_new (void)
{
return g_malloc0 (sizeof (cipher_table_item_t));
}
/**
* @brief Free and remove a cipher handler from the cipher table.
*
* @param[in] cipher_id ID of the cipher handler to free and remove.
* @return 0 on success, -1 on error.
*/
static void
delete_cipher_item (int cipher_id)
{
GList *hd_item;
cipher_table_item_t *hd;
hd_item = g_list_find_custom (cipher_table, &cipher_id,
(GCompareFunc) find_cipher_hd);
hd = (cipher_table_item_t *) hd_item->data;
gcry_cipher_close ((gcry_cipher_hd_t) hd->hd);
g_free (hd_item->data);
cipher_table = g_list_remove (cipher_table, hd_item->data);
}
/**
* @brief Converts a string to a gcry_mpi_t.
*
* The string of len bytes at data
* should contain the MPI as an unsigned int in bigendian form
* (libgcrypt's GCRYMPI_FMT_USG). The new MPI object is stored in dest.
* The parameters function and parameter are used in error messages to
* indicate the nasl function and nasl parameter name of the MPI. The
* lexic parameter is passed through to the error reporting functions.
*
* The function return 0 on success and -1 on failure.
*/
static int
mpi_from_string (lex_ctxt *lexic, gcry_mpi_t *dest, void *data, size_t len,
const char *parameter, const char *function)
{
gcry_error_t err;
unsigned char *buffer = data;
err = gcry_mpi_scan (dest, GCRYMPI_FMT_USG, buffer, len, NULL);
if (err)
{
nasl_perror (lexic, "%s(): gcry_mpi_scan failed for %s: %s/%s\n",
function, parameter, gcry_strsource (err),
gcry_strerror (err));
return -1;
}
return 0;
}
/**
* @brief Converts a named nasl parameter to a gcry_mpi_t.
*
* The new MPI object
* is stored in dest. The parameter parameter is the name of the
* parameter to be taken from lexic. The parameter function is used in
* error messages to indicate the name of the nasl function.
*
* @return 0 on success and -1 on failure.
*/
static int
mpi_from_named_parameter (lex_ctxt *lexic, gcry_mpi_t *dest,
const char *parameter, const char *function)
{
long size;
char *s;
s = get_str_var_by_name (lexic, parameter);
size = get_var_size_by_name (lexic, parameter);
if (!s)
return -1;
return mpi_from_string (lexic, dest, s, size, parameter, function);
}
/**
* @brief Sets the return value in retc from the MPI mpi.
*
* The MPI is converted to a byte string as an unsigned int in bigendian form
* (libgcrypts GCRYMPI_FMT_USG format).
*
* In an earlier implementation of this function, if first byte in the string
* had it's most significant bit set, i.e. if it would be considered negative
* when interpreted as two's-complement representation, a null-byte was
* prepended to make sure the number is always considered positive.
*
* However, this behavior caused problems during certain SSH operations because
* the buffer returned by this function would be one byte larger than expected.
* For now, the str_val of retc will always have the content and size returned
* by gcry_mpi_aprint ().
*
* @return 0 on success and -1 on failure.
*/
static int
set_mpi_retc (tree_cell *retc, gcry_mpi_t mpi)
{
unsigned char *buffer = NULL;
size_t size;
gcry_mpi_aprint (GCRYMPI_FMT_USG, &buffer, &size, mpi);
if (!buffer)
return -1;
retc->x.str_val = g_malloc0 (size);
memcpy (retc->x.str_val, buffer, size);
retc->size = size;
gcry_free (buffer);
return 0;
}
/**
* nasl function
*
* bn_cmp(key1:MPI1, key2:MPI2)
*
* Compares the MPIs key1 and key2 (given as binary strings). Returns
* -1 if key1 < key2, 0 if key1 == key2 and +1 if key1 > key2.
*/
tree_cell *
nasl_bn_cmp (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t key1 = NULL, key2 = NULL;
retc = g_malloc0 (sizeof (tree_cell));
retc->ref_count = 1;
retc->type = CONST_INT;
retc->x.i_val = 1;
if (mpi_from_named_parameter (lexic, &key1, "key1", "nasl_bn_cmp") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &key2, "key2", "nasl_bn_cmp") < 0)
goto fail;
retc->x.i_val = gcry_mpi_cmp (key1, key2);
/* make sure the return value is one of -1, 0, +1 */
if (retc->x.i_val > 0)
retc->x.i_val = 1;
if (retc->x.i_val < 0)
retc->x.i_val = -1;
fail:
gcry_mpi_release (key1);
gcry_mpi_release (key2);
return retc;
}
/**
* nasl function
*
* bn_random(need:numBits)
*
* @return An MPI as a string with need bits of random data.
*/
tree_cell *
nasl_bn_random (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t key = NULL;
long need;
retc = alloc_typed_cell (CONST_DATA);
/* number of random bits */
need = get_int_var_by_name (lexic, "need", 0);
key = gcry_mpi_new (0);
if (!key)
goto fail;
gcry_mpi_randomize (key, need, GCRY_STRONG_RANDOM);
if (set_mpi_retc (retc, key) >= 0)
goto ret;
fail:
retc->size = 0;
retc->x.str_val = g_malloc0 (1);
ret:
gcry_mpi_release (key);
return retc;
}
/**
* @brief Loads a private key from a string.
*
* The string is taken from the nasl
* parameter whose name is given by priv_name. The passphrase_name is
* the name of the parameter holding the passphrase if any. The string
* with the key must be in PEM format.
*
* @return The GnuTLS private key object on success, NULL on failure.
*/
static gnutls_x509_privkey_t
nasl_load_privkey_param (lex_ctxt *lexic, const char *priv_name,
const char *passphrase_name)
{
char *priv = NULL, *passphrase = NULL;
long privlen;
gnutls_x509_privkey_t privkey = NULL;
gnutls_datum_t pem;
int err;
/* PEM encoded privkey */
priv = get_str_var_by_name (lexic, priv_name);
privlen = get_var_size_by_name (lexic, priv_name);
/* passphrase */
passphrase = get_str_var_by_name (lexic, passphrase_name);
pem.data = (unsigned char *) priv;
pem.size = privlen;
err = gnutls_x509_privkey_init (&privkey);
if (err)
{
print_tls_error (lexic, "gnutls_x509_privkey_init", err);
goto fail;
}
if (passphrase && !*passphrase)
passphrase = NULL;
err =
gnutls_x509_privkey_import2 (privkey, &pem, GNUTLS_X509_FMT_PEM, passphrase,
passphrase ? 0 : GNUTLS_PKCS_PLAIN);
if (err)
{
print_tls_error (lexic, "gnutls_x509_privkey_import_pkcs8", err);
goto fail;
}
return privkey;
fail:
gnutls_x509_privkey_deinit (privkey);
return NULL;
}
/**
* @brief Implements the nasl functions pem_to_rsa and pem_to_dsa.
*/
tree_cell *
nasl_pem_to (lex_ctxt *lexic, int type)
{
tree_cell *retc = NULL;
gnutls_x509_privkey_t privkey = NULL;
gcry_mpi_t key = NULL;
int err;
retc = alloc_typed_cell (CONST_DATA);
privkey = nasl_load_privkey_param (lexic, "priv", "passphrase");
if (!privkey)
goto fail;
if (!type)
{
gnutls_datum_t m, e, d, p, q, u;
err =
gnutls_x509_privkey_export_rsa_raw (privkey, &m, &e, &d, &p, &q, &u);
if (err)
{
print_tls_error (lexic, "gnutls_x509_privkey_export_rsa_raw", err);
goto fail;
}
err =
mpi_from_string (lexic, &key, d.data, d.size, "rsa d", "nasl_pem_to");
gnutls_free (m.data);
gnutls_free (e.data);
gnutls_free (d.data);
gnutls_free (p.data);
gnutls_free (q.data);
gnutls_free (u.data);
if (err < 0)
goto fail;
}
else
{
gnutls_datum_t p, q, g, y, x;
err = gnutls_x509_privkey_export_dsa_raw (privkey, &p, &q, &g, &y, &x);
if (err)
{
print_tls_error (lexic, "gnutls_x509_privkey_export_dsa_raw", err);
goto fail;
}
err =
mpi_from_string (lexic, &key, x.data, x.size, "dsa x", "nasl_pem_to");
gnutls_free (p.data);
gnutls_free (q.data);
gnutls_free (g.data);
gnutls_free (y.data);
gnutls_free (x.data);
if (err < 0)
goto fail;
}
if (set_mpi_retc (retc, key) >= 0)
goto ret;
fail:
retc->size = 0;
retc->x.str_val = g_malloc0 (1);
ret:
gcry_mpi_release (key);
gnutls_x509_privkey_deinit (privkey);
return retc;
}
/**
* nasl function
*
* pem_to_rsa(priv:PEM, passphrase:PASSPHRASE)
*
* Reads the private key from the string priv which contains a private
* RSA key in PEM format. Passphrase is the passphrase needed to
* decrypt the private key. The function returns the parameter "d" of
* the RSA key as an MPI.
*/
tree_cell *
nasl_pem_to_rsa (lex_ctxt *lexic)
{
return nasl_pem_to (lexic, 0);
}
/**
* nasl function
*
* pem_to_dsa(priv:PEM, passphrase:PASSPHRASE)
*
* Reads the private key from the string priv which contains a private
* DSA key in PEM format. Passphrase is the passphrase needed to
* decrypt the private key. The function returns the parameter "x" of
* the DSA key as an MPI.
*/
tree_cell *
nasl_pem_to_dsa (lex_ctxt *lexic)
{
return nasl_pem_to (lexic, 1);
}
/**
* @brief compute the diffie hellman public key.
*
* Neither GnuTLS nor Libgcrypt
* contain a direct counterpart to OpenSSL's DH_generate_key, so we
* implement it ourselves. This function was copied from from gnutls
* and adapted to use gcrypt directly and to use a private key given as
* parameter to the function.
*
* @return The key on success and NULL on failure.
*/
static gcry_mpi_t
calc_dh_public (gcry_mpi_t g, gcry_mpi_t prime, gcry_mpi_t priv)
{
gcry_mpi_t e;
e = gcry_mpi_new (gcry_mpi_get_nbits (prime));
if (e == NULL)
{
return NULL;
}
gcry_mpi_powm (e, g, priv, prime);
return e;
}
/**
* @brief Compute the diffie hellman shared secret key.
*
* Neither GnuTLS nor
* libgcrypt contain a direct counterpart to OpenSSL's DH_compute_key,
* so we implement it ourselves. This function was copied from from
* gnutls and adapted to use gcrypt directly and to use a private key
* given as parameter to the function.
*
* @return The key on success and NULL on failure.
*/
static gcry_mpi_t
calc_dh_key (gcry_mpi_t pub, gcry_mpi_t prime, gcry_mpi_t priv)
{
gcry_mpi_t e;
e = gcry_mpi_new (gcry_mpi_get_nbits (prime));
if (e == NULL)
{
return NULL;
}
gcry_mpi_powm (e, pub, priv, prime);
return e;
}
/**
* nasl function
*
* dh_generate_key(p:mpi_p, g:mpi_g, priv:mpi_priv)
*
* Generates a Diffie-Hellman public key from the shared parameters p
* and g and the private parameter priv. The return value is the public
* key as an MPI.
*/
tree_cell *
nasl_dh_generate_key (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t p = NULL, g = NULL, priv = NULL, pub_mpi = NULL;
retc = alloc_typed_cell (CONST_DATA);
if (mpi_from_named_parameter (lexic, &p, "p", "nasl_dh_generate_key") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &g, "g", "nasl_dh_generate_key") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &priv, "priv", "nasl_dh_generate_key")
< 0)
goto fail;
pub_mpi = calc_dh_public (g, p, priv);
if (pub_mpi == NULL)
goto fail;
if (set_mpi_retc (retc, pub_mpi) >= 0)
goto ret;
fail:
retc->x.str_val = g_malloc0 (1);
retc->size = 0;
ret:
gcry_mpi_release (p);
gcry_mpi_release (g);
gcry_mpi_release (priv);
gcry_mpi_release (pub_mpi);
return retc;
}
/**
* nasl function
*
* dh_compute_key(p:mpi_p, g:mpi_g, dh_server_pub:mpi_server_pub,
* pub_key:mpi_client_pub, priv_key:mpi_client_priv)
*
* Computes the Diffie-Hellman shared secret key from the shared
* parameters p and g, the server's public key dh_server_pub and the
* client's public and private keys pub_key an priv_key. The return
* value is the shared secret key as an MPI.
*/
tree_cell *
nasl_dh_compute_key (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t p = NULL, g = NULL, dh_server_pub = NULL;
gcry_mpi_t pub_key = NULL, priv_key = NULL;
gcry_mpi_t shared = NULL;
retc = alloc_typed_cell (CONST_DATA);
if (mpi_from_named_parameter (lexic, &p, "p", "nasl_dh_compute_key") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &g, "g", "nasl_dh_compute_key") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &dh_server_pub, "dh_server_pub",
"nasl_dh_compute_key")
< 0)
goto fail;
if (mpi_from_named_parameter (lexic, &pub_key, "pub_key",
"nasl_dh_compute_key")
< 0)
goto fail;
if (mpi_from_named_parameter (lexic, &priv_key, "priv_key",
"nasl_dh_compute_key")
< 0)
goto fail;
shared = calc_dh_key (dh_server_pub, p, priv_key);
if (set_mpi_retc (retc, shared) >= 0)
goto ret;
fail:
retc->size = 0;
retc->x.str_val = g_malloc0 (1);
ret:
gcry_mpi_release (p);
gcry_mpi_release (g);
gcry_mpi_release (dh_server_pub);
gcry_mpi_release (priv_key);
gcry_mpi_release (pub_key);
gcry_mpi_release (shared);
return retc;
}
/**
* @brief Extracts an MPI value from a libgcryt s-expression.
*
* The return value
* is the cadr of the subexpression whose car is given by token. The
* function returns NULL if the token doesn't occur in the expression or
* on other errors.
*/
static gcry_mpi_t
extract_mpi_from_sexp (gcry_sexp_t sexp, const char *token)
{
gcry_sexp_t child = NULL;
gcry_mpi_t mpi = NULL;
child = gcry_sexp_find_token (sexp, token, strlen (token));
if (!child)
{
g_message ("set_retc_from_sexp: no subexpression with token <%s>", token);
}
else
{
mpi = gcry_sexp_nth_mpi (child, 1, GCRYMPI_FMT_USG);
}
gcry_sexp_release (child);
return mpi;
}
/**
* @brief Sets the return value in retc from an sexpression.
*
* The function uses
* extract_mpi_from_sexp to extract an MPI from the sexpression sexp and
* the subexpression given by token.
* The function return 1 on success
* and 0 on failure.
*/
static int
set_retc_from_sexp (tree_cell *retc, gcry_sexp_t sexp, const char *token)
{
int ret = 0;
gcry_mpi_t mpi = extract_mpi_from_sexp (sexp, token);
if (mpi)
{
ret = set_mpi_retc (retc, mpi);
gcry_mpi_release (mpi);
}
return ret;
}
/**
* @brief Strips PKCS#1 padding from the string in retc.
*/
static int
strip_pkcs1_padding (tree_cell *retc)
{
char *p;
if (retc->x.str_val == NULL || retc->size < 1)
return -1;
/* Find type of padding. PKCS#1 padding normally starts with a 0 byte.
* However, due to the way the value in retc has been created, any
* leading zeros have already been stripped. So the byte that
* describes the type of padding is the first byte in str_val. Also,
* the only padding types we can actually find are 1 and 2. padding
* type 0 means that the padding is done with zeros and those will
* have been already stripped too. */
p = retc->x.str_val;
if (p[0] == 1 || p[0] == 2)
{
/* for padding type 1 and 2 we simply have to strip all non-zero
* bytes at the beginning of the value */
int i = 0;
char *temp;
while (i < retc->size && p[i])
i++;
/* skip the zero byte */
i++;
if (i <= retc->size)
{
int rest = retc->size - i;
temp = g_malloc0 (rest);
memcpy (temp, p + i, rest);
g_free (retc->x.str_val);
retc->x.str_val = temp;
retc->size = rest;
}
else
return -1;
}
return 0;
}
/**
* nasl function
*
* rsa_public_encrypt(data:data, e:mpi_e, n:mpi_n, pad:<TRUE:FALSE>)
*
* Encrypt the provided data with the public RSA key given by its parameters e
* and n. The return value is the encrypted data.
*/
tree_cell *
nasl_rsa_public_encrypt (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t e = NULL, n = NULL, dt = NULL;
gcry_sexp_t key = NULL, data = NULL, encrypted = NULL;
gcry_error_t err;
int type = get_var_type_by_name (lexic, "pad");
int pad = 0;
if (type == VAR2_INT)
pad = get_int_var_by_name (lexic, "pad", 0);
/** TODO: In future releases, string support for padding should be removed */
else if (type == VAR2_STRING)
{
if (!strcmp (get_str_var_by_name (lexic, "pad"), "TRUE"))
pad = 1;
}
else
{
nasl_perror (lexic, "Syntax : rsa_public_encrypt(data:<d>,"
"n:<n>, e:<e>, pad:<TRUE:FALSE>)");
return NULL;
}
retc = alloc_typed_cell (CONST_DATA);
if (mpi_from_named_parameter (lexic, &dt, "data", "nasl_rsa_public_encrypt")
< 0)
goto fail;
if (mpi_from_named_parameter (lexic, &e, "e", "nasl_rsa_public_encrypt") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &n, "n", "nasl_rsa_public_encrypt") < 0)
goto fail;
err = gcry_sexp_build (&key, NULL, "(public-key (rsa (n %m) (e %m)))", n, e);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build pubkey", err);
goto fail;
}
if (pad == 1)
err = gcry_sexp_build (&data, NULL, "(data (flags pkcs1) (value %m))", dt);
else
err = gcry_sexp_build (&data, NULL, "(data (flags raw) (value %m))", dt);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build data", err);
goto fail;
}
err = gcry_pk_encrypt (&encrypted, data, key);
if (err)
{
print_gcrypt_error (lexic, "gcry_pk_encrypt", err);
goto fail;
}
if (pad == 1)
{
if (set_retc_from_sexp (retc, encrypted, "a") >= 0
&& strip_pkcs1_padding (retc) >= 0)
goto ret;
}
else
{
if (set_retc_from_sexp (retc, encrypted, "a") >= 0)
goto ret;
}
fail:
retc->size = 0;
retc->x.str_val = g_malloc0 (1);
ret:
gcry_sexp_release (encrypted);
gcry_sexp_release (key);
gcry_sexp_release (data);
gcry_mpi_release (dt);
gcry_mpi_release (e);
gcry_mpi_release (n);
return retc;
}
/**
* nasl function
*
* rsa_private_decrypt(data:data, d:mpi_d, e:mpi_e, n:mpi_n, pad:<TRUE:FALSE>)
*
* Decrypt the provided data with the private RSA key given by its parameters
* d, e and n. The return value is the decrypted data in plaintext format.
*/
tree_cell *
nasl_rsa_private_decrypt (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t e = NULL, n = NULL, d = NULL, dt = NULL;
gcry_sexp_t key = NULL, data = NULL, decrypted = NULL;
gcry_error_t err;
int type = get_var_type_by_name (lexic, "pad");
int pad = 0;
if (type == VAR2_INT)
pad = get_int_var_by_name (lexic, "pad", 0);
/** TODO: In future releases, string support for padding should be removed */
else if (type == VAR2_STRING)
{
if (!strcmp (get_str_var_by_name (lexic, "pad"), "TRUE"))
pad = 1;
}
else
{
nasl_perror (lexic, "Syntax : rsa_public_encrypt(data:<d>,"
"n:<n>, e:<e>, pad:<TRUE:FALSE>)");
return NULL;
}
retc = alloc_typed_cell (CONST_DATA);
if (mpi_from_named_parameter (lexic, &dt, "data", "nasl_rsa_private_decrypt")
< 0)
goto fail;
if (mpi_from_named_parameter (lexic, &e, "e", "nasl_rsa_private_decrypt") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &n, "n", "nasl_rsa_private_decrypt") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &d, "d", "nasl_rsa_private_decrypt") < 0)
goto fail;
err = gcry_sexp_build (&key, NULL, "(private-key (rsa (n %m) (e %m) (d %m)))",
n, e, d);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build privkey", err);
goto fail;
}
if (pad == 1)
err =
gcry_sexp_build (&data, NULL, "(enc-val (flags pkcs1) (rsa (a %m)))", dt);
else
err =
gcry_sexp_build (&data, NULL, "(enc-val (flags raw) (rsa (a %m)))", dt);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build data", err);
goto fail;
}
err = gcry_pk_decrypt (&decrypted, data, key);
if (err)
{
print_gcrypt_error (lexic, "gcry_pk_decrypt", err);
goto fail;
}
if (pad == 1)
{
if (set_retc_from_sexp (retc, decrypted, "value") >= 0
&& strip_pkcs1_padding (retc) >= 0)
goto ret;
}
else
{
if (set_retc_from_sexp (retc, decrypted, "value") >= 0)
goto ret;
}
fail:
retc->size = 0;
retc->x.str_val = g_malloc0 (1);
ret:
gcry_sexp_release (decrypted);
gcry_sexp_release (key);
gcry_sexp_release (data);
gcry_mpi_release (dt);
gcry_mpi_release (e);
gcry_mpi_release (n);
gcry_mpi_release (d);
return retc;
}
/**
* nasl function
*
* rsa_public_decrypt(sig:signature, e:mpi_e, n:mpi_n)
*
* Decrypt the data in signature (usually an rsa-encrypted hash) with
* the public RSA key given by its parameters e and n. The return value
* is the decrypted data.
*/
tree_cell *
nasl_rsa_public_decrypt (lex_ctxt *lexic)
{
tree_cell *retc = NULL;
gcry_mpi_t e = NULL, n = NULL, s = NULL;
gcry_sexp_t key = NULL, sig = NULL, decrypted = NULL;
gcry_error_t err;
retc = alloc_typed_cell (CONST_DATA);
if (mpi_from_named_parameter (lexic, &s, "sig", "nasl_rsa_public_decrypt")
< 0)
goto fail;
if (mpi_from_named_parameter (lexic, &e, "e", "nasl_rsa_public_decrypt") < 0)
goto fail;
if (mpi_from_named_parameter (lexic, &n, "n", "nasl_rsa_public_decrypt") < 0)
goto fail;
err = gcry_sexp_build (&key, NULL, "(public-key (rsa (n %m) (e %m)))", n, e);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build pubkey", err);
goto fail;
}
err = gcry_sexp_build (&sig, NULL, "(data (flags raw) (value %m))", s);
if (err)
{
print_gcrypt_error (lexic, "gcry_sexp_build sig", err);
goto fail;
}
/* gcry_pk_encrypt is equivalent to the public key decryption at least
* for RSA keys. */
err = gcry_pk_encrypt (&decrypted, sig, key);
if (err)
{
print_gcrypt_error (lexic, "gcry_pk_encrypt", err);
goto fail;
}
if (set_retc_from_sexp (retc, decrypted, "a") >= 0