Permalink
Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
2703 lines (2419 sloc) 79.4 KB
/*
* Code for PuTTY to import and export private key files in other
* SSH clients' formats.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <ctype.h>
#include "putty.h"
#include "ssh.h"
#include "misc.h"
int openssh_pem_encrypted(const Filename *filename);
int openssh_new_encrypted(const Filename *filename);
struct ssh2_userkey *openssh_pem_read(const Filename *filename,
char *passphrase,
const char **errmsg_p);
struct ssh2_userkey *openssh_new_read(const Filename *filename,
char *passphrase,
const char **errmsg_p);
int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase);
int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase);
int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase);
int sshcom_encrypted(const Filename *filename, char **comment);
struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
const char **errmsg_p);
int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase);
/*
* Given a key type, determine whether we know how to import it.
*/
int import_possible(int type)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM)
return 1;
if (type == SSH_KEYTYPE_OPENSSH_NEW)
return 1;
if (type == SSH_KEYTYPE_SSHCOM)
return 1;
return 0;
}
/*
* Given a key type, determine what native key type
* (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
* we've imported it.
*/
int import_target_type(int type)
{
/*
* There are no known foreign SSH-1 key formats.
*/
return SSH_KEYTYPE_SSH2;
}
/*
* Determine whether a foreign key is encrypted.
*/
int import_encrypted(const Filename *filename, int type, char **comment)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM) {
/* OpenSSH PEM format doesn't contain a key comment at all */
*comment = dupstr(filename_to_str(filename));
return openssh_pem_encrypted(filename);
} else if (type == SSH_KEYTYPE_OPENSSH_NEW) {
/* OpenSSH new format does, but it's inside the encrypted
* section for some reason */
*comment = dupstr(filename_to_str(filename));
return openssh_new_encrypted(filename);
} else if (type == SSH_KEYTYPE_SSHCOM) {
return sshcom_encrypted(filename, comment);
}
return 0;
}
/*
* Import an SSH-1 key.
*/
int import_ssh1(const Filename *filename, int type,
struct RSAKey *key, char *passphrase, const char **errmsg_p)
{
return 0;
}
/*
* Import an SSH-2 key.
*/
struct ssh2_userkey *import_ssh2(const Filename *filename, int type,
char *passphrase, const char **errmsg_p)
{
if (type == SSH_KEYTYPE_OPENSSH_PEM)
return openssh_pem_read(filename, passphrase, errmsg_p);
else if (type == SSH_KEYTYPE_OPENSSH_NEW)
return openssh_new_read(filename, passphrase, errmsg_p);
if (type == SSH_KEYTYPE_SSHCOM)
return sshcom_read(filename, passphrase, errmsg_p);
return NULL;
}
/*
* Export an SSH-1 key.
*/
int export_ssh1(const Filename *filename, int type, struct RSAKey *key,
char *passphrase)
{
return 0;
}
/*
* Export an SSH-2 key.
*/
int export_ssh2(const Filename *filename, int type,
struct ssh2_userkey *key, char *passphrase)
{
if (type == SSH_KEYTYPE_OPENSSH_AUTO)
return openssh_auto_write(filename, key, passphrase);
if (type == SSH_KEYTYPE_OPENSSH_NEW)
return openssh_new_write(filename, key, passphrase);
if (type == SSH_KEYTYPE_SSHCOM)
return sshcom_write(filename, key, passphrase);
return 0;
}
/*
* Strip trailing CRs and LFs at the end of a line of text.
*/
void strip_crlf(char *str)
{
char *p = str + strlen(str);
while (p > str && (p[-1] == '\r' || p[-1] == '\n'))
*--p = '\0';
}
/* ----------------------------------------------------------------------
* Helper routines. (The base64 ones are defined in sshpubk.c.)
*/
#define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
((c) >= 'a' && (c) <= 'z') || \
((c) >= '0' && (c) <= '9') || \
(c) == '+' || (c) == '/' || (c) == '=' \
)
/*
* Read an ASN.1/BER identifier and length pair.
*
* Flags are a combination of the #defines listed below.
*
* Returns -1 if unsuccessful; otherwise returns the number of
* bytes used out of the source data.
*/
/* ASN.1 tag classes. */
#define ASN1_CLASS_UNIVERSAL (0 << 6)
#define ASN1_CLASS_APPLICATION (1 << 6)
#define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
#define ASN1_CLASS_PRIVATE (3 << 6)
#define ASN1_CLASS_MASK (3 << 6)
/* Primitive versus constructed bit. */
#define ASN1_CONSTRUCTED (1 << 5)
static int ber_read_id_len(void *source, int sourcelen,
int *id, int *length, int *flags)
{
unsigned char *p = (unsigned char *) source;
if (sourcelen == 0)
return -1;
*flags = (*p & 0xE0);
if ((*p & 0x1F) == 0x1F) {
*id = 0;
while (*p & 0x80) {
p++, sourcelen--;
if (sourcelen == 0)
return -1;
*id = (*id << 7) | (*p & 0x7F);
}
p++, sourcelen--;
} else {
*id = *p & 0x1F;
p++, sourcelen--;
}
if (sourcelen == 0)
return -1;
if (*p & 0x80) {
unsigned len;
int n = *p & 0x7F;
p++, sourcelen--;
if (sourcelen < n)
return -1;
len = 0;
while (n--)
len = (len << 8) | (*p++);
sourcelen -= n;
*length = toint(len);
} else {
*length = *p;
p++, sourcelen--;
}
return p - (unsigned char *) source;
}
/*
* Write an ASN.1/BER identifier and length pair. Returns the
* number of bytes consumed. Assumes dest contains enough space.
* Will avoid writing anything if dest is NULL, but still return
* amount of space required.
*/
static int ber_write_id_len(void *dest, int id, int length, int flags)
{
unsigned char *d = (unsigned char *)dest;
int len = 0;
if (id <= 30) {
/*
* Identifier is one byte.
*/
len++;
if (d) *d++ = id | flags;
} else {
int n;
/*
* Identifier is multiple bytes: the first byte is 11111
* plus the flags, and subsequent bytes encode the value of
* the identifier, 7 bits at a time, with the top bit of
* each byte 1 except the last one which is 0.
*/
len++;
if (d) *d++ = 0x1F | flags;
for (n = 1; (id >> (7*n)) > 0; n++)
continue; /* count the bytes */
while (n--) {
len++;
if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
}
}
if (length < 128) {
/*
* Length is one byte.
*/
len++;
if (d) *d++ = length;
} else {
int n;
/*
* Length is multiple bytes. The first is 0x80 plus the
* number of subsequent bytes, and the subsequent bytes
* encode the actual length.
*/
for (n = 1; (length >> (8*n)) > 0; n++)
continue; /* count the bytes */
len++;
if (d) *d++ = 0x80 | n;
while (n--) {
len++;
if (d) *d++ = (length >> (8*n)) & 0xFF;
}
}
return len;
}
static int put_uint32(void *target, unsigned val)
{
unsigned char *d = (unsigned char *)target;
PUT_32BIT(d, val);
return 4;
}
static int put_string(void *target, const void *data, int len)
{
unsigned char *d = (unsigned char *)target;
PUT_32BIT(d, len);
memcpy(d+4, data, len);
return len+4;
}
static int put_string_z(void *target, const char *string)
{
return put_string(target, string, strlen(string));
}
static int put_mp(void *target, void *data, int len)
{
unsigned char *d = (unsigned char *)target;
unsigned char *i = (unsigned char *)data;
if (*i & 0x80) {
PUT_32BIT(d, len+1);
d[4] = 0;
memcpy(d+5, data, len);
return len+5;
} else {
PUT_32BIT(d, len);
memcpy(d+4, data, len);
return len+4;
}
}
/* Simple structure to point to an mp-int within a blob. */
struct mpint_pos { void *start; int bytes; };
static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
{
int bytes;
unsigned char *d = (unsigned char *) data;
if (len < 4)
goto error;
bytes = toint(GET_32BIT(d));
if (bytes < 0 || len-4 < bytes)
goto error;
ret->start = d + 4;
ret->bytes = bytes;
return bytes+4;
error:
ret->start = NULL;
ret->bytes = -1;
return len; /* ensure further calls fail as well */
}
/* ----------------------------------------------------------------------
* Code to read and write OpenSSH private keys, in the old-style PEM
* format.
*/
typedef enum {
OP_DSA, OP_RSA, OP_ECDSA
} openssh_pem_keytype;
typedef enum {
OP_E_3DES, OP_E_AES
} openssh_pem_enc;
struct openssh_pem_key {
openssh_pem_keytype keytype;
int encrypted;
openssh_pem_enc encryption;
char iv[32];
unsigned char *keyblob;
int keyblob_len, keyblob_size;
};
static struct openssh_pem_key *load_openssh_pem_key(const Filename *filename,
const char **errmsg_p)
{
struct openssh_pem_key *ret;
FILE *fp = NULL;
char *line = NULL;
const char *errmsg;
char *p;
int headers_done;
char base64_bit[4];
int base64_chars = 0;
ret = snew(struct openssh_pem_key);
ret->keyblob = NULL;
ret->keyblob_len = ret->keyblob_size = 0;
fp = f_open(filename, "r", FALSE);
if (!fp) {
errmsg = "unable to open key file";
goto error;
}
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (!strstartswith(line, "-----BEGIN ") ||
!strendswith(line, "PRIVATE KEY-----")) {
errmsg = "file does not begin with OpenSSH key header";
goto error;
}
/*
* Parse the BEGIN line. For old-format keys, this tells us the
* type of the key; for new-format keys, all it tells us is the
* format, and we'll find out the key type once we parse the
* base64.
*/
if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) {
ret->keytype = OP_RSA;
} else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) {
ret->keytype = OP_DSA;
} else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----")) {
ret->keytype = OP_ECDSA;
} else if (!strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
errmsg = "this is a new-style OpenSSH key";
goto error;
} else {
errmsg = "unrecognised key type";
goto error;
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
ret->encrypted = FALSE;
memset(ret->iv, 0, sizeof(ret->iv));
headers_done = 0;
while (1) {
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (strstartswith(line, "-----END ") &&
strendswith(line, "PRIVATE KEY-----")) {
sfree(line);
line = NULL;
break; /* done */
}
if ((p = strchr(line, ':')) != NULL) {
if (headers_done) {
errmsg = "header found in body of key data";
goto error;
}
*p++ = '\0';
while (*p && isspace((unsigned char)*p)) p++;
if (!strcmp(line, "Proc-Type")) {
if (p[0] != '4' || p[1] != ',') {
errmsg = "Proc-Type is not 4 (only 4 is supported)";
goto error;
}
p += 2;
if (!strcmp(p, "ENCRYPTED"))
ret->encrypted = TRUE;
} else if (!strcmp(line, "DEK-Info")) {
int i, ivlen;
if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
ret->encryption = OP_E_3DES;
ivlen = 8;
} else if (!strncmp(p, "AES-128-CBC,", 12)) {
ret->encryption = OP_E_AES;
ivlen = 16;
} else {
errmsg = "unsupported cipher";
goto error;
}
p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
for (i = 0; i < ivlen; i++) {
unsigned j;
if (1 != sscanf(p, "%2x", &j)) {
errmsg = "expected more iv data in DEK-Info";
goto error;
}
ret->iv[i] = j;
p += 2;
}
if (*p) {
errmsg = "more iv data than expected in DEK-Info";
goto error;
}
}
} else {
headers_done = 1;
p = line;
while (isbase64(*p)) {
base64_bit[base64_chars++] = *p;
if (base64_chars == 4) {
unsigned char out[3];
int len;
base64_chars = 0;
len = base64_decode_atom(base64_bit, out);
if (len <= 0) {
errmsg = "invalid base64 encoding";
goto error;
}
if (ret->keyblob_len + len > ret->keyblob_size) {
ret->keyblob_size = ret->keyblob_len + len + 256;
ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
unsigned char);
}
memcpy(ret->keyblob + ret->keyblob_len, out, len);
ret->keyblob_len += len;
smemclr(out, sizeof(out));
}
p++;
}
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
fclose(fp);
fp = NULL;
if (ret->keyblob_len == 0 || !ret->keyblob) {
errmsg = "key body not present";
goto error;
}
if (ret->encrypted && ret->keyblob_len % 8 != 0) {
errmsg = "encrypted key blob is not a multiple of "
"cipher block size";
goto error;
}
smemclr(base64_bit, sizeof(base64_bit));
if (errmsg_p) *errmsg_p = NULL;
return ret;
error:
if (line) {
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
smemclr(base64_bit, sizeof(base64_bit));
if (ret) {
if (ret->keyblob) {
smemclr(ret->keyblob, ret->keyblob_size);
sfree(ret->keyblob);
}
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
if (fp) fclose(fp);
return NULL;
}
int openssh_pem_encrypted(const Filename *filename)
{
struct openssh_pem_key *key = load_openssh_pem_key(filename, NULL);
int ret;
if (!key)
return 0;
ret = key->encrypted;
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
return ret;
}
struct ssh2_userkey *openssh_pem_read(const Filename *filename,
char *passphrase,
const char **errmsg_p)
{
struct openssh_pem_key *key = load_openssh_pem_key(filename, errmsg_p);
struct ssh2_userkey *retkey;
unsigned char *p, *q;
int ret, id, len, flags;
int i, num_integers;
struct ssh2_userkey *retval = NULL;
const char *errmsg;
unsigned char *blob;
int blobsize = 0, blobptr, privptr;
char *modptr = NULL;
int modlen = 0;
blob = NULL;
if (!key)
return NULL;
if (key->encrypted) {
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*
* (Note that only 8 bytes of the iv are used for key
* derivation, even when the key is encrypted with AES and
* hence there are 16 bytes available.)
*/
struct MD5Context md5c;
unsigned char keybuf[32];
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, (unsigned char *)key->iv, 8);
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
MD5Update(&md5c, keybuf, 16);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, (unsigned char *)key->iv, 8);
MD5Final(keybuf+16, &md5c);
/*
* Now decrypt the key blob.
*/
if (key->encryption == OP_E_3DES)
des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
key->keyblob, key->keyblob_len);
else {
void *ctx;
assert(key->encryption == OP_E_AES);
ctx = aes_make_context();
aes128_key(ctx, keybuf);
aes_iv(ctx, (unsigned char *)key->iv);
aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len);
aes_free_context(ctx);
}
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
/*
* Now we have a decrypted key blob, which contains an ASN.1
* encoded private key. We must now untangle the ASN.1.
*
* We expect the whole key blob to be formatted as a SEQUENCE
* (0x30 followed by a length code indicating that the rest of
* the blob is part of the sequence). Within that SEQUENCE we
* expect to see a bunch of INTEGERs. What those integers mean
* depends on the key type:
*
* - For RSA, we expect the integers to be 0, n, e, d, p, q,
* dmp1, dmq1, iqmp in that order. (The last three are d mod
* (p-1), d mod (q-1), inverse of q mod p respectively.)
*
* - For DSA, we expect them to be 0, p, q, g, y, x in that
* order.
*
* - In ECDSA the format is totally different: we see the
* SEQUENCE, but beneath is an INTEGER 1, OCTET STRING priv
* EXPLICIT [0] OID curve, EXPLICIT [1] BIT STRING pubPoint
*/
p = key->keyblob;
/* Expect the SEQUENCE header. Take its absence as a failure to
* decrypt, if the key was encrypted. */
ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
p += ret;
if (ret < 0 || id != 16 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
/* Expect a load of INTEGERs. */
if (key->keytype == OP_RSA)
num_integers = 9;
else if (key->keytype == OP_DSA)
num_integers = 6;
else
num_integers = 0; /* placate compiler warnings */
if (key->keytype == OP_ECDSA) {
/* And now for something completely different */
unsigned char *priv;
int privlen;
const struct ssh_signkey *alg;
const struct ec_curve *curve;
int algnamelen, curvenamelen;
/* Read INTEGER 1 */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 2 || len != 1 ||
key->keyblob+key->keyblob_len-p < len || p[0] != 1) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
p += 1;
/* Read private key OCTET STRING */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 4 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
priv = p;
privlen = len;
p += len;
/* Read curve OID */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 0 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 6 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
alg = ec_alg_by_oid(len, p, &curve);
if (!alg) {
errmsg = "Unsupported ECDSA curve.";
retval = NULL;
goto error;
}
p += len;
/* Read BIT STRING point */
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 1 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 3 || len < 0 ||
key->keyblob+key->keyblob_len-p < len ||
len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
p += 1; len -= 1; /* Skip 0x00 before point */
/* Construct the key */
retkey = snew(struct ssh2_userkey);
if (!retkey) {
errmsg = "out of memory";
goto error;
}
retkey->alg = alg;
blob = snewn((4+19 + 4+8 + 4+len) + (4+1+privlen), unsigned char);
if (!blob) {
sfree(retkey);
errmsg = "out of memory";
goto error;
}
q = blob;
algnamelen = strlen(alg->name);
PUT_32BIT(q, algnamelen); q += 4;
memcpy(q, alg->name, algnamelen); q += algnamelen;
curvenamelen = strlen(curve->name);
PUT_32BIT(q, curvenamelen); q += 4;
memcpy(q, curve->name, curvenamelen); q += curvenamelen;
PUT_32BIT(q, len); q += 4;
memcpy(q, p, len); q += len;
/*
* To be acceptable to our createkey(), the private blob must
* contain a valid mpint, i.e. without the top bit set. But
* the input private string may have the top bit set, so we
* prefix a zero byte to ensure createkey() doesn't fail for
* that reason.
*/
PUT_32BIT(q, privlen+1);
q[4] = 0;
memcpy(q+5, priv, privlen);
retkey->data = retkey->alg->createkey(retkey->alg,
blob, q-blob,
q, 5+privlen);
if (!retkey->data) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
} else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
/*
* Space to create key blob in.
*/
blobsize = 256+key->keyblob_len;
blob = snewn(blobsize, unsigned char);
PUT_32BIT(blob, 7);
if (key->keytype == OP_DSA)
memcpy(blob+4, "ssh-dss", 7);
else if (key->keytype == OP_RSA)
memcpy(blob+4, "ssh-rsa", 7);
blobptr = 4+7;
privptr = -1;
for (i = 0; i < num_integers; i++) {
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 2 || len < 0 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
goto error;
}
if (i == 0) {
/*
* The first integer should be zero always (I think
* this is some sort of version indication).
*/
if (len != 1 || p[0] != 0) {
errmsg = "version number mismatch";
goto error;
}
} else if (key->keytype == OP_RSA) {
/*
* Integers 1 and 2 go into the public blob but in the
* opposite order; integers 3, 4, 5 and 8 go into the
* private blob. The other two (6 and 7) are ignored.
*/
if (i == 1) {
/* Save the details for after we deal with number 2. */
modptr = (char *)p;
modlen = len;
} else if (i != 6 && i != 7) {
PUT_32BIT(blob+blobptr, len);
memcpy(blob+blobptr+4, p, len);
blobptr += 4+len;
if (i == 2) {
PUT_32BIT(blob+blobptr, modlen);
memcpy(blob+blobptr+4, modptr, modlen);
blobptr += 4+modlen;
privptr = blobptr;
}
}
} else if (key->keytype == OP_DSA) {
/*
* Integers 1-4 go into the public blob; integer 5 goes
* into the private blob.
*/
PUT_32BIT(blob+blobptr, len);
memcpy(blob+blobptr+4, p, len);
blobptr += 4+len;
if (i == 4)
privptr = blobptr;
}
/* Skip past the number. */
p += len;
}
/*
* Now put together the actual key. Simplest way to do this is
* to assemble our own key blobs and feed them to the createkey
* functions; this is a bit faffy but it does mean we get all
* the sanity checks for free.
*/
assert(privptr > 0); /* should have bombed by now if not */
retkey = snew(struct ssh2_userkey);
retkey->alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dss);
retkey->data = retkey->alg->createkey(retkey->alg, blob, privptr,
blob+privptr,
blobptr-privptr);
if (!retkey->data) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
} else {
assert(0 && "Bad key type from load_openssh_pem_key");
errmsg = "Bad key type from load_openssh_pem_key";
goto error;
}
/*
* The old key format doesn't include a comment in the private
* key file.
*/
retkey->comment = dupstr("imported-openssh-key");
errmsg = NULL; /* no error */
retval = retkey;
error:
if (blob) {
smemclr(blob, blobsize);
sfree(blob);
}
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return retval;
}
int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase)
{
unsigned char *pubblob, *privblob, *spareblob;
int publen, privlen, sparelen = 0;
unsigned char *outblob;
int outlen;
struct mpint_pos numbers[9];
int nnumbers, pos, len, seqlen, i;
const char *header, *footer;
char zero[1];
unsigned char iv[8];
int ret = 0;
FILE *fp;
/*
* Fetch the key blobs.
*/
pubblob = key->alg->public_blob(key->data, &publen);
privblob = key->alg->private_blob(key->data, &privlen);
spareblob = outblob = NULL;
outblob = NULL;
len = 0;
/*
* Encode the OpenSSH key blob, and also decide on the header
* line.
*/
if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
/*
* The RSA and DSS handlers share some code because the two
* key types have very similar ASN.1 representations, as a
* plain SEQUENCE of big integers. So we set up a list of
* bignums per key type and then construct the actual blob in
* common code after that.
*/
if (key->alg == &ssh_rsa) {
int pos;
struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
Bignum bd, bp, bq, bdmp1, bdmq1;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
assert(e.start && iqmp.start); /* can't go wrong */
/* We also need d mod (p-1) and d mod (q-1). */
bd = bignum_from_bytes(d.start, d.bytes);
bp = bignum_from_bytes(p.start, p.bytes);
bq = bignum_from_bytes(q.start, q.bytes);
decbn(bp);
decbn(bq);
bdmp1 = bigmod(bd, bp);
bdmq1 = bigmod(bd, bq);
freebn(bd);
freebn(bp);
freebn(bq);
dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
sparelen = dmp1.bytes + dmq1.bytes;
spareblob = snewn(sparelen, unsigned char);
dmp1.start = spareblob;
dmq1.start = spareblob + dmp1.bytes;
for (i = 0; i < dmp1.bytes; i++)
spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
for (i = 0; i < dmq1.bytes; i++)
spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
freebn(bdmp1);
freebn(bdmq1);
numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
numbers[1] = n;
numbers[2] = e;
numbers[3] = d;
numbers[4] = p;
numbers[5] = q;
numbers[6] = dmp1;
numbers[7] = dmq1;
numbers[8] = iqmp;
nnumbers = 9;
header = "-----BEGIN RSA PRIVATE KEY-----\n";
footer = "-----END RSA PRIVATE KEY-----\n";
} else { /* ssh-dss */
int pos;
struct mpint_pos p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
assert(y.start && x.start); /* can't go wrong */
numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
numbers[1] = p;
numbers[2] = q;
numbers[3] = g;
numbers[4] = y;
numbers[5] = x;
nnumbers = 6;
header = "-----BEGIN DSA PRIVATE KEY-----\n";
footer = "-----END DSA PRIVATE KEY-----\n";
}
/*
* Now count up the total size of the ASN.1 encoded integers,
* so as to determine the length of the containing SEQUENCE.
*/
len = 0;
for (i = 0; i < nnumbers; i++) {
len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
len += numbers[i].bytes;
}
seqlen = len;
/* Now add on the SEQUENCE header. */
len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
/*
* Now we know how big outblob needs to be. Allocate it.
*/
outblob = snewn(len, unsigned char);
/*
* And write the data into it.
*/
pos = 0;
pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
for (i = 0; i < nnumbers; i++) {
pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
pos += numbers[i].bytes;
}
} else if (key->alg == &ssh_ecdsa_nistp256 ||
key->alg == &ssh_ecdsa_nistp384 ||
key->alg == &ssh_ecdsa_nistp521) {
const unsigned char *oid;
int oidlen;
int pointlen;
/*
* Structure of asn1:
* SEQUENCE
* INTEGER 1
* OCTET STRING (private key)
* [0]
* OID (curve)
* [1]
* BIT STRING (0x00 public key point)
*/
oid = ec_alg_oid(key->alg, &oidlen);
pointlen = (((struct ec_key *)key->data)->publicKey.curve->fieldBits
+ 7) / 8 * 2;
len = ber_write_id_len(NULL, 2, 1, 0);
len += 1;
len += ber_write_id_len(NULL, 4, privlen - 4, 0);
len+= privlen - 4;
len += ber_write_id_len(NULL, 0, oidlen +
ber_write_id_len(NULL, 6, oidlen, 0),
ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
len += ber_write_id_len(NULL, 6, oidlen, 0);
len += oidlen;
len += ber_write_id_len(NULL, 1, 2 + pointlen +
ber_write_id_len(NULL, 3, 2 + pointlen, 0),
ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
len += 2 + pointlen;
seqlen = len;
len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
outblob = snewn(len, unsigned char);
assert(outblob);
pos = 0;
pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
pos += ber_write_id_len(outblob+pos, 2, 1, 0);
outblob[pos++] = 1;
pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
memcpy(outblob+pos, privblob + 4, privlen - 4);
pos += privlen - 4;
pos += ber_write_id_len(outblob+pos, 0, oidlen +
ber_write_id_len(NULL, 6, oidlen, 0),
ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
memcpy(outblob+pos, oid, oidlen);
pos += oidlen;
pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
ber_write_id_len(NULL, 3, 2 + pointlen, 0),
ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
outblob[pos++] = 0;
memcpy(outblob+pos, pubblob+39, 1 + pointlen);
pos += 1 + pointlen;
header = "-----BEGIN EC PRIVATE KEY-----\n";
footer = "-----END EC PRIVATE KEY-----\n";
} else {
assert(0); /* zoinks! */
exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
}
/*
* Encrypt the key.
*
* For the moment, we still encrypt our OpenSSH keys using
* old-style 3DES.
*/
if (passphrase) {
struct MD5Context md5c;
unsigned char keybuf[32];
/*
* Round up to the cipher block size, ensuring we have at
* least one byte of padding (see below).
*/
outlen = (len+8) &~ 7;
{
unsigned char *tmp = snewn(outlen, unsigned char);
memcpy(tmp, outblob, len);
smemclr(outblob, len);
sfree(outblob);
outblob = tmp;
}
/*
* Padding on OpenSSH keys is deterministic. The number of
* padding bytes is always more than zero, and always at most
* the cipher block length. The value of each padding byte is
* equal to the number of padding bytes. So a plaintext that's
* an exact multiple of the block size will be padded with 08
* 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
* plaintext one byte less than a multiple of the block size
* will be padded with just 01.
*
* This enables the OpenSSL key decryption function to strip
* off the padding algorithmically and return the unpadded
* plaintext to the next layer: it looks at the final byte, and
* then expects to find that many bytes at the end of the data
* with the same value. Those are all removed and the rest is
* returned.
*/
assert(pos == len);
while (pos < outlen) {
outblob[pos++] = outlen - len;
}
/*
* Invent an iv. Then derive encryption key from passphrase
* and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*/
for (i = 0; i < 8; i++) iv[i] = random_byte();
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, iv, 8);
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
MD5Update(&md5c, keybuf, 16);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, iv, 8);
MD5Final(keybuf+16, &md5c);
/*
* Now encrypt the key blob.
*/
des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
} else {
/*
* If no encryption, the blob has exactly its original
* cleartext size.
*/
outlen = len;
}
/*
* And save it. We'll use Unix line endings just in case it's
* subsequently transferred in binary mode.
*/
fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
if (!fp)
goto error;
fputs(header, fp);
if (passphrase) {
fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
for (i = 0; i < 8; i++)
fprintf(fp, "%02X", iv[i]);
fprintf(fp, "\n\n");
}
base64_encode(fp, outblob, outlen, 64);
fputs(footer, fp);
fclose(fp);
ret = 1;
error:
if (outblob) {
smemclr(outblob, outlen);
sfree(outblob);
}
if (spareblob) {
smemclr(spareblob, sparelen);
sfree(spareblob);
}
if (privblob) {
smemclr(privblob, privlen);
sfree(privblob);
}
if (pubblob) {
smemclr(pubblob, publen);
sfree(pubblob);
}
return ret;
}
/* ----------------------------------------------------------------------
* Code to read and write OpenSSH private keys in the new-style format.
*/
typedef enum {
ON_E_NONE, ON_E_AES256CBC
} openssh_new_cipher;
typedef enum {
ON_K_NONE, ON_K_BCRYPT
} openssh_new_kdf;
struct openssh_new_key {
openssh_new_cipher cipher;
openssh_new_kdf kdf;
union {
struct {
int rounds;
/* This points to a position within keyblob, not a
* separately allocated thing */
const unsigned char *salt;
int saltlen;
} bcrypt;
} kdfopts;
int nkeys, key_wanted;
/* This too points to a position within keyblob */
unsigned char *privatestr;
int privatelen;
unsigned char *keyblob;
int keyblob_len, keyblob_size;
};
static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
const char **errmsg_p)
{
struct openssh_new_key *ret;
FILE *fp = NULL;
char *line = NULL;
const char *errmsg;
char *p;
char base64_bit[4];
int base64_chars = 0;
const void *filedata;
int filelen;
const void *string, *kdfopts, *bcryptsalt, *pubkey;
int stringlen, kdfoptlen, bcryptsaltlen, pubkeylen;
unsigned bcryptrounds, nkeys, key_index;
ret = snew(struct openssh_new_key);
ret->keyblob = NULL;
ret->keyblob_len = ret->keyblob_size = 0;
fp = f_open(filename, "r", FALSE);
if (!fp) {
errmsg = "unable to open key file";
goto error;
}
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (0 != strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
errmsg = "file does not begin with OpenSSH new-style key header";
goto error;
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
while (1) {
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (0 == strcmp(line, "-----END OPENSSH PRIVATE KEY-----")) {
sfree(line);
line = NULL;
break; /* done */
}
p = line;
while (isbase64(*p)) {
base64_bit[base64_chars++] = *p;
if (base64_chars == 4) {
unsigned char out[3];
int len;
base64_chars = 0;
len = base64_decode_atom(base64_bit, out);
if (len <= 0) {
errmsg = "invalid base64 encoding";
goto error;
}
if (ret->keyblob_len + len > ret->keyblob_size) {
ret->keyblob_size = ret->keyblob_len + len + 256;
ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
unsigned char);
}
memcpy(ret->keyblob + ret->keyblob_len, out, len);
ret->keyblob_len += len;
smemclr(out, sizeof(out));
}
p++;
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
fclose(fp);
fp = NULL;
if (ret->keyblob_len == 0 || !ret->keyblob) {
errmsg = "key body not present";
goto error;
}
filedata = ret->keyblob;
filelen = ret->keyblob_len;
if (filelen < 15 || 0 != memcmp(filedata, "openssh-key-v1\0", 15)) {
errmsg = "new-style OpenSSH magic number missing\n";
goto error;
}
filedata = (const char *)filedata + 15;
filelen -= 15;
if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
errmsg = "encountered EOF before cipher name\n";
goto error;
}
if (match_ssh_id(stringlen, string, "none")) {
ret->cipher = ON_E_NONE;
} else if (match_ssh_id(stringlen, string, "aes256-cbc")) {
ret->cipher = ON_E_AES256CBC;
} else {
errmsg = "unrecognised cipher name\n";
goto error;
}
if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
errmsg = "encountered EOF before kdf name\n";
goto error;
}
if (match_ssh_id(stringlen, string, "none")) {
ret->kdf = ON_K_NONE;
} else if (match_ssh_id(stringlen, string, "bcrypt")) {
ret->kdf = ON_K_BCRYPT;
} else {
errmsg = "unrecognised kdf name\n";
goto error;
}
if (!(kdfopts = get_ssh_string(&filelen, &filedata, &kdfoptlen))) {
errmsg = "encountered EOF before kdf options\n";
goto error;
}
switch (ret->kdf) {
case ON_K_NONE:
if (kdfoptlen != 0) {
errmsg = "expected empty options string for 'none' kdf";
goto error;
}
break;
case ON_K_BCRYPT:
if (!(bcryptsalt = get_ssh_string(&kdfoptlen, &kdfopts,
&bcryptsaltlen))) {
errmsg = "bcrypt options string did not contain salt\n";
goto error;
}
if (!get_ssh_uint32(&kdfoptlen, &kdfopts, &bcryptrounds)) {
errmsg = "bcrypt options string did not contain round count\n";
goto error;
}
ret->kdfopts.bcrypt.salt = bcryptsalt;
ret->kdfopts.bcrypt.saltlen = bcryptsaltlen;
ret->kdfopts.bcrypt.rounds = bcryptrounds;
break;
}
/*
* At this point we expect a uint32 saying how many keys are
* stored in this file. OpenSSH new-style key files can
* contain more than one. Currently we don't have any user
* interface to specify which one we're trying to extract, so
* we just bomb out with an error if more than one is found in
* the file. However, I've put in all the mechanism here to
* extract the nth one for a given n, in case we later connect
* up some UI to that mechanism. Just arrange that the
* 'key_wanted' field is set to a value in the range [0,
* nkeys) by some mechanism.
*/
if (!get_ssh_uint32(&filelen, &filedata, &nkeys)) {
errmsg = "encountered EOF before key count\n";
goto error;
}
if (nkeys != 1) {
errmsg = "multiple keys in new-style OpenSSH key file "
"not supported\n";
goto error;
}
ret->nkeys = nkeys;
ret->key_wanted = 0;
for (key_index = 0; key_index < nkeys; key_index++) {
if (!(pubkey = get_ssh_string(&filelen, &filedata, &pubkeylen))) {
errmsg = "encountered EOF before kdf options\n";
goto error;
}
}
/*
* Now we expect a string containing the encrypted part of the
* key file.
*/
if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
errmsg = "encountered EOF before private key container\n";
goto error;
}
ret->privatestr = (unsigned char *)string;
ret->privatelen = stringlen;
/*
* And now we're done, until asked to actually decrypt.
*/
smemclr(base64_bit, sizeof(base64_bit));
if (errmsg_p) *errmsg_p = NULL;
return ret;
error:
if (line) {
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
smemclr(base64_bit, sizeof(base64_bit));
if (ret) {
if (ret->keyblob) {
smemclr(ret->keyblob, ret->keyblob_size);
sfree(ret->keyblob);
}
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
if (fp) fclose(fp);
return NULL;
}
int openssh_new_encrypted(const Filename *filename)
{
struct openssh_new_key *key = load_openssh_new_key(filename, NULL);
int ret;
if (!key)
return 0;
ret = (key->cipher != ON_E_NONE);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
return ret;
}
struct ssh2_userkey *openssh_new_read(const Filename *filename,
char *passphrase,
const char **errmsg_p)
{
struct openssh_new_key *key = load_openssh_new_key(filename, errmsg_p);
struct ssh2_userkey *retkey = NULL;
int i;
struct ssh2_userkey *retval = NULL;
const char *errmsg;
unsigned checkint0, checkint1;
const void *priv, *string;
int privlen, stringlen, key_index;
const struct ssh_signkey *alg = NULL;
if (!key)
return NULL;
if (key->cipher != ON_E_NONE) {
unsigned char keybuf[48];
int keysize;
/*
* Construct the decryption key, and decrypt the string.
*/
switch (key->cipher) {
case ON_E_NONE:
keysize = 0;
break;
case ON_E_AES256CBC:
keysize = 48; /* 32 byte key + 16 byte IV */
break;
default:
assert(0 && "Bad cipher enumeration value");
}
assert(keysize <= sizeof(keybuf));
switch (key->kdf) {
case ON_K_NONE:
memset(keybuf, 0, keysize);
break;
case ON_K_BCRYPT:
openssh_bcrypt(passphrase,
key->kdfopts.bcrypt.salt,
key->kdfopts.bcrypt.saltlen,
key->kdfopts.bcrypt.rounds,
keybuf, keysize);
break;
default:
assert(0 && "Bad kdf enumeration value");
}
switch (key->cipher) {
case ON_E_NONE:
break;
case ON_E_AES256CBC:
if (key->privatelen % 16 != 0) {
errmsg = "private key container length is not a"
" multiple of AES block size\n";
goto error;
}
{
void *ctx = aes_make_context();
aes256_key(ctx, keybuf);
aes_iv(ctx, keybuf + 32);
aes_ssh2_decrypt_blk(ctx, key->privatestr,
key->privatelen);
aes_free_context(ctx);
}
break;
default:
assert(0 && "Bad cipher enumeration value");
}
}
/*
* Now parse the entire encrypted section, and extract the key
* identified by key_wanted.
*/
priv = key->privatestr;
privlen = key->privatelen;
if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
!get_ssh_uint32(&privlen, &priv, &checkint1) ||
checkint0 != checkint1) {
errmsg = "decryption check failed";
goto error;
}
retkey = NULL;
for (key_index = 0; key_index < key->nkeys; key_index++) {
const unsigned char *thiskey;
int thiskeylen;
/*
* Read the key type, which will tell us how to scan over
* the key to get to the next one.
*/
if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
errmsg = "expected key type in private string";
goto error;
}
/*
* Preliminary key type identification, and decide how
* many pieces of key we expect to see. Currently
* (conveniently) all key types can be seen as some number
* of strings, so we just need to know how many of them to
* skip over. (The numbers below exclude the key comment.)
*/
{
/* find_pubkey_alg needs a zero-terminated copy of the
* algorithm name */
char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
alg = find_pubkey_alg(name_zt);
sfree(name_zt);
}
if (!alg) {
errmsg = "private key type not recognised\n";
goto error;
}
thiskey = priv;
/*
* Skip over the pieces of key.
*/
for (i = 0; i < alg->openssh_private_npieces; i++) {
if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
errmsg = "ran out of data in mid-private-key";
goto error;
}
}
thiskeylen = (int)((const unsigned char *)priv -
(const unsigned char *)thiskey);
if (key_index == key->key_wanted) {
retkey = snew(struct ssh2_userkey);
retkey->comment = NULL;
retkey->alg = alg;
retkey->data = alg->openssh_createkey(alg, &thiskey, &thiskeylen);
if (!retkey->data) {
errmsg = "unable to create key data structure";
goto error;
}
}
/*
* Read the key comment.
*/
if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
errmsg = "ran out of data at key comment";
goto error;
}
if (key_index == key->key_wanted) {
assert(retkey);
retkey->comment = dupprintf("%.*s", stringlen,
(const char *)string);
}
}
if (!retkey) {
errmsg = "key index out of range";
goto error;
}
/*
* Now we expect nothing left but padding.
*/
for (i = 0; i < privlen; i++) {
if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
errmsg = "padding at end of private string did not match";
goto error;
}
}
errmsg = NULL; /* no error */
retval = retkey;
retkey = NULL; /* prevent the free */
error:
if (retkey) {
sfree(retkey->comment);
if (retkey->data) {
assert(alg);
alg->freekey(retkey->data);
}
sfree(retkey);
}
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return retval;
}
int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase)
{
unsigned char *pubblob, *privblob, *outblob, *p;
unsigned char *private_section_start, *private_section_length_field;
int publen, privlen, commentlen, maxsize, padvalue, i;
unsigned checkint;
int ret = 0;
unsigned char bcrypt_salt[16];
const int bcrypt_rounds = 16;
FILE *fp;
/*
* Fetch the key blobs and find out the lengths of things.
*/
pubblob = key->alg->public_blob(key->data, &publen);
i = key->alg->openssh_fmtkey(key->data, NULL, 0);
privblob = snewn(i, unsigned char);
privlen = key->alg->openssh_fmtkey(key->data, privblob, i);
assert(privlen == i);
commentlen = strlen(key->comment);
/*
* Allocate enough space for the full binary key format. No need
* to be absolutely precise here.
*/
maxsize = (16 + /* magic number */
32 + /* cipher name string */
32 + /* kdf name string */
64 + /* kdf options string */
4 + /* key count */
4+publen + /* public key string */
4 + /* string header for private section */
8 + /* checkint x 2 */
4+strlen(key->alg->name) + /* key type string */
privlen + /* private blob */
4+commentlen + /* comment string */
16); /* padding at end of private section */
outblob = snewn(maxsize, unsigned char);
/*
* Construct the cleartext version of the blob.
*/
p = outblob;
/* Magic number. */
memcpy(p, "openssh-key-v1\0", 15);
p += 15;
/* Cipher and kdf names, and kdf options. */
if (!passphrase) {
memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
p += put_string_z(p, "none");
p += put_string_z(p, "none");
p += put_string_z(p, "");
} else {
unsigned char *q;
for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
bcrypt_salt[i] = random_byte();
p += put_string_z(p, "aes256-cbc");
p += put_string_z(p, "bcrypt");
q = p;
p += 4;
p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
p += put_uint32(p, bcrypt_rounds);
PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
}
/* Number of keys. */
p += put_uint32(p, 1);
/* Public blob. */
p += put_string(p, pubblob, publen);
/* Begin private section. */
private_section_length_field = p;
p += 4;
private_section_start = p;
/* checkint. */
checkint = 0;
for (i = 0; i < 4; i++)
checkint = (checkint << 8) + random_byte();
p += put_uint32(p, checkint);
p += put_uint32(p, checkint);
/* Private key. The main private blob goes inline, with no string
* wrapper. */
p += put_string_z(p, key->alg->name);
memcpy(p, privblob, privlen);
p += privlen;
/* Comment. */
p += put_string_z(p, key->comment);
/* Pad out the encrypted section. */
padvalue = 1;
do {
*p++ = padvalue++;
} while ((p - private_section_start) & 15);
assert(p - outblob < maxsize);
/* Go back and fill in the length field for the private section. */
PUT_32BIT_MSB_FIRST(private_section_length_field,
p - private_section_start);
if (passphrase) {
/*
* Encrypt the private section. We need 48 bytes of key
* material: 32 bytes AES key + 16 bytes iv.
*/
unsigned char keybuf[48];
void *ctx;
openssh_bcrypt(passphrase,
bcrypt_salt, sizeof(bcrypt_salt), bcrypt_rounds,
keybuf, sizeof(keybuf));
ctx = aes_make_context();
aes256_key(ctx, keybuf);
aes_iv(ctx, keybuf + 32);
aes_ssh2_encrypt_blk(ctx, private_section_start,
p - private_section_start);
aes_free_context(ctx);
smemclr(keybuf, sizeof(keybuf));
}
/*
* And save it. We'll use Unix line endings just in case it's
* subsequently transferred in binary mode.
*/
fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
if (!fp)
goto error;
fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
base64_encode(fp, outblob, p - outblob, 64);
fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
fclose(fp);
ret = 1;
error:
if (outblob) {
smemclr(outblob, maxsize);
sfree(outblob);
}
if (privblob) {
smemclr(privblob, privlen);
sfree(privblob);
}
if (pubblob) {
smemclr(pubblob, publen);
sfree(pubblob);
}
return ret;
}
/* ----------------------------------------------------------------------
* The switch function openssh_auto_write(), which chooses one of the
* concrete OpenSSH output formats based on the key type.
*/
int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase)
{
/*
* The old OpenSSH format supports a fixed list of key types. We
* assume that anything not in that fixed list is newer, and hence
* will use the new format.
*/
if (key->alg == &ssh_dss ||
key->alg == &ssh_rsa ||
key->alg == &ssh_ecdsa_nistp256 ||
key->alg == &ssh_ecdsa_nistp384 ||
key->alg == &ssh_ecdsa_nistp521)
return openssh_pem_write(filename, key, passphrase);
else
return openssh_new_write(filename, key, passphrase);
}
/* ----------------------------------------------------------------------
* Code to read ssh.com private keys.
*/
/*
* The format of the base64 blob is largely SSH-2-packet-formatted,
* except that mpints are a bit different: they're more like the
* old SSH-1 mpint. You have a 32-bit bit count N, followed by
* (N+7)/8 bytes of data.
*
* So. The blob contains:
*
* - uint32 0x3f6ff9eb (magic number)
* - uint32 size (total blob size)
* - string key-type (see below)
* - string cipher-type (tells you if key is encrypted)
* - string encrypted-blob
*
* (The first size field includes the size field itself and the
* magic number before it. All other size fields are ordinary SSH-2
* strings, so the size field indicates how much data is to
* _follow_.)
*
* The encrypted blob, once decrypted, contains a single string
* which in turn contains the payload. (This allows padding to be
* added after that string while still making it clear where the
* real payload ends. Also it probably makes for a reasonable
* decryption check.)
*
* The payload blob, for an RSA key, contains:
* - mpint e
* - mpint d
* - mpint n (yes, the public and private stuff is intermixed)
* - mpint u (presumably inverse of p mod q)
* - mpint p (p is the smaller prime)
* - mpint q (q is the larger)
*
* For a DSA key, the payload blob contains:
* - uint32 0
* - mpint p
* - mpint g
* - mpint q
* - mpint y
* - mpint x
*
* Alternatively, if the parameters are `predefined', that
* (0,p,g,q) sequence can be replaced by a uint32 1 and a string
* containing some predefined parameter specification. *shudder*,
* but I doubt we'll encounter this in real life.
*
* The key type strings are ghastly. The RSA key I looked at had a
* type string of
*
* `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
*
* and the DSA key wasn't much better:
*
* `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
*
* It isn't clear that these will always be the same. I think it
* might be wise just to look at the `if-modn{sign{rsa' and
* `dl-modp{sign{dsa' prefixes.
*
* Finally, the encryption. The cipher-type string appears to be
* either `none' or `3des-cbc'. Looks as if this is SSH-2-style
* 3des-cbc (i.e. outer cbc rather than inner). The key is created
* from the passphrase by means of yet another hashing faff:
*
* - first 16 bytes are MD5(passphrase)
* - next 16 bytes are MD5(passphrase || first 16 bytes)
* - if there were more, they'd be MD5(passphrase || first 32),
* and so on.
*/
#define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
struct sshcom_key {
char comment[256]; /* allowing any length is overkill */
unsigned char *keyblob;
int keyblob_len, keyblob_size;
};
static struct sshcom_key *load_sshcom_key(const Filename *filename,
const char **errmsg_p)
{
struct sshcom_key *ret;
FILE *fp;
char *line = NULL;
int hdrstart, len;
const char *errmsg;
char *p;
int headers_done;
char base64_bit[4];
int base64_chars = 0;
ret = snew(struct sshcom_key);
ret->comment[0] = '\0';
ret->keyblob = NULL;
ret->keyblob_len = ret->keyblob_size = 0;
fp = f_open(filename, "r", FALSE);
if (!fp) {
errmsg = "unable to open key file";
goto error;
}
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
errmsg = "file does not begin with ssh.com key header";
goto error;
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
headers_done = 0;
while (1) {
if (!(line = fgetline(fp))) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line);
if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
sfree(line);
line = NULL;
break; /* done */
}
if ((p = strchr(line, ':')) != NULL) {
if (headers_done) {
errmsg = "header found in body of key data";
goto error;
}
*p++ = '\0';
while (*p && isspace((unsigned char)*p)) p++;
hdrstart = p - line;
/*
* Header lines can end in a trailing backslash for
* continuation.
*/
len = hdrstart + strlen(line+hdrstart);
assert(!line[len]);
while (line[len-1] == '\\') {
char *line2;
int line2len;
line2 = fgetline(fp);
if (!line2) {
errmsg = "unexpected end of file";
goto error;
}
strip_crlf(line2);
line2len = strlen(line2);
line = sresize(line, len + line2len + 1, char);
strcpy(line + len - 1, line2);
len += line2len - 1;
assert(!line[len]);
smemclr(line2, strlen(line2));
sfree(line2);
line2 = NULL;
}
p = line + hdrstart;
strip_crlf(p);
if (!strcmp(line, "Comment")) {
/* Strip quotes in comment if present. */
if (p[0] == '"' && p[strlen(p)-1] == '"') {
p++;
p[strlen(p)-1] = '\0';
}
strncpy(ret->comment, p, sizeof(ret->comment));
ret->comment[sizeof(ret->comment)-1] = '\0';
}
} else {
headers_done = 1;
p = line;
while (isbase64(*p)) {
base64_bit[base64_chars++] = *p;
if (base64_chars == 4) {
unsigned char out[3];
base64_chars = 0;
len = base64_decode_atom(base64_bit, out);
if (len <= 0) {
errmsg = "invalid base64 encoding";
goto error;
}
if (ret->keyblob_len + len > ret->keyblob_size) {
ret->keyblob_size = ret->keyblob_len + len + 256;
ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
unsigned char);
}
memcpy(ret->keyblob + ret->keyblob_len, out, len);
ret->keyblob_len += len;
}
p++;
}
}
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
if (ret->keyblob_len == 0 || !ret->keyblob) {
errmsg = "key body not present";
goto error;
}
fclose(fp);
if (errmsg_p) *errmsg_p = NULL;
return ret;
error:
if (fp)
fclose(fp);
if (line) {
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
if (ret) {
if (ret->keyblob) {
smemclr(ret->keyblob, ret->keyblob_size);
sfree(ret->keyblob);
}
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
return NULL;
}
int sshcom_encrypted(const Filename *filename, char **comment)
{
struct sshcom_key *key = load_sshcom_key(filename, NULL);
int pos, len, answer;
answer = 0;
*comment = NULL;
if (!key)
goto done;
/*
* Check magic number.
*/
if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
goto done; /* key is invalid */
}
/*
* Find the cipher-type string.
*/
pos = 8;
if (key->keyblob_len < pos+4)
goto done; /* key is far too short */
len = toint(GET_32BIT(key->keyblob + pos));
if (len < 0 || len > key->keyblob_len - pos - 4)
goto done; /* key is far too short */
pos += 4 + len; /* skip key type */
len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
if (len < 0 || len > key->keyblob_len - pos - 4)
goto done; /* cipher type string is incomplete */
if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
answer = 1;
done:
if (key) {
*comment = dupstr(key->comment);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
} else {
*comment = dupstr("");
}
return answer;
}
static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
{
unsigned bits, bytes;
unsigned char *d = (unsigned char *) data;
if (len < 4)
goto error;
bits = GET_32BIT(d);
bytes = (bits + 7) / 8;
if (len < 4+bytes)
goto error;
ret->start = d + 4;
ret->bytes = bytes;
return bytes+4;
error:
ret->start = NULL;
ret->bytes = -1;
return len; /* ensure further calls fail as well */
}
static int sshcom_put_mpint(void *target, void *data, int len)
{
unsigned char *d = (unsigned char *)target;
unsigned char *i = (unsigned char *)data;
int bits = len * 8 - 1;
while (bits > 0) {
if (*i & (1 << (bits & 7)))
break;
if (!(bits-- & 7))
i++, len--;
}
PUT_32BIT(d, bits+1);
memcpy(d+4, i, len);
return len+4;
}
struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
const char **errmsg_p)
{
struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
const char *errmsg;
int pos, len;
const char prefix_rsa[] = "if-modn{sign{rsa";
const char prefix_dsa[] = "dl-modp{sign{dsa";
enum { RSA, DSA } type;
int encrypted;
char *ciphertext;
int cipherlen;
struct ssh2_userkey *ret = NULL, *retkey;
const struct ssh_signkey *alg;
unsigned char *blob = NULL;
int blobsize = 0, publen, privlen;
if (!key)
return NULL;
/*
* Check magic number.
*/
if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
errmsg = "key does not begin with magic number";
goto error;
}
/*
* Determine the key type.
*/
pos = 8;
if (key->keyblob_len < pos+4 ||
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain a key type string";
goto error;
}
if (len > sizeof(prefix_rsa) - 1 &&
!memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
type = RSA;
} else if (len > sizeof(prefix_dsa) - 1 &&
!memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
type = DSA;
} else {
errmsg = "key is of unknown type";
goto error;
}
pos += 4+len;
/*
* Determine the cipher type.
*/
if (key->keyblob_len < pos+4 ||
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain a cipher type string";
goto error;
}
if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
encrypted = 0;
else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
encrypted = 1;
else {
errmsg = "key encryption is of unknown type";
goto error;
}
pos += 4+len;
/*
* Get hold of the encrypted part of the key.
*/
if (key->keyblob_len < pos+4 ||
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain actual key data";
goto error;
}
ciphertext = (char *)key->keyblob + pos + 4;
cipherlen = len;
if (cipherlen == 0) {
errmsg = "length of key data is zero";
goto error;
}
/*
* Decrypt it if necessary.
*/
if (encrypted) {
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase)
* - let block B equal MD5(passphrase || A)
* - block C would be MD5(passphrase || A || B) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32], iv[8];
if (cipherlen % 8 != 0) {
errmsg = "encrypted part of key is not a multiple of cipher block"
" size";
goto error;
}
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, keybuf, 16);
MD5Final(keybuf+16, &md5c);
/*
* Now decrypt the key blob.
*/
memset(iv, 0, sizeof(iv));
des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
cipherlen);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
/*
* Hereafter we return WRONG_PASSPHRASE for any parsing
* error. (But only if we've just tried to decrypt it!
* Returning WRONG_PASSPHRASE for an unencrypted key is
* automatic doom.)
*/
if (encrypted)
ret = SSH2_WRONG_PASSPHRASE;
}
/*
* Strip away the containing string to get to the real meat.
*/
len = toint(GET_32BIT(ciphertext));
if (len < 0 || len > cipherlen-4) {
errmsg = "containing string was ill-formed";
goto error;
}
ciphertext += 4;
cipherlen = len;
/*
* Now we break down into RSA versus DSA. In either case we'll
* construct public and private blobs in our own format, and
* end up feeding them to alg->createkey().
*/
blobsize = cipherlen + 256;
blob = snewn(blobsize, unsigned char);
privlen = 0;
if (type == RSA) {
struct mpint_pos n, e, d, u, p, q;
int pos = 0;
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
if (!q.start) {
errmsg = "key data did not contain six integers";
goto error;
}
alg = &ssh_rsa;
pos = 0;
pos += put_string(blob+pos, "ssh-rsa", 7);
pos += put_mp(blob+pos, e.start, e.bytes);
pos += put_mp(blob+pos, n.start, n.bytes);
publen = pos;
pos += put_string(blob+pos, d.start, d.bytes);
pos += put_mp(blob+pos, q.start, q.bytes);
pos += put_mp(blob+pos, p.start, p.bytes);
pos += put_mp(blob+pos, u.start, u.bytes);
privlen = pos - publen;
} else {
struct mpint_pos p, q, g, x, y;
int pos = 4;
assert(type == DSA); /* the only other option from the if above */
if (GET_32BIT(ciphertext) != 0) {
errmsg = "predefined DSA parameters not supported";
goto error;
}
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
if (!x.start) {
errmsg = "key data did not contain five integers";
goto error;
}
alg = &ssh_dss;
pos = 0;
pos += put_string(blob+pos, "ssh-dss", 7);
pos += put_mp(blob+pos, p.start, p.bytes);
pos += put_mp(blob+pos, q.start, q.bytes);
pos += put_mp(blob+pos, g.start, g.bytes);
pos += put_mp(blob+pos, y.start, y.bytes);
publen = pos;
pos += put_mp(blob+pos, x.start, x.bytes);
privlen = pos - publen;
}
assert(privlen > 0); /* should have bombed by now if not */
retkey = snew(struct ssh2_userkey);
retkey->alg = alg;
retkey->data = alg->createkey(alg, blob, publen, blob+publen, privlen);
if (!retkey->data) {
sfree(retkey);
errmsg = "unable to create key data structure";
goto error;
}
retkey->comment = dupstr(key->comment);
errmsg = NULL; /* no error */
ret = retkey;
error:
if (blob) {
smemclr(blob, blobsize);
sfree(blob);
}
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return ret;
}
int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
char *passphrase)
{
unsigned char *pubblob, *privblob;
int publen, privlen;
unsigned char *outblob;
int outlen;
struct mpint_pos numbers[6];
int nnumbers, initial_zero, pos, lenpos, i;
const char *type;
char *ciphertext;
int cipherlen;
int ret = 0;
FILE *fp;
/*
* Fetch the key blobs.
*/
pubblob = key->alg->public_blob(key->data, &publen);
privblob = key->alg->private_blob(key->data, &privlen);
outblob = NULL;
/*
* Find the sequence of integers to be encoded into the OpenSSH
* key blob, and also decide on the header line.
*/
if (key->alg == &ssh_rsa) {
int pos;
struct mpint_pos n, e, d, p, q, iqmp;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
assert(e.start && iqmp.start); /* can't go wrong */
numbers[0] = e;
numbers[1] = d;
numbers[2] = n;
numbers[3] = iqmp;
numbers[4] = q;
numbers[5] = p;
nnumbers = 6;
initial_zero = 0;
type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
} else if (key->alg == &ssh_dss) {
int pos;
struct mpint_pos p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
pos = 0;
pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
assert(y.start && x.start); /* can't go wrong */
numbers[0] = p;
numbers[1] = g;
numbers[2] = q;
numbers[3] = y;
numbers[4] = x;
nnumbers = 5;
initial_zero = 1;
type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
} else {
assert(0); /* zoinks! */
exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
}
/*
* Total size of key blob will be somewhere under 512 plus
* combined length of integers. We'll calculate the more
* precise size as we construct the blob.
*/
outlen = 512;
for (i = 0; i < nnumbers; i++)
outlen += 4 + numbers[i].bytes;
outblob = snewn(outlen, unsigned char);
/*
* Create the unencrypted key blob.
*/
pos = 0;
PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
pos += 4; /* length field, fill in later */
pos += put_string(outblob+pos, type, strlen(type));
{
const char *ciphertype = passphrase ? "3des-cbc" : "none";
pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
}
lenpos = pos; /* remember this position */
pos += 4; /* encrypted-blob size */
pos += 4; /* encrypted-payload size */
if (initial_zero) {
PUT_32BIT(outblob+pos, 0);
pos += 4;
}
for (i = 0; i < nnumbers; i++)
pos += sshcom_put_mpint(outblob+pos,
numbers[i].start, numbers[i].bytes);
/* Now wrap up the encrypted payload. */
PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
/* Pad encrypted blob to a multiple of cipher block size. */
if (passphrase) {
int padding = -(pos - (lenpos+4)) & 7;
while (padding--)
outblob[pos++] = random_byte();
}
ciphertext = (char *)outblob+lenpos+4;
cipherlen = pos - (lenpos+4);
assert(!passphrase || cipherlen % 8 == 0);
/* Wrap up the encrypted blob string. */
PUT_32BIT(outblob+lenpos, cipherlen);
/* And finally fill in the total length field. */
PUT_32BIT(outblob+4, pos);
assert(pos < outlen);
/*
* Encrypt the key.
*/
if (passphrase) {
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase)
* - let block B equal MD5(passphrase || A)
* - block C would be MD5(passphrase || A || B) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32], iv[8];
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, keybuf, 16);
MD5Final(keybuf+16, &md5c);
/*
* Now decrypt the key blob.
*/
memset(iv, 0, sizeof(iv));
des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
cipherlen);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
/*
* And save it. We'll use Unix line endings just in case it's
* subsequently transferred in binary mode.
*/
fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
if (!fp)
goto error;
fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
fprintf(fp, "Comment: \"");
/*
* Comment header is broken with backslash-newline if it goes
* over 70 chars. Although it's surrounded by quotes, it
* _doesn't_ escape backslashes or quotes within the string.
* Don't ask me, I didn't design it.
*/
{
int slen = 60; /* starts at 60 due to "Comment: " */
char *c = key->comment;
while ((int)strlen(c) > slen) {
fprintf(fp, "%.*s\\\n", slen, c);
c += slen;
slen = 70; /* allow 70 chars on subsequent lines */
}
fprintf(fp, "%s\"\n", c);
}
base64_encode(fp, outblob, pos, 70);
fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
fclose(fp);
ret = 1;
error:
if (outblob) {
smemclr(outblob, outlen);
sfree(outblob);
}
if (privblob) {
smemclr(privblob, privlen);
sfree(privblob);
}
if (pubblob) {
smemclr(pubblob, publen);
sfree(pubblob);
}
return ret;
}