mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-07-12 16:47:42 -05:00
Elliptic-curve cryptography support.
This provides support for ECDSA public keys, for both hosts and users, and also ECDH key exchange. Supported curves are currently just the three NIST curves required by RFC 5656.
This commit is contained in:
Chris Staite
committed by
Simon Tatham
Simon Tatham
parent
7d1c30cd50
commit
2bf8688355
209
import.c
209
import.c
@ -307,7 +307,7 @@ static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
|
||||
* Code to read and write OpenSSH private keys.
|
||||
*/
|
||||
|
||||
enum { OSSH_DSA, OSSH_RSA };
|
||||
enum { OSSH_DSA, OSSH_RSA, OSSH_ECDSA };
|
||||
enum { OSSH_ENC_3DES, OSSH_ENC_AES };
|
||||
struct openssh_key {
|
||||
int type;
|
||||
@ -354,6 +354,8 @@ static struct openssh_key *load_openssh_key(const Filename *filename,
|
||||
ret->type = OSSH_RSA;
|
||||
else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----"))
|
||||
ret->type = OSSH_DSA;
|
||||
else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----"))
|
||||
ret->type = OSSH_ECDSA;
|
||||
else {
|
||||
errmsg = "unrecognised key type";
|
||||
goto error;
|
||||
@ -591,6 +593,10 @@ struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
|
||||
*
|
||||
* - 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;
|
||||
@ -613,7 +619,122 @@ struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
|
||||
else
|
||||
num_integers = 0; /* placate compiler warnings */
|
||||
|
||||
if (key->type == OSSH_RSA || key->type == OSSH_DSA) {
|
||||
|
||||
if (key->type == OSSH_ECDSA)
|
||||
{
|
||||
/* And now for something completely different */
|
||||
unsigned char *priv;
|
||||
int privlen;
|
||||
struct ec_curve *curve;
|
||||
/* 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 || key->keyblob+key->keyblob_len-p < len ||
|
||||
len != 1 || 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 || 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 || 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 || key->keyblob+key->keyblob_len-p < len) {
|
||||
errmsg = "ASN.1 decoding failure";
|
||||
retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
|
||||
goto error;
|
||||
}
|
||||
if (len == 8 && !memcmp(p, nistp256_oid, nistp256_oid_len)) {
|
||||
curve = ec_p256();
|
||||
} else if (len == 5 && !memcmp(p, nistp384_oid, nistp384_oid_len)) {
|
||||
curve = ec_p384();
|
||||
} else if (len == 5 && !memcmp(p, nistp521_oid, nistp521_oid_len)) {
|
||||
curve = ec_p521();
|
||||
} else {
|
||||
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 || 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 || 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;
|
||||
}
|
||||
if (curve->fieldBits == 256) {
|
||||
retkey->alg = &ssh_ecdsa_nistp256;
|
||||
} else if (curve->fieldBits == 384) {
|
||||
retkey->alg = &ssh_ecdsa_nistp384;
|
||||
} else {
|
||||
retkey->alg = &ssh_ecdsa_nistp521;
|
||||
}
|
||||
blob = snewn((4+19 + 4+8 + 4+len) + (4+privlen), unsigned char);
|
||||
if (!blob) {
|
||||
sfree(retkey);
|
||||
errmsg = "out of memory";
|
||||
goto error;
|
||||
}
|
||||
PUT_32BIT(blob, 19);
|
||||
sprintf((char*)blob+4, "ecdsa-sha2-nistp%d", curve->fieldBits);
|
||||
PUT_32BIT(blob+4+19, 8);
|
||||
sprintf((char*)blob+4+19+4, "nistp%d", curve->fieldBits);
|
||||
PUT_32BIT(blob+4+19+4+8, len);
|
||||
memcpy(blob+4+19+4+8+4, p, len);
|
||||
PUT_32BIT(blob+4+19+4+8+4+len, privlen);
|
||||
memcpy(blob+4+19+4+8+4+len+4, priv, privlen);
|
||||
retkey->data = retkey->alg->createkey(blob, 4+19+4+8+4+len,
|
||||
blob+4+19+4+8+4+len, 4+privlen);
|
||||
if (!retkey->data) {
|
||||
sfree(retkey);
|
||||
errmsg = "unable to create key data structure";
|
||||
goto error;
|
||||
}
|
||||
|
||||
} else if (key->type == OSSH_RSA || key->type == OSSH_DSA) {
|
||||
|
||||
/*
|
||||
* Space to create key blob in.
|
||||
*/
|
||||
@ -875,6 +996,90 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
|
||||
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) {
|
||||
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)
|
||||
*/
|
||||
switch (((struct ec_key *)key->data)->publicKey.curve->fieldBits) {
|
||||
case 256:
|
||||
/* OID: 1.2.840.10045.3.1.7 (ansiX9p256r1) */
|
||||
oid = nistp256_oid;
|
||||
oidlen = nistp256_oid_len;
|
||||
pointlen = 32 * 2;
|
||||
break;
|
||||
case 384:
|
||||
/* OID: 1.3.132.0.34 (secp384r1) */
|
||||
oid = nistp384_oid;
|
||||
oidlen = nistp384_oid_len;
|
||||
pointlen = 48 * 2;
|
||||
break;
|
||||
case 521:
|
||||
/* OID: 1.3.132.0.35 (secp521r1) */
|
||||
oid = nistp521_oid;
|
||||
oidlen = nistp521_oid_len;
|
||||
pointlen = 66 * 2;
|
||||
break;
|
||||
default:
|
||||
assert(0);
|
||||
}
|
||||
|
||||
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. */
|
||||
|
||||
Reference in New Issue
Block a user