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Elliptic-curve cryptography support.

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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
2014-11-01 09:45:20 +00:00
committed by Simon Tatham
parent 7d1c30cd50
commit 2bf8688355
14 changed files with 2602 additions and 15 deletions
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90
ssh.c
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@ -32,6 +32,7 @@ typedef enum {
SSH2_PKTCTX_NOKEX,
SSH2_PKTCTX_DHGROUP,
SSH2_PKTCTX_DHGEX,
SSH2_PKTCTX_ECDHKEX,
SSH2_PKTCTX_RSAKEX
} Pkt_KCtx;
typedef enum {
@ -254,6 +255,8 @@ static char *ssh2_pkt_type(Pkt_KCtx pkt_kctx, Pkt_ACtx pkt_actx, int type)
translatek(SSH2_MSG_KEXRSA_PUBKEY, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEXRSA_SECRET, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEXRSA_DONE, SSH2_PKTCTX_RSAKEX);
translatek(SSH2_MSG_KEX_ECDH_INIT, SSH2_PKTCTX_ECDHKEX);
translatek(SSH2_MSG_KEX_ECDH_REPLY, SSH2_PKTCTX_ECDHKEX);
translate(SSH2_MSG_USERAUTH_REQUEST);
translate(SSH2_MSG_USERAUTH_FAILURE);
translate(SSH2_MSG_USERAUTH_SUCCESS);
@ -397,7 +400,10 @@ static void ssh_channel_destroy(struct ssh_channel *c);
#define OUR_V2_MAXPKT 0x4000UL
#define OUR_V2_PACKETLIMIT 0x9000UL
const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
const static struct ssh_signkey *hostkey_algs[] = {
&ssh_ecdsa_nistp256, &ssh_ecdsa_nistp384, &ssh_ecdsa_nistp521,
&ssh_rsa, &ssh_dss
};
const static struct ssh_mac *macs[] = {
&ssh_hmac_sha256, &ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
@ -6024,6 +6030,7 @@ static void do_ssh2_transport(Ssh ssh, void *vin, int inlen,
int hostkeylen, siglen, rsakeylen;
void *hkey; /* actual host key */
void *rsakey; /* for RSA kex */
void *eckey; /* for ECDH kex */
unsigned char exchange_hash[SSH2_KEX_MAX_HASH_LEN];
int n_preferred_kex;
const struct ssh_kexes *preferred_kex[KEX_MAX];
@ -6087,6 +6094,10 @@ static void do_ssh2_transport(Ssh ssh, void *vin, int inlen,
s->preferred_kex[s->n_preferred_kex++] =
&ssh_rsa_kex;
break;
case KEX_ECDH:
s->preferred_kex[s->n_preferred_kex++] =
&ssh_ecdh_kex;
break;
case KEX_WARN:
/* Flag for later. Don't bother if it's the last in
* the list. */
@ -6653,6 +6664,83 @@ static void do_ssh2_transport(Ssh ssh, void *vin, int inlen,
freebn(s->g);
freebn(s->p);
}
} else if (ssh->kex->main_type == KEXTYPE_ECDH) {
logeventf(ssh, "Doing ECDH key exchange with hash %s",
ssh->kex->hash->text_name);
ssh->pkt_kctx = SSH2_PKTCTX_ECDHKEX;
s->eckey = NULL;
if (!strcmp(ssh->kex->name, "ecdh-sha2-nistp256")) {
s->eckey = ssh_ecdhkex_newkey(ec_p256());
} else if (!strcmp(ssh->kex->name, "ecdh-sha2-nistp384")) {
s->eckey = ssh_ecdhkex_newkey(ec_p384());
} else if (!strcmp(ssh->kex->name, "ecdh-sha2-nistp521")) {
s->eckey = ssh_ecdhkex_newkey(ec_p521());
}
if (!s->eckey) {
bombout(("Unable to generate key for ECDH"));
crStopV;
}
{
char *publicPoint;
int publicPointLength;
publicPoint = ssh_ecdhkex_getpublic(s->eckey, &publicPointLength);
if (!publicPoint) {
ssh_ecdhkex_freekey(s->eckey);
bombout(("Unable to encode public key for ECDH"));
crStopV;
}
s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_ECDH_INIT);
ssh2_pkt_addstring_start(s->pktout);
ssh2_pkt_addstring_data(s->pktout, publicPoint, publicPointLength);
sfree(publicPoint);
}
ssh2_pkt_send_noqueue(ssh, s->pktout);
crWaitUntilV(pktin);
if (pktin->type != SSH2_MSG_KEX_ECDH_REPLY) {
ssh_ecdhkex_freekey(s->eckey);
bombout(("expected ECDH reply packet from server"));
crStopV;
}
ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
hash_string(ssh->kex->hash, ssh->exhash, s->hostkeydata, s->hostkeylen);
s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
{
char *publicPoint;
int publicPointLength;
publicPoint = ssh_ecdhkex_getpublic(s->eckey, &publicPointLength);
if (!publicPoint) {
ssh_ecdhkex_freekey(s->eckey);
bombout(("Unable to encode public key for ECDH hash"));
crStopV;
}
hash_string(ssh->kex->hash, ssh->exhash,
publicPoint, publicPointLength);
sfree(publicPoint);
}
{
char *keydata;
int keylen;
ssh_pkt_getstring(pktin, &keydata, &keylen);
hash_string(ssh->kex->hash, ssh->exhash, keydata, keylen);
s->K = ssh_ecdhkex_getkey(s->eckey, keydata, keylen);
if (!s->K) {
ssh_ecdhkex_freekey(s->eckey);
bombout(("point received in ECDH was not valid"));
crStopV;
}
}
ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
ssh_ecdhkex_freekey(s->eckey);
} else {
logeventf(ssh, "Doing RSA key exchange with hash %s",
ssh->kex->hash->text_name);