static int
input_kex_ecdh_init(int type, u_int32_t seq, struct ssh *ssh)
{
struct kex *kex = ssh->kex;
EC_POINT *client_public;
EC_KEY *server_key = NULL;
const EC_GROUP *group;
const EC_POINT *public_key;
BIGNUM *shared_secret = NULL;
struct sshkey *server_host_private, *server_host_public;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t slen, sbloblen;
size_t klen = 0, hashlen;
int r;
if ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (EC_KEY_generate_key(server_key) != 1) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
group = EC_KEY_get0_group(server_key);
#ifdef DEBUG_KEXECDH
fputs("server private key:\n", stderr);
sshkey_dump_ec_key(server_key);
#endif
if (kex->load_host_public_key == NULL ||
kex->load_host_private_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
server_host_public = kex->load_host_public_key(kex->hostkey_type,
kex->hostkey_nid, ssh);
server_host_private = kex->load_host_private_key(kex->hostkey_type,
kex->hostkey_nid, ssh);
if (server_host_public == NULL) {
r = SSH_ERR_NO_HOSTKEY_LOADED;
goto out;
}
if ((client_public = EC_POINT_new(group)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshpkt_get_ec(ssh, client_public, group)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXECDH
fputs("client public key:\n", stderr);
sshkey_dump_ec_point(group, client_public);
#endif
if (sshkey_ec_validate_public(group, client_public) != 0) {
sshpkt_disconnect(ssh, "invalid client public key");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
/* Calculate shared_secret */
klen = (EC_GROUP_get_degree(group) + 7) / 8;
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (ECDH_compute_key(kbuf, klen, client_public,
server_key, NULL) != (int)klen ||
BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXECDH
dump_digest("shared secret", kbuf, klen);
#endif
/* calc H */
if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
&sbloblen)) != 0)
goto out;
hashlen = sizeof(hash);
if ((r = kex_ecdh_hash(
kex->hash_alg,
group,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
server_host_key_blob, sbloblen,
client_public,
EC_KEY_get0_public_key(server_key),
shared_secret,
hash, &hashlen)) != 0)
goto out;
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
if ((r = kex->sign(server_host_private, server_host_public, &signature,
&slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
goto out;
/* destroy_sensitive_data(); */
public_key = EC_KEY_get0_public_key(server_key);
/* send server hostkey, ECDH pubkey 'Q_S' and signed H */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
(r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
(r = sshpkt_put_ec(ssh, public_key, group)) != 0 ||
(r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
if (kex->ec_client_key) {
EC_KEY_free(kex->ec_client_key);
kex->ec_client_key = NULL;
}
if (server_key)
EC_KEY_free(server_key);
if (kbuf) {
explicit_bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
free(server_host_key_blob);
free(signature);
return r;
}
int
input_kex_dh_init(int type, u_int32_t seq, void *ctxt)
{
struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
struct sshkey *server_host_public, *server_host_private;
u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t sbloblen, slen;
size_t klen = 0, hashlen;
int kout, r;
if (kex->load_host_public_key == NULL ||
kex->load_host_private_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
server_host_public = kex->load_host_public_key(kex->hostkey_type,
kex->hostkey_nid, ssh);
server_host_private = kex->load_host_private_key(kex->hostkey_type,
kex->hostkey_nid, ssh);
if (server_host_public == NULL) {
r = SSH_ERR_NO_HOSTKEY_LOADED;
goto out;
}
/* key, cert */
if ((dh_client_pub = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_client_pub= ");
BN_print_fp(stderr, dh_client_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_client_pub));
#endif
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, kex->dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, kex->dh->pub_key);
fprintf(stderr, "\n");
#endif
if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
sshpkt_disconnect(ssh, "bad client public DH value");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
klen = DH_size(kex->dh);
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
&sbloblen)) != 0)
goto out;
/* calc H */
hashlen = sizeof(hash);
if ((r = kex_dh_hash(
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
server_host_key_blob, sbloblen,
dh_client_pub,
kex->dh->pub_key,
shared_secret,
hash, &hashlen)) != 0)
goto out;
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
if ((r = kex->sign(server_host_private, server_host_public, &signature,
&slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
goto out;
/* destroy_sensitive_data(); */
/* send server hostkey, DH pubkey 'f' and singed H */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 ||
(r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
(r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */
(r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
DH_free(kex->dh);
kex->dh = NULL;
if (dh_client_pub)
BN_clear_free(dh_client_pub);
if (kbuf) {
explicit_bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
free(server_host_key_blob);
free(signature);
return r;
}
static int
input_kex_ecdh_reply(int type, u_int32_t seq, void *ctxt)
{
struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
const EC_GROUP *group;
EC_POINT *server_public = NULL;
EC_KEY *client_key;
BIGNUM *shared_secret = NULL;
struct sshkey *server_host_key = NULL;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t slen, sbloblen;
size_t klen = 0, hashlen;
int r;
if (kex->verify_host_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
group = kex->ec_group;
client_key = kex->ec_client_key;
/* hostkey */
if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
&sbloblen)) != 0 ||
(r = sshkey_from_blob(server_host_key_blob, sbloblen,
&server_host_key)) != 0)
goto out;
if (server_host_key->type != kex->hostkey_type ||
(kex->hostkey_type == KEY_ECDSA &&
server_host_key->ecdsa_nid != kex->hostkey_nid)) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (kex->verify_host_key(server_host_key, ssh) == -1) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* Q_S, server public key */
/* signed H */
if ((server_public = EC_POINT_new(group)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXECDH
fputs("server public key:\n", stderr);
sshkey_dump_ec_point(group, server_public);
#endif
if (sshkey_ec_validate_public(group, server_public) != 0) {
sshpkt_disconnect(ssh, "invalid server public key");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
klen = (EC_GROUP_get_degree(group) + 7) / 8;
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (ECDH_compute_key(kbuf, klen, server_public,
client_key, NULL) != (int)klen ||
BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXECDH
dump_digest("shared secret", kbuf, klen);
#endif
/* calc and verify H */
hashlen = sizeof(hash);
if ((r = kex_ecdh_hash(
kex->hash_alg,
group,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
EC_KEY_get0_public_key(client_key),
server_public,
shared_secret,
hash, &hashlen)) != 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash,
hashlen, ssh->compat)) != 0)
goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
if (kex->ec_client_key) {
EC_KEY_free(kex->ec_client_key);
kex->ec_client_key = NULL;
}
if (server_public)
EC_POINT_clear_free(server_public);
if (kbuf) {
explicit_bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
sshkey_free(server_host_key);
free(server_host_key_blob);
free(signature);
return r;
}
static int
input_kex_dh_gex_reply(int type, u_int32_t seq, void *ctxt)
{
struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
struct sshkey *server_host_key = NULL;
u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t klen = 0, slen, sbloblen, hashlen;
int kout, r;
debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
if (kex->verify_host_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
/* key, cert */
if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
&sbloblen)) != 0 ||
(r = sshkey_from_blob(server_host_key_blob, sbloblen,
&server_host_key)) != 0)
goto out;
if (server_host_key->type != kex->hostkey_type) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (server_host_key->type != kex->hostkey_type ||
(kex->hostkey_type == KEY_ECDSA &&
server_host_key->ecdsa_nid != kex->hostkey_nid)) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (kex->verify_host_key(server_host_key, ssh) == -1) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
/* signed H */
if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
sshpkt_disconnect(ssh, "bad server public DH value");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
klen = DH_size(kex->dh);
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if (ssh->compat & SSH_OLD_DHGEX)
kex->min = kex->max = -1;
/* calc and verify H */
hashlen = sizeof(hash);
if ((r = kexgex_hash(
kex->hash_alg,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
kex->min, kex->nbits, kex->max,
kex->dh->p, kex->dh->g,
kex->dh->pub_key,
dh_server_pub,
shared_secret,
hash, &hashlen)) != 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash,
hashlen, ssh->compat)) != 0)
goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
DH_free(kex->dh);
kex->dh = NULL;
if (dh_server_pub)
BN_clear_free(dh_server_pub);
if (kbuf) {
explicit_bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
sshkey_free(server_host_key);
free(server_host_key_blob);
free(signature);
return r;
}
void
kexgex_client(Kex *kex)
{
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
BIGNUM *p = NULL, *g = NULL;
Key *server_host_key;
u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
u_int klen, slen, sbloblen, hashlen;
int kout;
int min, max, nbits;
DH *dh;
nbits = dh_estimate(kex->dh_need * 8);
if (datafellows & SSH_OLD_DHGEX) {
/* Old GEX request */
packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
packet_put_int(nbits);
min = DH_GRP_MIN;
max = DH_GRP_MAX;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
} else {
/* New GEX request */
min = DH_GRP_MIN;
max = DH_GRP_MAX;
packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
packet_put_int(min);
packet_put_int(nbits);
packet_put_int(max);
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
min, nbits, max);
}
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
min, nbits, max);
#endif
packet_send();
debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
if ((p = BN_new()) == NULL)
fatal("BN_new");
packet_get_bignum2(p);
if ((g = BN_new()) == NULL)
fatal("BN_new");
packet_get_bignum2(g);
packet_check_eom();
if (BN_num_bits(p) < min || BN_num_bits(p) > max)
fatal("DH_GEX group out of range: %d !< %d !< %d",
min, BN_num_bits(p), max);
dh = dh_new_group(g, p);
dh_gen_key(dh, kex->we_need * 8);
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
/* generate and send 'e', client DH public key */
packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
packet_put_bignum2(dh->pub_key);
packet_send();
debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
/* key, cert */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL)
fatal("dh_server_pub == NULL");
packet_get_bignum2(dh_server_pub);
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexgex_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexgex_client: BN_bin2bn failed");
explicit_bzero(kbuf, klen);
free(kbuf);
if (datafellows & SSH_OLD_DHGEX)
min = max = -1;
/* calc and verify H */
kexgex_hash(
kex->hash_alg,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
min, nbits, max,
dh->p, dh->g,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
/* have keys, free DH */
DH_free(dh);
free(server_host_key_blob);
BN_clear_free(dh_server_pub);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexecdh_client(Kex *kex)
{
EC_KEY *client_key;
EC_POINT *server_public;
const EC_GROUP *group;
BIGNUM *shared_secret;
Key *server_host_key;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf, *hash;
u_int klen, slen, sbloblen, hashlen;
if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL)
fatal("%s: EC_KEY_new_by_curve_name failed", __func__);
if (EC_KEY_generate_key(client_key) != 1)
fatal("%s: EC_KEY_generate_key failed", __func__);
group = EC_KEY_get0_group(client_key);
packet_start(SSH2_MSG_KEX_ECDH_INIT);
packet_put_ecpoint(group, EC_KEY_get0_public_key(client_key));
packet_send();
debug("sending SSH2_MSG_KEX_ECDH_INIT");
#ifdef DEBUG_KEXECDH
fputs("client private key:\n", stderr);
key_dump_ec_key(client_key);
#endif
debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
/* hostkey */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* Q_S, server public key */
if ((server_public = EC_POINT_new(group)) == NULL)
fatal("%s: EC_POINT_new failed", __func__);
packet_get_ecpoint(group, server_public);
if (sshkey_ec_validate_public(group, server_public) != 0)
fatal("%s: invalid server public key", __func__);
#ifdef DEBUG_KEXECDH
fputs("server public key:\n", stderr);
key_dump_ec_point(group, server_public);
#endif
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
klen = (EC_GROUP_get_degree(group) + 7) / 8;
kbuf = xmalloc(klen);
if (ECDH_compute_key(kbuf, klen, server_public,
client_key, NULL) != (int)klen)
fatal("%s: ECDH_compute_key failed", __func__);
#ifdef DEBUG_KEXECDH
dump_digest("shared secret", kbuf, klen);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("%s: BN_new failed", __func__);
if (BN_bin2bn(kbuf, klen, shared_secret) == NULL)
fatal("%s: BN_bin2bn failed", __func__);
explicit_bzero(kbuf, klen);
free(kbuf);
/* calc and verify H */
kex_ecdh_hash(
kex->hash_alg,
group,
kex->client_version_string,
kex->server_version_string,
(char *)buffer_ptr(&kex->my), buffer_len(&kex->my),
(char *)buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
EC_KEY_get0_public_key(client_key),
server_public,
shared_secret,
&hash, &hashlen
);
free(server_host_key_blob);
EC_POINT_clear_free(server_public);
EC_KEY_free(client_key);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexdh_client(Kex *kex)
{
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
DH *dh;
Key *server_host_key;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf, *hash;
u_int klen, slen, sbloblen, hashlen;
int kout;
/* generate and send 'e', client DH public key */
switch (kex->kex_type) {
case KEX_DH_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_DH_GRP14_SHA1:
dh = dh_new_group14();
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
dh_gen_key(dh, kex->we_need * 8);
packet_start(SSH2_MSG_KEXDH_INIT);
packet_put_bignum2(dh->pub_key);
packet_send();
debug("sending SSH2_MSG_KEXDH_INIT");
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
debug("expecting SSH2_MSG_KEXDH_REPLY");
packet_read_expect(SSH2_MSG_KEXDH_REPLY);
/* key, cert */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL)
fatal("dh_server_pub == NULL");
packet_get_bignum2(dh_server_pub);
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexdh_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexdh_client: BN_bin2bn failed");
memset(kbuf, 0, klen);
free(kbuf);
/* calc and verify H */
kex_dh_hash(
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
free(server_host_key_blob);
BN_clear_free(dh_server_pub);
DH_free(dh);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexdh_server(Kex *kex)
{
BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
DH *dh;
Key *server_host_public, *server_host_private;
u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
u_int sbloblen, klen, hashlen, slen;
int kout;
/* generate server DH public key */
switch (kex->kex_type) {
case KEX_DH_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_DH_GRP14_SHA1:
dh = dh_new_group14();
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
dh_gen_key(dh, kex->we_need * 8);
debug("expecting SSH2_MSG_KEXDH_INIT");
packet_read_expect(SSH2_MSG_KEXDH_INIT);
if (kex->load_host_public_key == NULL ||
kex->load_host_private_key == NULL)
fatal("Cannot load hostkey");
server_host_public = kex->load_host_public_key(kex->hostkey_type);
if (server_host_public == NULL)
fatal("Unsupported hostkey type %d", kex->hostkey_type);
server_host_private = kex->load_host_private_key(kex->hostkey_type);
/* key, cert */
if ((dh_client_pub = BN_new()) == NULL)
fatal("dh_client_pub == NULL");
packet_get_bignum2(dh_client_pub);
packet_check_eom();
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_client_pub= ");
BN_print_fp(stderr, dh_client_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_client_pub));
#endif
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
if (!dh_pub_is_valid(dh, dh_client_pub))
packet_disconnect("bad client public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexdh_server: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexdh_server: BN_bin2bn failed");
memset(kbuf, 0, klen);
free(kbuf);
key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
/* calc H */
kex_dh_hash(
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
buffer_ptr(&kex->my), buffer_len(&kex->my),
server_host_key_blob, sbloblen,
dh_client_pub,
dh->pub_key,
shared_secret,
&hash, &hashlen
);
BN_clear_free(dh_client_pub);
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
kex->sign(server_host_private, server_host_public, &signature, &slen,
hash, hashlen);
/* destroy_sensitive_data(); */
/* send server hostkey, DH pubkey 'f' and singed H */
packet_start(SSH2_MSG_KEXDH_REPLY);
packet_put_string(server_host_key_blob, sbloblen);
packet_put_bignum2(dh->pub_key); /* f */
packet_put_string(signature, slen);
packet_send();
free(signature);
free(server_host_key_blob);
/* have keys, free DH */
DH_free(dh);
kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
