const EVP_MD *
kex_ecdh_name_to_evpmd(const char *kexname)
{
int nid = kex_ecdh_name_to_nid(kexname);
if (nid == -1)
fatal("%s: unsupported ECDH curve \"%s\"", __func__, kexname);
return key_ec_nid_to_evpmd(nid);
}
int
ssh_ecdsa_sign(const Key *key, u_char **sigp, u_int *lenp,
const u_char *data, u_int datalen)
{
ECDSA_SIG *sig;
const EVP_MD *evp_md;
EVP_MD_CTX md;
u_char digest[EVP_MAX_MD_SIZE];
u_int len, dlen;
Buffer b, bb;
if (key == NULL || key->ecdsa == NULL ||
(key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) {
error("%s: no ECDSA key", __func__);
return -1;
}
evp_md = key_ec_nid_to_evpmd(key->ecdsa_nid);
EVP_DigestInit(&md, evp_md);
EVP_DigestUpdate(&md, data, datalen);
EVP_DigestFinal(&md, digest, &dlen);
sig = ECDSA_do_sign(digest, dlen, key->ecdsa);
memset(digest, 'd', sizeof(digest));
if (sig == NULL) {
error("%s: sign failed", __func__);
return -1;
}
buffer_init(&bb);
buffer_put_bignum2(&bb, sig->r);
buffer_put_bignum2(&bb, sig->s);
ECDSA_SIG_free(sig);
buffer_init(&b);
buffer_put_cstring(&b, key_ssh_name_plain(key));
buffer_put_string(&b, buffer_ptr(&bb), buffer_len(&bb));
buffer_free(&bb);
len = buffer_len(&b);
if (lenp != NULL)
*lenp = len;
if (sigp != NULL) {
*sigp = xmalloc(len);
memcpy(*sigp, buffer_ptr(&b), len);
}
buffer_free(&b);
return 0;
}
int
ssh_ecdsa_verify(const Key *key, const u_char *signature, u_int signaturelen,
const u_char *data, u_int datalen)
{
ECDSA_SIG *sig;
const EVP_MD *evp_md;
EVP_MD_CTX md;
u_char digest[EVP_MAX_MD_SIZE], *sigblob;
u_int len, dlen;
int rlen, ret;
Buffer b, bb;
char *ktype;
if (key == NULL || key->ecdsa == NULL ||
(key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) {
error("%s: no ECDSA key", __func__);
return -1;
}
evp_md = key_ec_nid_to_evpmd(key->ecdsa_nid);
/* fetch signature */
buffer_init(&b);
buffer_append(&b, signature, signaturelen);
ktype = buffer_get_string(&b, NULL);
if (strcmp(key_ssh_name_plain(key), ktype) != 0) {
error("%s: cannot handle type %s", __func__, ktype);
buffer_free(&b);
free(ktype);
return -1;
}
free(ktype);
sigblob = buffer_get_string(&b, &len);
rlen = buffer_len(&b);
buffer_free(&b);
if (rlen != 0) {
error("%s: remaining bytes in signature %d", __func__, rlen);
free(sigblob);
return -1;
}
/* parse signature */
if ((sig = ECDSA_SIG_new()) == NULL)
fatal("%s: ECDSA_SIG_new failed", __func__);
if ((sig->r = BN_new()) == NULL ||
(sig->s = BN_new()) == NULL)
fatal("%s: BN_new failed", __func__);
buffer_init(&bb);
buffer_append(&bb, sigblob, len);
buffer_get_bignum2(&bb, sig->r);
buffer_get_bignum2(&bb, sig->s);
if (buffer_len(&bb) != 0)
fatal("%s: remaining bytes in inner sigblob", __func__);
buffer_free(&bb);
/* clean up */
memset(sigblob, 0, len);
free(sigblob);
/* hash the data */
EVP_DigestInit(&md, evp_md);
EVP_DigestUpdate(&md, data, datalen);
EVP_DigestFinal(&md, digest, &dlen);
ret = ECDSA_do_verify(digest, dlen, sig, key->ecdsa);
memset(digest, 'd', sizeof(digest));
ECDSA_SIG_free(sig);
debug("%s: signature %s", __func__,
ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
return ret;
}
