static int input_kex_c25519_init(int type, u_int32_t seq, struct ssh *ssh) { struct kex *kex = ssh->kex; struct sshkey *server_host_private, *server_host_public; struct sshbuf *shared_secret = NULL; u_char *server_host_key_blob = NULL, *signature = NULL; u_char server_key[CURVE25519_SIZE]; u_char *client_pubkey = NULL; u_char server_pubkey[CURVE25519_SIZE]; u_char hash[SSH_DIGEST_MAX_LENGTH]; size_t slen, pklen, sbloblen, hashlen; int r; /* generate private key */ kexc25519_keygen(server_key, server_pubkey); #ifdef DEBUG_KEXECDH dump_digest("server private key:", server_key, sizeof(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 ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 || (r = sshpkt_get_end(ssh)) != 0) goto out; if (pklen != CURVE25519_SIZE) { r = SSH_ERR_SIGNATURE_INVALID; goto out; } #ifdef DEBUG_KEXECDH dump_digest("client public key:", client_pubkey, CURVE25519_SIZE); #endif if ((shared_secret = sshbuf_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = kexc25519_shared_key(server_key, client_pubkey, shared_secret)) < 0) goto out; /* calc H */ if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob, &sbloblen)) != 0) goto out; hashlen = sizeof(hash); if ((r = kex_c25519_hash( kex->hash_alg, 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_pubkey, server_pubkey, sshbuf_ptr(shared_secret), sshbuf_len(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; /* 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_string(ssh, server_pubkey, sizeof(server_pubkey))) != 0 || (r = sshpkt_put_string(ssh, signature, slen)) != 0 || (r = sshpkt_send(ssh)) != 0) goto out; if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) r = kex_send_newkeys(ssh); out: explicit_bzero(hash, sizeof(hash)); explicit_bzero(server_key, sizeof(server_key)); free(server_host_key_blob); free(signature); free(client_pubkey); sshbuf_free(shared_secret); return r; }
static int input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh) { struct kex *kex = ssh->kex; struct sshkey *server_host_key = NULL; struct sshbuf *shared_secret = NULL; u_char *server_pubkey = NULL; u_char *server_host_key_blob = NULL, *signature = NULL; u_char *hash; size_t slen, pklen, sbloblen, hashlen; int r; if (kex->verify_host_key == NULL) { r = SSH_ERR_INVALID_ARGUMENT; goto out; } /* 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) { 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 ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 || (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 || (r = sshpkt_get_end(ssh)) != 0) goto out; if (pklen != CURVE25519_SIZE) { r = SSH_ERR_SIGNATURE_INVALID; goto out; } #ifdef DEBUG_KEXECDH dump_digest("server public key:", server_pubkey, CURVE25519_SIZE); #endif if ((shared_secret = sshbuf_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey, shared_secret)) < 0) goto out; /* calc and verify H */ if ((r = kex_c25519_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->c25519_client_pubkey, server_pubkey, sshbuf_ptr(shared_secret), sshbuf_len(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(ssh, hash, hashlen, sshbuf_ptr(shared_secret), sshbuf_len(shared_secret))) == 0) r = kex_send_newkeys(ssh); r = 0; out: explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key)); free(server_host_key_blob); free(server_pubkey); free(signature); sshkey_free(server_host_key); sshbuf_free(shared_secret); return r; }