PR: 1921

Submitted by: Michael Tuexen <tuexen@fh-muenster.de>
Reviewed by: steve@openssl.org

Add ECDHE and PSK support to DTLS.

1 files changed, 304 insertions, 3 deletions

diff --git a/ssl/d1_clnt.c b/ssl/d1_clnt.c
index 0425af5a58..2364ad2f8d 100644
--- a/ssl/d1_clnt.c
+++ b/ssl/d1_clnt.c
@@ -284,8 +284,9 @@ int dtls1_connect(SSL *s)
 
 		case SSL3_ST_CR_CERT_A:
 		case SSL3_ST_CR_CERT_B:
-			/* Check if it is anon DH */
-			if (!(s->s3->tmp.new_cipher->algorithm_auth & SSL_aNULL))
+			/* Check if it is anon DH or PSK */
+			if (!(s->s3->tmp.new_cipher->algorithm_auth & SSL_aNULL) &&
+			    !(s->s3->tmp.new_cipher->algorithm_mkey & SSL_kPSK))
 				{
 				ret=ssl3_get_server_certificate(s);
 				if (ret <= 0) goto end;
@@ -716,6 +717,14 @@ int dtls1_send_client_key_exchange(SSL *s)
 #ifndef OPENSSL_NO_KRB5
         KSSL_ERR kssl_err;
 #endif /* OPENSSL_NO_KRB5 */
+#ifndef OPENSSL_NO_ECDH
+	EC_KEY *clnt_ecdh = NULL;
+	const EC_POINT *srvr_ecpoint = NULL;
+	EVP_PKEY *srvr_pub_pkey = NULL;
+	unsigned char *encodedPoint = NULL;
+	int encoded_pt_len = 0;
+	BN_CTX * bn_ctx = NULL;
+#endif
 
 	if (s->state == SSL3_ST_CW_KEY_EXCH_A)
 		{
@@ -973,6 +982,274 @@ int dtls1_send_client_key_exchange(SSL *s)
 			/* perhaps clean things up a bit EAY EAY EAY EAY*/
 			}
 #endif
+#ifndef OPENSSL_NO_ECDH 
+		else if (alg_k & (SSL_kEECDH|SSL_kECDHr|SSL_kECDHe))
+			{
+			const EC_GROUP *srvr_group = NULL;
+			EC_KEY *tkey;
+			int ecdh_clnt_cert = 0;
+			int field_size = 0;
+
+			/* Did we send out the client's
+			 * ECDH share for use in premaster
+			 * computation as part of client certificate?
+			 * If so, set ecdh_clnt_cert to 1.
+			 */
+			if ((alg_k & (SSL_kECDHr|SSL_kECDHe)) && (s->cert != NULL)) 
+				{
+				/* XXX: For now, we do not support client
+				 * authentication using ECDH certificates.
+				 * To add such support, one needs to add
+				 * code that checks for appropriate 
+				 * conditions and sets ecdh_clnt_cert to 1.
+				 * For example, the cert have an ECC
+				 * key on the same curve as the server's
+				 * and the key should be authorized for
+				 * key agreement.
+				 *
+				 * One also needs to add code in ssl3_connect
+				 * to skip sending the certificate verify
+				 * message.
+				 *
+				 * if ((s->cert->key->privatekey != NULL) &&
+				 *     (s->cert->key->privatekey->type ==
+				 *      EVP_PKEY_EC) && ...)
+				 * ecdh_clnt_cert = 1;
+				 */
+				}
+
+			if (s->session->sess_cert->peer_ecdh_tmp != NULL)
+				{
+				tkey = s->session->sess_cert->peer_ecdh_tmp;
+				}
+			else
+				{
+				/* Get the Server Public Key from Cert */
+				srvr_pub_pkey = X509_get_pubkey(s->session-> \
+				    sess_cert->peer_pkeys[SSL_PKEY_ECC].x509);
+				if ((srvr_pub_pkey == NULL) ||
+				    (srvr_pub_pkey->type != EVP_PKEY_EC) ||
+				    (srvr_pub_pkey->pkey.ec == NULL))
+					{
+					SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					    ERR_R_INTERNAL_ERROR);
+					goto err;
+					}
+
+				tkey = srvr_pub_pkey->pkey.ec;
+				}
+
+			srvr_group   = EC_KEY_get0_group(tkey);
+			srvr_ecpoint = EC_KEY_get0_public_key(tkey);
+
+			if ((srvr_group == NULL) || (srvr_ecpoint == NULL))
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+				    ERR_R_INTERNAL_ERROR);
+				goto err;
+				}
+
+			if ((clnt_ecdh=EC_KEY_new()) == NULL) 
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,ERR_R_MALLOC_FAILURE);
+				goto err;
+				}
+
+			if (!EC_KEY_set_group(clnt_ecdh, srvr_group))
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,ERR_R_EC_LIB);
+				goto err;
+				}
+			if (ecdh_clnt_cert) 
+				{ 
+				/* Reuse key info from our certificate
+				 * We only need our private key to perform
+				 * the ECDH computation.
+				 */
+				const BIGNUM *priv_key;
+				tkey = s->cert->key->privatekey->pkey.ec;
+				priv_key = EC_KEY_get0_private_key(tkey);
+				if (priv_key == NULL)
+					{
+					SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,ERR_R_MALLOC_FAILURE);
+					goto err;
+					}
+				if (!EC_KEY_set_private_key(clnt_ecdh, priv_key))
+					{
+					SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,ERR_R_EC_LIB);
+					goto err;
+					}
+				}
+			else 
+				{
+				/* Generate a new ECDH key pair */
+				if (!(EC_KEY_generate_key(clnt_ecdh)))
+					{
+					SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE, ERR_R_ECDH_LIB);
+					goto err;
+					}
+				}
+
+			/* use the 'p' output buffer for the ECDH key, but
+			 * make sure to clear it out afterwards
+			 */
+
+			field_size = EC_GROUP_get_degree(srvr_group);
+			if (field_size <= 0)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE, 
+				       ERR_R_ECDH_LIB);
+				goto err;
+				}
+			n=ECDH_compute_key(p, (field_size+7)/8, srvr_ecpoint, clnt_ecdh, NULL);
+			if (n <= 0)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE, 
+				       ERR_R_ECDH_LIB);
+				goto err;
+				}
+
+			/* generate master key from the result */
+			s->session->master_key_length = s->method->ssl3_enc \
+			    -> generate_master_secret(s, 
+				s->session->master_key,
+				p, n);
+
+			memset(p, 0, n); /* clean up */
+
+			if (ecdh_clnt_cert) 
+				{
+				/* Send empty client key exch message */
+				n = 0;
+				}
+			else 
+				{
+				/* First check the size of encoding and
+				 * allocate memory accordingly.
+				 */
+				encoded_pt_len = 
+				    EC_POINT_point2oct(srvr_group, 
+					EC_KEY_get0_public_key(clnt_ecdh), 
+					POINT_CONVERSION_UNCOMPRESSED, 
+					NULL, 0, NULL);
+
+				encodedPoint = (unsigned char *) 
+				    OPENSSL_malloc(encoded_pt_len * 
+					sizeof(unsigned char)); 
+				bn_ctx = BN_CTX_new();
+				if ((encodedPoint == NULL) || 
+				    (bn_ctx == NULL)) 
+					{
+					SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,ERR_R_MALLOC_FAILURE);
+					goto err;
+					}
+
+				/* Encode the public key */
+				n = EC_POINT_point2oct(srvr_group, 
+				    EC_KEY_get0_public_key(clnt_ecdh), 
+				    POINT_CONVERSION_UNCOMPRESSED, 
+				    encodedPoint, encoded_pt_len, bn_ctx);
+
+				*p = n; /* length of encoded point */
+				/* Encoded point will be copied here */
+				p += 1; 
+				/* copy the point */
+				memcpy((unsigned char *)p, encodedPoint, n);
+				/* increment n to account for length field */
+				n += 1; 
+				}
+
+			/* Free allocated memory */
+			BN_CTX_free(bn_ctx);
+			if (encodedPoint != NULL) OPENSSL_free(encodedPoint);
+			if (clnt_ecdh != NULL) 
+				 EC_KEY_free(clnt_ecdh);
+			EVP_PKEY_free(srvr_pub_pkey);
+			}
+#endif /* !OPENSSL_NO_ECDH */
+
+#ifndef OPENSSL_NO_PSK
+		else if (alg_k & SSL_kPSK)
+			{
+			char identity[PSK_MAX_IDENTITY_LEN];
+			unsigned char *t = NULL;
+			unsigned char psk_or_pre_ms[PSK_MAX_PSK_LEN*2+4];
+			unsigned int pre_ms_len = 0, psk_len = 0;
+			int psk_err = 1;
+
+			n = 0;
+			if (s->psk_client_callback == NULL)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					SSL_R_PSK_NO_CLIENT_CB);
+				goto err;
+				}
+
+			psk_len = s->psk_client_callback(s, s->ctx->psk_identity_hint,
+				identity, PSK_MAX_IDENTITY_LEN,
+				psk_or_pre_ms, sizeof(psk_or_pre_ms));
+			if (psk_len > PSK_MAX_PSK_LEN)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					ERR_R_INTERNAL_ERROR);
+				goto psk_err;
+				}
+			else if (psk_len == 0)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					SSL_R_PSK_IDENTITY_NOT_FOUND);
+				goto psk_err;
+				}
+
+			/* create PSK pre_master_secret */
+			pre_ms_len = 2+psk_len+2+psk_len;
+			t = psk_or_pre_ms;
+			memmove(psk_or_pre_ms+psk_len+4, psk_or_pre_ms, psk_len);
+			s2n(psk_len, t);
+			memset(t, 0, psk_len);
+			t+=psk_len;
+			s2n(psk_len, t);
+
+			if (s->session->psk_identity_hint != NULL)
+				OPENSSL_free(s->session->psk_identity_hint);
+			s->session->psk_identity_hint = BUF_strdup(s->ctx->psk_identity_hint);
+			if (s->ctx->psk_identity_hint != NULL &&
+				s->session->psk_identity_hint == NULL)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					ERR_R_MALLOC_FAILURE);
+				goto psk_err;
+				}
+
+			if (s->session->psk_identity != NULL)
+				OPENSSL_free(s->session->psk_identity);
+			s->session->psk_identity = BUF_strdup(identity);
+			if (s->session->psk_identity == NULL)
+				{
+				SSLerr(SSL_F_DTLS1_SEND_CLIENT_KEY_EXCHANGE,
+					ERR_R_MALLOC_FAILURE);
+				goto psk_err;
+				}
+
+			s->session->master_key_length =
+				s->method->ssl3_enc->generate_master_secret(s,
+					s->session->master_key,
+					psk_or_pre_ms, pre_ms_len); 
+			n = strlen(identity);
+			s2n(n, p);
+			memcpy(p, identity, n);
+			n+=2;
+			psk_err = 0;
+		psk_err:
+			OPENSSL_cleanse(identity, PSK_MAX_IDENTITY_LEN);
+			OPENSSL_cleanse(psk_or_pre_ms, sizeof(psk_or_pre_ms));
+			if (psk_err != 0)
+				{
+				ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
+				goto err;
+				}
+			}
+#endif
 		else
 			{
 			ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_HANDSHAKE_FAILURE);
@@ -1001,6 +1278,13 @@ int dtls1_send_client_key_exchange(SSL *s)
 	/* SSL3_ST_CW_KEY_EXCH_B */
 	return(dtls1_do_write(s,SSL3_RT_HANDSHAKE));
 err:
+#ifndef OPENSSL_NO_ECDH
+	BN_CTX_free(bn_ctx);
+	if (encodedPoint != NULL) OPENSSL_free(encodedPoint);
+	if (clnt_ecdh != NULL) 
+		EC_KEY_free(clnt_ecdh);
+	EVP_PKEY_free(srvr_pub_pkey);
+#endif
 	return(-1);
 	}
 
@@ -1013,7 +1297,7 @@ int dtls1_send_client_verify(SSL *s)
 	unsigned u=0;
 #endif
 	unsigned long n;
-#ifndef OPENSSL_NO_DSA
+#if !defined(OPENSSL_NO_DSA) || !defined(OPENSSL_NO_ECDSA)
 	int j;
 #endif
 
@@ -1061,6 +1345,23 @@ int dtls1_send_client_verify(SSL *s)
 			}
 		else
 #endif
+#ifndef OPENSSL_NO_ECDSA
+			if (pkey->type == EVP_PKEY_EC)
+			{
+			if (!ECDSA_sign(pkey->save_type,
+				&(data[MD5_DIGEST_LENGTH]),
+				SHA_DIGEST_LENGTH,&(p[2]),
+				(unsigned int *)&j,pkey->pkey.ec))
+				{
+				SSLerr(SSL_F_SSL3_SEND_CLIENT_VERIFY,
+				    ERR_R_ECDSA_LIB);
+				goto err;
+				}
+			s2n(j,p);
+			n=j+2;
+			}
+		else
+#endif
 			{
 			SSLerr(SSL_F_DTLS1_SEND_CLIENT_VERIFY,ERR_R_INTERNAL_ERROR);
 			goto err;