Use the ChaCha-Poly1305 cipher for the SPTPS protocol.
[tinc] / src / sptps.c
index 0369d28..0989b14 100644 (file)
@@ -20,7 +20,7 @@
 
 #include "system.h"
 
-#include "cipher.h"
+#include "chacha-poly1305/chacha-poly1305.h"
 #include "crypto.h"
 #include "ecdh.h"
 #include "ecdsa.h"
@@ -85,26 +85,19 @@ static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const char *data
        char buffer[len + 21UL];
 
        // Create header with sequence number, length and record type
-       uint32_t seqno = htonl(s->outseqno++);
+       uint32_t seqno = s->outseqno++;
+       uint32_t netseqno = ntohl(seqno);
 
-       memcpy(buffer, &seqno, 4);
+       memcpy(buffer, &netseqno, 4);
        buffer[4] = type;
+       memcpy(buffer + 5, data, len);
 
        if(s->outstate) {
                // If first handshake has finished, encrypt and HMAC
-               if(!cipher_set_counter(s->outcipher, &seqno, sizeof seqno))
-                       return error(s, EINVAL, "Failed to set counter");
-
-               if(!cipher_gcm_encrypt_start(s->outcipher, buffer + 4, 1, buffer + 4, NULL))
-                       return error(s, EINVAL, "Error encrypting record");
-
-               if(!cipher_gcm_encrypt_finish(s->outcipher, data, len, buffer + 5, NULL))
-                       return error(s, EINVAL, "Error encrypting record");
-
+               chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL);
                return s->send_data(s->handle, type, buffer, len + 21UL);
        } else {
                // Otherwise send as plaintext
-               memcpy(buffer + 5, data, len);
                return s->send_data(s->handle, type, buffer, len + 5UL);
        }
 }
@@ -116,27 +109,19 @@ static bool send_record_priv(sptps_t *s, uint8_t type, const char *data, uint16_
        char buffer[len + 19UL];
 
        // Create header with sequence number, length and record type
-       uint32_t seqno = htonl(s->outseqno++);
+       uint32_t seqno = s->outseqno++;
        uint16_t netlen = htons(len);
 
        memcpy(buffer, &netlen, 2);
        buffer[2] = type;
+       memcpy(buffer + 3, data, len);
 
        if(s->outstate) {
                // If first handshake has finished, encrypt and HMAC
-               if(!cipher_set_counter(s->outcipher, &seqno, 4))
-                       return error(s, EINVAL, "Failed to set counter");
-
-               if(!cipher_gcm_encrypt_start(s->outcipher, buffer, 3, buffer, NULL))
-                       return error(s, EINVAL, "Error encrypting record");
-
-               if(!cipher_gcm_encrypt_finish(s->outcipher, data, len, buffer + 3, NULL))
-                       return error(s, EINVAL, "Error encrypting record");
-
+               chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL);
                return s->send_data(s->handle, type, buffer, len + 19UL);
        } else {
                // Otherwise send as plaintext
-               memcpy(buffer + 3, data, len);
                return s->send_data(s->handle, type, buffer, len + 3UL);
        }
 }
@@ -204,14 +189,14 @@ static bool send_sig(sptps_t *s) {
 static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
        // Initialise cipher and digest structures if necessary
        if(!s->outstate) {
-               s->incipher = cipher_open_by_name("aes-256-gcm");
-               s->outcipher = cipher_open_by_name("aes-256-gcm");
+               s->incipher = chacha_poly1305_init();
+               s->outcipher = chacha_poly1305_init();
                if(!s->incipher || !s->outcipher)
                        return error(s, EINVAL, "Failed to open cipher");
        }
 
        // Allocate memory for key material
-       size_t keylen = cipher_keylength(s->incipher) + cipher_keylength(s->outcipher);
+       size_t keylen = 2 * CHACHA_POLY1305_KEYLEN;
 
        s->key = realloc(s->key, keylen);
        if(!s->key)
@@ -247,10 +232,10 @@ static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
                return error(s, EIO, "Invalid ACK record length");
 
        if(s->initiator) {
-               if(!cipher_set_counter_key(s->incipher, s->key))
+               if(!chacha_poly1305_set_key(s->incipher, s->key))
                        return error(s, EINVAL, "Failed to set counter");
        } else {
-               if(!cipher_set_counter_key(s->incipher, s->key + cipher_keylength(s->outcipher)))
+               if(!chacha_poly1305_set_key(s->incipher, s->key + CHACHA_POLY1305_KEYLEN))
                        return error(s, EINVAL, "Failed to set counter");
        }
 
@@ -324,11 +309,11 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
 
        // TODO: only set new keys after ACK has been set/received
        if(s->initiator) {
-               if(!cipher_set_counter_key(s->outcipher, s->key + cipher_keylength(s->incipher)))
-                       return error(s, EINVAL, "Failed to set counter");
+               if(!chacha_poly1305_set_key(s->outcipher, s->key + CHACHA_POLY1305_KEYLEN))
+                       return error(s, EINVAL, "Failed to set key");
        } else {
-               if(!cipher_set_counter_key(s->outcipher, s->key))
-                       return error(s, EINVAL, "Failed to set counter");
+               if(!chacha_poly1305_set_key(s->outcipher, s->key))
+                       return error(s, EINVAL, "Failed to set key");
        }
 
        return true;
@@ -422,11 +407,9 @@ static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len
 
        char buffer[len];
 
-       if(!cipher_set_counter(s->incipher, data, sizeof seqno))
-               return error(s, EINVAL, "Failed to set counter");
        size_t outlen;
 
-       if(!cipher_gcm_decrypt(s->incipher, data + 4, len - 4, buffer, &outlen))
+       if(!chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen))
                return error(s, EIO, "Failed to decrypt and verify packet");
 
        // Replay protection using a sliding window of configurable size.
@@ -514,22 +497,9 @@ bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
                        if(s->buflen < 2)
                                return true;
 
-                       // Update sequence number.
-
-                       uint32_t seqno = htonl(s->inseqno++);
-
-                       // Decrypt the length bytes
-
-                       if(s->instate) {
-                               if(!cipher_set_counter(s->incipher, &seqno, 4))
-                                       return error(s, EINVAL, "Failed to set counter");
-
-                               if(!cipher_gcm_decrypt_start(s->incipher, s->inbuf, 2, &s->reclen, NULL))
-                                       return error(s, EINVAL, "Failed to decrypt record");
-                       } else {
-                               memcpy(&s->reclen, s->inbuf, 2);
-                       }
+                       // Get the length bytes
 
+                       memcpy(&s->reclen, s->inbuf, 2);
                        s->reclen = ntohs(s->reclen);
 
                        // If we have the length bytes, ensure our buffer can hold the whole request.
@@ -556,9 +526,13 @@ bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
                if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL))
                        return true;
 
+               // Update sequence number.
+
+               uint32_t seqno = s->inseqno++;
+
                // Check HMAC and decrypt.
                if(s->instate) {
-                       if(!cipher_gcm_decrypt_finish(s->incipher, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
+                       if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
                                return error(s, EINVAL, "Failed to decrypt and verify record");
                }
 
@@ -628,10 +602,8 @@ bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_
 // Stop a SPTPS session.
 bool sptps_stop(sptps_t *s) {
        // Clean up any resources.
-       cipher_close(s->incipher);
-       cipher_close(s->outcipher);
-       digest_close(s->indigest);
-       digest_close(s->outdigest);
+       chacha_poly1305_exit(s->incipher);
+       chacha_poly1305_exit(s->outcipher);
        ecdh_free(s->ecdh);
        free(s->inbuf);
        free(s->mykex);