#include "random.h"
#include "xalloc.h"
+#ifdef HAVE_OPENSSL
+#include <openssl/evp.h>
+#endif
+
unsigned int sptps_replaywin = 16;
/*
xzfree(key, sizeof(sptps_key_t));
}
+static bool cipher_init(uint8_t suite, void **ctx, const sptps_key_t *keys, bool key_half) {
+ const uint8_t *key = key_half ? keys->key1 : keys->key0;
+
+ switch(suite) {
+ case SPTPS_CHACHA_POLY1305:
+ *ctx = chacha_poly1305_init();
+ return ctx && chacha_poly1305_set_key(*ctx, key);
+
+ case SPTPS_AES256_GCM:
+#ifdef HAVE_OPENSSL
+ *ctx = EVP_CIPHER_CTX_new();
+
+ if(!ctx) {
+ return false;
+ }
+
+ return EVP_EncryptInit_ex(*ctx, EVP_aes_256_gcm(), NULL, NULL, NULL)
+ && EVP_CIPHER_CTX_ctrl(*ctx, EVP_CTRL_AEAD_SET_IVLEN, 4, NULL)
+ && EVP_EncryptInit_ex(*ctx, NULL, NULL, key, key + 32);
+#endif
+
+ default:
+ return false;
+ }
+}
+
+static void cipher_exit(uint8_t suite, void *ctx) {
+ switch(suite) {
+ case SPTPS_CHACHA_POLY1305:
+ chacha_poly1305_exit(ctx);
+ break;
+
+ case SPTPS_AES256_GCM:
+#ifdef HAVE_OPENSSL
+ EVP_CIPHER_CTX_free(ctx);
+ break;
+#endif
+
+ default:
+ break;
+ }
+}
+
+static bool cipher_encrypt(uint8_t suite, void *ctx, uint32_t seqno, const uint8_t *in, size_t inlen, uint8_t *out, size_t *outlen) {
+ switch(suite) {
+ case SPTPS_CHACHA_POLY1305:
+ chacha_poly1305_encrypt(ctx, seqno, in, inlen, out, outlen);
+ return true;
+
+ case SPTPS_AES256_GCM:
+#ifdef HAVE_OPENSSL
+ {
+ if(!EVP_EncryptInit_ex(ctx, NULL, NULL, NULL, (uint8_t *)&seqno)) {
+ return false;
+ }
+
+ int outlen1 = 0, outlen2 = 0;
+
+ if(!EVP_EncryptUpdate(ctx, out, &outlen1, in, (int)inlen)) {
+ return false;
+ }
+
+ if(!EVP_EncryptFinal_ex(ctx, out + outlen1, &outlen2)) {
+ return false;
+ }
+
+ outlen1 += outlen2;
+
+ if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, out + outlen1)) {
+ return false;
+ }
+
+ outlen1 += 16;
+
+ if(outlen) {
+ *outlen = outlen1;
+ }
+
+ return true;
+ }
+
+#endif
+
+ default:
+ return false;
+ }
+}
+
+static bool cipher_decrypt(uint8_t suite, void *ctx, uint32_t seqno, const uint8_t *in, size_t inlen, uint8_t *out, size_t *outlen) {
+ switch(suite) {
+ case SPTPS_CHACHA_POLY1305:
+ return chacha_poly1305_decrypt(ctx, seqno, in, inlen, out, outlen);
+
+ case SPTPS_AES256_GCM:
+#ifdef HAVE_OPENSSL
+ {
+ if(inlen < 16) {
+ return false;
+ }
+
+ inlen -= 16;
+
+ if(!EVP_DecryptInit_ex(ctx, NULL, NULL, NULL, (uint8_t *)&seqno)) {
+ return false;
+ }
+
+ int outlen1 = 0, outlen2 = 0;
+
+ if(!EVP_DecryptUpdate(ctx, out, &outlen1, in, (int)inlen)) {
+ return false;
+ }
+
+ if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16, (void *)(in + inlen))) {
+ return false;
+ }
+
+ if(!EVP_DecryptFinal_ex(ctx, out + outlen1, &outlen2)) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = outlen1 + outlen2;
+ }
+
+ return true;
+ }
+
+#endif
+
+ default:
+ return false;
+ }
+}
+
// Send a record (datagram version, accepts all record types, handles encryption and authentication).
static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
- uint8_t *buffer = alloca(len + 21UL);
-
+ uint8_t *buffer = alloca(len + SPTPS_DATAGRAM_OVERHEAD);
// Create header with sequence number, length and record type
uint32_t seqno = s->outseqno++;
- uint32_t netseqno = ntohl(seqno);
- memcpy(buffer, &netseqno, 4);
+ memcpy(buffer, &seqno, 4);
buffer[4] = type;
memcpy(buffer + 5, data, len);
if(s->outstate) {
// If first handshake has finished, encrypt and HMAC
- chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL);
- return s->send_data(s->handle, type, buffer, len + 21UL);
+ if(!cipher_encrypt(s->cipher_suite, s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL)) {
+ return error(s, EINVAL, "Failed to encrypt message");
+ }
+
+ return s->send_data(s->handle, type, buffer, len + SPTPS_DATAGRAM_OVERHEAD);
} else {
// Otherwise send as plaintext
- return s->send_data(s->handle, type, buffer, len + 5UL);
+ return s->send_data(s->handle, type, buffer, len + SPTPS_DATAGRAM_HEADER);
}
}
// Send a record (private version, accepts all record types, handles encryption and authentication).
return send_record_priv_datagram(s, type, data, len);
}
- uint8_t *buffer = alloca(len + 19UL);
+ uint8_t *buffer = alloca(len + SPTPS_OVERHEAD);
// Create header with sequence number, length and record type
uint32_t seqno = s->outseqno++;
- uint16_t netlen = htons(len);
+ uint16_t netlen = len;
memcpy(buffer, &netlen, 2);
buffer[2] = type;
if(s->outstate) {
// If first handshake has finished, encrypt and HMAC
- chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL);
- return s->send_data(s->handle, type, buffer, len + 19UL);
+ if(!cipher_encrypt(s->cipher_suite, s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL)) {
+ return error(s, EINVAL, "Failed to encrypt message");
+ }
+
+ return s->send_data(s->handle, type, buffer, len + SPTPS_OVERHEAD);
} else {
// Otherwise send as plaintext
- return s->send_data(s->handle, type, buffer, len + 3UL);
+ return s->send_data(s->handle, type, buffer, len + SPTPS_HEADER);
}
}
// Set version byte to zero.
s->mykex->version = SPTPS_VERSION;
+ s->mykex->preferred_suite = s->preferred_suite;
+ s->mykex->cipher_suites = s->cipher_suites;
// Create a random nonce.
randomize(s->mykex->nonce, ECDH_SIZE);
// Generate key material from the shared secret created from the ECDHE key exchange.
static bool generate_key_material(sptps_t *s, const uint8_t *shared, size_t len) {
- // Initialise cipher and digest structures if necessary
- if(!s->outstate) {
- 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
s->key = new_sptps_key();
return error(s, EIO, "Invalid ACK record length");
}
- uint8_t *key = s->initiator ? s->key->key0 : s->key->key1;
-
- if(!chacha_poly1305_set_key(s->incipher, key)) {
- return error(s, EINVAL, "Failed to set counter");
+ if(!cipher_init(s->cipher_suite, &s->incipher, s->key, s->initiator)) {
+ return error(s, EINVAL, "Failed to initialize cipher");
}
free_sptps_key(s->key);
return true;
}
+static uint8_t select_cipher_suite(uint16_t mask, uint8_t pref1, uint8_t pref2) {
+ // Check if there is a viable preference, if so select the lowest one
+ uint8_t selection = 255;
+
+ if(mask & (1U << pref1)) {
+ selection = pref1;
+ }
+
+ if(pref2 < selection && (mask & (1U << pref2))) {
+ selection = pref2;
+ }
+
+ // Otherwise, select the lowest cipher suite both sides support
+ if(selection == 255) {
+ selection = 0;
+
+ while(!(mask & 1U)) {
+ selection++;
+ mask >>= 1;
+ }
+ }
+
+ return selection;
+}
+
// Receive a Key EXchange record, respond by sending a SIG record.
static bool receive_kex(sptps_t *s, const uint8_t *data, uint16_t len) {
// Verify length of the HELLO record
+
if(len != sizeof(sptps_kex_t)) {
return error(s, EIO, "Invalid KEX record length");
}
return error(s, EINVAL, "Received incorrect version %d", *data);
}
+ uint16_t suites;
+ memcpy(&suites, data + 2, 2);
+ suites &= s->cipher_suites;
+
+ if(!suites) {
+ return error(s, EIO, "No matching cipher suites");
+ }
+
+ s->cipher_suite = select_cipher_suite(suites, s->preferred_suite, data[1] & 0xf);
+
// Make a copy of the KEX message, send_sig() and receive_sig() need it
if(s->hiskex) {
return error(s, EINVAL, "Received a second KEX message before first has been processed");
return false;
}
- // TODO: only set new keys after ACK has been set/received
- uint8_t *key = s->initiator ? s->key->key1 : s->key->key0;
-
- if(!chacha_poly1305_set_key(s->outcipher, key)) {
- return error(s, EINVAL, "Failed to set key");
+ if(!cipher_init(s->cipher_suite, &s->outcipher, s->key, !s->initiator)) {
+ return error(s, EINVAL, "Failed to initialize cipher");
}
return true;
const uint8_t *data = vdata;
uint32_t seqno;
memcpy(&seqno, data, 4);
- seqno = ntohl(seqno);
if(!sptps_check_seqno(s, seqno, false)) {
return false;
}
uint8_t *buffer = alloca(len);
- size_t outlen;
- return chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen);
+ return cipher_decrypt(s->cipher_suite, s->incipher, seqno, data + 4, len - 4, buffer, NULL);
}
// Receive incoming data, datagram version.
uint32_t seqno;
memcpy(&seqno, data, 4);
- seqno = ntohl(seqno);
data += 4;
len -= 4;
uint8_t *buffer = alloca(len);
size_t outlen;
- if(!chacha_poly1305_decrypt(s->incipher, seqno, data, len, buffer, &outlen)) {
+ if(!cipher_decrypt(s->cipher_suite, s->incipher, seqno, data, len, buffer, &outlen)) {
return error(s, EIO, "Failed to decrypt and verify packet");
}
// 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.
- s->inbuf = realloc(s->inbuf, s->reclen + 19UL);
+ s->inbuf = realloc(s->inbuf, s->reclen + SPTPS_OVERHEAD);
if(!s->inbuf) {
return error(s, errno, "%s", strerror(errno));
}
// Read up to the end of the record.
- size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
+ size_t toread = s->reclen + (s->instate ? SPTPS_OVERHEAD : SPTPS_HEADER) - s->buflen;
if(toread > len) {
toread = len;
s->buflen += toread;
// If we don't have a whole record, exit.
- if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL)) {
+ if(s->buflen < s->reclen + (s->instate ? SPTPS_OVERHEAD : SPTPS_HEADER)) {
return total_read;
}
// Check HMAC and decrypt.
if(s->instate) {
- if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL)) {
+ if(!cipher_decrypt(s->cipher_suite, s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL)) {
return error(s, EINVAL, "Failed to decrypt and verify record");
}
}
// Append a NULL byte for safety.
- s->inbuf[s->reclen + 3UL] = 0;
+ s->inbuf[s->reclen + SPTPS_HEADER] = 0;
uint8_t type = s->inbuf[2];
}
// Start a SPTPS session.
-bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t *mykey, ecdsa_t *hiskey, const void *label, size_t labellen, send_data_t send_data, receive_record_t receive_record) {
+bool sptps_start(sptps_t *s, const sptps_params_t *params) {
// Initialise struct sptps
memset(s, 0, sizeof(*s));
- s->handle = handle;
- s->initiator = initiator;
- s->datagram = datagram;
- s->mykey = mykey;
- s->hiskey = hiskey;
+ s->handle = params->handle;
+ s->initiator = params->initiator;
+ s->datagram = params->datagram;
+ s->mykey = params->mykey;
+ s->hiskey = params->hiskey;
s->replaywin = sptps_replaywin;
+ s->cipher_suites = params->cipher_suites ? params->cipher_suites & SPTPS_ALL_CIPHER_SUITES : SPTPS_ALL_CIPHER_SUITES;
+ s->preferred_suite = params->preferred_suite;
if(s->replaywin) {
s->late = malloc(s->replaywin);
memset(s->late, 0, s->replaywin);
}
- s->label = malloc(labellen);
+ s->labellen = params->labellen ? params->labellen : strlen(params->label);
+ s->label = malloc(s->labellen);
if(!s->label) {
return error(s, errno, "%s", strerror(errno));
}
- if(!datagram) {
+ memcpy(s->label, params->label, s->labellen);
+
+ if(!s->datagram) {
s->inbuf = malloc(7);
if(!s->inbuf) {
s->buflen = 0;
}
- memcpy(s->label, label, labellen);
- s->labellen = labellen;
- s->send_data = send_data;
- s->receive_record = receive_record;
+ s->send_data = params->send_data;
+ s->receive_record = params->receive_record;
// Do first KEX immediately
s->state = SPTPS_KEX;
// Stop a SPTPS session.
bool sptps_stop(sptps_t *s) {
// Clean up any resources.
- chacha_poly1305_exit(s->incipher);
- chacha_poly1305_exit(s->outcipher);
+ cipher_exit(s->cipher_suite, s->incipher);
+ cipher_exit(s->cipher_suite, s->outcipher);
ecdh_free(s->ecdh);
free(s->inbuf);
free_sptps_kex(s->mykex);
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