Use AES-256-GCM for the SPTPS protocol.
It is faster than AES-256-CTR + HMAC-SHA256, especially on Intel chips with AES and PCLMULQDQ instructions.
This commit is contained in:
Guus Sliepen
parent
e42bd60097
commit
0da0728088
4 changed files with 251 additions and 169 deletions
199
src/sptps.c
199
src/sptps.c
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@ -22,7 +22,6 @@
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#include "cipher.h"
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#include "crypto.h"
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#include "digest.h"
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#include "ecdh.h"
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#include "ecdsa.h"
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#include "logger.h"
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@ -83,34 +82,30 @@ static void warning(sptps_t *s, const char *format, ...) {
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// Send a record (datagram version, accepts all record types, handles encryption and authentication).
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static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
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char buffer[len + 23UL];
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char buffer[len + 21UL];
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// Create header with sequence number, length and record type
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uint32_t seqno = htonl(s->outseqno++);
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uint16_t netlen = htons(len);
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memcpy(buffer, &netlen, 2);
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memcpy(buffer + 2, &seqno, 4);
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buffer[6] = type;
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// Add plaintext (TODO: avoid unnecessary copy)
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memcpy(buffer + 7, data, len);
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memcpy(buffer, &seqno, 4);
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buffer[4] = type;
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if(s->outstate) {
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// If first handshake has finished, encrypt and HMAC
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if(!cipher_set_counter(s->outcipher, &seqno, sizeof seqno))
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return false;
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return error(s, EINVAL, "Failed to set counter");
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if(!cipher_counter_xor(s->outcipher, buffer + 6, len + 1UL, buffer + 6))
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return false;
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if(!cipher_gcm_encrypt_start(s->outcipher, buffer + 4, 1, buffer + 4, NULL))
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return error(s, EINVAL, "Error encrypting record");
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if(!digest_create(s->outdigest, buffer, len + 7UL, buffer + 7UL + len))
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return false;
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if(!cipher_gcm_encrypt_finish(s->outcipher, data, len, buffer + 5, NULL))
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return error(s, EINVAL, "Error encrypting record");
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return s->send_data(s->handle, type, buffer + 2, len + 21UL);
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return s->send_data(s->handle, type, buffer, len + 21UL);
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} else {
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// Otherwise send as plaintext
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return s->send_data(s->handle, type, buffer + 2, len + 5UL);
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memcpy(buffer + 5, data, len);
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return s->send_data(s->handle, type, buffer, len + 5UL);
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}
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}
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// Send a record (private version, accepts all record types, handles encryption and authentication).
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@ -118,31 +113,31 @@ static bool send_record_priv(sptps_t *s, uint8_t type, const char *data, uint16_
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if(s->datagram)
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return send_record_priv_datagram(s, type, data, len);
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char buffer[len + 23UL];
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char buffer[len + 19UL];
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// Create header with sequence number, length and record type
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uint32_t seqno = htonl(s->outseqno++);
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uint16_t netlen = htons(len);
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memcpy(buffer, &seqno, 4);
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memcpy(buffer + 4, &netlen, 2);
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buffer[6] = type;
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// Add plaintext (TODO: avoid unnecessary copy)
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memcpy(buffer + 7, data, len);
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memcpy(buffer, &netlen, 2);
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buffer[2] = type;
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if(s->outstate) {
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// If first handshake has finished, encrypt and HMAC
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if(!cipher_counter_xor(s->outcipher, buffer + 4, len + 3UL, buffer + 4))
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return false;
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if(!cipher_set_counter(s->outcipher, &seqno, 4))
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return error(s, EINVAL, "Failed to set counter");
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if(!digest_create(s->outdigest, buffer, len + 7UL, buffer + 7UL + len))
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return false;
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if(!cipher_gcm_encrypt_start(s->outcipher, buffer, 3, buffer, NULL))
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return error(s, EINVAL, "Error encrypting record");
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return s->send_data(s->handle, type, buffer + 4, len + 19UL);
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if(!cipher_gcm_encrypt_finish(s->outcipher, data, len, buffer + 3, NULL))
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return error(s, EINVAL, "Error encrypting record");
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return s->send_data(s->handle, type, buffer, len + 19UL);
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} else {
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// Otherwise send as plaintext
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return s->send_data(s->handle, type, buffer + 4, len + 3UL);
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memcpy(buffer + 3, data, len);
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return s->send_data(s->handle, type, buffer, len + 3UL);
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}
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}
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@ -165,7 +160,7 @@ static bool send_kex(sptps_t *s) {
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// Make room for our KEX message, which we will keep around since send_sig() needs it.
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if(s->mykex)
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abort();
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return false;
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s->mykex = realloc(s->mykex, 1 + 32 + keylen);
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if(!s->mykex)
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return error(s, errno, strerror(errno));
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@ -178,7 +173,7 @@ static bool send_kex(sptps_t *s) {
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// Create a new ECDH public key.
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if(!(s->ecdh = ecdh_generate_public(s->mykex + 1 + 32)))
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return false;
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return error(s, EINVAL, "Failed to generate ECDH public key");
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return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, 1 + 32 + keylen);
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}
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@ -199,7 +194,7 @@ static bool send_sig(sptps_t *s) {
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// Sign the result.
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if(!ecdsa_sign(s->mykey, msg, sizeof msg, sig))
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return false;
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return error(s, EINVAL, "Failed to sign SIG record");
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// Send the SIG exchange record.
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return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof sig);
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@ -209,16 +204,14 @@ static bool send_sig(sptps_t *s) {
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static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
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// Initialise cipher and digest structures if necessary
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if(!s->outstate) {
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s->incipher = cipher_open_by_name("aes-256-ecb");
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s->outcipher = cipher_open_by_name("aes-256-ecb");
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s->indigest = digest_open_by_name("sha256", 16);
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s->outdigest = digest_open_by_name("sha256", 16);
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if(!s->incipher || !s->outcipher || !s->indigest || !s->outdigest)
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return false;
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s->incipher = cipher_open_by_name("aes-256-gcm");
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s->outcipher = cipher_open_by_name("aes-256-gcm");
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if(!s->incipher || !s->outcipher)
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return error(s, EINVAL, "Failed to open cipher");
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}
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// Allocate memory for key material
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size_t keylen = digest_keylength(s->indigest) + digest_keylength(s->outdigest) + cipher_keylength(s->incipher) + cipher_keylength(s->outcipher);
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size_t keylen = cipher_keylength(s->incipher) + cipher_keylength(s->outcipher);
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s->key = realloc(s->key, keylen);
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if(!s->key)
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@ -238,7 +231,7 @@ static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
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// Use PRF to generate the key material
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if(!prf(shared, len, seed, s->labellen + 64 + 13, s->key, keylen))
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return false;
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return error(s, EINVAL, "Failed to generate key material");
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return true;
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}
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@ -254,17 +247,11 @@ static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
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return error(s, EIO, "Invalid ACK record length");
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if(s->initiator) {
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bool result
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= cipher_set_counter_key(s->incipher, s->key)
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&& digest_set_key(s->indigest, s->key + cipher_keylength(s->incipher), digest_keylength(s->indigest));
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if(!result)
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return false;
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if(!cipher_set_counter_key(s->incipher, s->key))
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return error(s, EINVAL, "Failed to set counter");
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} else {
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bool result
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= cipher_set_counter_key(s->incipher, s->key + cipher_keylength(s->outcipher) + digest_keylength(s->outdigest))
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&& digest_set_key(s->indigest, s->key + cipher_keylength(s->outcipher) + digest_keylength(s->outdigest) + cipher_keylength(s->incipher), digest_keylength(s->indigest));
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if(!result)
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return false;
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if(!cipher_set_counter_key(s->incipher, s->key + cipher_keylength(s->outcipher)))
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return error(s, EINVAL, "Failed to set counter");
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}
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free(s->key);
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@ -284,7 +271,7 @@ static bool receive_kex(sptps_t *s, const char *data, uint16_t len) {
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// Make a copy of the KEX message, send_sig() and receive_sig() need it
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if(s->hiskex)
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abort();
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return error(s, EINVAL, "Received a second KEX message before first has been processed");
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s->hiskex = realloc(s->hiskex, len);
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if(!s->hiskex)
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return error(s, errno, strerror(errno));
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@ -313,12 +300,12 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
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// Verify signature.
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if(!ecdsa_verify(s->hiskey, msg, sizeof msg, data))
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return false;
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return error(s, EIO, "Failed to verify SIG record");
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// Compute shared secret.
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char shared[ECDH_SHARED_SIZE];
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if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared))
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return false;
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return error(s, EINVAL, "Failed to compute ECDH shared secret");
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s->ecdh = NULL;
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// Generate key material from shared secret.
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@ -337,17 +324,11 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
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// TODO: only set new keys after ACK has been set/received
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if(s->initiator) {
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bool result
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= cipher_set_counter_key(s->outcipher, s->key + cipher_keylength(s->incipher) + digest_keylength(s->indigest))
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&& digest_set_key(s->outdigest, s->key + cipher_keylength(s->incipher) + digest_keylength(s->indigest) + cipher_keylength(s->outcipher), digest_keylength(s->outdigest));
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if(!result)
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return false;
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if(!cipher_set_counter_key(s->outcipher, s->key + cipher_keylength(s->incipher)))
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return error(s, EINVAL, "Failed to set counter");
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} else {
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bool result
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= cipher_set_counter_key(s->outcipher, s->key)
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&& digest_set_key(s->outdigest, s->key + cipher_keylength(s->outcipher), digest_keylength(s->outdigest));
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if(!result)
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return false;
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if(!cipher_set_counter_key(s->outcipher, s->key))
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return error(s, EINVAL, "Failed to set counter");
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}
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return true;
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@ -407,15 +388,11 @@ static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
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// Check datagram for valid HMAC
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bool sptps_verify_datagram(sptps_t *s, const char *data, size_t len) {
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if(!s->instate || len < 21)
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return false;
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return error(s, EIO, "Received short packet");
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char buffer[len + 23];
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uint16_t netlen = htons(len - 21);
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// TODO: just decrypt without updating the replay window
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memcpy(buffer, &netlen, 2);
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memcpy(buffer + 2, data, len);
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return digest_verify(s->indigest, buffer, len - 14, buffer + len - 14);
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return true;
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}
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// Receive incoming data, datagram version.
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@ -441,16 +418,16 @@ static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len
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return receive_handshake(s, data + 5, len - 5);
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}
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// Check HMAC.
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uint16_t netlen = htons(len - 21);
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// Decrypt
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char buffer[len + 23];
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char buffer[len];
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memcpy(buffer, &netlen, 2);
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memcpy(buffer + 2, data, len);
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if(!cipher_set_counter(s->incipher, data, sizeof seqno))
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return error(s, EINVAL, "Failed to set counter");
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size_t outlen;
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if(!digest_verify(s->indigest, buffer, len - 14, buffer + len - 14))
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return error(s, EIO, "Invalid HMAC");
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if(!cipher_gcm_decrypt(s->incipher, data + 4, len - 4, buffer, &outlen))
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return error(s, EIO, "Failed to decrypt and verify packet");
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// Replay protection using a sliding window of configurable size.
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// s->inseqno is expected sequence number
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@ -492,26 +469,19 @@ static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len
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else
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s->received++;
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// Decrypt.
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memcpy(&seqno, buffer + 2, 4);
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if(!cipher_set_counter(s->incipher, &seqno, sizeof seqno))
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return false;
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if(!cipher_counter_xor(s->incipher, buffer + 6, len - 4, buffer + 6))
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return false;
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// Append a NULL byte for safety.
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buffer[len - 14] = 0;
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buffer[len - 20] = 0;
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uint8_t type = buffer[6];
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uint8_t type = buffer[0];
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if(type < SPTPS_HANDSHAKE) {
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if(!s->instate)
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return error(s, EIO, "Application record received before handshake finished");
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if(!s->receive_record(s->handle, type, buffer + 7, len - 21))
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return false;
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if(!s->receive_record(s->handle, type, buffer + 1, len - 21))
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abort();
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} else if(type == SPTPS_HANDSHAKE) {
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if(!receive_handshake(s, buffer + 7, len - 21))
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return false;
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if(!receive_handshake(s, buffer + 1, len - 21))
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abort();
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} else {
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return error(s, EIO, "Invalid record type %d", type);
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}
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@ -529,8 +499,8 @@ bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
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while(len) {
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// First read the 2 length bytes.
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if(s->buflen < 6) {
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size_t toread = 6 - s->buflen;
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if(s->buflen < 2) {
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size_t toread = 2 - s->buflen;
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if(toread > len)
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toread = len;
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@ -541,36 +511,39 @@ bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
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data += toread;
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// Exit early if we don't have the full length.
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if(s->buflen < 6)
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if(s->buflen < 2)
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return true;
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// Update sequence number.
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uint32_t seqno = htonl(s->inseqno++);
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// Decrypt the length bytes
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if(s->instate) {
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if(!cipher_counter_xor(s->incipher, s->inbuf + 4, 2, &s->reclen))
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return false;
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if(!cipher_set_counter(s->incipher, &seqno, 4))
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return error(s, EINVAL, "Failed to set counter");
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if(!cipher_gcm_decrypt_start(s->incipher, s->inbuf, 2, &s->reclen, NULL))
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return error(s, EINVAL, "Failed to decrypt record");
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} else {
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memcpy(&s->reclen, s->inbuf + 4, 2);
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memcpy(&s->reclen, s->inbuf, 2);
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}
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s->reclen = ntohs(s->reclen);
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// If we have the length bytes, ensure our buffer can hold the whole request.
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s->inbuf = realloc(s->inbuf, s->reclen + 23UL);
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s->inbuf = realloc(s->inbuf, s->reclen + 19UL);
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if(!s->inbuf)
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return error(s, errno, strerror(errno));
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// Add sequence number.
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uint32_t seqno = htonl(s->inseqno++);
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memcpy(s->inbuf, &seqno, 4);
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// Exit early if we have no more data to process.
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if(!len)
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return true;
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}
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// Read up to the end of the record.
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size_t toread = s->reclen + (s->instate ? 23UL : 7UL) - s->buflen;
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size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
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if(toread > len)
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toread = len;
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@ -580,36 +553,33 @@ bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
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data += toread;
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// If we don't have a whole record, exit.
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if(s->buflen < s->reclen + (s->instate ? 23UL : 7UL))
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if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL))
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return true;
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// Check HMAC and decrypt.
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if(s->instate) {
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if(!digest_verify(s->indigest, s->inbuf, s->reclen + 7UL, s->inbuf + s->reclen + 7UL))
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return error(s, EIO, "Invalid HMAC");
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if(!cipher_counter_xor(s->incipher, s->inbuf + 6UL, s->reclen + 1UL, s->inbuf + 6UL))
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return false;
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if(!cipher_gcm_decrypt_finish(s->incipher, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
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return error(s, EINVAL, "Failed to decrypt and verify record");
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}
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// Append a NULL byte for safety.
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s->inbuf[s->reclen + 7UL] = 0;
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s->inbuf[s->reclen + 3UL] = 0;
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uint8_t type = s->inbuf[6];
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uint8_t type = s->inbuf[2];
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if(type < SPTPS_HANDSHAKE) {
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if(!s->instate)
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return error(s, EIO, "Application record received before handshake finished");
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||||
if(!s->receive_record(s->handle, type, s->inbuf + 7, s->reclen))
|
||||
if(!s->receive_record(s->handle, type, s->inbuf + 3, s->reclen))
|
||||
return false;
|
||||
} else if(type == SPTPS_HANDSHAKE) {
|
||||
if(!receive_handshake(s, s->inbuf + 7, s->reclen))
|
||||
if(!receive_handshake(s, s->inbuf + 3, s->reclen))
|
||||
return false;
|
||||
} else {
|
||||
return error(s, EIO, "Invalid record type %d", type);
|
||||
}
|
||||
|
||||
s->buflen = 4;
|
||||
s->buflen = 0;
|
||||
}
|
||||
|
||||
return true;
|
||||
|
|
@ -641,8 +611,7 @@ bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_
|
|||
s->inbuf = malloc(7);
|
||||
if(!s->inbuf)
|
||||
return error(s, errno, strerror(errno));
|
||||
s->buflen = 4;
|
||||
memset(s->inbuf, 0, 4);
|
||||
s->buflen = 0;
|
||||
}
|
||||
|
||||
memcpy(s->label, label, labellen);
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue