/**
* @brief Initiate an XSSL connection with server.
*
* @param xssl
*
* @return 1 on success, <1 on failure
*/
int XSSL_connect(XSSL *xssl) {
char buf[XIA_MAXBUF];
int n;
/* Send CLIENT HELLO */
sprintf(buf, "CLIENT HELLO");
if ((n = Xsend(xssl->sockfd, buf, strlen(buf), 0)) != strlen(buf)) {
ERROR("ERROR sending CLIENT HELLO");
return 0;
}
/* Wait for SERVER HELLO */
// Receive public key + temporary public key signed by server's long-term private key
// Continue receiving until we see "SERVER DONE"
int offset = 0;
while ( offset < 11 || strcmp("SERVER DONE", &buf[offset-11]) != 0 ) {
n = Xrecv(xssl->sockfd, &buf[offset], sizeof(buf)-offset, 0);
if (n < 0) {
ERROR("ERROR receiving SERVER HELLO");
return n;
}
if (n == 0) {
ERROR("ERROR: server closed connection during SERVER HELLO");
return n;
}
offset += n;
}
/* Parse public keys from SERVER HELLO */
offset = strlen("SERVER HELLO");
char *keys = &buf[offset]; // start of signed portion of message
uint32_t *keybufsizeptr = (uint32_t*)&buf[offset];
uint32_t keybufsize = *keybufsizeptr; // TODO: error checking here
offset += sizeof(uint32_t);
RSA *pubkey = deserialize_rsa_pub_key(&buf[offset], keybufsize);
offset += keybufsize;
uint32_t *tempkeybufsizeptr = (uint32_t*)&buf[offset];
uint32_t tempkeybufsize = *tempkeybufsizeptr;
offset += sizeof(uint32_t);
RSA *sessionPubkey = deserialize_rsa_pub_key(&buf[offset], tempkeybufsize);
offset += tempkeybufsize;
uint32_t *siglenptr = (uint32_t*)&buf[offset];
uint32_t siglen = *siglenptr;
offset += sizeof(uint32_t);
char* sig = &buf[offset];
offset += siglen;
DBGF("Received keys:\n\tkeylen: %d\n\ttempkeylen: %d\n\tsiglen: %d", keybufsize, tempkeybufsize, siglen);
/* Verify two things:
* 1) hash(key) == SID so we trust the signature
* 2) verify the sig so we trust the temp key
*/
sockaddr_x *sa = (sockaddr_x*)malloc(sizeof(sockaddr_x));
socklen_t len = sizeof(sockaddr_x);
if (Xgetpeername(xssl->sockfd, (struct sockaddr*)sa, &len) < 0) {
ERRORF("Error in Xgetpeername on socket %d: %s", xssl->sockfd, strerror(errno));
return 0;
}
Graph g(sa);
Node sid_node = g.get_final_intent();
DBGF("SID: %s", sid_node.to_string().c_str());
char *sid_from_key_hash = SID_from_keypair(pubkey);
DBGF("Pub key hash: %s", sid_from_key_hash);
if (strcmp(sid_node.to_string().c_str(), sid_from_key_hash) != 0) {
WARN("Hash of received public key does not match SID! Closing connection.");
return 0;
}
if (verify(pubkey, keys, keybufsize+tempkeybufsize+2*sizeof(uint32_t), sig, siglen) != 1) {
WARN("Unable to verify signature on temporary RSA keypair! Closing connection.");
return 0;
}
/* Generate pre-master secret and send to server, encrypted with sessionPubKey */
unsigned char* pms = (unsigned char*)malloc(PRE_MASTER_SECRET_LENGTH);
if (RAND_bytes(pms, PRE_MASTER_SECRET_LENGTH) != 1) {
ERROR("ERROR: Couldn't generate pre-master secret");
return 0;
}
if (VERBOSITY >= V_DEBUG) {
DBG("Pre-Master Secret:");
print_bytes(pms, PRE_MASTER_SECRET_LENGTH);
}
int ciphertext_len;
if ( (ciphertext_len = pub_encrypt(sessionPubkey,
pms, PRE_MASTER_SECRET_LENGTH,
buf, XIA_MAXBUF)) == -1 ) {
ERROR("ERROR: Unable to encrypt session key");
return 0;
}
n = 0;
offset = 0;
while (offset < ciphertext_len) {
if ((n = Xsend(xssl->sockfd, &buf[offset], ciphertext_len-offset, 0)) < 0) {
ERROR("ERROR sending pre-master secret");
return 0;
}
offset += n;
}
/* Init symmetric session ciphers with pre-master secret.
Client encrypt context initialized with same key data as
server decrypt context and vice versa. */
uint32_t salt[] = SALT;
if (aes_init(pms, PRE_MASTER_SECRET_LENGTH/2,
&pms[PRE_MASTER_SECRET_LENGTH/2], PRE_MASTER_SECRET_LENGTH/2,
(unsigned char *)&salt, xssl->en, xssl->de)) {
ERROR("ERROR initializing AES ciphers");
return 0;
}
free(pms);
/* For now, omitting CLIENT DONE */
return 1;
}
int EncryptionModule::handshake_in(char *buf, size_t *datalen, size_t *buflen) {
(void)buflen;
/* pick up where we left off in the handshake */
switch(handshake_status_) {
case kWaitForClientHello: // server-side
{
/* make sure the data is a complete client hello */
if (strncmp("CLIENT HELLO", buf, 12) != 0) {
ERROR("ERROR: received message was not CLIENT HELLO\n");
return ERR_NEED_MORE_DATA;
} else {
// FIXME: inefficient!
// int hello_len = strlen("CLIENT HELLO");
// char* newbuf = (char*)malloc(*buflen);
// memcpy(newbuf, buf+hello_len, *datalen-hello_len);
// *datalen -= hello_len;
// free(buf);
// buf = newbuf; // FIXME: need pointer to pointer
handshake_status_ = kSendServerHello;
return 0;
}
}
case kWaitForServerHello: // client-side
{
/* Wait for SERVER HELLO */
// Receive public key + temporary public key signed by server's long-term private key
// Continue receiving until we see "SERVER DONE"
// FIXME: this assumes there's no handshake data after us!
if (*datalen < 11 || strcmp("SERVER DONE", (buf+*datalen-11)) != 0) {
ERROR("Did not receive complete SERVER DONE. Waiting for more data\n");
return ERR_NEED_MORE_DATA;
}
/* Parse public keys from SERVER HELLO */
int offset = strlen("SERVER HELLO");
char *keys = buf+offset; // start of signed portion of message
uint32_t *keybufsizeptr = (uint32_t*)(buf+offset);
uint32_t keybufsize = *keybufsizeptr; // TODO: error checking here
offset += sizeof(uint32_t);
RSA *pubkey = deserialize_rsa_pub_key(buf+offset, keybufsize);
offset += keybufsize;
uint32_t *tempkeybufsizeptr = (uint32_t*)(buf+offset);
uint32_t tempkeybufsize = *tempkeybufsizeptr;
offset += sizeof(uint32_t);
session_pub_key_ = deserialize_rsa_pub_key(buf+offset, tempkeybufsize);
offset += tempkeybufsize;
uint32_t *siglenptr = (uint32_t*)(buf+offset);
uint32_t siglen = *siglenptr;
offset += sizeof(uint32_t);
char* sig = buf+offset;
offset += siglen;
DBGF("Received keys:\n\tkeylen: %d\n\ttempkeylen: %d\n\tsiglen: %d", keybufsize, tempkeybufsize, siglen);
/* Verify two things:
* 1) in the real world, verify the key in the cert
* 2) verify the sig so we trust the temp key
*/
if (verify(pubkey, keys, keybufsize+tempkeybufsize+2*sizeof(uint32_t), sig, siglen) != 1) {
WARN("Unable to verify signature on temporary RSA keypair! Closing connection.");
return ERR_GENERIC;
}
// FIXME: inefficient!
// char* newbuf = (char*)malloc(*buflen);
// int used_len = offset + strlen("SERVER DONE");
// memcpy(newbuf, buf+used_len, *datalen-used_len);
// *datalen -= used_len;
// free(buf);
// buf = newbuf; // FIXME need pointer to pointer
handshake_status_ = kSendPreMasterSecret;
return 0;
}
case kWaitForPreMasterSecret: // server-side
{
/* Receive and decrypt pre-master secret */
size_t expecting = RSA_size(session_keypair_); // TODO: have client send key size?
if (*datalen < expecting) {
WARN("Did not receive full PMS. Waiting for more data.\n");
return ERR_NEED_MORE_DATA;
}
unsigned char* pms = (unsigned char*)malloc(RSA_size(session_keypair_));
int plaintext_len;
if ( (plaintext_len = priv_decrypt(session_keypair_,
pms, RSA_size(session_keypair_),
(unsigned char*)buf, *datalen)) == -1) { // FIXME what if there's more data for modules above us?
ERROR("ERROR decrypting session key");
return ERR_GENERIC;
}
if (plaintext_len != PRE_MASTER_SECRET_LENGTH) {
ERROR("Decrypted key material is not of size PRE_MASTER_SECRET_LENGTH");
return ERR_GENERIC;
}
if (VERBOSITY >= V_DEBUG) {
DBG("Pre_Master Secret:");
//print_bytes(pms, PRE_MASTER_SECRET_LENGTH);
}
/* Init symmetric session ciphers with pre-master secret.
Client encrypt context initialized with same key data as
server decrypt context and vice versa. */
uint32_t salt[] = SALT;
if (aes_init(&pms[PRE_MASTER_SECRET_LENGTH/2], PRE_MASTER_SECRET_LENGTH/2,
pms, PRE_MASTER_SECRET_LENGTH/2,
(unsigned char *)&salt, en_, de_)) {
ERROR("ERROR initializing AES ciphers");
return ERR_GENERIC;
}
free(pms);
/* remove our handshake data before next module gets buf */
// FIXME: inefficient!
// char* newbuf = (char*)malloc(*buflen);
// memcpy(newbuf, buf+expecting, *datalen-expecting);
// *datalen -= expecting;
// free(buf);
// buf = newbuf; // FIXME need pointer to pointer
/* done with handshake */
handshake_status_ = kDone;
handshake_done_ = true;
ready_ = true;
return 0;
}
default:
ERROR("Unknown handshake status\n");
//printf("handshake status: %d\n", handshake_status_);
return ERR_GENERIC;
}
}
