/** Respond to an ESTABLISH_INTRO cell by checking the signed data and
* setting the circuit's purpose and service pk digest.
*/
int
rend_mid_establish_intro(or_circuit_t *circ, const uint8_t *request,
size_t request_len)
{
crypto_pk_t *pk = NULL;
char buf[DIGEST_LEN+9];
char expected_digest[DIGEST_LEN];
char pk_digest[DIGEST_LEN];
size_t asn1len;
or_circuit_t *c;
char serviceid[REND_SERVICE_ID_LEN_BASE32+1];
int reason = END_CIRC_REASON_INTERNAL;
log_info(LD_REND,
"Received an ESTABLISH_INTRO request on circuit %u",
(unsigned) circ->p_circ_id);
if (circ->base_.purpose != CIRCUIT_PURPOSE_OR || circ->base_.n_chan) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Rejecting ESTABLISH_INTRO on non-OR or non-edge circuit.");
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
if (request_len < 2+DIGEST_LEN)
goto truncated;
/* First 2 bytes: length of asn1-encoded key. */
asn1len = ntohs(get_uint16(request));
/* Next asn1len bytes: asn1-encoded key. */
if (request_len < 2+DIGEST_LEN+asn1len)
goto truncated;
pk = crypto_pk_asn1_decode((char*)(request+2), asn1len);
if (!pk) {
reason = END_CIRC_REASON_TORPROTOCOL;
log_warn(LD_PROTOCOL, "Couldn't decode public key.");
goto err;
}
/* Next 20 bytes: Hash of rend_circ_nonce | "INTRODUCE" */
memcpy(buf, circ->rend_circ_nonce, DIGEST_LEN);
memcpy(buf+DIGEST_LEN, "INTRODUCE", 9);
if (crypto_digest(expected_digest, buf, DIGEST_LEN+9) < 0) {
log_warn(LD_BUG, "Internal error computing digest.");
goto err;
}
if (tor_memneq(expected_digest, request+2+asn1len, DIGEST_LEN)) {
log_warn(LD_PROTOCOL, "Hash of session info was not as expected.");
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
/* Rest of body: signature of previous data */
note_crypto_pk_op(REND_MID);
if (crypto_pk_public_checksig_digest(pk,
(char*)request, 2+asn1len+DIGEST_LEN,
(char*)(request+2+DIGEST_LEN+asn1len),
request_len-(2+DIGEST_LEN+asn1len))<0) {
log_warn(LD_PROTOCOL,
"Incorrect signature on ESTABLISH_INTRO cell; rejecting.");
reason = END_CIRC_REASON_TORPROTOCOL;
goto err;
}
/* The request is valid. First, compute the hash of Bob's PK.*/
if (crypto_pk_get_digest(pk, pk_digest)<0) {
log_warn(LD_BUG, "Internal error: couldn't hash public key.");
goto err;
}
crypto_pk_free(pk); /* don't need it anymore */
pk = NULL; /* so we don't free it again if err */
base32_encode(serviceid, REND_SERVICE_ID_LEN_BASE32+1,
pk_digest, REND_SERVICE_ID_LEN);
/* Close any other intro circuits with the same pk. */
c = NULL;
while ((c = circuit_get_intro_point((const uint8_t *)pk_digest))) {
log_info(LD_REND, "Replacing old circuit for service %s",
safe_str(serviceid));
circuit_mark_for_close(TO_CIRCUIT(c), END_CIRC_REASON_FINISHED);
/* Now it's marked, and it won't be returned next time. */
}
/* Acknowledge the request. */
if (relay_send_command_from_edge(0, TO_CIRCUIT(circ),
RELAY_COMMAND_INTRO_ESTABLISHED,
"", 0, NULL)<0) {
log_info(LD_GENERAL, "Couldn't send INTRO_ESTABLISHED cell.");
goto err;
}
/* Now, set up this circuit. */
circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT);
circuit_set_intro_point_digest(circ, (uint8_t *)pk_digest);
log_info(LD_REND,
"Established introduction point on circuit %u for service %s",
(unsigned) circ->p_circ_id, safe_str(serviceid));
return 0;
truncated:
log_warn(LD_PROTOCOL, "Rejecting truncated ESTABLISH_INTRO cell.");
reason = END_CIRC_REASON_TORPROTOCOL;
err:
if (pk) crypto_pk_free(pk);
circuit_mark_for_close(TO_CIRCUIT(circ), reason);
return -1;
}
/** Run unit tests for our public key crypto functions */
static void
test_crypto_pk(void)
{
crypto_pk_t *pk1 = NULL, *pk2 = NULL;
char *encoded = NULL;
char data1[1024], data2[1024], data3[1024];
size_t size;
int i, j, p, len;
/* Public-key ciphers */
pk1 = pk_generate(0);
pk2 = crypto_pk_new();
test_assert(pk1 && pk2);
test_assert(! crypto_pk_write_public_key_to_string(pk1, &encoded, &size));
test_assert(! crypto_pk_read_public_key_from_string(pk2, encoded, size));
test_eq(0, crypto_pk_cmp_keys(pk1, pk2));
/* comparison between keys and NULL */
tt_int_op(crypto_pk_cmp_keys(NULL, pk1), <, 0);
tt_int_op(crypto_pk_cmp_keys(NULL, NULL), ==, 0);
tt_int_op(crypto_pk_cmp_keys(pk1, NULL), >, 0);
test_eq(128, crypto_pk_keysize(pk1));
test_eq(1024, crypto_pk_num_bits(pk1));
test_eq(128, crypto_pk_keysize(pk2));
test_eq(1024, crypto_pk_num_bits(pk2));
test_eq(128, crypto_pk_public_encrypt(pk2, data1, sizeof(data1),
"Hello whirled.", 15,
PK_PKCS1_OAEP_PADDING));
test_eq(128, crypto_pk_public_encrypt(pk1, data2, sizeof(data1),
"Hello whirled.", 15,
PK_PKCS1_OAEP_PADDING));
/* oaep padding should make encryption not match */
test_memneq(data1, data2, 128);
test_eq(15, crypto_pk_private_decrypt(pk1, data3, sizeof(data3), data1, 128,
PK_PKCS1_OAEP_PADDING,1));
test_streq(data3, "Hello whirled.");
memset(data3, 0, 1024);
test_eq(15, crypto_pk_private_decrypt(pk1, data3, sizeof(data3), data2, 128,
PK_PKCS1_OAEP_PADDING,1));
test_streq(data3, "Hello whirled.");
/* Can't decrypt with public key. */
test_eq(-1, crypto_pk_private_decrypt(pk2, data3, sizeof(data3), data2, 128,
PK_PKCS1_OAEP_PADDING,1));
/* Try again with bad padding */
memcpy(data2+1, "XYZZY", 5); /* This has fails ~ once-in-2^40 */
test_eq(-1, crypto_pk_private_decrypt(pk1, data3, sizeof(data3), data2, 128,
PK_PKCS1_OAEP_PADDING,1));
/* File operations: save and load private key */
test_assert(! crypto_pk_write_private_key_to_filename(pk1,
get_fname("pkey1")));
/* failing case for read: can't read. */
test_assert(crypto_pk_read_private_key_from_filename(pk2,
get_fname("xyzzy")) < 0);
write_str_to_file(get_fname("xyzzy"), "foobar", 6);
/* Failing case for read: no key. */
test_assert(crypto_pk_read_private_key_from_filename(pk2,
get_fname("xyzzy")) < 0);
test_assert(! crypto_pk_read_private_key_from_filename(pk2,
get_fname("pkey1")));
test_eq(15, crypto_pk_private_decrypt(pk2, data3, sizeof(data3), data1, 128,
PK_PKCS1_OAEP_PADDING,1));
/* Now try signing. */
strlcpy(data1, "Ossifrage", 1024);
test_eq(128, crypto_pk_private_sign(pk1, data2, sizeof(data2), data1, 10));
test_eq(10,
crypto_pk_public_checksig(pk1, data3, sizeof(data3), data2, 128));
test_streq(data3, "Ossifrage");
/* Try signing digests. */
test_eq(128, crypto_pk_private_sign_digest(pk1, data2, sizeof(data2),
data1, 10));
test_eq(20,
crypto_pk_public_checksig(pk1, data3, sizeof(data3), data2, 128));
test_eq(0, crypto_pk_public_checksig_digest(pk1, data1, 10, data2, 128));
test_eq(-1, crypto_pk_public_checksig_digest(pk1, data1, 11, data2, 128));
/*XXXX test failed signing*/
/* Try encoding */
crypto_pk_free(pk2);
pk2 = NULL;
i = crypto_pk_asn1_encode(pk1, data1, 1024);
test_assert(i>0);
pk2 = crypto_pk_asn1_decode(data1, i);
test_assert(crypto_pk_cmp_keys(pk1,pk2) == 0);
/* Try with hybrid encryption wrappers. */
crypto_rand(data1, 1024);
for (i = 0; i < 2; ++i) {
for (j = 85; j < 140; ++j) {
memset(data2,0,1024);
memset(data3,0,1024);
p = (i==0)?PK_PKCS1_PADDING:PK_PKCS1_OAEP_PADDING;
len = crypto_pk_public_hybrid_encrypt(pk1,data2,sizeof(data2),
data1,j,p,0);
test_assert(len>=0);
len = crypto_pk_private_hybrid_decrypt(pk1,data3,sizeof(data3),
data2,len,p,1);
test_eq(len,j);
test_memeq(data1,data3,j);
}
}
/* Try copy_full */
crypto_pk_free(pk2);
pk2 = crypto_pk_copy_full(pk1);
test_assert(pk2 != NULL);
test_neq_ptr(pk1, pk2);
test_assert(crypto_pk_cmp_keys(pk1,pk2) == 0);
done:
if (pk1)
crypto_pk_free(pk1);
if (pk2)
crypto_pk_free(pk2);
tor_free(encoded);
}