c-libp2p/secio/secio.c

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#include <stdlib.h>
#include <stdio.h> // for debugging, can remove
#include <string.h>
#include <stdint.h>
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#include "libp2p/secio/secio.h"
#include "libp2p/secio/propose.h"
#include "libp2p/secio/exchange.h"
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#include "libp2p/net/multistream.h"
#include "libp2p/crypto/sha256.h"
#include "libp2p/crypto/ephemeral.h"
#include "libp2p/utils/string_list.h"
#include "libp2p/utils/vector.h"
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const char* SupportedExchanges = "P-256,P-384,P-521";
const char* SupportedCiphers = "AES-256,AES-128,Blowfish";
const char* SupportedHashes = "SHA256,SHA512";
/***
* Create a new SecureSession struct
* @returns a pointer to a new SecureSession object
*/
struct SecureSession* libp2p_secio_secure_session_new() {
struct SecureSession* ss = (struct SecureSession*) malloc(sizeof(struct SecureSession));
if (ss == NULL)
return NULL;
ss->socket_descriptor = -1;
return ss;
}
/***
* Clean up resources from a SecureSession struct
* @param in the SecureSession to be deallocated
*/
void libp2p_secio_secure_session_free(struct SecureSession* in) {
//TODO: should we close the socket?
free(in);
}
/**
* Generate a random nonce
* @param results where to put the results
* @param length the length of the nonce
* @returns true(1) on success, otherwise false(0)
*/
int libp2p_secio_generate_nonce(char* results, int length) {
FILE* fd = fopen("/dev/urandom", "r");
fread(results, 1, length, fd);
fclose(fd);
return 1;
}
/**
* Compute a hash based on a Propose struct
* @param in the struct Propose
* @param result where to put the result (should be char[32])
* @returns true(1) on success
*/
int libp2p_secio_hash(struct Propose* in, unsigned char result[32]) {
// append public key and nonce
unsigned char buffer[in->public_key_size + in->rand_size];
memcpy(buffer, in->public_key, in->public_key_size);
memcpy(&buffer[in->public_key_size], in->rand, in->rand_size);
return libp2p_crypto_hashing_sha256(buffer, in->public_key_size + in->rand_size, result);
}
/***
* Compare 2 hashes lexicographically
* @param a the a side
* @param b the b side
* @param length the length of a and b
* @returns a -1, 0, or 1
*/
int libp2p_secio_bytes_compare(const char* a, const char* b, int length) {
for(int i = 0; i < length; i++) {
if (b[i] > a[i])
return -1;
if (a[i] > b[i])
return 1;
}
return 0;
}
int libp2p_secio_string_allocate(char* in, char** out) {
*out = (char*)malloc(strlen(in) + 1);
strcpy(*out, in);
return 1;
}
struct StringList* libp2p_secio_split_list(const char* list, int list_size) {
struct StringList* head = NULL;
struct StringList* last = NULL;
struct StringList* current = NULL;
char* curr_tok = NULL;
// make a copy
char copy[list_size+1];
memcpy(&copy[0], list, list_size);
copy[list_size] = 0;
curr_tok = strtok(copy, ",");
while (curr_tok != NULL) {
current = libp2p_utils_string_list_new();
libp2p_secio_string_allocate(curr_tok, &current->string);
if ( head == NULL) {
head = current;
last = current;
} else {
last->next = current;
}
last = current;
curr_tok = strtok(NULL, ",");
}
return head;
}
/**
* Compare 2 lists, and pick the best one
* @param order which carries more weight
* @param local_list the list to compare
* @param local_list_size the size of the list
* @param remote_list the list to compare
* @param remote_list_size the size of the list
* @param results where to put the results (NOTE: Allocate memory for this)
* @returns true(1) on success, otherwise, false(0)
*/
int libp2p_secio_select_best(int order, const char* local_list, int local_list_size, const char* remote_list, int remote_list_size, char** results) {
struct StringList* lead_head = libp2p_secio_split_list(local_list, local_list_size);
struct StringList* follower_head = NULL;
struct StringList* lead = NULL;
struct StringList* follower = NULL;
int match = 0;
//shortcut
if (order == 0)
{
libp2p_secio_string_allocate(lead_head->string, results);
libp2p_utils_string_list_free(lead_head);
return 1;
}
// this list doesn't match. Do further investigation
if (order > 0) { // lead is local
follower_head = libp2p_secio_split_list(remote_list, remote_list_size);
} else {
follower_head = lead_head;
lead_head = libp2p_secio_split_list(remote_list, remote_list_size);
}
lead = lead_head;
follower = follower_head;
// now work through the list, looking for a match
while ( lead != NULL ) {
while (follower != NULL) {
if (strcmp(lead->string, follower->string) == 0) {
match = 1;
break;
}
follower = follower->next;
}
if (match)
break;
follower = follower_head;
lead = lead->next;
}
if (!match)
return 0;
return 1;
}
/**
* Check to see if the signature is correct based on the given bytes in "in"
* @param public_key the public key to use
* @param in the bytes that were signed
* @param in_length the number of bytes
* @param signature the signature that was given to us
* @param signature_length the length of the signature
* @returns true(1) if the signature is correct, false(0) otherwise
*/
int libp2p_secio_verify_signature(struct PublicKey* public_key, const unsigned char* in, size_t in_length, unsigned char* signature) {
if (public_key->type == KEYTYPE_RSA) {
struct RsaPublicKey rsa_key;
rsa_key.der = (char*)public_key->data;
rsa_key.der_length = public_key->data_size;
return libp2p_crypto_rsa_verify(&rsa_key, in, in_length, signature);
}
// TODO: Implement this method for non-RSA
return 0;
}
int libp2p_secio_sign(struct PrivateKey* private_key, unsigned char* in, size_t in_length, unsigned char** signature, size_t* signature_size) {
if (private_key->type == KEYTYPE_RSA) {
struct RsaPrivateKey rsa_key;
rsa_key.der = (char*)private_key->data;
rsa_key.der_length = private_key->data_size;
// SHA2-256 signatures are 32 bytes
*signature = (unsigned char*)malloc(32);
return libp2p_crypto_rsa_sign(&rsa_key, in, in_length, *signature);
}
// TODO: Implement this method for non-RSA
return 0;
}
/**
* This will generate the ephimeral key and the shared key and place them in the session struct
* @param in the incoming Exchange struct
* @param session where to put the generated keys
* @returns true(1) on success, otherwise 0
*/
int libp2p_secio_generate_public_and_shared_key(struct Exchange* in, struct SecureSession* session) {
// TODO: Implement this method
// pick the right curve method
if (strcmp(session->chosen_curve, "P-256") == 0) {
} else if (strcmp(session->chosen_curve, "P-384") == 0) {
} else if (strcmp(session->chosen_curve, "P-521") == 0) {
}
// generate priv, x, and y
// marshal x and y into a public key
return 0;
}
int libp2p_secio_stretch_keys(struct SecureSession* local_session, struct SecureSession* remote_session, int order_preference) {
// TODO: Implement this method
return 0;
}
int libp2p_secio_make_mac_and_cipher(struct SecureSession* session) {
// TODO: Implement this method
return 0;
}
int libp2p_secio_write(struct SecureSession* session, unsigned char* bytes, size_t length) {
// TODO: Implement this method
return 0;
}
int libp2p_secio_read(struct SecureSession* session, unsigned char** bytes, size_t* bytes_read) {
// TODO: Implement this method
return 0;
}
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/***
* performs initial communication over an insecure channel to share
* keys, IDs, and initiate connection. This is a framed messaging system
* NOTE: session must contain a valid socket_descriptor that is a multistream.
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* @param session the secure session to be filled
* @param private_key our private key to use
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* @returns true(1) on success, false(0) otherwise
*/
int libp2p_secio_handshake(struct SecureSession* local_session, struct RsaPrivateKey* private_key) {
int retVal = 0;
size_t results_size = 0, bytes_written = 0;
unsigned char* propose_in_bytes = NULL; // the remote protobuf
size_t propose_in_size = 0;
unsigned char* propose_out_bytes = NULL; // the local protobuf
size_t propose_out_size = 0;
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unsigned char* results = NULL;
struct Propose* propose_out = NULL;
struct Propose* propose_in = NULL;
struct PublicKey* public_key = NULL;
unsigned char order_hash_in[32];
unsigned char order_hash_out[32];
int order;
struct Exchange* exchange_out;
unsigned char* exchange_out_protobuf;
size_t exchange_out_protobuf_size;
struct Exchange* exchange_in;
struct Libp2pVector* char_buffer;
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const unsigned char* protocol = (unsigned char*)"/secio/1.0.0\n";
bytes_written = libp2p_net_multistream_send(local_session->socket_descriptor, protocol, strlen((char*)protocol));
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if (bytes_written <= 0)
goto exit;
// we should get back the protocol to signify it was accepted, as well as the protobuf of the Propose struct
bytes_written = libp2p_net_multistream_receive(local_session->socket_descriptor, (char**)&results, &results_size);
if (bytes_written < 1 || strstr((char*)results, "secio") == NULL)
goto exit;
// skip to the protobuf section
propose_in_bytes = (unsigned char*)strchr((char*)results, '\n');
if (propose_in_bytes == NULL)
goto exit;
propose_in_bytes++;
propose_in_size = results_size - (propose_in_bytes - results);
if (!libp2p_secio_propose_protobuf_decode(propose_in_bytes, propose_in_size, &propose_in))
goto exit;
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// clear results
free(results);
results = NULL;
results_size = 0;
// get public key and put it in a struct PublicKey
if (!libp2p_crypto_public_key_protobuf_decode(propose_in->public_key, propose_in->public_key_size, &public_key))
goto exit;
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// generate their peer id
char* remote_peer_id;
libp2p_crypto_public_key_to_peer_id(public_key, &remote_peer_id);
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//TODO: make sure we're not talking to ourself
// generate 16 byte nonce
if (!libp2p_secio_generate_nonce(&local_session->nonce[0], 16)) {
goto exit;
}
propose_out = libp2p_secio_propose_new();
libp2p_secio_propose_set_property((void**)&propose_out->rand, &propose_out->rand_size, local_session->nonce, 16);
// we have their information, now we need to gather ours.
// public key
propose_out->public_key_size = public_key->data_size;
propose_out->public_key = (unsigned char*)malloc(public_key->data_size);
memcpy(propose_out->public_key, public_key->data, public_key->data_size);
// supported exchanges
libp2p_secio_propose_set_property((void**)&propose_out->exchanges, &propose_out->exchanges_size, SupportedExchanges, strlen(SupportedExchanges));
// supported ciphers
libp2p_secio_propose_set_property((void**)&propose_out->ciphers, &propose_out->ciphers_size, SupportedCiphers, strlen(SupportedCiphers));
// supported hashes
libp2p_secio_propose_set_property((void**)&propose_out->hashes, &propose_out->hashes_size, SupportedHashes, strlen(SupportedHashes));
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// negotiate encryption parameters NOTE: SelectBest must match, otherwise this won't work
// first determine order
libp2p_secio_hash(propose_in, order_hash_in);
libp2p_secio_hash(propose_out, order_hash_out);
order = libp2p_secio_bytes_compare((char*)order_hash_in, (char*)order_hash_out, 32);
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// curve
libp2p_secio_select_best(order, propose_out->exchanges, propose_out->exchanges_size, propose_in->exchanges, propose_in->exchanges_size, &local_session->chosen_curve);
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// cipher
libp2p_secio_select_best(order, propose_out->ciphers, propose_out->ciphers_size, propose_in->ciphers, propose_in->ciphers_size, &local_session->chosen_cipher);
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// hash
libp2p_secio_select_best(order, propose_out->hashes, propose_out->hashes_size, propose_in->hashes, propose_in->hashes_size, &local_session->chosen_hash);
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// prepare exchange of encryption parameters
struct SecureSession remote_session;
remote_session.chosen_cipher = local_session->chosen_cipher;
remote_session.chosen_curve = local_session->chosen_curve;
remote_session.chosen_hash = local_session->chosen_hash;
// generate EphemeralPubKey
struct EphemeralPrivateKey* e_private_key;
libp2p_crypto_ephemeral_key_generate(local_session->chosen_curve, &e_private_key);
// build buffer to sign
char_buffer = libp2p_utils_vector_new();
if (char_buffer == NULL)
goto exit;
libp2p_utils_vector_add(char_buffer, propose_in_bytes, propose_in_size);
libp2p_utils_vector_add(char_buffer, propose_out_bytes, propose_out_size);
libp2p_utils_vector_add(char_buffer, local_session->ephemeral_public_key, local_session->ephemeral_public_key_size);
// send Exchange packet
exchange_out = libp2p_secio_exchange_new();
exchange_out->epubkey = (unsigned char*)malloc(local_session->ephemeral_public_key_size);
memcpy(exchange_out->epubkey, local_session->ephemeral_public_key, local_session->ephemeral_public_key_size);
exchange_out->epubkey_size = local_session->ephemeral_public_key_size;
struct PrivateKey priv;
priv.data = (unsigned char*)private_key->der;
priv.data_size = private_key->der_length;
libp2p_secio_sign(&priv, char_buffer->buffer, char_buffer->buffer_size, &exchange_out->signature, &exchange_out->signature_size);
libp2p_utils_vector_free(char_buffer);
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exchange_out_protobuf_size = libp2p_secio_exchange_protobuf_encode_size(exchange_out);
exchange_out_protobuf = (unsigned char*)malloc(exchange_out_protobuf_size);
if (exchange_out_protobuf == NULL)
goto exit;
libp2p_secio_exchange_protobuf_encode(exchange_out, exchange_out_protobuf, exchange_out_protobuf_size, &bytes_written);
bytes_written = libp2p_net_multistream_send(local_session->socket_descriptor, exchange_out_protobuf, exchange_out_protobuf_size);
free(exchange_out_protobuf);
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// receive Exchange packet
bytes_written = libp2p_net_multistream_receive(local_session->socket_descriptor, (char**)&results, &results_size);
libp2p_secio_exchange_protobuf_decode(results, results_size, &exchange_in);
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// parse and verify
remote_session.ephemeral_public_key = exchange_in->epubkey;
remote_session.ephemeral_public_key_size = exchange_in->epubkey_size;
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char_buffer = libp2p_utils_vector_new();
if (char_buffer == NULL)
goto exit;
libp2p_utils_vector_add(char_buffer, propose_in_bytes, propose_in_size);
libp2p_utils_vector_add(char_buffer, propose_out_bytes, propose_out_size);
libp2p_utils_vector_add(char_buffer, remote_session.ephemeral_public_key, remote_session.ephemeral_public_key_size);
if (!libp2p_secio_verify_signature(public_key, char_buffer->buffer, char_buffer->buffer_size, exchange_in->signature))
goto exit;
libp2p_utils_vector_free(char_buffer);
// 2.2 generate shared key NOTE: this was done above
// generate 2 sets of keys (stretching)
libp2p_secio_stretch_keys(local_session, &remote_session, order);
// prepare MAC + cipher
libp2p_secio_make_mac_and_cipher(local_session);
libp2p_secio_make_mac_and_cipher(&remote_session);
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// send expected message (local nonce) to verify encryption works
libp2p_secio_write(local_session, (unsigned char*)local_session->nonce, 16);
libp2p_secio_read(local_session, &results, &results_size);
if (results_size != 16)
goto exit;
if (libp2p_secio_bytes_compare((char*)results, local_session->nonce, 16) != 0)
goto exit;
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retVal = 1;
exit:
libp2p_secio_propose_free(propose_out);
libp2p_secio_propose_free(propose_in);
return retVal;
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}