tomato/toxcore/crypto_core.c

539 lines
17 KiB
C
Raw Normal View History

/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2016-2018 The TokTok team.
* Copyright © 2013 Tox project.
*/
/**
* Functions for the core crypto.
*
* NOTE: This code has to be perfect. We don't mess around with encryption.
*/
#include "crypto_core.h"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <sodium.h>
#include "ccompat.h"
#ifndef crypto_box_MACBYTES
#define crypto_box_MACBYTES (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES)
#endif
// Need dht because of ENC_SECRET_KEY_SIZE and ENC_PUBLIC_KEY_SIZE
#define ENC_PUBLIC_KEY_SIZE CRYPTO_PUBLIC_KEY_SIZE
#define ENC_SECRET_KEY_SIZE CRYPTO_SECRET_KEY_SIZE
static_assert(CRYPTO_PUBLIC_KEY_SIZE == crypto_box_PUBLICKEYBYTES,
"CRYPTO_PUBLIC_KEY_SIZE should be equal to crypto_box_PUBLICKEYBYTES");
static_assert(CRYPTO_SECRET_KEY_SIZE == crypto_box_SECRETKEYBYTES,
"CRYPTO_SECRET_KEY_SIZE should be equal to crypto_box_SECRETKEYBYTES");
static_assert(CRYPTO_SHARED_KEY_SIZE == crypto_box_BEFORENMBYTES,
"CRYPTO_SHARED_KEY_SIZE should be equal to crypto_box_BEFORENMBYTES");
static_assert(CRYPTO_SYMMETRIC_KEY_SIZE == crypto_box_BEFORENMBYTES,
"CRYPTO_SYMMETRIC_KEY_SIZE should be equal to crypto_box_BEFORENMBYTES");
static_assert(CRYPTO_MAC_SIZE == crypto_box_MACBYTES,
"CRYPTO_MAC_SIZE should be equal to crypto_box_MACBYTES");
static_assert(CRYPTO_NONCE_SIZE == crypto_box_NONCEBYTES,
"CRYPTO_NONCE_SIZE should be equal to crypto_box_NONCEBYTES");
static_assert(CRYPTO_HMAC_SIZE == crypto_auth_BYTES,
"CRYPTO_HMAC_SIZE should be equal to crypto_auth_BYTES");
static_assert(CRYPTO_HMAC_KEY_SIZE == crypto_auth_KEYBYTES,
"CRYPTO_HMAC_KEY_SIZE should be equal to crypto_auth_KEYBYTES");
static_assert(CRYPTO_SHA256_SIZE == crypto_hash_sha256_BYTES,
"CRYPTO_SHA256_SIZE should be equal to crypto_hash_sha256_BYTES");
static_assert(CRYPTO_SHA512_SIZE == crypto_hash_sha512_BYTES,
"CRYPTO_SHA512_SIZE should be equal to crypto_hash_sha512_BYTES");
static_assert(CRYPTO_PUBLIC_KEY_SIZE == 32,
"CRYPTO_PUBLIC_KEY_SIZE is required to be 32 bytes for pk_equal to work");
static_assert(CRYPTO_SIGNATURE_SIZE == crypto_sign_BYTES,
"CRYPTO_SIGNATURE_SIZE should be equal to crypto_sign_BYTES");
static_assert(CRYPTO_SIGN_PUBLIC_KEY_SIZE == crypto_sign_PUBLICKEYBYTES,
"CRYPTO_SIGN_PUBLIC_KEY_SIZE should be equal to crypto_sign_PUBLICKEYBYTES");
static_assert(CRYPTO_SIGN_SECRET_KEY_SIZE == crypto_sign_SECRETKEYBYTES,
"CRYPTO_SIGN_SECRET_KEY_SIZE should be equal to crypto_sign_SECRETKEYBYTES");
bool create_extended_keypair(uint8_t *pk, uint8_t *sk)
{
/* create signature key pair */
crypto_sign_keypair(pk + ENC_PUBLIC_KEY_SIZE, sk + ENC_SECRET_KEY_SIZE);
/* convert public signature key to public encryption key */
const int res1 = crypto_sign_ed25519_pk_to_curve25519(pk, pk + ENC_PUBLIC_KEY_SIZE);
/* convert secret signature key to secret encryption key */
const int res2 = crypto_sign_ed25519_sk_to_curve25519(sk, sk + ENC_SECRET_KEY_SIZE);
return res1 == 0 && res2 == 0;
}
const uint8_t *get_enc_key(const uint8_t *key)
{
return key;
}
const uint8_t *get_sig_pk(const uint8_t *key)
{
return key + ENC_PUBLIC_KEY_SIZE;
}
void set_sig_pk(uint8_t *key, const uint8_t *sig_pk)
{
memcpy(key + ENC_PUBLIC_KEY_SIZE, sig_pk, SIG_PUBLIC_KEY_SIZE);
}
const uint8_t *get_sig_sk(const uint8_t *key)
{
return key + ENC_SECRET_KEY_SIZE;
}
const uint8_t *get_chat_id(const uint8_t *key)
{
return key + ENC_PUBLIC_KEY_SIZE;
}
#if !defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
static uint8_t *crypto_malloc(size_t bytes)
{
uint8_t *ptr = (uint8_t *)malloc(bytes);
if (ptr != nullptr) {
crypto_memlock(ptr, bytes);
}
return ptr;
}
nullable(1)
static void crypto_free(uint8_t *ptr, size_t bytes)
{
if (ptr != nullptr) {
crypto_memzero(ptr, bytes);
crypto_memunlock(ptr, bytes);
}
free(ptr);
}
#endif // !defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
void crypto_memzero(void *data, size_t length)
{
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
memset(data, 0, length);
#else
sodium_memzero(data, length);
#endif
}
bool crypto_memlock(void *data, size_t length)
{
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
return false;
#else
if (sodium_mlock(data, length) != 0) {
return false;
}
return true;
#endif
}
bool crypto_memunlock(void *data, size_t length)
{
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
return false;
#else
if (sodium_munlock(data, length) != 0) {
return false;
}
return true;
#endif
}
bool pk_equal(const uint8_t pk1[CRYPTO_PUBLIC_KEY_SIZE], const uint8_t pk2[CRYPTO_PUBLIC_KEY_SIZE])
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
// Hope that this is better for the fuzzer
return memcmp(pk1, pk2, CRYPTO_PUBLIC_KEY_SIZE) == 0;
#else
return crypto_verify_32(pk1, pk2) == 0;
#endif
}
void pk_copy(uint8_t dest[CRYPTO_PUBLIC_KEY_SIZE], const uint8_t src[CRYPTO_PUBLIC_KEY_SIZE])
{
memcpy(dest, src, CRYPTO_PUBLIC_KEY_SIZE);
}
bool crypto_sha512_eq(const uint8_t *cksum1, const uint8_t *cksum2)
{
#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
// Hope that this is better for the fuzzer
return memcmp(cksum1, cksum2, CRYPTO_SHA512_SIZE) == 0;
#else
return crypto_verify_64(cksum1, cksum2) == 0;
#endif
}
bool crypto_sha256_eq(const uint8_t *cksum1, const uint8_t *cksum2)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
// Hope that this is better for the fuzzer
return memcmp(cksum1, cksum2, CRYPTO_SHA256_SIZE) == 0;
#else
return crypto_verify_32(cksum1, cksum2) == 0;
#endif
}
uint8_t random_u08(const Random *rng)
{
uint8_t randnum;
random_bytes(rng, &randnum, 1);
return randnum;
}
uint16_t random_u16(const Random *rng)
{
uint16_t randnum;
random_bytes(rng, (uint8_t *)&randnum, sizeof(randnum));
return randnum;
}
uint32_t random_u32(const Random *rng)
{
uint32_t randnum;
random_bytes(rng, (uint8_t *)&randnum, sizeof(randnum));
return randnum;
}
uint64_t random_u64(const Random *rng)
{
uint64_t randnum;
random_bytes(rng, (uint8_t *)&randnum, sizeof(randnum));
return randnum;
}
uint32_t random_range_u32(const Random *rng, uint32_t upper_bound)
{
return rng->funcs->random_uniform(rng->obj, upper_bound);
}
bool crypto_signature_create(uint8_t *signature, const uint8_t *message, uint64_t message_length,
const uint8_t *secret_key)
{
return crypto_sign_detached(signature, nullptr, message, message_length, secret_key) == 0;
}
bool crypto_signature_verify(const uint8_t *signature, const uint8_t *message, uint64_t message_length,
const uint8_t *public_key)
{
return crypto_sign_verify_detached(signature, message, message_length, public_key) == 0;
}
bool public_key_valid(const uint8_t *public_key)
{
/* Last bit of key is always zero. */
return public_key[31] < 128;
}
int32_t encrypt_precompute(const uint8_t *public_key, const uint8_t *secret_key,
uint8_t *shared_key)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
memcpy(shared_key, public_key, CRYPTO_SHARED_KEY_SIZE);
return 0;
#else
return crypto_box_beforenm(shared_key, public_key, secret_key);
#endif
}
int32_t encrypt_data_symmetric(const uint8_t *shared_key, const uint8_t *nonce,
const uint8_t *plain, size_t length, uint8_t *encrypted)
{
if (length == 0 || shared_key == nullptr || nonce == nullptr || plain == nullptr || encrypted == nullptr) {
return -1;
}
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
// Don't encrypt anything.
memcpy(encrypted, plain, length);
// Zero MAC to avoid uninitialized memory reads.
memset(encrypted + length, 0, crypto_box_MACBYTES);
#else
const size_t size_temp_plain = length + crypto_box_ZEROBYTES;
const size_t size_temp_encrypted = length + crypto_box_MACBYTES + crypto_box_BOXZEROBYTES;
uint8_t *temp_plain = crypto_malloc(size_temp_plain);
uint8_t *temp_encrypted = crypto_malloc(size_temp_encrypted);
if (temp_plain == nullptr || temp_encrypted == nullptr) {
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
return -1;
}
// crypto_box_afternm requires the entire range of the output array be
// initialised with something. It doesn't matter what it's initialised with,
// so we'll pick 0x00.
memset(temp_encrypted, 0, size_temp_encrypted);
memset(temp_plain, 0, crypto_box_ZEROBYTES);
// Pad the message with 32 0 bytes.
memcpy(temp_plain + crypto_box_ZEROBYTES, plain, length);
if (crypto_box_afternm(temp_encrypted, temp_plain, length + crypto_box_ZEROBYTES, nonce,
shared_key) != 0) {
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
return -1;
}
// Unpad the encrypted message.
memcpy(encrypted, temp_encrypted + crypto_box_BOXZEROBYTES, length + crypto_box_MACBYTES);
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
#endif
assert(length < INT32_MAX - crypto_box_MACBYTES);
return (int32_t)(length + crypto_box_MACBYTES);
}
int32_t decrypt_data_symmetric(const uint8_t *shared_key, const uint8_t *nonce,
const uint8_t *encrypted, size_t length, uint8_t *plain)
{
if (length <= crypto_box_BOXZEROBYTES || shared_key == nullptr || nonce == nullptr || encrypted == nullptr
|| plain == nullptr) {
return -1;
}
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
assert(length >= crypto_box_MACBYTES);
memcpy(plain, encrypted, length - crypto_box_MACBYTES); // Don't encrypt anything
#else
const size_t size_temp_plain = length + crypto_box_ZEROBYTES;
const size_t size_temp_encrypted = length + crypto_box_BOXZEROBYTES;
uint8_t *temp_plain = crypto_malloc(size_temp_plain);
uint8_t *temp_encrypted = crypto_malloc(size_temp_encrypted);
if (temp_plain == nullptr || temp_encrypted == nullptr) {
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
return -1;
}
// crypto_box_open_afternm requires the entire range of the output array be
// initialised with something. It doesn't matter what it's initialised with,
// so we'll pick 0x00.
memset(temp_plain, 0, size_temp_plain);
memset(temp_encrypted, 0, crypto_box_BOXZEROBYTES);
// Pad the message with 16 0 bytes.
memcpy(temp_encrypted + crypto_box_BOXZEROBYTES, encrypted, length);
if (crypto_box_open_afternm(temp_plain, temp_encrypted, length + crypto_box_BOXZEROBYTES, nonce,
shared_key) != 0) {
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
return -1;
}
memcpy(plain, temp_plain + crypto_box_ZEROBYTES, length - crypto_box_MACBYTES);
crypto_free(temp_plain, size_temp_plain);
crypto_free(temp_encrypted, size_temp_encrypted);
#endif
assert(length > crypto_box_MACBYTES);
assert(length < INT32_MAX);
return (int32_t)(length - crypto_box_MACBYTES);
}
int32_t encrypt_data(const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *nonce,
const uint8_t *plain, size_t length, uint8_t *encrypted)
{
if (public_key == nullptr || secret_key == nullptr) {
return -1;
}
uint8_t k[crypto_box_BEFORENMBYTES];
encrypt_precompute(public_key, secret_key, k);
const int ret = encrypt_data_symmetric(k, nonce, plain, length, encrypted);
crypto_memzero(k, sizeof(k));
return ret;
}
int32_t decrypt_data(const uint8_t *public_key, const uint8_t *secret_key, const uint8_t *nonce,
const uint8_t *encrypted, size_t length, uint8_t *plain)
{
if (public_key == nullptr || secret_key == nullptr) {
return -1;
}
uint8_t k[crypto_box_BEFORENMBYTES];
encrypt_precompute(public_key, secret_key, k);
const int ret = decrypt_data_symmetric(k, nonce, encrypted, length, plain);
crypto_memzero(k, sizeof(k));
return ret;
}
void increment_nonce(uint8_t *nonce)
{
/* TODO(irungentoo): use `increment_nonce_number(nonce, 1)` or
* sodium_increment (change to little endian).
*
* NOTE don't use breaks inside this loop.
* In particular, make sure, as far as possible,
* that loop bounds and their potential underflow or overflow
* are independent of user-controlled input (you may have heard of the Heartbleed bug).
*/
uint_fast16_t carry = 1U;
for (uint32_t i = crypto_box_NONCEBYTES; i != 0; --i) {
carry += (uint_fast16_t)nonce[i - 1];
nonce[i - 1] = (uint8_t)carry;
carry >>= 8;
}
}
void increment_nonce_number(uint8_t *nonce, uint32_t increment)
{
/* NOTE don't use breaks inside this loop
* In particular, make sure, as far as possible,
* that loop bounds and their potential underflow or overflow
* are independent of user-controlled input (you may have heard of the Heartbleed bug).
*/
uint8_t num_as_nonce[crypto_box_NONCEBYTES] = {0};
num_as_nonce[crypto_box_NONCEBYTES - 4] = increment >> 24;
num_as_nonce[crypto_box_NONCEBYTES - 3] = increment >> 16;
num_as_nonce[crypto_box_NONCEBYTES - 2] = increment >> 8;
num_as_nonce[crypto_box_NONCEBYTES - 1] = increment;
uint_fast16_t carry = 0U;
for (uint32_t i = crypto_box_NONCEBYTES; i != 0; --i) {
carry += (uint_fast16_t)nonce[i - 1] + (uint_fast16_t)num_as_nonce[i - 1];
nonce[i - 1] = (uint8_t)carry;
carry >>= 8;
}
}
void random_nonce(const Random *rng, uint8_t *nonce)
{
random_bytes(rng, nonce, crypto_box_NONCEBYTES);
}
void new_symmetric_key(const Random *rng, uint8_t *key)
{
random_bytes(rng, key, CRYPTO_SYMMETRIC_KEY_SIZE);
}
int32_t crypto_new_keypair(const Random *rng, uint8_t *public_key, uint8_t *secret_key)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
random_bytes(rng, secret_key, CRYPTO_SECRET_KEY_SIZE);
memset(public_key, 0, CRYPTO_PUBLIC_KEY_SIZE); // Make MSAN happy
crypto_derive_public_key(public_key, secret_key);
return 0;
#else
return crypto_box_keypair(public_key, secret_key);
#endif
}
void crypto_derive_public_key(uint8_t *public_key, const uint8_t *secret_key)
{
crypto_scalarmult_curve25519_base(public_key, secret_key);
}
void new_hmac_key(const Random *rng, uint8_t key[CRYPTO_HMAC_KEY_SIZE])
{
random_bytes(rng, key, CRYPTO_HMAC_KEY_SIZE);
}
void crypto_hmac(uint8_t auth[CRYPTO_HMAC_SIZE], const uint8_t key[CRYPTO_HMAC_KEY_SIZE], const uint8_t *data,
size_t length)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
memcpy(auth, key, 16);
memcpy(auth + 16, data, length < 16 ? length : 16);
#else
crypto_auth(auth, data, length, key);
#endif
}
bool crypto_hmac_verify(const uint8_t auth[CRYPTO_HMAC_SIZE], const uint8_t key[CRYPTO_HMAC_KEY_SIZE],
const uint8_t *data, size_t length)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
return memcmp(auth, key, 16) == 0 && memcmp(auth + 16, data, length < 16 ? length : 16) == 0;
#else
return crypto_auth_verify(auth, data, length, key) == 0;
#endif
}
void crypto_sha256(uint8_t *hash, const uint8_t *data, size_t length)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
memset(hash, 0, CRYPTO_SHA256_SIZE);
memcpy(hash, data, length < CRYPTO_SHA256_SIZE ? length : CRYPTO_SHA256_SIZE);
#else
crypto_hash_sha256(hash, data, length);
#endif
}
void crypto_sha512(uint8_t *hash, const uint8_t *data, size_t length)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
memset(hash, 0, CRYPTO_SHA512_SIZE);
memcpy(hash, data, length < CRYPTO_SHA512_SIZE ? length : CRYPTO_SHA512_SIZE);
#else
crypto_hash_sha512(hash, data, length);
#endif
}
non_null()
static void sys_random_bytes(void *obj, uint8_t *bytes, size_t length)
{
randombytes(bytes, length);
}
non_null()
static uint32_t sys_random_uniform(void *obj, uint32_t upper_bound)
{
return randombytes_uniform(upper_bound);
}
static const Random_Funcs system_random_funcs = {
sys_random_bytes,
sys_random_uniform,
};
static const Random system_random_obj = {&system_random_funcs};
const Random *system_random(void)
{
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if ((true)) {
return nullptr;
}
#endif
// It is safe to call this function more than once and from different
// threads -- subsequent calls won't have any effects.
if (sodium_init() == -1) {
return nullptr;
}
return &system_random_obj;
}
void random_bytes(const Random *rng, uint8_t *bytes, size_t length)
{
rng->funcs->random_bytes(rng->obj, bytes, length);
}