toxencryptsave/toxencryptsave.c
Rama master · réplica de lectura del repositorio original.
/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2016-2026 The TokTok team.
* Copyright © 2013 Tox project.
*/
/**
* Batch encryption functions.
*/
#include "toxencryptsave.h"
#include <sodium.h>
#include <stdlib.h>
#include <string.h>
#include "../toxcore/ccompat.h"
#include "../toxcore/crypto_core.h"
#include "../toxcore/mem.h"
#include "../toxcore/os_memory.h"
#include "../toxcore/os_random.h"
#include "../toxcore/rng.h"
#include "defines.h"
static_assert(TOX_PASS_SALT_LENGTH == crypto_pwhash_scryptsalsa208sha256_SALTBYTES,
"TOX_PASS_SALT_LENGTH is assumed to be equal to crypto_pwhash_scryptsalsa208sha256_SALTBYTES");
static_assert(TOX_PASS_KEY_LENGTH == CRYPTO_SHARED_KEY_SIZE,
"TOX_PASS_KEY_LENGTH is assumed to be equal to CRYPTO_SHARED_KEY_SIZE");
static_assert(TOX_PASS_ENCRYPTION_EXTRA_LENGTH == (crypto_box_MACBYTES + crypto_box_NONCEBYTES +
crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH),
"TOX_PASS_ENCRYPTION_EXTRA_LENGTH is assumed to be equal to (crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH)");
#define SET_ERROR_PARAMETER(param, x) \
do { \
if (param != nullptr) { \
*param = x; \
} \
} while (0)
uint32_t tox_pass_salt_length(void)
{
return TOX_PASS_SALT_LENGTH;
}
uint32_t tox_pass_key_length(void)
{
return TOX_PASS_KEY_LENGTH;
}
uint32_t tox_pass_encryption_extra_length(void)
{
return TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
}
struct Tox_Pass_Key {
uint8_t salt[TOX_PASS_SALT_LENGTH];
uint8_t key[TOX_PASS_KEY_LENGTH];
};
void tox_pass_key_free(Tox_Pass_Key *_Nullable key)
{
if (key == nullptr) {
return;
}
/* wipe sensitive state */
crypto_memzero(key->salt, TOX_PASS_SALT_LENGTH);
crypto_memzero(key->key, TOX_PASS_KEY_LENGTH);
free(key);
}
/* Clients should consider alerting their users that, unlike plain data, if even one bit
* becomes corrupted, the data will be entirely unrecoverable.
* Ditto if they forget their password, there is no way to recover the data.
*/
/**
* Retrieves the salt used to encrypt the given data.
*
* The retrieved salt can then be passed to tox_pass_key_derive_with_salt to
* produce the same key as was previously used. Any data encrypted with this
* module can be used as input.
*
* The cipher text must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in
* length.
* The salt must be TOX_PASS_SALT_LENGTH bytes in length.
* If the passed byte arrays are smaller than required, the behaviour is
* undefined.
*
* If the cipher text pointer or the salt is NULL, this function returns false.
*
* Success does not say anything about the validity of the data, only that
* data of the appropriate size was copied.
*
* @param ciphertext The encrypted data; at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes are read.
* @param salt An array of exactly TOX_PASS_SALT_LENGTH bytes to write the salt to.
*
* @return true on success.
*/
bool tox_get_salt(
const uint8_t ciphertext[TOX_PASS_ENCRYPTION_EXTRA_LENGTH],
Tox_Pass_Salt salt, Tox_Err_Get_Salt *_Nullable error)
{
if (ciphertext == nullptr || salt == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_NULL);
return false;
}
if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_BAD_FORMAT);
return false;
}
ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
memcpy(salt, ciphertext, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_OK);
return true;
}
/**
* Generates a secret symmetric key from the given passphrase.
*
* Be sure to not compromise the key! Only keep it in memory, do not write
* it to disk.
*
* Note that this function is not deterministic; to derive the same key from
* a password, you also must know the random salt that was used. A
* deterministic version of this function is `tox_pass_key_derive_with_salt`.
*
* @param passphrase The user-provided password. Can be empty.
* @param passphrase_len The length of the password.
*
* @return new symmetric key on success, NULL on failure.
*/
Tox_Pass_Key *_Nullable tox_pass_key_derive(
const uint8_t passphrase[], size_t passphrase_len,
Tox_Err_Key_Derivation *_Nullable error)
{
const Random *rng = os_random();
if (rng == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
return nullptr;
}
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
random_bytes(rng, salt, sizeof(salt));
return tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, error);
}
/**
* Same as above, except use the given salt for deterministic key derivation.
*
* @param passphrase The user-provided password. Can be empty.
* @param passphrase_len The length of the password.
* @param salt An array of exactly TOX_PASS_SALT_LENGTH bytes.
*
* @return new symmetric key on success, NULL on failure.
*/
Tox_Pass_Key *_Nullable tox_pass_key_derive_with_salt(
const uint8_t passphrase[], size_t passphrase_len,
const Tox_Pass_Salt salt, Tox_Err_Key_Derivation *_Nullable error)
{
if (salt == nullptr || (passphrase == nullptr && passphrase_len != 0)) {
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_NULL);
return nullptr;
}
uint8_t passkey[crypto_hash_sha256_BYTES];
crypto_hash_sha256(passkey, passphrase, passphrase_len);
uint8_t key[CRYPTO_SHARED_KEY_SIZE];
// Derive a key from the password
// http://doc.libsodium.org/key_derivation/README.html
// note that, according to the documentation, a generic pwhash interface will be created
// once the pwhash competition (https://password-hashing.net/) is over */
if (crypto_pwhash_scryptsalsa208sha256(
key, sizeof(key), (char *)passkey, sizeof(passkey), salt,
crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE * 2, /* slightly stronger */
crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) != 0) {
/* out of memory most likely */
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
crypto_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
return nullptr;
}
crypto_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
Tox_Pass_Key *out_key = (Tox_Pass_Key *)calloc(1, sizeof(Tox_Pass_Key));
if (out_key == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
return nullptr;
}
memcpy(out_key->salt, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
memcpy(out_key->key, key, CRYPTO_SHARED_KEY_SIZE);
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_OK);
return out_key;
}
/**
* Encrypt a plain text with a key produced by tox_pass_key_derive or
* tox_pass_key_derive_with_salt.
*
* The output array must be at least
* `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH` bytes long.
*
* @param plaintext A byte array of length `plaintext_len`.
* @param plaintext_len The length of the plain text array. Bigger than 0.
* @param ciphertext The cipher text array to write the encrypted data to.
*
* @return true on success.
*/
bool tox_pass_key_encrypt(const Tox_Pass_Key *_Nonnull key, const uint8_t plaintext[], size_t plaintext_len,
uint8_t ciphertext[], Tox_Err_Encryption *_Nullable error)
{
const Memory *mem = os_memory();
const Random *rng = os_random();
if (mem == nullptr || rng == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
return false;
}
if (plaintext_len == 0 || plaintext == nullptr || key == nullptr || ciphertext == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
return false;
}
// the output data consists of, in order:
// salt, nonce, mac, enc_data
// where the mac is automatically prepended by the encrypt()
// the salt+nonce is called the prefix
// I'm not sure what else I'm supposed to do with the salt and nonce, since we
// need them to decrypt the data
/* first add the magic number */
memcpy(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
/* then add the rest prefix */
memcpy(ciphertext, key->salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
uint8_t nonce[crypto_box_NONCEBYTES];
random_nonce(rng, nonce);
memcpy(ciphertext, nonce, crypto_box_NONCEBYTES);
ciphertext += crypto_box_NONCEBYTES;
/* now encrypt */
const int32_t encrypted_len = encrypt_data_symmetric((const Memory * _Nonnull)mem, key->key, nonce, plaintext, plaintext_len, ciphertext);
if (encrypted_len < 0 || (size_t)encrypted_len != plaintext_len + crypto_box_MACBYTES) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
return false;
}
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_OK);
return true;
}
/**
* Encrypts the given data with the given passphrase.
*
* The output array must be at least
* `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH` bytes long. This delegates
* to tox_pass_key_derive and tox_pass_key_encrypt.
*
* @param plaintext A byte array of length `plaintext_len`.
* @param plaintext_len The length of the plain text array. Bigger than 0.
* @param passphrase The user-provided password. Can be empty.
* @param passphrase_len The length of the password.
* @param ciphertext The cipher text array to write the encrypted data to.
*
* @return true on success.
*/
bool tox_pass_encrypt(const uint8_t plaintext[], size_t plaintext_len, const uint8_t passphrase[], size_t passphrase_len,
uint8_t ciphertext[/*! plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH */], Tox_Err_Encryption *_Nullable error)
{
Tox_Err_Key_Derivation err;
Tox_Pass_Key *key = tox_pass_key_derive(passphrase, passphrase_len, &err);
if (key == nullptr) {
if (err == TOX_ERR_KEY_DERIVATION_NULL) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
} else if (err == TOX_ERR_KEY_DERIVATION_FAILED) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED);
}
return false;
}
const bool result = tox_pass_key_encrypt(key, plaintext, plaintext_len, ciphertext, error);
tox_pass_key_free(key);
return result;
}
/**
* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
* tox_pass_key_derive or tox_pass_key_derive_with_salt.
*
* @param ciphertext A byte array of length `ciphertext_len`.
* @param ciphertext_len The length of the cipher text array. At least
* TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
* @param plaintext The plain text array to write the decrypted data to.
*
* @return true on success.
*/
bool tox_pass_key_decrypt(const Tox_Pass_Key *_Nonnull key, const uint8_t ciphertext[], size_t ciphertext_len,
uint8_t plaintext[], Tox_Err_Decryption *_Nullable error)
{
const Memory *mem = os_memory();
if (mem == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
return false;
}
if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
return false;
}
if (ciphertext == nullptr || key == nullptr || plaintext == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
return false;
}
if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
return false;
}
ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // salt only affects key derivation
const size_t decrypt_length = ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
uint8_t nonce[crypto_box_NONCEBYTES];
memcpy(nonce, ciphertext, crypto_box_NONCEBYTES);
ciphertext += crypto_box_NONCEBYTES;
/* decrypt the ciphertext */
const int32_t decrypted_len = decrypt_data_symmetric((const Memory * _Nonnull)mem, key->key, nonce, ciphertext, decrypt_length + crypto_box_MACBYTES, plaintext);
if (decrypted_len < 0 || (size_t)decrypted_len != decrypt_length) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
return false;
}
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_OK);
return true;
}
/**
* Decrypts the given data with the given passphrase.
*
* The output array must be at least
* `ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH` bytes long. This
* delegates to tox_pass_key_decrypt.
*
* @param ciphertext A byte array of length `ciphertext_len`.
* @param ciphertext_len The length of the cipher text array. At least
* TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
* @param passphrase The user-provided password. Can be empty.
* @param passphrase_len The length of the password.
* @param plaintext The plain text array to write the decrypted data to.
*
* @return true on success.
*/
bool tox_pass_decrypt(const uint8_t ciphertext[], size_t ciphertext_len, const uint8_t passphrase[],
size_t passphrase_len, uint8_t plaintext[/*! ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH */], Tox_Err_Decryption *_Nullable error)
{
if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
return false;
}
if (ciphertext == nullptr || passphrase == nullptr || plaintext == nullptr) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
return false;
}
if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
return false;
}
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
memcpy(salt, ciphertext + TOX_ENC_SAVE_MAGIC_LENGTH, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
/* derive the key */
Tox_Pass_Key *key = tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, nullptr);
if (key == nullptr) {
/* out of memory most likely */
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
return false;
}
const bool result = tox_pass_key_decrypt(key, ciphertext, ciphertext_len, plaintext, error);
tox_pass_key_free(key);
return result;
}
/**
* Determines whether or not the given data is encrypted by this module.
*
* It does this check by verifying that the magic number is the one put in
* place by the encryption functions.
*
* The data must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in length.
* If the passed byte array is smaller than required, the behaviour is
* undefined.
*
* If the data pointer is NULL, the behaviour is undefined
*
* @param data The data to check; at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes are read.
*
* @return true if the data is encrypted by this module.
*/
bool tox_is_data_encrypted(const uint8_t data[TOX_PASS_ENCRYPTION_EXTRA_LENGTH])
{
return memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0;
}
const char *_Nonnull tox_err_key_derivation_to_string(Tox_Err_Key_Derivation error)
{
switch (error) {
case TOX_ERR_KEY_DERIVATION_OK:
return "TOX_ERR_KEY_DERIVATION_OK";
case TOX_ERR_KEY_DERIVATION_NULL:
return "TOX_ERR_KEY_DERIVATION_NULL";
case TOX_ERR_KEY_DERIVATION_FAILED:
return "TOX_ERR_KEY_DERIVATION_FAILED";
}
return "<invalid Tox_Err_Key_Derivation>";
}
const char *_Nonnull tox_err_encryption_to_string(Tox_Err_Encryption error)
{
switch (error) {
case TOX_ERR_ENCRYPTION_OK:
return "TOX_ERR_ENCRYPTION_OK";
case TOX_ERR_ENCRYPTION_NULL:
return "TOX_ERR_ENCRYPTION_NULL";
case TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED:
return "TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED";
case TOX_ERR_ENCRYPTION_FAILED:
return "TOX_ERR_ENCRYPTION_FAILED";
}
return "<invalid Tox_Err_Encryption>";
}
const char *_Nonnull tox_err_decryption_to_string(Tox_Err_Decryption error)
{
switch (error) {
case TOX_ERR_DECRYPTION_OK:
return "TOX_ERR_DECRYPTION_OK";
case TOX_ERR_DECRYPTION_NULL:
return "TOX_ERR_DECRYPTION_NULL";
case TOX_ERR_DECRYPTION_INVALID_LENGTH:
return "TOX_ERR_DECRYPTION_INVALID_LENGTH";
case TOX_ERR_DECRYPTION_BAD_FORMAT:
return "TOX_ERR_DECRYPTION_BAD_FORMAT";
case TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED:
return "TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED";
case TOX_ERR_DECRYPTION_FAILED:
return "TOX_ERR_DECRYPTION_FAILED";
}
return "<invalid Tox_Err_Decryption>";
}
const char *_Nonnull tox_err_get_salt_to_string(Tox_Err_Get_Salt error)
{
switch (error) {
case TOX_ERR_GET_SALT_OK:
return "TOX_ERR_GET_SALT_OK";
case TOX_ERR_GET_SALT_NULL:
return "TOX_ERR_GET_SALT_NULL";
case TOX_ERR_GET_SALT_BAD_FORMAT:
return "TOX_ERR_GET_SALT_BAD_FORMAT";
}
return "<invalid Tox_Err_Get_Salt>";
}