/* Decrypts the given data with the given passphrase. The output array must be
* at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
* to tox_pass_key_decrypt.
*
* the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
*
* returns true on success
*/
bool tox_pass_decrypt(const uint8_t *data, size_t length, const uint8_t *passphrase, size_t pplength, uint8_t *out,
TOX_ERR_DECRYPTION *error)
{
if (length <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
return 0;
}
if (!data || !passphrase || !out) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
return 0;
}
if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
return 0;
}
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
memcpy(salt, data + TOX_ENC_SAVE_MAGIC_LENGTH, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
/* derive the key */
Tox_Pass_Key key;
if (!tox_pass_key_derive_with_salt(&key, passphrase, pplength, salt, NULL)) {
/* out of memory most likely */
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
return 0;
}
return tox_pass_key_decrypt(&key, data, length, out, error);
}
/* Generates a secret symmetric key from the given passphrase. out_key must be at least
* TOX_PASS_KEY_LENGTH bytes long.
* Be sure to not compromise the key! Only keep it in memory, do not write to disk.
* The password is zeroed after key derivation.
* The key should only be used with the other functions in this module, as it
* includes a salt.
* 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. See below.
*
* returns true on success
*/
bool tox_pass_key_derive(Tox_Pass_Key *out_key, const uint8_t *passphrase, size_t pplength,
TOX_ERR_KEY_DERIVATION *error)
{
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
randombytes(salt, sizeof salt);
return tox_pass_key_derive_with_salt(out_key, passphrase, pplength, salt, error);
}
std::shared_ptr<Tox_Pass_Key> Core::createPasskey(const QString& password, uint8_t* salt)
{
std::shared_ptr<Tox_Pass_Key> encryptionKey(tox_pass_key_new(), tox_pass_key_free);
CString str(password);
if (salt)
tox_pass_key_derive_with_salt(encryptionKey.get(), str.data(), str.size(), salt, nullptr);
else
tox_pass_key_derive(encryptionKey.get(), str.data(), str.size(), nullptr);
return encryptionKey;
}
