/* 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);
}
/* Same as above, except with use the given salt for deterministic key derivation.
* The salt must be TOX_PASS_SALT_LENGTH bytes in length.
*/
bool tox_pass_key_derive_with_salt(Tox_Pass_Key *out_key, const uint8_t *passphrase, size_t pplength,
const uint8_t *salt, TOX_ERR_KEY_DERIVATION *error)
{
if (!salt || !out_key || (!passphrase && pplength != 0)) {
SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_NULL);
return 0;
}
uint8_t passkey[crypto_hash_sha256_BYTES];
crypto_hash_sha256(passkey, passphrase, pplength);
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);
return 0;
}
sodium_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
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 1;
}
struct Tox_Options *tox_options_new(TOX_ERR_OPTIONS_NEW *error)
{
struct Tox_Options *options = (struct Tox_Options *)malloc(sizeof(struct Tox_Options));
if (options) {
tox_options_default(options);
SET_ERROR_PARAMETER(error, TOX_ERR_OPTIONS_NEW_OK);
return options;
}
SET_ERROR_PARAMETER(error, TOX_ERR_OPTIONS_NEW_MALLOC);
return nullptr;
}
/* This retrieves the salt used to encrypt the given data, which can then be passed to
* tox_pass_key_derive_with_salt to produce the same key as was previously used. Any encrpyted
* data with this module can be used as input.
*
* returns true if magic number matches
* success does not say anything about the validity of the data, only that data of
* the appropriate size was copied
*/
bool tox_get_salt(const uint8_t *data, uint8_t *salt, TOX_ERR_GET_SALT *error)
{
if (!data || !salt) {
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_NULL);
return false;
}
if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_BAD_FORMAT);
return false;
}
data += TOX_ENC_SAVE_MAGIC_LENGTH;
memcpy(salt, data, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_OK);
return true;
}
/* Encrypts 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_derive_key and tox_pass_key_encrypt.
*
* returns true on success
*/
bool tox_pass_encrypt(const uint8_t *data, size_t data_len, const uint8_t *passphrase, size_t pplength, uint8_t *out,
TOX_ERR_ENCRYPTION *error)
{
Tox_Pass_Key key;
TOX_ERR_KEY_DERIVATION _error;
if (!tox_pass_key_derive(&key, passphrase, pplength, &_error)) {
if (_error == TOX_ERR_KEY_DERIVATION_NULL) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
} else if (_error == TOX_ERR_KEY_DERIVATION_FAILED) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED);
}
return 0;
}
return tox_pass_key_encrypt(&key, data, data_len, out, error);
}
/* Encrypt arbitrary with a key produced by tox_derive_key_*. The output
* array must be at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
* key must be TOX_PASS_KEY_LENGTH bytes.
* If you already have a symmetric key from somewhere besides this module, simply
* call encrypt_data_symmetric in toxcore/crypto_core directly.
*
* returns true on success
*/
bool tox_pass_key_encrypt(const Tox_Pass_Key *key, const uint8_t *data, size_t data_len, uint8_t *out,
TOX_ERR_ENCRYPTION *error)
{
if (data_len == 0 || !data || !key || !out) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
return 0;
}
/* 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(out, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
out += TOX_ENC_SAVE_MAGIC_LENGTH;
/* then add the rest prefix */
memcpy(out, key->salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
out += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
uint8_t nonce[crypto_box_NONCEBYTES];
random_nonce(nonce);
memcpy(out, nonce, crypto_box_NONCEBYTES);
out += crypto_box_NONCEBYTES;
/* now encrypt */
if (encrypt_data_symmetric(key->key, nonce, data, data_len, out)
!= data_len + crypto_box_MACBYTES) {
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
return 0;
}
SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_OK);
return 1;
}
/* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
* tox_derive_key.
*
* the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
*
* returns true on success
*/
bool tox_pass_key_decrypt(const Tox_Pass_Key *key, const uint8_t *data, size_t length, 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 || !key || !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;
}
data += TOX_ENC_SAVE_MAGIC_LENGTH;
data += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // salt only affects key derivation
size_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
uint8_t nonce[crypto_box_NONCEBYTES];
memcpy(nonce, data, crypto_box_NONCEBYTES);
data += crypto_box_NONCEBYTES;
/* decrypt the data */
if (decrypt_data_symmetric(key->key, nonce, data, decrypt_length + crypto_box_MACBYTES, out)
!= decrypt_length) {
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
return 0;
}
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_OK);
return 1;
}
