/* 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_derive_key_from_pass(const uint8_t *passphrase, size_t pplength, TOX_PASS_KEY *out_key,
TOX_ERR_KEY_DERIVATION *error)
{
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
randombytes(salt, sizeof salt);
return tox_derive_key_with_salt(passphrase, pplength, salt, out_key, error);
}
/* 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_derive_key_with_salt(passphrase, pplength, salt, &key, NULL)) {
/* out of memory most likely */
SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
return 0;
}
return tox_pass_key_decrypt(data, length, &key, out, error);
}
void Core::setPassword(QString& password, PasswordType passtype, uint8_t* salt)
{
clearPassword(passtype);
if (password.isEmpty())
return;
pwsaltedkeys[passtype] = new TOX_PASS_KEY;
CString str(password);
if (salt)
tox_derive_key_with_salt(str.data(), str.size(), salt, pwsaltedkeys[passtype], nullptr);
else
tox_derive_key_from_pass(str.data(), str.size(), pwsaltedkeys[passtype], nullptr);
password.clear();
}
END_TEST
START_TEST(test_keys)
{
TOX_ERR_ENCRYPTION encerr;
TOX_ERR_DECRYPTION decerr;
TOX_ERR_KEY_DERIVATION keyerr;
TOX_PASS_KEY key;
bool ret = tox_derive_key_from_pass("123qweasdzxc", 12, &key, &keyerr);
ck_assert_msg(ret, "generic failure 1: %u", keyerr);
uint8_t *string = "No Patrick, mayonnaise is not an instrument."; // 44
uint8_t encrypted[44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH];
ret = tox_pass_key_encrypt(string, 44, &key, encrypted, &encerr);
ck_assert_msg(ret, "generic failure 2: %u", encerr);
uint8_t encrypted2[44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH];
ret = tox_pass_encrypt(string, 44, "123qweasdzxc", 12, encrypted2, &encerr);
ck_assert_msg(ret, "generic failure 3: %u", encerr);
uint8_t out1[44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH];
uint8_t out2[44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH];
ret = tox_pass_key_decrypt(encrypted, 44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH, &key, out1, &decerr);
ck_assert_msg(ret, "generic failure 4: %u", decerr);
ck_assert_msg(memcmp(out1, string, 44) == 0, "decryption 1 failed");
ret = tox_pass_decrypt(encrypted2, 44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH, "123qweasdzxc", 12, out2, &decerr);
ck_assert_msg(ret, "generic failure 5: %u", decerr);
ck_assert_msg(memcmp(out2, string, 44) == 0, "decryption 2 failed");
// test that pass_decrypt can decrypt things from pass_key_encrypt
ret = tox_pass_decrypt(encrypted, 44 + TOX_PASS_ENCRYPTION_EXTRA_LENGTH, "123qweasdzxc", 12, out1, &decerr);
ck_assert_msg(ret, "generic failure 6: %u", decerr);
ck_assert_msg(memcmp(out1, string, 44) == 0, "decryption 3 failed");
uint8_t salt[TOX_PASS_SALT_LENGTH];
ck_assert_msg(tox_get_salt(encrypted, salt), "couldn't get salt");
TOX_PASS_KEY key2;
ret = tox_derive_key_with_salt("123qweasdzxc", 12, salt, &key2, &keyerr);
ck_assert_msg(ret, "generic failure 7: %u", keyerr);
ck_assert_msg(0 == memcmp(&key, &key2, sizeof(TOX_PASS_KEY)), "salt comparison failed");
}