diff options
Diffstat (limited to 'libs/libtox/src/toxencryptsave/toxencryptsave.c')
| -rw-r--r-- | libs/libtox/src/toxencryptsave/toxencryptsave.c | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/libs/libtox/src/toxencryptsave/toxencryptsave.c b/libs/libtox/src/toxencryptsave/toxencryptsave.c new file mode 100644 index 0000000000..5640e82fc7 --- /dev/null +++ b/libs/libtox/src/toxencryptsave/toxencryptsave.c @@ -0,0 +1,338 @@ +/* + * Batch encryption functions. + */ + +/* + * Copyright © 2016-2017 The TokTok team. + * Copyright © 2013 Tox project. + * + * This file is part of Tox, the free peer to peer instant messenger. + * + * Tox is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * Tox is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with Tox. If not, see <http://www.gnu.org/licenses/>. + */ +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "../toxcore/crypto_core.h" +#include "defines.h" +#include "toxencryptsave.h" +#define SET_ERROR_PARAMETER(param, x) {if(param) {*param = x;}} + +#ifdef VANILLA_NACL +#include <crypto_box.h> +#include <crypto_hash_sha256.h> +#include "crypto_pwhash_scryptsalsa208sha256/crypto_pwhash_scryptsalsa208sha256.h" +#define crypto_box_MACBYTES (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES) +#else +#include <sodium.h> +#endif + +#include <string.h> + +#if TOX_PASS_SALT_LENGTH != crypto_pwhash_scryptsalsa208sha256_SALTBYTES +#error TOX_PASS_SALT_LENGTH is assumed to be equal to crypto_pwhash_scryptsalsa208sha256_SALTBYTES +#endif + +#if TOX_PASS_KEY_LENGTH != CRYPTO_SHARED_KEY_SIZE +#error TOX_PASS_KEY_LENGTH is assumed to be equal to CRYPTO_SHARED_KEY_SIZE +#endif + +#if TOX_PASS_ENCRYPTION_EXTRA_LENGTH != (crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH) +#error 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) +#endif + +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]; +}; + +Tox_Pass_Key *tox_pass_key_new(void) +{ + return (Tox_Pass_Key *)malloc(sizeof(Tox_Pass_Key)); +} + +void tox_pass_key_free(Tox_Pass_Key *pass_key) +{ + free(pass_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. + */ + +/* 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; +} + +/* 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); +} + +/* 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; +} + +/* 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; +} + +/* 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); +} + +/* 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; +} + +/* 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); +} + +/* Determines whether or not the given data is encrypted (by checking the magic number) + */ +bool tox_is_data_encrypted(const uint8_t *data) +{ + if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0) { + return 1; + } + + return 0; +} |