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/* Copyright (c) 2001, Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file crypto_cipher.c
* \brief Symmetric cryptography (low-level) with AES.
**/
#include "orconfig.h"
#include "lib/crypt_ops/crypto_cipher.h"
#include "lib/crypt_ops/crypto_rand.h"
#include "lib/crypt_ops/crypto_util.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/cc/torint.h"
#include "lib/crypt_ops/aes.h"
#include <string.h>
/** Allocate and return a new symmetric cipher using the provided key and iv.
* The key is <b>bits</b> bits long; the IV is CIPHER_IV_LEN bytes. Both
* must be provided. Key length must be 128, 192, or 256 */
crypto_cipher_t *
crypto_cipher_new_with_iv_and_bits(const uint8_t *key,
const uint8_t *iv,
int bits)
{
tor_assert(key);
tor_assert(iv);
return aes_new_cipher((const uint8_t*)key, (const uint8_t*)iv, bits);
}
/** Allocate and return a new symmetric cipher using the provided key and iv.
* The key is CIPHER_KEY_LEN bytes; the IV is CIPHER_IV_LEN bytes. Both
* must be provided.
*/
crypto_cipher_t *
crypto_cipher_new_with_iv(const char *key, const char *iv)
{
return crypto_cipher_new_with_iv_and_bits((uint8_t*)key, (uint8_t*)iv,
128);
}
/** Return a new crypto_cipher_t with the provided <b>key</b> and an IV of all
* zero bytes and key length <b>bits</b>. Key length must be 128, 192, or
* 256. */
crypto_cipher_t *
crypto_cipher_new_with_bits(const char *key, int bits)
{
char zeroiv[CIPHER_IV_LEN];
memset(zeroiv, 0, sizeof(zeroiv));
return crypto_cipher_new_with_iv_and_bits((uint8_t*)key, (uint8_t*)zeroiv,
bits);
}
/** Return a new crypto_cipher_t with the provided <b>key</b> (of
* CIPHER_KEY_LEN bytes) and an IV of all zero bytes. */
crypto_cipher_t *
crypto_cipher_new(const char *key)
{
return crypto_cipher_new_with_bits(key, 128);
}
/** Free a symmetric cipher.
*/
void
crypto_cipher_free_(crypto_cipher_t *env)
{
if (!env)
return;
aes_cipher_free(env);
}
/* symmetric crypto */
/** Encrypt <b>fromlen</b> bytes from <b>from</b> using the cipher
* <b>env</b>; on success, store the result to <b>to</b> and return 0.
* Does not check for failure.
*/
int
crypto_cipher_encrypt(crypto_cipher_t *env, char *to,
const char *from, size_t fromlen)
{
tor_assert(env);
tor_assert(env);
tor_assert(from);
tor_assert(fromlen);
tor_assert(to);
tor_assert(fromlen < SIZE_T_CEILING);
memcpy(to, from, fromlen);
aes_crypt_inplace(env, to, fromlen);
return 0;
}
/** Decrypt <b>fromlen</b> bytes from <b>from</b> using the cipher
* <b>env</b>; on success, store the result to <b>to</b> and return 0.
* Does not check for failure.
*/
int
crypto_cipher_decrypt(crypto_cipher_t *env, char *to,
const char *from, size_t fromlen)
{
tor_assert(env);
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < SIZE_T_CEILING);
memcpy(to, from, fromlen);
aes_crypt_inplace(env, to, fromlen);
return 0;
}
/** Encrypt <b>len</b> bytes on <b>from</b> using the cipher in <b>env</b>;
* on success. Does not check for failure.
*/
void
crypto_cipher_crypt_inplace(crypto_cipher_t *env, char *buf, size_t len)
{
tor_assert(len < SIZE_T_CEILING);
aes_crypt_inplace(env, buf, len);
}
/** Encrypt <b>fromlen</b> bytes (at least 1) from <b>from</b> with the key in
* <b>key</b> to the buffer in <b>to</b> of length
* <b>tolen</b>. <b>tolen</b> must be at least <b>fromlen</b> plus
* CIPHER_IV_LEN bytes for the initialization vector. On success, return the
* number of bytes written, on failure, return -1.
*/
int
crypto_cipher_encrypt_with_iv(const char *key,
char *to, size_t tolen,
const char *from, size_t fromlen)
{
crypto_cipher_t *cipher;
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < INT_MAX);
if (fromlen < 1)
return -1;
if (tolen < fromlen + CIPHER_IV_LEN)
return -1;
char iv[CIPHER_IV_LEN];
crypto_rand(iv, sizeof(iv));
cipher = crypto_cipher_new_with_iv(key, iv);
memcpy(to, iv, CIPHER_IV_LEN);
crypto_cipher_encrypt(cipher, to+CIPHER_IV_LEN, from, fromlen);
crypto_cipher_free(cipher);
memwipe(iv, 0, sizeof(iv));
return (int)(fromlen + CIPHER_IV_LEN);
}
/** Decrypt <b>fromlen</b> bytes (at least 1+CIPHER_IV_LEN) from <b>from</b>
* with the key in <b>key</b> to the buffer in <b>to</b> of length
* <b>tolen</b>. <b>tolen</b> must be at least <b>fromlen</b> minus
* CIPHER_IV_LEN bytes for the initialization vector. On success, return the
* number of bytes written, on failure, return -1.
*/
int
crypto_cipher_decrypt_with_iv(const char *key,
char *to, size_t tolen,
const char *from, size_t fromlen)
{
crypto_cipher_t *cipher;
tor_assert(key);
tor_assert(from);
tor_assert(to);
tor_assert(fromlen < INT_MAX);
if (fromlen <= CIPHER_IV_LEN)
return -1;
if (tolen < fromlen - CIPHER_IV_LEN)
return -1;
cipher = crypto_cipher_new_with_iv(key, from);
crypto_cipher_encrypt(cipher, to, from+CIPHER_IV_LEN, fromlen-CIPHER_IV_LEN);
crypto_cipher_free(cipher);
return (int)(fromlen - CIPHER_IV_LEN);
}
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