diff options
Diffstat (limited to 'src/util/crypto_aes.c')
| -rw-r--r-- | src/util/crypto_aes.c | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/src/util/crypto_aes.c b/src/util/crypto_aes.c new file mode 100644 index 0000000..8b031f3 --- /dev/null +++ b/src/util/crypto_aes.c @@ -0,0 +1,185 @@ +/* + This file is part of GNUnet. + (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors) + + GNUnet 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 2, or (at your + option) any later version. + + GNUnet 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 GNUnet; see the file COPYING. If not, write to the + Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. +*/ + +/** + * @file util/crypto_aes.c + * @brief Symmetric encryption services. + * @author Christian Grothoff + * @author Ioana Patrascu + */ + +#include "platform.h" +#include "gnunet_common.h" +#include "gnunet_crypto_lib.h" +#include <gcrypt.h> + +#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__) + +/** + * Create a new SessionKey (for AES-256). + */ +void +GNUNET_CRYPTO_aes_create_session_key (struct GNUNET_CRYPTO_AesSessionKey *key) +{ + gcry_randomize (&key->key[0], GNUNET_CRYPTO_AES_KEY_LENGTH, + GCRY_STRONG_RANDOM); + key->crc32 = + htonl (GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH)); +} + +/** + * Check that a new session key is well-formed. + * + * @return GNUNET_OK if the key is valid + */ +int +GNUNET_CRYPTO_aes_check_session_key (const struct GNUNET_CRYPTO_AesSessionKey + *key) +{ + uint32_t crc; + + crc = GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH); + if (ntohl (key->crc32) == crc) + return GNUNET_OK; + GNUNET_break_op (0); + return GNUNET_SYSERR; +} + + +/** + * Encrypt a block with the public key of another + * host that uses the same cyper. + * @param block the block to encrypt + * @param len the size of the block + * @param sessionkey the key used to encrypt + * @param iv the initialization vector to use, use INITVALUE + * for streams. + * @param result the output parameter in which to store the encrypted result + * @returns the size of the encrypted block, -1 for errors + */ +ssize_t +GNUNET_CRYPTO_aes_encrypt (const void *block, size_t len, + const struct GNUNET_CRYPTO_AesSessionKey * + sessionkey, + const struct GNUNET_CRYPTO_AesInitializationVector * + iv, void *result) +{ + gcry_cipher_hd_t handle; + int rc; + + if (sessionkey->crc32 != + htonl (GNUNET_CRYPTO_crc32_n (sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH))) + { + GNUNET_break (0); + return -1; + } + GNUNET_assert (0 == + gcry_cipher_open (&handle, GCRY_CIPHER_AES256, + GCRY_CIPHER_MODE_CFB, 0)); + rc = gcry_cipher_setkey (handle, sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH); + GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY)); + rc = gcry_cipher_setiv (handle, iv, + sizeof (struct + GNUNET_CRYPTO_AesInitializationVector)); + GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY)); + GNUNET_assert (0 == gcry_cipher_encrypt (handle, result, len, block, len)); + gcry_cipher_close (handle); + return len; +} + +/** + * Decrypt a given block with the sessionkey. + * + * @param block the data to decrypt, encoded as returned by encrypt + * @param size the size of the block to decrypt + * @param sessionkey the key used to decrypt + * @param iv the initialization vector to use, use INITVALUE + * for streams. + * @param result address to store the result at + * @return -1 on failure, size of decrypted block on success + */ +ssize_t +GNUNET_CRYPTO_aes_decrypt (const void *block, size_t size, + const struct GNUNET_CRYPTO_AesSessionKey * + sessionkey, + const struct GNUNET_CRYPTO_AesInitializationVector * + iv, void *result) +{ + gcry_cipher_hd_t handle; + int rc; + + if (sessionkey->crc32 != + htonl (GNUNET_CRYPTO_crc32_n (sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH))) + { + GNUNET_break (0); + return -1; + } + GNUNET_assert (0 == + gcry_cipher_open (&handle, GCRY_CIPHER_AES256, + GCRY_CIPHER_MODE_CFB, 0)); + rc = gcry_cipher_setkey (handle, sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH); + GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY)); + rc = gcry_cipher_setiv (handle, iv, + sizeof (struct + GNUNET_CRYPTO_AesInitializationVector)); + GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY)); + GNUNET_assert (0 == gcry_cipher_decrypt (handle, result, size, block, size)); + gcry_cipher_close (handle); + return size; +} + +/** + * @brief Derive an IV + * @param iv initialization vector + * @param skey session key + * @param salt salt for the derivation + * @param salt_len size of the salt + * @param ... pairs of void * & size_t for context chunks, terminated by NULL + */ +void +GNUNET_CRYPTO_aes_derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv, + const struct GNUNET_CRYPTO_AesSessionKey *skey, + const void *salt, size_t salt_len, ...) +{ + va_list argp; + + va_start (argp, salt_len); + GNUNET_CRYPTO_aes_derive_iv_v (iv, skey, salt, salt_len, argp); + va_end (argp); +} + +/** + * @brief Derive an IV + * @param iv initialization vector + * @param skey session key + * @param salt salt for the derivation + * @param salt_len size of the salt + * @param argp pairs of void * & size_t for context chunks, terminated by NULL + */ +void +GNUNET_CRYPTO_aes_derive_iv_v (struct GNUNET_CRYPTO_AesInitializationVector *iv, + const struct GNUNET_CRYPTO_AesSessionKey *skey, + const void *salt, size_t salt_len, va_list argp) +{ + GNUNET_CRYPTO_kdf_v (iv->iv, sizeof (iv->iv), salt, salt_len, skey->key, + sizeof (skey->key), argp); +} + +/* end of crypto_aes.c */ |