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3 (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors)
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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22 * @file util/crypto_aes.c
23 * @brief Symmetric encryption services.
24 * @author Christian Grothoff
25 * @author Ioana Patrascu
29 #include "gnunet_common.h"
30 #include "gnunet_crypto_lib.h"
34 * Create a new SessionKey (for AES-256).
37 GNUNET_CRYPTO_aes_create_session_key (struct GNUNET_CRYPTO_AesSessionKey *key)
39 gcry_randomize (&key->key[0], GNUNET_CRYPTO_AES_KEY_LENGTH,
42 htonl (GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH));
46 * Check that a new session key is well-formed.
48 * @return GNUNET_OK if the key is valid
51 GNUNET_CRYPTO_aes_check_session_key (const struct GNUNET_CRYPTO_AesSessionKey
56 crc = GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH);
57 if (ntohl (key->crc32) == crc)
65 * Encrypt a block with the public key of another
66 * host that uses the same cyper.
67 * @param block the block to encrypt
68 * @param len the size of the block
69 * @param sessionkey the key used to encrypt
70 * @param iv the initialization vector to use, use INITVALUE
72 * @param result the output parameter in which to store the encrypted result
73 * @returns the size of the encrypted block, -1 for errors
76 GNUNET_CRYPTO_aes_encrypt (const void *block,
78 const struct GNUNET_CRYPTO_AesSessionKey
80 const struct GNUNET_CRYPTO_AesInitializationVector
83 gcry_cipher_hd_t handle;
86 if (sessionkey->crc32 !=
87 htonl (GNUNET_CRYPTO_crc32_n
88 (sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH)))
93 GNUNET_assert (0 == gcry_cipher_open (&handle,
95 GCRY_CIPHER_MODE_CFB, 0));
96 rc = gcry_cipher_setkey (handle, sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH);
97 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
99 gcry_cipher_setiv (handle, iv,
100 sizeof (struct GNUNET_CRYPTO_AesInitializationVector));
101 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
102 GNUNET_assert (0 == gcry_cipher_encrypt (handle, result, len, block, len));
103 gcry_cipher_close (handle);
108 * Decrypt a given block with the sessionkey.
110 * @param block the data to decrypt, encoded as returned by encrypt
111 * @param size the size of the block to decrypt
112 * @param sessionkey the key used to decrypt
113 * @param iv the initialization vector to use, use INITVALUE
115 * @param result address to store the result at
116 * @return -1 on failure, size of decrypted block on success
119 GNUNET_CRYPTO_aes_decrypt (const void *block,
121 const struct GNUNET_CRYPTO_AesSessionKey
123 const struct GNUNET_CRYPTO_AesInitializationVector
126 gcry_cipher_hd_t handle;
129 if (sessionkey->crc32 !=
130 htonl (GNUNET_CRYPTO_crc32_n
131 (sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH)))
136 GNUNET_assert (0 == gcry_cipher_open (&handle,
138 GCRY_CIPHER_MODE_CFB, 0));
139 rc = gcry_cipher_setkey (handle, sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH);
140 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
142 gcry_cipher_setiv (handle, iv,
143 sizeof (struct GNUNET_CRYPTO_AesInitializationVector));
144 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
146 gcry_cipher_decrypt (handle, result, size, block, size));
147 gcry_cipher_close (handle);
152 * @brief Derive an IV
153 * @param iv initialization vector
154 * @param skey session key
155 * @param salt salt for the derivation
156 * @param salt_len size of the salt
157 * @param ... pairs of void * & size_t for context chunks, terminated by NULL
160 GNUNET_CRYPTO_aes_derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
161 const struct GNUNET_CRYPTO_AesSessionKey *skey,
162 const void *salt, size_t salt_len,
167 va_start (argp, salt_len);
168 GNUNET_CRYPTO_aes_derive_iv_v (iv, skey, salt, salt_len, argp);
173 * @brief Derive an IV
174 * @param iv initialization vector
175 * @param skey session key
176 * @param salt salt for the derivation
177 * @param salt_len size of the salt
178 * @param argp pairs of void * & size_t for context chunks, terminated by NULL
181 GNUNET_CRYPTO_aes_derive_iv_v (struct GNUNET_CRYPTO_AesInitializationVector *iv,
182 const struct GNUNET_CRYPTO_AesSessionKey *skey,
183 const void *salt, size_t salt_len,
186 GNUNET_CRYPTO_kdf_v (iv->iv, sizeof(iv->iv), salt, salt_len, skey->key,
187 sizeof(skey->key), argp);
190 /* end of crypto_aes.c */