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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"
33 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
36 * Create a new SessionKey (for AES-256).
38 * @param key session key to initialize
41 GNUNET_CRYPTO_aes_create_session_key (struct GNUNET_CRYPTO_AesSessionKey *key)
43 gcry_randomize (&key->key[0], GNUNET_CRYPTO_AES_KEY_LENGTH,
46 htonl (GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH));
51 * Check that a new session key is well-formed.
53 * @return GNUNET_OK if the key is valid
56 GNUNET_CRYPTO_aes_check_session_key (const struct GNUNET_CRYPTO_AesSessionKey
61 crc = GNUNET_CRYPTO_crc32_n (key, GNUNET_CRYPTO_AES_KEY_LENGTH);
62 if (ntohl (key->crc32) == crc)
70 * Initialize AES cipher.
72 * @param handle handle to initialize
73 * @param sessionkey session key to use
74 * @param iv initialization vector to use
75 * @return GNUNET_OK on success, GNUNET_SYSERR on error
78 setup_cipher (gcry_cipher_hd_t *handle,
79 const struct GNUNET_CRYPTO_AesSessionKey *
81 const struct GNUNET_CRYPTO_AesInitializationVector *
87 GNUNET_CRYPTO_aes_check_session_key (sessionkey))
93 gcry_cipher_open (handle, GCRY_CIPHER_AES256,
94 GCRY_CIPHER_MODE_CFB, 0));
95 rc = gcry_cipher_setkey (*handle, sessionkey, GNUNET_CRYPTO_AES_KEY_LENGTH);
96 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
97 rc = gcry_cipher_setiv (*handle, iv,
99 GNUNET_CRYPTO_AesInitializationVector));
100 GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
106 * Encrypt a block with the public key of another
107 * host that uses the same cyper.
109 * @param block the block to encrypt
110 * @param len the size of the block
111 * @param sessionkey the key used to encrypt
112 * @param iv the initialization vector to use, use INITVALUE
114 * @param result the output parameter in which to store the encrypted result
115 * @returns the size of the encrypted block, -1 for errors
118 GNUNET_CRYPTO_aes_encrypt (const void *block, size_t len,
119 const struct GNUNET_CRYPTO_AesSessionKey *
121 const struct GNUNET_CRYPTO_AesInitializationVector *
124 gcry_cipher_hd_t handle;
126 if (GNUNET_OK != setup_cipher (&handle, sessionkey, iv))
128 GNUNET_assert (0 == gcry_cipher_encrypt (handle, result, len, block, len));
129 gcry_cipher_close (handle);
135 * Decrypt a given block with the sessionkey.
137 * @param block the data to decrypt, encoded as returned by encrypt
138 * @param size the size of the block to decrypt
139 * @param sessionkey the key used to decrypt
140 * @param iv the initialization vector to use, use INITVALUE
142 * @param result address to store the result at
143 * @return -1 on failure, size of decrypted block on success
146 GNUNET_CRYPTO_aes_decrypt (const void *block, size_t size,
147 const struct GNUNET_CRYPTO_AesSessionKey *
149 const struct GNUNET_CRYPTO_AesInitializationVector *
152 gcry_cipher_hd_t handle;
154 if (GNUNET_OK != setup_cipher (&handle, sessionkey, iv))
156 GNUNET_assert (0 == gcry_cipher_decrypt (handle, result, size, block, size));
157 gcry_cipher_close (handle);
163 * @brief Derive an IV
165 * @param iv initialization vector
166 * @param skey session key
167 * @param salt salt for the derivation
168 * @param salt_len size of the salt
169 * @param ... pairs of void * & size_t for context chunks, terminated by NULL
172 GNUNET_CRYPTO_aes_derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
173 const struct GNUNET_CRYPTO_AesSessionKey *skey,
174 const void *salt, size_t salt_len, ...)
178 va_start (argp, salt_len);
179 GNUNET_CRYPTO_aes_derive_iv_v (iv, skey, salt, salt_len, argp);
185 * @brief Derive an IV
187 * @param iv initialization vector
188 * @param skey session key
189 * @param salt salt for the derivation
190 * @param salt_len size of the salt
191 * @param argp pairs of void * & size_t for context chunks, terminated by NULL
194 GNUNET_CRYPTO_aes_derive_iv_v (struct GNUNET_CRYPTO_AesInitializationVector *iv,
195 const struct GNUNET_CRYPTO_AesSessionKey *skey,
196 const void *salt, size_t salt_len, va_list argp)
198 GNUNET_CRYPTO_kdf_v (iv->iv, sizeof (iv->iv), salt, salt_len, skey->key,
199 sizeof (skey->key), argp);
202 /* end of crypto_aes.c */