- <sect1><title>Code Example For Synchronous Block Cipher Operation</title>
- <programlisting>
-
-static int test_blkcipher(void)
-{
- struct crypto_blkcipher *blkcipher = NULL;
- char *cipher = "cbc(aes)";
- // AES 128
- charkey =
-"\x12\x34\x56\x78\x90\xab\xcd\xef\x12\x34\x56\x78\x90\xab\xcd\xef";
- chariv =
-"\x12\x34\x56\x78\x90\xab\xcd\xef\x12\x34\x56\x78\x90\xab\xcd\xef";
- unsigned int ivsize = 0;
- char *scratchpad = NULL; // holds plaintext and ciphertext
- struct scatterlist sg;
- struct blkcipher_desc desc;
- int ret = -EFAULT;
-
- blkcipher = crypto_alloc_blkcipher(cipher, 0, 0);
- if (IS_ERR(blkcipher)) {
- printk("could not allocate blkcipher handle for %s\n", cipher);
- return -PTR_ERR(blkcipher);
- }
-
- if (crypto_blkcipher_setkey(blkcipher, key, strlen(key))) {
- printk("key could not be set\n");
- ret = -EAGAIN;
- goto out;
- }
-
- ivsize = crypto_blkcipher_ivsize(blkcipher);
- if (ivsize) {
- if (ivsize != strlen(iv))
- printk("IV length differs from expected length\n");
- crypto_blkcipher_set_iv(blkcipher, iv, ivsize);
- }
-
- scratchpad = kmalloc(crypto_blkcipher_blocksize(blkcipher), GFP_KERNEL);
- if (!scratchpad) {
- printk("could not allocate scratchpad for %s\n", cipher);
- goto out;
- }
- /* get some random data that we want to encrypt */
- get_random_bytes(scratchpad, crypto_blkcipher_blocksize(blkcipher));
-
- desc.flags = 0;
- desc.tfm = blkcipher;
- sg_init_one(&sg, scratchpad, crypto_blkcipher_blocksize(blkcipher));
-
- /* encrypt data in place */
- crypto_blkcipher_encrypt(&desc, &sg, &sg,
- crypto_blkcipher_blocksize(blkcipher));
-
- /* decrypt data in place
- * crypto_blkcipher_decrypt(&desc, &sg, &sg,
- */ crypto_blkcipher_blocksize(blkcipher));
-
-
- printk("Cipher operation completed\n");
- return 0;
-
-out:
- if (blkcipher)
- crypto_free_blkcipher(blkcipher);
- if (scratchpad)
- kzfree(scratchpad);
- return ret;
-}
- </programlisting>
- </sect1>
-