openssl/crypto/aes/aes_cbc.c

/* crypto/aes/aes_cbc.c -*- mode:C; c-file-style: "eay" -*- */
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 *    distribution.
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 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
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#ifndef AES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#include <openssl/aes.h>
#include "aes_locl.h"

void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
		     const unsigned long length, const AES_KEY *key,
		     unsigned char *ivec, const int enc) {

	unsigned long n;
	unsigned long len = length;
	unsigned char tmp[AES_BLOCK_SIZE];
	const unsigned char *iv = ivec;

	assert(in && out && key && ivec);
	assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));

	if (AES_ENCRYPT == enc) {
		while (len >= AES_BLOCK_SIZE) {
			for(n=0; n < AES_BLOCK_SIZE; ++n)
				out[n] = in[n] ^ iv[n];
			AES_encrypt(out, out, key);
			iv = out;
			len -= AES_BLOCK_SIZE;
			in += AES_BLOCK_SIZE;
			out += AES_BLOCK_SIZE;
		}
		if (len) {
			for(n=0; n < len; ++n)
				out[n] = in[n] ^ iv[n];
			for(n=len; n < AES_BLOCK_SIZE; ++n)
				out[n] = iv[n];
			AES_encrypt(out, out, key);
			iv = out;
		}
		memcpy(ivec,iv,AES_BLOCK_SIZE);
	} else if (in != out) {
		while (len >= AES_BLOCK_SIZE) {
			AES_decrypt(in, out, key);
			for(n=0; n < AES_BLOCK_SIZE; ++n)
				out[n] ^= iv[n];
			iv = in;
			len -= AES_BLOCK_SIZE;
			in  += AES_BLOCK_SIZE;
			out += AES_BLOCK_SIZE;
		}
		if (len) {
			AES_decrypt(in,tmp,key);
			for(n=0; n < len; ++n)
				out[n] = tmp[n] ^ iv[n];
			iv = in;
		}
		memcpy(ivec,iv,AES_BLOCK_SIZE);
	} else {
		while (len >= AES_BLOCK_SIZE) {
			memcpy(tmp, in, AES_BLOCK_SIZE);
			AES_decrypt(in, out, key);
			for(n=0; n < AES_BLOCK_SIZE; ++n)
				out[n] ^= ivec[n];
			memcpy(ivec, tmp, AES_BLOCK_SIZE);
			len -= AES_BLOCK_SIZE;
			in += AES_BLOCK_SIZE;
			out += AES_BLOCK_SIZE;
		}
		if (len) {
			memcpy(tmp, in, AES_BLOCK_SIZE);
			AES_decrypt(tmp, out, key);
			for(n=0; n < len; ++n)
				out[n] ^= ivec[n];
			for(n=len; n < AES_BLOCK_SIZE; ++n)
				out[n] = tmp[n];
			memcpy(ivec, tmp, AES_BLOCK_SIZE);
		}
	}
}