openssl/crypto/aes/aes_cbc.c

/* crypto/aes/aes_cbc.c -*- mode:C; c-file-style: "eay" -*- */
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#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) {

	int n;
	unsigned long len = length;
	unsigned char tmp[16];

	assert(in && out && key && ivec);
	assert(length % AES_BLOCK_SIZE == 0);
	assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));

	if (AES_ENCRYPT == enc)
		while (len > 0) {
			for(n=0; n < 16; ++n)
				tmp[n] = in[n] ^ ivec[n];
			AES_encrypt(tmp, out, key);
			memcpy(ivec, out, 16);
			len -= 16;
			in += 16;
			out += 16;
		}
	else
		while (len > 0) {
			memcpy(tmp, in, 16);
			AES_decrypt(in, out, key);
			for(n=0; n < 16; ++n)
				out[n] ^= ivec[n];
			memcpy(ivec, tmp, 16);
			len -= 16;
			in += 16;
			out += 16;
		}
}