- unsigned long n;
- unsigned long len = length;
- unsigned char tmp[AES_BLOCK_SIZE], *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)
- tmp[n] = in[n] ^ iv[n];
- for(n=len; n < AES_BLOCK_SIZE; ++n)
- tmp[n] = iv[n];
- AES_encrypt(tmp, tmp, key);
- memcpy(out, tmp, AES_BLOCK_SIZE);
- 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, tmp, key);
- for(n=0; n < len; ++n)
- out[n] = tmp[n] ^ ivec[n];
- memcpy(ivec, tmp, AES_BLOCK_SIZE);
- }
- }