/* crypto/aes/aes_cbc.c -*- mode:C; c-file-style: "eay" -*- */
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#ifndef AES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#include "aes.h"
#include "aes_locl.h"
#include <string.h>

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

    unsigned long n;
    unsigned long len = length;
    unsigned char tmp[AES_BLOCK_SIZE];
    unsigned char tempiv[AES_BLOCK_SIZE];
    const unsigned char *iv;
    unsigned int paddingLen;

    assert(in && out && key && ivec);
    assert((AES_ENCRYPT == enc) || (AES_DECRYPT == enc));
    memcpy(tempiv, ivec, AES_BLOCK_SIZE);
    iv = tempiv;
    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) {
            paddingLen = AES_BLOCK_SIZE - len;
            for (n = 0; n < len; ++n) {
                out[n] = in[n] ^ iv[n];
            }
            for (n = len; n < AES_BLOCK_SIZE; ++n) {
                out[n] = paddingLen ^ iv[n];
            }
            AES_encrypt(out, out, key);
            iv = out;
            *outlength = length + paddingLen;
        } else if (0 == len) {
            paddingLen = AES_BLOCK_SIZE;
            for (n = 0; n < AES_BLOCK_SIZE; ++n) {
                out[n] = paddingLen ^ iv[n];
            }
            AES_encrypt(out, out, key);
            iv = out;
            *outlength = length + paddingLen;
        }

    } 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;
            *outlength = length - out[len - 1];
        } else if (0 == len) {
            *outlength = length - *(out - 1);
        }

    } 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);
            *outlength = length - out[len - 1];
        } else if (0 == len) {
            *outlength = length - *(out - 1);
        }
    }
}

void CT_AES_CBC_Encrypt(
    unsigned char *PlainText,
    unsigned int PlainTextLength,
    unsigned char *Key,
    unsigned int KeyLength,
    unsigned char *IV,
    unsigned int IVLength,
    unsigned char *CipherText,
    unsigned int *CipherTextLength)
{
    AES_KEY struKey;
    AES_set_encrypt_key(Key, KeyLength * 8,
                        &struKey);
    AES_cbc_core(PlainText, CipherText,
                 PlainTextLength, CipherTextLength, &struKey,
                 IV, AES_ENCRYPT);
    return;
}

void CT_AES_CBC_Decrypt(
    unsigned char *CipherText,
    unsigned int CipherTextLength,
    unsigned char *Key,
    unsigned int KeyLength,
    unsigned char *IV,
    unsigned int IVLength,
    unsigned char *PlainText,
    unsigned int *PlainTextLength)
{
    AES_KEY struKey;
    AES_set_decrypt_key(Key, KeyLength * 8,
                        &struKey);
    AES_cbc_core(CipherText, PlainText,
                 CipherTextLength, PlainTextLength, &struKey,
                 IV, AES_DECRYPT);
    return;
}