/*	$NetBSD: rijndael-api-fst.c,v 1.25 2016/12/11 00:28:44 alnsn Exp $	*/

/**
 * rijndael-api-fst.c
 *
 * @version 2.9 (December 2000)
 *
 * Optimised ANSI C code for the Rijndael cipher (now AES)
 *
 * @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
 * @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
 * @author Paulo Barreto <paulo.barreto@terra.com.br>
 *
 * This code is hereby placed in the public domain.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Acknowledgements:
 *
 * We are deeply indebted to the following people for their bug reports,
 * fixes, and improvement suggestions to this implementation. Though we
 * tried to list all contributions, we apologise in advance for any
 * missing reference.
 *
 * Andrew Bales <Andrew.Bales@Honeywell.com>
 * Markus Friedl <markus.friedl@informatik.uni-erlangen.de>
 * John Skodon <skodonj@webquill.com>
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rijndael-api-fst.c,v 1.25 2016/12/11 00:28:44 alnsn Exp $");

#include <sys/param.h>
#ifdef _KERNEL
#include <sys/systm.h>
#else
#include <stdlib.h>
#include <string.h>
#endif

#include <crypto/rijndael/rijndael_local.h>
#include <crypto/rijndael/rijndael-alg-fst.h>
#include <crypto/rijndael/rijndael-api-fst.h>

#define XTS_ALPHA 0x87

static void xor16(uint8_t *d, const uint8_t *a, const uint8_t* b)
{
	for (size_t i = 0; i < 4; i++) {
		*d++ = *a++ ^ *b++;
		*d++ = *a++ ^ *b++;
		*d++ = *a++ ^ *b++;
		*d++ = *a++ ^ *b++;
	}
}

static void
xts_exponentiate(uint8_t *iv)
{
	unsigned int carry = 0;

	for (size_t i = 0; i < 16; i++) {
		unsigned int msb = iv[i] >> 7;

		iv[i] = (iv[i] << 1) | carry;
		carry = msb;
	}

	if (carry != 0)
		iv[0] ^= XTS_ALPHA;
}

int
rijndael_makeKey(keyInstance *key, BYTE direction, int keyLen,
    const char *keyMaterial)
{
	u_int8_t cipherKey[RIJNDAEL_MAXKB];

	if (key == NULL) {
		return BAD_KEY_INSTANCE;
	}

	if ((direction == DIR_ENCRYPT) || (direction == DIR_DECRYPT)) {
		key->direction = direction;
	} else {
		return BAD_KEY_DIR;
	}

	if ((keyLen == 128) || (keyLen == 192) || (keyLen == 256)) {
		key->keyLen = keyLen;
	} else {
		return BAD_KEY_MAT;
	}

	if (keyMaterial != NULL) {
		memcpy(key->keyMaterial, keyMaterial, keyLen/8);
	}

	/* initialize key schedule: */
	memcpy(cipherKey, key->keyMaterial, keyLen/8);
	if (direction == DIR_ENCRYPT) {
		key->Nr = rijndaelKeySetupEnc(key->rk, cipherKey, keyLen);
	} else {
		key->Nr = rijndaelKeySetupDec(key->rk, cipherKey, keyLen);
	}
	rijndaelKeySetupEnc(key->ek, cipherKey, keyLen);
	return TRUE;
}

int
rijndael_cipherInit(cipherInstance *cipher, BYTE mode, const char *IV)
{
	if ((mode == MODE_ECB) || (mode == MODE_CBC) ||
	    (mode == MODE_XTS) || (mode == MODE_CFB1)) {
		cipher->mode = mode;
	} else {
		return BAD_CIPHER_MODE;
	}
	if (IV != NULL) {
		memcpy(cipher->IV, IV, RIJNDAEL_MAX_IV_SIZE);
	} else {
		memset(cipher->IV, 0, RIJNDAEL_MAX_IV_SIZE);
	}
	return TRUE;
}

int
rijndael_blockEncrypt(cipherInstance *cipher, keyInstance *key,
    const BYTE *input, int inputLen, BYTE *outBuffer)
{
	int i, k, t, numBlocks;
	u_int8_t block[16], *iv;

	if (cipher == NULL ||
		key == NULL ||
		key->direction == DIR_DECRYPT) {
		return BAD_CIPHER_STATE;
	}
	if (input == NULL || inputLen <= 0) {
		return 0; /* nothing to do */
	}

	numBlocks = inputLen/128;

	switch (cipher->mode) {
	case MODE_ECB:
		for (i = numBlocks; i > 0; i--) {
			rijndaelEncrypt(key->rk, key->Nr, input, outBuffer);
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_CBC:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			xor16(block, input, iv);
			rijndaelEncrypt(key->rk, key->Nr, block, outBuffer);
			iv = outBuffer;
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_XTS:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			xor16(block, input, iv);
			rijndaelEncrypt(key->rk, key->Nr, block, block);
			xor16(outBuffer, block, iv);
			xts_exponentiate(iv);
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_CFB1:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			memcpy(outBuffer, input, 16);
			for (k = 0; k < 128; k++) {
				rijndaelEncrypt(key->ek, key->Nr, iv, block);
				outBuffer[k >> 3] ^=
				    (block[0] & 0x80U) >> (k & 7);
				for (t = 0; t < 15; t++) {
					iv[t] = (iv[t] << 1) | (iv[t + 1] >> 7);
				}
				iv[15] = (iv[15] << 1) |
				    ((outBuffer[k >> 3] >> (7 - (k & 7))) & 1);
			}
			outBuffer += 16;
			input += 16;
		}
		break;

	default:
		return BAD_CIPHER_STATE;
	}

	return 128 * numBlocks;
}

/**
 * Encrypt data partitioned in octets, using RFC 2040-like padding.
 *
 * @param   input           data to be encrypted (octet sequence)
 * @param   inputOctets		input length in octets (not bits)
 * @param   outBuffer       encrypted output data
 *
 * @return	length in octets (not bits) of the encrypted output buffer.
 */
int
rijndael_padEncrypt(cipherInstance *cipher, keyInstance *key,
    const BYTE *input, int inputOctets, BYTE *outBuffer)
{
	int i, numBlocks, padLen;
	u_int8_t block[16], *iv;

	if (cipher == NULL ||
		key == NULL ||
		key->direction == DIR_DECRYPT) {
		return BAD_CIPHER_STATE;
	}
	if (input == NULL || inputOctets <= 0) {
		return 0; /* nothing to do */
	}

	numBlocks = inputOctets / 16;

	switch (cipher->mode) {
	case MODE_ECB:
		for (i = numBlocks; i > 0; i--) {
			rijndaelEncrypt(key->rk, key->Nr, input, outBuffer);
			input += 16;
			outBuffer += 16;
		}
		padLen = 16 - (inputOctets - 16*numBlocks);
		memcpy(block, input, 16 - padLen);
		memset(block + 16 - padLen, padLen, padLen);
		rijndaelEncrypt(key->rk, key->Nr, block, outBuffer);
		break;

	case MODE_CBC:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			xor16(block, input, iv);
			rijndaelEncrypt(key->rk, key->Nr, block, outBuffer);
			iv = outBuffer;
			input += 16;
			outBuffer += 16;
		}
		padLen = 16 - (inputOctets - 16*numBlocks);
		for (i = 0; i < 16 - padLen; i++) {
			block[i] = input[i] ^ iv[i];
		}
		for (i = 16 - padLen; i < 16; i++) {
			block[i] = (BYTE)padLen ^ iv[i];
		}
		rijndaelEncrypt(key->rk, key->Nr, block, outBuffer);
		break;

	default:
		return BAD_CIPHER_STATE;
	}

	return 16 * (numBlocks + 1);
}

int
rijndael_blockDecrypt(cipherInstance *cipher, keyInstance *key,
    const BYTE *input, int inputLen, BYTE *outBuffer)
{
	int i, k, t, numBlocks;
	u_int8_t block[16], *iv;

	if (cipher == NULL ||
		key == NULL ||
		(cipher->mode != MODE_CFB1 && key->direction == DIR_ENCRYPT)) {
		return BAD_CIPHER_STATE;
	}
	if (input == NULL || inputLen <= 0) {
		return 0; /* nothing to do */
	}

	numBlocks = inputLen/128;

	switch (cipher->mode) {
	case MODE_ECB:
		for (i = numBlocks; i > 0; i--) {
			rijndaelDecrypt(key->rk, key->Nr, input, outBuffer);
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_CBC:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			rijndaelDecrypt(key->rk, key->Nr, input, block);
			xor16(block, block, iv);
			memcpy(cipher->IV, input, 16);
			memcpy(outBuffer, block, 16);
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_XTS:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			xor16(block, input, iv);
			rijndaelDecrypt(key->rk, key->Nr, block, block);
			xor16(outBuffer, block, iv);
			xts_exponentiate(iv);
			input += 16;
			outBuffer += 16;
		}
		break;

	case MODE_CFB1:
		iv = (u_int8_t *)cipher->IV;
		for (i = numBlocks; i > 0; i--) {
			memcpy(outBuffer, input, 16);
			for (k = 0; k < 128; k++) {
				rijndaelEncrypt(key->ek, key->Nr, iv, block);
				for (t = 0; t < 15; t++) {
					iv[t] = (iv[t] << 1) | (iv[t + 1] >> 7);
				}
				iv[15] = (iv[15] << 1) |
				    ((input[k >> 3] >> (7 - (k & 7))) & 1);
				outBuffer[k >> 3] ^= (block[0] & 0x80U) >>
				    (k & 7);
			}
			outBuffer += 16;
			input += 16;
		}
		break;

	default:
		return BAD_CIPHER_STATE;
	}

	return 128 * numBlocks;
}

int
rijndael_padDecrypt(cipherInstance *cipher, keyInstance *key,
    const BYTE *input, int inputOctets, BYTE *outBuffer)
{
	int i, numBlocks, padLen;
	u_int8_t block[16], *iv;

	if (cipher == NULL ||
		key == NULL ||
		key->direction == DIR_ENCRYPT) {
		return BAD_CIPHER_STATE;
	}
	if (input == NULL || inputOctets <= 0) {
		return 0; /* nothing to do */
	}
	if (inputOctets % 16 != 0) {
		return BAD_DATA;
	}

	numBlocks = inputOctets/16;

	switch (cipher->mode) {
	case MODE_ECB:
		/* all blocks but last */
		for (i = numBlocks - 1; i > 0; i--) {
			rijndaelDecrypt(key->rk, key->Nr, input, outBuffer);
			input += 16;
			outBuffer += 16;
		}
		/* last block */
		rijndaelDecrypt(key->rk, key->Nr, input, block);
		padLen = block[15];
		if (padLen >= 16) {
			return BAD_DATA;
		}
		for (i = 16 - padLen; i < 16; i++) {
			if (block[i] != padLen) {
				return BAD_DATA;
			}
		}
		memcpy(outBuffer, block, 16 - padLen);
		break;

	case MODE_CBC:
		iv = (u_int8_t *)cipher->IV;
		/* all blocks but last */
		for (i = numBlocks - 1; i > 0; i--) {
			rijndaelDecrypt(key->rk, key->Nr, input, block);
			xor16(block, block, iv);
			memcpy(cipher->IV, input, 16);
			memcpy(outBuffer, block, 16);
			input += 16;
			outBuffer += 16;
		}
		/* last block */
		rijndaelDecrypt(key->rk, key->Nr, input, block);
		xor16(block, block, iv);
		padLen = block[15];
		if (padLen <= 0 || padLen > 16) {
			return BAD_DATA;
		}
		for (i = 16 - padLen; i < 16; i++) {
			if (block[i] != padLen) {
				return BAD_DATA;
			}
		}
		memcpy(outBuffer, block, 16 - padLen);
		break;

	default:
		return BAD_CIPHER_STATE;
	}

	return 16 * numBlocks - padLen;
}