/* crypto/modes/wrap128.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 * Mode with padding contributed by Petr Spacek (pspacek@redhat.com).
 */
/* ====================================================================
 * Copyright (c) 2013 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
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 *    distribution.
 *
 * 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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 *    licensing@OpenSSL.org.
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 * 5. Products derived from this software may not be called "OpenSSL"
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
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/**  Beware!
 *
 *  Following wrapping modes were designed for AES but this implementation
 *  allows you to use them for any 128 bit block cipher.
 */

#include "cryptlib.h"
#include <openssl/modes.h>

/** RFC 3394 section 2.2.3.1 Default Initial Value */
static const unsigned char default_iv[] = {
  0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
};

/** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
static const unsigned char default_aiv[] = {
  0xA6, 0x59, 0x59, 0xA6
};

/** Input size limit: lower than maximum of standards but far larger than
 *  anything that will be used in practice.
 */
#define CRYPTO128_WRAP_MAX (1UL << 31)

/** Wrapping according to RFC 3394 section 2.2.1.
 *
 *  @param[in]  key    Key value. 
 *  @param[in]  iv     IV value. Length = 8 bytes. NULL = use default_iv.
 *  @param[in]  in     Plain text as n 64-bit blocks, n >= 2.
 *  @param[in]  inlen  Length of in.
 *  @param[out] out    Cipher text. Minimal buffer length = (inlen + 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen does not consist of n 64-bit blocks, n >= 2.
 *                     or if inlen > CRYPTO128_WRAP_MAX.
 *                     Output length if wrapping succeeded.
 */
size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
		unsigned char *out,
		const unsigned char *in, size_t inlen, block128_f block)
	{
	unsigned char *A, B[16], *R;
	size_t i, j, t;
	if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
		return 0;
	A = B;
	t = 1;
	memmove(out + 8, in, inlen);
	if (!iv)
		iv = default_iv;

	memcpy(A, iv, 8);

	for (j = 0; j < 6; j++)
		{
		R = out + 8;
		for (i = 0; i < inlen; i += 8, t++, R += 8)
			{
			memcpy(B + 8, R, 8);
			block(B, B, key);
			A[7] ^= (unsigned char)(t & 0xff);
			if (t > 0xff)	
				{
				A[6] ^= (unsigned char)((t >> 8) & 0xff);
				A[5] ^= (unsigned char)((t >> 16) & 0xff);
				A[4] ^= (unsigned char)((t >> 24) & 0xff);
				}
			memcpy(R, B + 8, 8);
			}
		}
	memcpy(out, A, 8);
	return inlen + 8;
	}


/** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
 *  IV check (step 3) is responsibility of the caller.
 *
 *  @param[in]  key    Key value. 
 *  @param[out] iv     Unchecked IV value. Minimal buffer length = 8 bytes.
 *  @param[out] out    Plain text without IV.
 *                     Minimal buffer length = (inlen - 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext text as n 64-bit blocks
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 *                     or if inlen is not multiply of 8.
 *                     Output length otherwise.
 */
static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
		unsigned char *out, const unsigned char *in,
		size_t inlen, block128_f block)
	{
	unsigned char *A, B[16], *R;
	size_t i, j, t;
	inlen -= 8;
	if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
		return 0;
	A = B;
	t =  6 * (inlen >> 3);
	memcpy(A, in, 8);
	memmove(out, in + 8, inlen);
	for (j = 0; j < 6; j++)
		{
		R = out + inlen - 8;
		for (i = 0; i < inlen; i += 8, t--, R -= 8)
			{
			A[7] ^= (unsigned char)(t & 0xff);
			if (t > 0xff)	
				{
				A[6] ^= (unsigned char)((t >> 8) & 0xff);
				A[5] ^= (unsigned char)((t >> 16) & 0xff);
				A[4] ^= (unsigned char)((t >> 24) & 0xff);
				}
			memcpy(B + 8, R, 8);
			block(B, B, key);
			memcpy(R, B + 8, 8);
			}
		}
	memcpy(iv, A, 8);
	return inlen;
	}

/** Unwrapping according to RFC 3394 section 2.2.2 including IV check.
 *  First block of plain text have to match supplied IV otherwise an error is
 *  returned.
 *
 *  @param[in]  key    Key value. 
 *  @param[out] iv     Unchecked IV value. Minimal buffer length = 8 bytes.
 *  @param[out] out    Plain text without IV.
 *                     Minimal buffer length = (inlen - 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext text as n 64-bit blocks
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 *                     or if inlen is not multiply of 8
 *                     or if IV doesn't match expected value.
 *                     Output length otherwise.
 */
size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
		unsigned char *out, const unsigned char *in, size_t inlen,
		block128_f block)
	{
	size_t ret;
	unsigned char got_iv[8];

	ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
	if (ret != inlen)
		return ret;

	if (!iv)
		iv = default_iv;
	if (CRYPTO_memcmp(out, iv, 8))
		{
		OPENSSL_cleanse(out, inlen);
		return 0;
		}
	return inlen;
	}

/** Wrapping according to RFC 5649 section 4.1.
 *
 *  @param[in]  key    Key value. 
 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 *  @param[out] out    Cipher text. Minimal buffer length = (inlen + 15) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Plain text as n 64-bit blocks, n >= 2.
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
 *                     Output length if wrapping succeeded.
 */
size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
		unsigned char *out,
		const unsigned char *in, size_t inlen, block128_f block)
	{
	/* n: number of 64-bit blocks in the padded key data */
	const size_t blocks_padded = (inlen + 8) / 8;
	const size_t padded_len = blocks_padded * 8;
	const size_t padding_len = padded_len - inlen;
	/* RFC 5649 section 3: Alternative Initial Value */
	unsigned char aiv[8];
	int ret;

	/* Section 1: use 32-bit fixed field for plaintext octet length */
	if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
		return 0;

	/* Section 3: Alternative Initial Value */
	if (!icv)
		memcpy(aiv, default_aiv, 4);
	else
		memcpy(aiv, icv, 4); /* Standard doesn't mention this. */

	aiv[4] = (inlen >> 24) & 0xFF;
	aiv[5] = (inlen >> 16) & 0xFF;
	aiv[6] = (inlen >> 8) & 0xFF;
	aiv[7] = inlen & 0xFF;

	if (padded_len == 8)
		{
		/* Section 4.1 - special case in step 2:
		 * If the padded plaintext contains exactly eight octets, then
		 * prepend the AIV and encrypt the resulting 128-bit block
		 * using AES in ECB mode. */
		memmove(out + 8, in, inlen);
		memcpy(out, aiv, 8);
		memset(out + 8 + inlen, 0, padding_len);
		block(out, out, key);
		ret = 16; /* AIV + padded input */
		}
		else
		{
		memmove(out, in, inlen);
		memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
		ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
		}

	return ret;
	}

/** Unwrapping according to RFC 5649 section 4.2.
 *
 *  @param[in]  key    Key value. 
 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 *  @param[out] out    Plain text. Minimal buffer length = inlen bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext text as n 64-bit blocks
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
 *                     or if inlen is not multiply of 8
 *                     or if IV and message length indicator doesn't match.
 *                     Output length if unwrapping succeeded and IV matches.
 */
size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
		unsigned char *out,
		const unsigned char *in, size_t inlen, block128_f block)
	{
	/* n: number of 64-bit blocks in the padded key data */
	size_t n = inlen / 8 - 1;
	size_t padded_len;
	size_t padding_len;
	size_t ptext_len;
	/* RFC 5649 section 3: Alternative Initial Value */
	unsigned char aiv[8];
	static unsigned char zeros[8] = {0x0};
	size_t ret;

	/* Section 4.2: Cipher text length has to be (n+1) 64-bit blocks. */
	if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
		return 0;

	memmove(out, in, inlen);
	if (inlen == 16)
		{
		/* Section 4.2 - special case in step 1:
		 * When n=1, the ciphertext contains exactly two 64-bit
		 * blocks and they are decrypted as a single AES
		 * block using AES in ECB mode:
		 * AIV | P[1] = DEC(K, C[0] | C[1])
		 */
		block(out, out, key);
		memcpy(aiv, out, 8);
		/* Remove AIV */
		memmove(out, out + 8, 8);
		padded_len = 8;
		}
		else
		{
		padded_len = inlen - 8;
		ret = crypto_128_unwrap_raw(key, aiv, out, out, inlen, block);
		if (padded_len != ret)
			{
			OPENSSL_cleanse(out, inlen);
			return 0;
			}
		}

	/* Section 3: AIV checks: Check that MSB(32,A) = A65959A6.
	 * Optionally a user-supplied value can be used
	 * (even if standard doesn't mention this). */
	if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
		|| (icv && CRYPTO_memcmp(aiv, icv, 4)))
		{
		OPENSSL_cleanse(out, inlen);
		return 0;
		}

	/* Check that 8*(n-1) < LSB(32,AIV) <= 8*n.
	 * If so, let ptext_len = LSB(32,AIV). */

	ptext_len = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | aiv[7];
	if (8*(n-1) >= ptext_len || ptext_len > 8*n)
		{
		OPENSSL_cleanse(out, inlen);
		return 0;
		}

	/* Check that the rightmost padding_len octets of the output data
	 * are zero. */
	padding_len = padded_len - ptext_len;
	if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0)
		{
		OPENSSL_cleanse(out, inlen);
		return 0;
		}

	/* Section 4.2 step 3: Remove padding */
	return ptext_len;
	}