332 lines
12 KiB
C
332 lines
12 KiB
C
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/*
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* Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/** Beware!
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*
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* Following wrapping modes were designed for AES but this implementation
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* allows you to use them for any 128 bit block cipher.
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*/
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#include "internal/cryptlib.h"
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#include <openssl/modes.h>
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/** RFC 3394 section 2.2.3.1 Default Initial Value */
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static const unsigned char default_iv[] = {
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0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
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};
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/** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
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static const unsigned char default_aiv[] = {
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0xA6, 0x59, 0x59, 0xA6
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};
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/** Input size limit: lower than maximum of standards but far larger than
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* anything that will be used in practice.
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*/
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#define CRYPTO128_WRAP_MAX (1UL << 31)
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/** Wrapping according to RFC 3394 section 2.2.1.
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*
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* @param[in] key Key value.
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* @param[in] iv IV value. Length = 8 bytes. NULL = use default_iv.
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* @param[in] in Plaintext as n 64-bit blocks, n >= 2.
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* @param[in] inlen Length of in.
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* @param[out] out Ciphertext. Minimal buffer length = (inlen + 8) bytes.
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* Input and output buffers can overlap if block function
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* supports that.
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* @param[in] block Block processing function.
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* @return 0 if inlen does not consist of n 64-bit blocks, n >= 2.
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* or if inlen > CRYPTO128_WRAP_MAX.
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* Output length if wrapping succeeded.
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*/
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size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
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unsigned char *out,
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const unsigned char *in, size_t inlen,
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block128_f block)
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{
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unsigned char *A, B[16], *R;
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size_t i, j, t;
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if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
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return 0;
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A = B;
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t = 1;
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memmove(out + 8, in, inlen);
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if (!iv)
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iv = default_iv;
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memcpy(A, iv, 8);
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for (j = 0; j < 6; j++) {
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R = out + 8;
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for (i = 0; i < inlen; i += 8, t++, R += 8) {
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memcpy(B + 8, R, 8);
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block(B, B, key);
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A[7] ^= (unsigned char)(t & 0xff);
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if (t > 0xff) {
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A[6] ^= (unsigned char)((t >> 8) & 0xff);
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A[5] ^= (unsigned char)((t >> 16) & 0xff);
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A[4] ^= (unsigned char)((t >> 24) & 0xff);
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}
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memcpy(R, B + 8, 8);
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}
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}
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memcpy(out, A, 8);
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return inlen + 8;
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}
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/** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
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* The IV check (step 3) is responsibility of the caller.
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*
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* @param[in] key Key value.
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* @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes.
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* @param[out] out Plaintext without IV.
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* Minimal buffer length = (inlen - 8) bytes.
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* Input and output buffers can overlap if block function
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* supports that.
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* @param[in] in Ciphertext as n 64-bit blocks.
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* @param[in] inlen Length of in.
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* @param[in] block Block processing function.
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* @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
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* or if inlen is not a multiple of 8.
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* Output length otherwise.
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*/
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static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
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unsigned char *out,
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const unsigned char *in, size_t inlen,
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block128_f block)
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{
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unsigned char *A, B[16], *R;
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size_t i, j, t;
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inlen -= 8;
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if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
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return 0;
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A = B;
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t = 6 * (inlen >> 3);
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memcpy(A, in, 8);
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memmove(out, in + 8, inlen);
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for (j = 0; j < 6; j++) {
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R = out + inlen - 8;
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for (i = 0; i < inlen; i += 8, t--, R -= 8) {
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A[7] ^= (unsigned char)(t & 0xff);
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if (t > 0xff) {
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A[6] ^= (unsigned char)((t >> 8) & 0xff);
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A[5] ^= (unsigned char)((t >> 16) & 0xff);
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A[4] ^= (unsigned char)((t >> 24) & 0xff);
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}
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memcpy(B + 8, R, 8);
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block(B, B, key);
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memcpy(R, B + 8, 8);
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}
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}
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memcpy(iv, A, 8);
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return inlen;
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}
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/** Unwrapping according to RFC 3394 section 2.2.2, including the IV check.
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* The first block of plaintext has to match the supplied IV, otherwise an
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* error is returned.
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*
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* @param[in] key Key value.
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* @param[out] iv IV value to match against. Length = 8 bytes.
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* NULL = use default_iv.
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* @param[out] out Plaintext without IV.
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* Minimal buffer length = (inlen - 8) bytes.
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* Input and output buffers can overlap if block function
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* supports that.
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* @param[in] in Ciphertext as n 64-bit blocks.
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* @param[in] inlen Length of in.
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* @param[in] block Block processing function.
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* @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
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* or if inlen is not a multiple of 8
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* or if IV doesn't match expected value.
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* Output length otherwise.
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*/
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size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
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unsigned char *out, const unsigned char *in,
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size_t inlen, block128_f block)
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{
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size_t ret;
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unsigned char got_iv[8];
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ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
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if (ret == 0)
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return 0;
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if (!iv)
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iv = default_iv;
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if (CRYPTO_memcmp(got_iv, iv, 8)) {
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OPENSSL_cleanse(out, ret);
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return 0;
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}
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return ret;
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}
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/** Wrapping according to RFC 5649 section 4.1.
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*
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* @param[in] key Key value.
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* @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv.
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* @param[out] out Ciphertext. Minimal buffer length = (inlen + 15) bytes.
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* Input and output buffers can overlap if block function
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* supports that.
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* @param[in] in Plaintext as n 64-bit blocks, n >= 2.
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* @param[in] inlen Length of in.
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* @param[in] block Block processing function.
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* @return 0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
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* Output length if wrapping succeeded.
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*/
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size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
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unsigned char *out,
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const unsigned char *in, size_t inlen,
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block128_f block)
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{
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/* n: number of 64-bit blocks in the padded key data
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*
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* If length of plain text is not a multiple of 8, pad the plain text octet
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* string on the right with octets of zeros, where final length is the
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* smallest multiple of 8 that is greater than length of plain text.
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* If length of plain text is a multiple of 8, then there is no padding. */
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const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
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const size_t padded_len = blocks_padded * 8;
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const size_t padding_len = padded_len - inlen;
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/* RFC 5649 section 3: Alternative Initial Value */
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unsigned char aiv[8];
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int ret;
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/* Section 1: use 32-bit fixed field for plaintext octet length */
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if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
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return 0;
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/* Section 3: Alternative Initial Value */
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if (!icv)
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memcpy(aiv, default_aiv, 4);
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else
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memcpy(aiv, icv, 4); /* Standard doesn't mention this. */
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aiv[4] = (inlen >> 24) & 0xFF;
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aiv[5] = (inlen >> 16) & 0xFF;
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aiv[6] = (inlen >> 8) & 0xFF;
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aiv[7] = inlen & 0xFF;
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if (padded_len == 8) {
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/*
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* Section 4.1 - special case in step 2: If the padded plaintext
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* contains exactly eight octets, then prepend the AIV and encrypt
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* the resulting 128-bit block using AES in ECB mode.
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*/
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memmove(out + 8, in, inlen);
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memcpy(out, aiv, 8);
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memset(out + 8 + inlen, 0, padding_len);
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block(out, out, key);
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ret = 16; /* AIV + padded input */
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} else {
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memmove(out, in, inlen);
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memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
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ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
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}
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return ret;
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}
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/** Unwrapping according to RFC 5649 section 4.2.
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*
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* @param[in] key Key value.
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* @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv.
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* @param[out] out Plaintext. Minimal buffer length = (inlen - 8) bytes.
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* Input and output buffers can overlap if block function
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* supports that.
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* @param[in] in Ciphertext as n 64-bit blocks.
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* @param[in] inlen Length of in.
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* @param[in] block Block processing function.
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* @return 0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
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* or if inlen is not a multiple of 8
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* or if IV and message length indicator doesn't match.
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* Output length if unwrapping succeeded and IV matches.
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*/
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size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
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unsigned char *out,
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const unsigned char *in, size_t inlen,
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block128_f block)
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{
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/* n: number of 64-bit blocks in the padded key data */
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size_t n = inlen / 8 - 1;
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size_t padded_len;
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size_t padding_len;
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size_t ptext_len;
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/* RFC 5649 section 3: Alternative Initial Value */
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unsigned char aiv[8];
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static unsigned char zeros[8] = { 0x0 };
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size_t ret;
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/* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */
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if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
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return 0;
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if (inlen == 16) {
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/*
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* Section 4.2 - special case in step 1: When n=1, the ciphertext
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* contains exactly two 64-bit blocks and they are decrypted as a
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* single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
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* C[1])
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*/
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unsigned char buff[16];
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block(in, buff, key);
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memcpy(aiv, buff, 8);
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/* Remove AIV */
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memcpy(out, buff + 8, 8);
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padded_len = 8;
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OPENSSL_cleanse(buff, inlen);
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} else {
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padded_len = inlen - 8;
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ret = crypto_128_unwrap_raw(key, aiv, out, in, inlen, block);
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if (padded_len != ret) {
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OPENSSL_cleanse(out, inlen);
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return 0;
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}
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}
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/*
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* Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
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* user-supplied value can be used (even if standard doesn't mention
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* this).
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*/
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if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
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|| (icv && CRYPTO_memcmp(aiv, icv, 4))) {
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OPENSSL_cleanse(out, inlen);
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return 0;
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}
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/*
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* Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
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* LSB(32,AIV).
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*/
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ptext_len = ((unsigned int)aiv[4] << 24)
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| ((unsigned int)aiv[5] << 16)
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| ((unsigned int)aiv[6] << 8)
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| (unsigned int)aiv[7];
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if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
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OPENSSL_cleanse(out, inlen);
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return 0;
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}
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/*
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* Check that the rightmost padding_len octets of the output data are
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* zero.
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*/
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padding_len = padded_len - ptext_len;
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if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
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OPENSSL_cleanse(out, inlen);
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return 0;
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}
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/* Section 4.2 step 3: Remove padding */
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return ptext_len;
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}
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