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330 lines
8 KiB
C
330 lines
8 KiB
C
/*
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* Copyright 2008-2016 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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#include <openssl/crypto.h>
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#include "modes_local.h"
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#include <string.h>
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/*
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* Trouble with Ciphertext Stealing, CTS, mode is that there is no
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* common official specification, but couple of cipher/application
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* specific ones: RFC2040 and RFC3962. Then there is 'Proposal to
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* Extend CBC Mode By "Ciphertext Stealing"' at NIST site, which
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* deviates from mentioned RFCs. Most notably it allows input to be
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* of block length and it doesn't flip the order of the last two
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* blocks. CTS is being discussed even in ECB context, but it's not
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* adopted for any known application. This implementation provides
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* two interfaces: one compliant with above mentioned RFCs and one
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* compliant with the NIST proposal, both extending CBC mode.
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*/
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size_t CRYPTO_cts128_encrypt_block(const unsigned char *in,
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unsigned char *out, size_t len,
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const void *key, unsigned char ivec[16],
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block128_f block)
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{
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size_t residue, n;
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if (len <= 16)
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return 0;
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if ((residue = len % 16) == 0)
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residue = 16;
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len -= residue;
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CRYPTO_cbc128_encrypt(in, out, len, key, ivec, block);
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in += len;
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out += len;
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for (n = 0; n < residue; ++n)
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ivec[n] ^= in[n];
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(*block) (ivec, ivec, key);
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memcpy(out, out - 16, residue);
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memcpy(out - 16, ivec, 16);
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return len + residue;
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}
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size_t CRYPTO_nistcts128_encrypt_block(const unsigned char *in,
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unsigned char *out, size_t len,
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const void *key,
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unsigned char ivec[16],
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block128_f block)
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{
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size_t residue, n;
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if (len < 16)
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return 0;
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residue = len % 16;
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len -= residue;
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CRYPTO_cbc128_encrypt(in, out, len, key, ivec, block);
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if (residue == 0)
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return len;
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in += len;
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out += len;
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for (n = 0; n < residue; ++n)
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ivec[n] ^= in[n];
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(*block) (ivec, ivec, key);
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memcpy(out - 16 + residue, ivec, 16);
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return len + residue;
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}
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size_t CRYPTO_cts128_encrypt(const unsigned char *in, unsigned char *out,
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size_t len, const void *key,
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unsigned char ivec[16], cbc128_f cbc)
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{
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size_t residue;
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union {
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size_t align;
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unsigned char c[16];
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} tmp;
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if (len <= 16)
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return 0;
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if ((residue = len % 16) == 0)
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residue = 16;
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len -= residue;
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(*cbc) (in, out, len, key, ivec, 1);
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in += len;
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out += len;
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#if defined(CBC_HANDLES_TRUNCATED_IO)
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memcpy(tmp.c, out - 16, 16);
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(*cbc) (in, out - 16, residue, key, ivec, 1);
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memcpy(out, tmp.c, residue);
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#else
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memset(tmp.c, 0, sizeof(tmp));
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memcpy(tmp.c, in, residue);
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memcpy(out, out - 16, residue);
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(*cbc) (tmp.c, out - 16, 16, key, ivec, 1);
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#endif
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return len + residue;
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}
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size_t CRYPTO_nistcts128_encrypt(const unsigned char *in, unsigned char *out,
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size_t len, const void *key,
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unsigned char ivec[16], cbc128_f cbc)
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{
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size_t residue;
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union {
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size_t align;
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unsigned char c[16];
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} tmp;
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if (len < 16)
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return 0;
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residue = len % 16;
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len -= residue;
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(*cbc) (in, out, len, key, ivec, 1);
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if (residue == 0)
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return len;
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in += len;
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out += len;
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#if defined(CBC_HANDLES_TRUNCATED_IO)
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(*cbc) (in, out - 16 + residue, residue, key, ivec, 1);
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#else
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memset(tmp.c, 0, sizeof(tmp));
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memcpy(tmp.c, in, residue);
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(*cbc) (tmp.c, out - 16 + residue, 16, key, ivec, 1);
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#endif
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return len + residue;
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}
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size_t CRYPTO_cts128_decrypt_block(const unsigned char *in,
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unsigned char *out, size_t len,
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const void *key, unsigned char ivec[16],
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block128_f block)
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{
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size_t residue, n;
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union {
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size_t align;
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unsigned char c[32];
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} tmp;
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if (len <= 16)
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return 0;
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if ((residue = len % 16) == 0)
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residue = 16;
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len -= 16 + residue;
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if (len) {
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CRYPTO_cbc128_decrypt(in, out, len, key, ivec, block);
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in += len;
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out += len;
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}
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(*block) (in, tmp.c + 16, key);
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memcpy(tmp.c, tmp.c + 16, 16);
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memcpy(tmp.c, in + 16, residue);
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(*block) (tmp.c, tmp.c, key);
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for (n = 0; n < 16; ++n) {
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unsigned char c = in[n];
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out[n] = tmp.c[n] ^ ivec[n];
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ivec[n] = c;
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}
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for (residue += 16; n < residue; ++n)
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out[n] = tmp.c[n] ^ in[n];
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return 16 + len + residue;
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}
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size_t CRYPTO_nistcts128_decrypt_block(const unsigned char *in,
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unsigned char *out, size_t len,
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const void *key,
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unsigned char ivec[16],
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block128_f block)
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{
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size_t residue, n;
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union {
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size_t align;
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unsigned char c[32];
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} tmp;
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if (len < 16)
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return 0;
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residue = len % 16;
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if (residue == 0) {
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CRYPTO_cbc128_decrypt(in, out, len, key, ivec, block);
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return len;
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}
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len -= 16 + residue;
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if (len) {
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CRYPTO_cbc128_decrypt(in, out, len, key, ivec, block);
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in += len;
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out += len;
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}
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(*block) (in + residue, tmp.c + 16, key);
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memcpy(tmp.c, tmp.c + 16, 16);
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memcpy(tmp.c, in, residue);
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(*block) (tmp.c, tmp.c, key);
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for (n = 0; n < 16; ++n) {
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unsigned char c = in[n];
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out[n] = tmp.c[n] ^ ivec[n];
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ivec[n] = in[n + residue];
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tmp.c[n] = c;
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}
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for (residue += 16; n < residue; ++n)
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out[n] = tmp.c[n] ^ tmp.c[n - 16];
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return 16 + len + residue;
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}
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size_t CRYPTO_cts128_decrypt(const unsigned char *in, unsigned char *out,
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size_t len, const void *key,
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unsigned char ivec[16], cbc128_f cbc)
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{
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size_t residue;
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union {
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size_t align;
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unsigned char c[32];
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} tmp;
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if (len <= 16)
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return 0;
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if ((residue = len % 16) == 0)
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residue = 16;
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len -= 16 + residue;
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if (len) {
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(*cbc) (in, out, len, key, ivec, 0);
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in += len;
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out += len;
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}
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memset(tmp.c, 0, sizeof(tmp));
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/*
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* this places in[16] at &tmp.c[16] and decrypted block at &tmp.c[0]
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*/
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(*cbc) (in, tmp.c, 16, key, tmp.c + 16, 0);
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memcpy(tmp.c, in + 16, residue);
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#if defined(CBC_HANDLES_TRUNCATED_IO)
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(*cbc) (tmp.c, out, 16 + residue, key, ivec, 0);
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#else
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(*cbc) (tmp.c, tmp.c, 32, key, ivec, 0);
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memcpy(out, tmp.c, 16 + residue);
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#endif
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return 16 + len + residue;
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}
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size_t CRYPTO_nistcts128_decrypt(const unsigned char *in, unsigned char *out,
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size_t len, const void *key,
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unsigned char ivec[16], cbc128_f cbc)
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{
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size_t residue;
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union {
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size_t align;
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unsigned char c[32];
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} tmp;
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if (len < 16)
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return 0;
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residue = len % 16;
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if (residue == 0) {
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(*cbc) (in, out, len, key, ivec, 0);
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return len;
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}
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len -= 16 + residue;
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if (len) {
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(*cbc) (in, out, len, key, ivec, 0);
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in += len;
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out += len;
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}
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memset(tmp.c, 0, sizeof(tmp));
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/*
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* this places in[16] at &tmp.c[16] and decrypted block at &tmp.c[0]
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*/
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(*cbc) (in + residue, tmp.c, 16, key, tmp.c + 16, 0);
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memcpy(tmp.c, in, residue);
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#if defined(CBC_HANDLES_TRUNCATED_IO)
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(*cbc) (tmp.c, out, 16 + residue, key, ivec, 0);
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#else
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(*cbc) (tmp.c, tmp.c, 32, key, ivec, 0);
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memcpy(out, tmp.c, 16 + residue);
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#endif
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return 16 + len + residue;
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}
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