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298 linhas
9.5 KiB
298 linhas
9.5 KiB
// Portions copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// This module provides a slow but portable implementation of
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// the SHA1 hash function.
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//
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// It is adapted from free code written by Paul E. Jones
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// <paulej@packetizer.com>. See http://www.packetizer.com/security/sha1/
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//
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// The license for the original code is:
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/*
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Copyright (C) 1998, 2009
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Paul E. Jones <paulej@packetizer.com>
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Freeware Public License (FPL)
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This software is licensed as "freeware." Permission to distribute
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this software in source and binary forms, including incorporation
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into other products, is hereby granted without a fee. THIS SOFTWARE
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IS PROVIDED 'AS IS' AND WITHOUT ANY EXPRESSED OR IMPLIED WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHOR SHALL NOT BE HELD
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LIABLE FOR ANY DAMAGES RESULTING FROM THE USE OF THIS SOFTWARE, EITHER
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DIRECTLY OR INDIRECTLY, INCLUDING, BUT NOT LIMITED TO, LOSS OF DATA
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OR DATA BEING RENDERED INACCURATE.
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*/
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#include "port/sha1_portable.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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namespace leveldb {
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namespace port {
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/*
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* Description:
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* This class implements the Secure Hashing Standard as defined
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* in FIPS PUB 180-1 published April 17, 1995.
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*/
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/*
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* This structure will hold context information for the hashing
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* operation
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*/
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typedef struct SHA1Context {
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unsigned Message_Digest[5]; /* Message Digest (output) */
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unsigned Length_Low; /* Message length in bits */
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unsigned Length_High; /* Message length in bits */
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unsigned char Message_Block[64]; /* 512-bit message blocks */
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int Message_Block_Index; /* Index into message block array */
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bool Computed; /* Is the digest computed? */
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bool Corrupted; /* Is the message digest corruped? */
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} SHA1Context;
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/*
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* Portability Issues:
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* SHA-1 is defined in terms of 32-bit "words". This code was
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* written with the expectation that the processor has at least
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* a 32-bit machine word size. If the machine word size is larger,
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* the code should still function properly. One caveat to that
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* is that the input functions taking characters and character
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* arrays assume that only 8 bits of information are stored in each
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* character.
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*/
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/*
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* Define the circular shift macro
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*/
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#define SHA1CircularShift(bits,word) \
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((((word) << (bits)) & 0xFFFFFFFF) | \
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((word) >> (32-(bits))))
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/* Function prototypes */
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static void SHA1ProcessMessageBlock(SHA1Context *);
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static void SHA1PadMessage(SHA1Context *);
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// Initialize the SHA1Context in preparation for computing a new
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// message digest.
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static void SHA1Reset(SHA1Context* context) {
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context->Length_Low = 0;
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context->Length_High = 0;
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context->Message_Block_Index = 0;
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context->Message_Digest[0] = 0x67452301;
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context->Message_Digest[1] = 0xEFCDAB89;
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context->Message_Digest[2] = 0x98BADCFE;
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context->Message_Digest[3] = 0x10325476;
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context->Message_Digest[4] = 0xC3D2E1F0;
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context->Computed = false;
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context->Corrupted = false;
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}
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// This function will return the 160-bit message digest into the
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// Message_Digest array within the SHA1Context provided
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static bool SHA1Result(SHA1Context *context) {
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if (context->Corrupted) {
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return false;
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}
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if (!context->Computed) {
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SHA1PadMessage(context);
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context->Computed = true;
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}
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return true;
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}
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// This function accepts an array of bytes as the next portion of
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// the message.
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static void SHA1Input(SHA1Context *context,
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const unsigned char *message_array,
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unsigned length) {
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if (!length) return;
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if (context->Computed || context->Corrupted) {
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context->Corrupted = true;
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return;
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}
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while(length-- && !context->Corrupted) {
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context->Message_Block[context->Message_Block_Index++] =
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(*message_array & 0xFF);
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context->Length_Low += 8;
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/* Force it to 32 bits */
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context->Length_Low &= 0xFFFFFFFF;
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if (context->Length_Low == 0) {
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context->Length_High++;
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/* Force it to 32 bits */
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context->Length_High &= 0xFFFFFFFF;
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if (context->Length_High == 0)
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{
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/* Message is too long */
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context->Corrupted = true;
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}
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}
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if (context->Message_Block_Index == 64)
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{
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SHA1ProcessMessageBlock(context);
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}
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message_array++;
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}
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}
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// This function will process the next 512 bits of the message stored
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// in the Message_Block array.
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static void SHA1ProcessMessageBlock(SHA1Context *context) {
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const unsigned K[] = // Constants defined in SHA-1
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{
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0x5A827999,
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0x6ED9EBA1,
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0x8F1BBCDC,
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0xCA62C1D6
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};
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int t; // Loop counter
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unsigned temp; // Temporary word value
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unsigned W[80]; // Word sequence
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unsigned A, B, C, D, E; // Word buffers
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// Initialize the first 16 words in the array W
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for(t = 0; t < 16; t++) {
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W[t] = ((unsigned) context->Message_Block[t * 4]) << 24;
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W[t] |= ((unsigned) context->Message_Block[t * 4 + 1]) << 16;
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W[t] |= ((unsigned) context->Message_Block[t * 4 + 2]) << 8;
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W[t] |= ((unsigned) context->Message_Block[t * 4 + 3]);
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}
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for(t = 16; t < 80; t++) {
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W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
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}
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A = context->Message_Digest[0];
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B = context->Message_Digest[1];
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C = context->Message_Digest[2];
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D = context->Message_Digest[3];
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E = context->Message_Digest[4];
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for(t = 0; t < 20; t++) {
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temp = SHA1CircularShift(5,A) +
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((B & C) | ((~B) & D)) + E + W[t] + K[0];
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temp &= 0xFFFFFFFF;
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E = D;
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D = C;
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C = SHA1CircularShift(30,B);
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B = A;
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A = temp;
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}
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for(t = 20; t < 40; t++) {
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temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
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temp &= 0xFFFFFFFF;
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E = D;
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D = C;
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C = SHA1CircularShift(30,B);
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B = A;
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A = temp;
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}
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for(t = 40; t < 60; t++) {
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temp = SHA1CircularShift(5,A) +
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((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
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temp &= 0xFFFFFFFF;
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E = D;
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D = C;
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C = SHA1CircularShift(30,B);
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B = A;
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A = temp;
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}
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for(t = 60; t < 80; t++) {
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temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
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temp &= 0xFFFFFFFF;
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E = D;
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D = C;
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C = SHA1CircularShift(30,B);
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B = A;
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A = temp;
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}
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context->Message_Digest[0] = (context->Message_Digest[0] + A) & 0xFFFFFFFF;
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context->Message_Digest[1] = (context->Message_Digest[1] + B) & 0xFFFFFFFF;
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context->Message_Digest[2] = (context->Message_Digest[2] + C) & 0xFFFFFFFF;
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context->Message_Digest[3] = (context->Message_Digest[3] + D) & 0xFFFFFFFF;
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context->Message_Digest[4] = (context->Message_Digest[4] + E) & 0xFFFFFFFF;
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context->Message_Block_Index = 0;
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}
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// According to the standard, the message must be padded to an even
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// 512 bits. The first padding bit must be a '1'. The last 64 bits
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// represent the length of the original message. All bits in between
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// should be 0. This function will pad the message according to those
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// rules by filling the Message_Block array accordingly. It will also
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// call SHA1ProcessMessageBlock() appropriately. When it returns, it
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// can be assumed that the message digest has been computed.
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static void SHA1PadMessage(SHA1Context *context) {
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// Check to see if the current message block is too small to hold
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// the initial padding bits and length. If so, we will pad the
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// block, process it, and then continue padding into a second block.
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if (context->Message_Block_Index > 55) {
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context->Message_Block[context->Message_Block_Index++] = 0x80;
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while(context->Message_Block_Index < 64) {
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context->Message_Block[context->Message_Block_Index++] = 0;
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}
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SHA1ProcessMessageBlock(context);
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while(context->Message_Block_Index < 56) {
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context->Message_Block[context->Message_Block_Index++] = 0;
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}
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} else {
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context->Message_Block[context->Message_Block_Index++] = 0x80;
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while(context->Message_Block_Index < 56) {
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context->Message_Block[context->Message_Block_Index++] = 0;
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}
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}
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// Store the message length as the last 8 octets
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context->Message_Block[56] = (context->Length_High >> 24) & 0xFF;
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context->Message_Block[57] = (context->Length_High >> 16) & 0xFF;
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context->Message_Block[58] = (context->Length_High >> 8) & 0xFF;
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context->Message_Block[59] = (context->Length_High) & 0xFF;
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context->Message_Block[60] = (context->Length_Low >> 24) & 0xFF;
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context->Message_Block[61] = (context->Length_Low >> 16) & 0xFF;
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context->Message_Block[62] = (context->Length_Low >> 8) & 0xFF;
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context->Message_Block[63] = (context->Length_Low) & 0xFF;
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SHA1ProcessMessageBlock(context);
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}
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void SHA1_Hash_Portable(const char* data, size_t len, char* hash_array) {
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SHA1Context context;
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SHA1Reset(&context);
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SHA1Input(&context, reinterpret_cast<const unsigned char*>(data), len);
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bool ok = SHA1Result(&context);
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if (!ok) {
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fprintf(stderr, "Unexpected error in SHA1_Hash_Portable code\n");
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exit(1);
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}
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for (int i = 0; i < 5; i++) {
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uint32_t value = context.Message_Digest[i];
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hash_array[i*4 + 0] = (value >> 24) & 0xff;
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hash_array[i*4 + 1] = (value >> 16) & 0xff;
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hash_array[i*4 + 2] = (value >> 8) & 0xff;
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hash_array[i*4 + 3] = value & 0xff;
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}
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}
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}
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}
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