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////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2008, Dennis Andriesse                                   //
// [email]dae400@few.vu.nl[/email]                                                     //
//                                                                        //
// This is a C++ implementation of NIST's SHA hash algorithms.            //
// This code was written for my entertainment and may contain unnoticed   //
// security flaws.                                                        //
//                                                                        //
// This code may be used non-commercially (for your entertainment).       //
// See the section "LICENSE" for details on terms of use.                 //
//                                                                        //
// Complete SHA library, Dennis Andriesse, v1.0 (rev July 2008)           //
////////////////////////////////////////////////////////////////////////////
 
/*
NOTES
Most importantly, if you find errors in my SHA implementations (e.g., you are
absolutely certain that something you're hashing is giving an incorrect result),
please take a minute to inform me so I can fix it. You can reach me about this or
any questions at the above e-mail address.
 
Also very importantly, I've included the SHA-0 and SHA-1 algorithms. This is
mostly for completeness, and in case you really need them for some good reason.
Otherwise, SHA-0 and SHA-1 should not be used, as they are considered broken
and outdated (in fact, SHA-0 was even officially withdrawn by NIST).
 
LICENSE
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
A copy of the GNU General Public License is available at
<http://www.gnu.org/licenses/>.
 
USAGE
To use these SHA implementations, simply include them in your source with
(for example) the following instruction:
   
    #include "SHA_lib/SHA256.h"
   
This assumes that SHA256.h is in a directory called SHA_lib, in the same directory
as the file you're including SHA256.h in. You can also place SHA256.h in your standard
header files/include directory and include it using:
   
    #include <SHA256.h>
   
Either way, once you've included the files, the SHA algorithms should be quite
easy to use. Simply choose which SHA version you wish to use (the classes are
called SHA0, SHA1, SHA256, SHA224, SHA512 and SHA384) and make an instance of
the corresponding class, for example:
   
    SHA256* yourInstanceName = new SHA256();
   
Then you can use the hash() function, which is in each of the classes,
to hash whatever you wish to hash. The hash() function returns a C++ style
string (so not a char[]). The hash() function takes either a C++ style string
or a char[] as arguments. The char[] version can be used for hashing binary
files, C-style strings, or anything else you can convert to a char[].
When using the char[] version of hash(), you must also specify the size of the
char[] you're passing (or of course the number of elements from it that you
want to include in the hash). I recommend that when you calculate the size of
a C-style string that you want to hash, you don't include the terminating null
character in your calculation, as including it can result in a different hash
than expected. Here's how to use the hash() function, short and simple:
   
    string digest = yourInstanceName->hash(stringYouWantToHash);
   
    or
   
    string digest = yourInstanceName->hash(charArrayYouWantToHash, sizeOfCharArray);
   
This will deliver the hash of your input into the string called digest.
 
If you ever want to see which version of the library you're using without going
into the source, simply use the shaVersion() method, like this:
   
    cout << yourInstanceName->shaVersion() << endl;
   
This will print information about the version of the library onto the screen.
The shaVersion() method returns a string, so you can store the version info in
a variable as well if you don't immediately want to show it on the screen.
 
Finally, once you're done using SHA, don't forget to delete the instance(s) you
made, to avoid memory leaks:
   
    delete yourInstanceName;
*/
 
#ifndef SHA256_H
#define SHA256_H
 
#include <iostream>
#include <string>
#include <vector>
#include <stdint.h>
 
using namespace std;
 
 
/* TYPEDEFS
   ======== */
 
typedef uint8_t  byte;
typedef uint32_t word;
typedef uint64_t longword;
   
   
/* CLASS DEFINITIONS
   ================= */
 
// Start of class SHA256
class SHA256
{
    protected:       
        // Protected class variables
        static const unsigned short EXTENDED_WORD_AMOUNT = 64,
                                    DIGEST_CHARS         = 64,
                                    SIZE_WITHOUT_LENGTH  = 448,
                                    WORD_BYTES           = 4,
                                    LONGWORD_BYTES       = 8,
                                    CHUNK_BYTES          = 64,
                                    BYTE_HEX_DIGITS      = 2, // 2 hex digits are needed to display a byte.
                                    HEX_DIGIT_BITS       = 4, // A single hex digit corresponds to 4 bits.
                                    BYTE_SIZE            = 8, // 8 Bits.
                                    WORD_SIZE            = WORD_BYTES * BYTE_SIZE, // 32 bits.
                                    LONGWORD_SIZE        = LONGWORD_BYTES * BYTE_SIZE, // 64 bits.
                                    CHUNK_SIZE           = CHUNK_BYTES * BYTE_SIZE; // 512 bits.
        static const byte FULL_BYTE = 0xFF, // A byte with all bits set to 1.
                          HALF_BYTE = 0x0F; // A byte with the 4 left bits set to 0 and the 4 right bits set to 1.
        static const string HEX_VALUES, SHA_VERSION;
        static const string ERRORS[]; // Contains at each index an error message corresponding to that error number.
        static const word ROUND_CONSTANTS[EXTENDED_WORD_AMOUNT],
                          INITIAL_VALUES[];
        static const short OUT_OF_BOUNDS_E       = 1,
                           INVALID_HASH_LENGTH_E = 2,
                           INVALID_CHUNK_SIZE_E  = 3;
       
        word h0, h1, h2, h3, h4, h5, h6, h7;
                                           
        // Protected class methods
        void setDefaults();
        vector<byte> preProcess(vector<byte> input);
        void processChunk(vector<byte> chunkContainer);
        word bytesToWord(vector<byte> input, unsigned int start);
        string wVectorToHexString(vector<word> input);
        word rightRotate(word w, unsigned int n);
        void handleException(short errorId);
        vector<word> hash(vector<byte> input);
    public:
        // Public class methods
        SHA256();
        ~SHA256();
        string hash(string input);
        string hash(char* input, longword size);
        string shaVersion();
};
// End of class SHA256
 
 
/* CLASS VARIABLE INITIALIZATIONS
   ============================== */
 
// Start of SHA256 variable initializations
const string SHA256::HEX_VALUES = "0123456789abcdef",
             SHA256::SHA_VERSION = "Complete SHA library, Dennis Andriesse, v1.0 (rev July 2008). ";
 
const string SHA256::ERRORS[] = { "EXCEPTION. ", "Out of bounds. ", "Invalid hash length. ", "Invalid chunk size. " };
 
const word SHA256::ROUND_CONSTANTS[EXTENDED_WORD_AMOUNT] =
{
    0x428a2f98ULL, 0x71374491ULL, 0xb5c0fbcfULL, 0xe9b5dba5ULL, 0x3956c25bULL, 0x59f111f1ULL, 0x923f82a4ULL, 0xab1c5ed5ULL,
    0xd807aa98ULL, 0x12835b01ULL, 0x243185beULL, 0x550c7dc3ULL, 0x72be5d74ULL, 0x80deb1feULL, 0x9bdc06a7ULL, 0xc19bf174ULL,
    0xe49b69c1ULL, 0xefbe4786ULL, 0x0fc19dc6ULL, 0x240ca1ccULL, 0x2de92c6fULL, 0x4a7484aaULL, 0x5cb0a9dcULL, 0x76f988daULL,
    0x983e5152ULL, 0xa831c66dULL, 0xb00327c8ULL, 0xbf597fc7ULL, 0xc6e00bf3ULL, 0xd5a79147ULL, 0x06ca6351ULL, 0x14292967ULL,
    0x27b70a85ULL, 0x2e1b2138ULL, 0x4d2c6dfcULL, 0x53380d13ULL, 0x650a7354ULL, 0x766a0abbULL, 0x81c2c92eULL, 0x92722c85ULL,
    0xa2bfe8a1ULL, 0xa81a664bULL, 0xc24b8b70ULL, 0xc76c51a3ULL, 0xd192e819ULL, 0xd6990624ULL, 0xf40e3585ULL, 0x106aa070ULL,
    0x19a4c116ULL, 0x1e376c08ULL, 0x2748774cULL, 0x34b0bcb5ULL, 0x391c0cb3ULL, 0x4ed8aa4aULL, 0x5b9cca4fULL, 0x682e6ff3ULL,
    0x748f82eeULL, 0x78a5636fULL, 0x84c87814ULL, 0x8cc70208ULL, 0x90befffaULL, 0xa4506cebULL, 0xbef9a3f7ULL, 0xc67178f2ULL
    // These values are round constants, based on the first 32 bits of the fractional parts of the
    // cube roots of the first 64 prime numbers.
};
 
const word SHA256::INITIAL_VALUES[] =
{
    0x6a09e667ULL, // These values are used to
    0xbb67ae85ULL, // initialize the chunks of the hash.
    0x3c6ef372ULL, // They are based on the first 32 bits
    0xa54ff53aULL, // of the fractional parts of the square roots
    0x510e527fULL, // of the first 8 prime numbers.
    0x9b05688cULL,
    0x1f83d9abULL,
    0x5be0cd19ULL
};
// End of SHA256 variable initializations
 
 
/* CLASS METHOD DEFINITIONS
   ======================== */
 
// Start of SHA256 method definitions
void SHA256::setDefaults()
{
    h0 = INITIAL_VALUES[0], // These values are used to
    h1 = INITIAL_VALUES[1], // initialize the chunks of the hash.
    h2 = INITIAL_VALUES[2], // They are based on the first 32 bits
    h3 = INITIAL_VALUES[3], // of the fractional parts of the square roots
    h4 = INITIAL_VALUES[4], // of the first 8 prime numbers.
    h5 = INITIAL_VALUES[5],
    h6 = INITIAL_VALUES[6],
    h7 = INITIAL_VALUES[7];
}
 
vector<byte> SHA256::preProcess(vector<byte> input)
{
    // Appends a 1 bit to the input, then pads with 0 bits
    // until the length of the input is congruent to 448 modulo 512.
    // Finally appends the size in bits of the input as it was before the
    // padding, as a 64-bit big-endian integer.
    // If the system the algorithm is executed on is not big-endian, the
    // longword inputSize is converted to big-endian.
    // Returns the result of the preprocessing.
       
    const byte INITIAL_PADDING = 0x80, // A 1 bit followed by 7 0 bits.
               EXTENDED_PADDING = 0x00;
       
    longword inputLength = input.size() * BYTE_SIZE; // The length of the input before any preprocessing.
   
    input.insert(input.end(), 1, INITIAL_PADDING);
    for(int i = input.size() * BYTE_SIZE; (i % CHUNK_SIZE) != SIZE_WITHOUT_LENGTH; i += BYTE_SIZE)
    {
        input.insert(input.end(), 1, EXTENDED_PADDING); // Build byte by byte and keep checking the size.
    }
   
    for(int i = LONGWORD_BYTES - 1; i >= 0; i--)
    {
        // Add bytes of inputLength to input, MSB first.
        byte b = (inputLength >> i * BYTE_SIZE) & FULL_BYTE;
        input.insert(input.end(), 1, b);
    }
   
    return input;
}
 
void SHA256::processChunk(vector<byte> chunkContainer)
{
    // Processes a 512 bit chunk according to the SHA256 hash algorithm.
   
    vector<word> chunkWordContainer(EXTENDED_WORD_AMOUNT);
    word s0, s1;
   
    try
    {
        if(chunkContainer.size() != CHUNK_BYTES) throw short(INVALID_CHUNK_SIZE_E); // Throw an invalid chunk size exception.
    }
    catch(short e)
    {
        handleException(e);
    }
       
    for(int i = 0; i < CHUNK_BYTES; i += WORD_BYTES)
    {
        word w = bytesToWord(chunkContainer, i);
        chunkWordContainer[i / WORD_BYTES] = w; // Break into 16 words.
    }
   
    for(int i = 16; i < EXTENDED_WORD_AMOUNT; i++)
    {
        word w0 = chunkWordContainer[i - 15],
             w1 = chunkWordContainer[i - 2];
             
        s0 = (rightRotate(w0, 7)) ^ (rightRotate(w0, 18)) ^ (w0 >> 3);
        s1 = (rightRotate(w1, 17)) ^ (rightRotate(w1, 19)) ^ (w1 >> 10);
       
        chunkWordContainer[i] = chunkWordContainer[i - 16] + s0 + chunkWordContainer[i - 7] + s1;
    }
   
    word a = h0,
         b = h1,
         c = h2,
         d = h3,
         e = h4,
         f = h5,
         g = h6,
         h = h7;
         
    // Go into main loop
    for(int i = 0; i < EXTENDED_WORD_AMOUNT; i++)
    {
        s0 = (rightRotate(a, 2)) ^ (rightRotate(a, 13)) ^ (rightRotate(a, 22));
        word maj = (a & b) ^ (a & c) ^ (b & c);
        word t2 = s0 + maj;
        s1 = (rightRotate(e, 6)) ^ (rightRotate(e, 11)) ^ (rightRotate(e, 25));
        word ch = (e & f) ^ ((~e) & g);
        word t1 = h + s1 + ch + ROUND_CONSTANTS[i] + chunkWordContainer[i];
       
        h = g;
        g = f;
        f = e;
        e = d + t1;
        d = c;
        c = b;
        b = a;
        a = t1 + t2;
    }
   
    // Add this chunk's hash to the overall result
    h0 = h0 + a;
    h1 = h1 + b;
    h2 = h2 + c;
    h3 = h3 + d;
    h4 = h4 + e;
    h5 = h5 + f;
    h6 = h6 + g;
    h7 = h7 + h;
}
 
word SHA256::bytesToWord(vector<byte> input, unsigned int start)
{
    // Combines 4 bytes from input
    // into a single word, starting at start.
    // Returns the generated word.
   
    word result = 0;
   
    try
    {
        if(WORD_BYTES - 1 + start >= input.size()) throw short(OUT_OF_BOUNDS_E); // Throw an out of bounds exception.
        for(int i = WORD_BYTES - 1; i >= 0; i--)
        {
            if(i != WORD_BYTES - 1) result >>= BYTE_SIZE;
            result |= ((word) input[i + start] << (WORD_BYTES - 1) * BYTE_SIZE);
        }
    }
    catch(short e)
    {
        handleException(e);
    }
   
    return result;
}
 
string SHA256::wVectorToHexString(vector<word> input)
{
    // Converts a vector<word> to a string containing the
    // hexadecimal representation of all words in the vector.
    // Returns this string.
   
    string result = "";
   
    for(int i = 0; i < input.size(); i++)
    {
        word w = input[i];
       
        for(int j = WORD_BYTES * BYTE_HEX_DIGITS - 1; j >= 0; j--)
        {
            result += HEX_VALUES.at((w >> j * HEX_DIGIT_BITS) & HALF_BYTE);
        }
    }
   
    return result;
}
 
word SHA256::rightRotate(word w, unsigned int n)
{
    // Rotates the word to the right by n bits, wrapping around to the left
    // if the end is reached. Returns the result.
   
    return ((w >> n) | (w << WORD_SIZE - n));
}
 
void SHA256::handleException(short errorId)
{
    cerr << shaVersion() << endl << ERRORS[0] << ERRORS[errorId] << endl;
    //exit(1);
}
 
vector<word> SHA256::hash(vector<byte> input)
{
    // Hashes the input and returns the result.
   
    vector<byte> formatted = preProcess(input), // Do preprocessing and set the result in formatted.
                 chunkContainer;
    vector<word> result;
   
    for(int i = 0; i < formatted.size(); i += CHUNK_BYTES)
    {
        chunkContainer.assign(formatted.begin() + i, formatted.begin() + i + CHUNK_BYTES);         
        processChunk(chunkContainer); // Process the current 512 bit chunk.
    }
   
    result.insert(result.end(), 1, h0);
    result.insert(result.end(), 1, h1);
    result.insert(result.end(), 1, h2);
    result.insert(result.end(), 1, h3);
    result.insert(result.end(), 1, h4);
    result.insert(result.end(), 1, h5);
    result.insert(result.end(), 1, h6);
    result.insert(result.end(), 1, h7);
   
    setDefaults();
   
    return result;
}
 
SHA256::SHA256()
{
    // SHA256 main constructor.
   
    setDefaults();
}
 
SHA256::~SHA256()
{
    // SHA256 main destructor.
}
 
string SHA256::hash(string input)
{
    // Hashes a string using this class's generic hash(vector<byte> input) function.
    // Returns the result as a string.
   
    vector<byte> inputBytes;
    string result;
   
    for(int i = 0; i < input.size(); i++)
    {
        inputBytes.insert(inputBytes.end(), 1, input.at(i));
    }
   
    try
    {
        result = wVectorToHexString(hash(inputBytes));
        if(result.size() != DIGEST_CHARS) throw short(INVALID_HASH_LENGTH_E); // Throw an invalid hash length exception.
    }
    catch(short e)
    {
        handleException(e);
    }
   
    return result;
}
 
string SHA256::hash(char* input, longword size)
{
    // Hashes an array of chars, meant for use when hashing binary files
    // or other data read in as a stream of bytes.
    // Can also be used for C-style strings. When using this function
    // for that purpose, don't include the terminating character at the end
    // of the string when calculating size, as this may lead to incorrect
    // hash values.
    // Uses this class's generic hash(vector<byte> input) function.
    // The size of input (or the amount of bytes you want to be taken from
    // input) must be passed to this function.
    // Returns the result as a string.
   
    vector<byte> inputBytes;
    string result;
   
    for(longword i = 0; i < size; i++)
    {
        inputBytes.insert(inputBytes.end(), 1, input[i]);
    }
   
    try
    {
        result = wVectorToHexString(hash(inputBytes));
        if(result.size() != DIGEST_CHARS) throw short(INVALID_HASH_LENGTH_E); // Throw an invalid hash length exception.
    }
    catch(short e)
    {
        handleException(e);
    }
   
    return result;
}
 
string SHA256::shaVersion()
{
    // Returns a string containing information
    // about the version of the library.
   
    return SHA_VERSION;
}
// End of SHA256 method definitions
 
#endif

#include <cstdio>
#include <cstddef>
#include "sha256.h"
#include <string>
 
int main(int argc, char **argv) {
 
  SHA256* yourInstanceName = new SHA256();
  std::string digest = yourInstanceName->hash("ABCDEFGHIJKLMN");
 
  printf("%s\n", digest.c_str());
 
  return 0;
}