/*
             LUFA Library
     Copyright (C) Dean Camera, 2017.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/

/*
  Copyright 2017  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  Copyright 2012  Simon Foster (simon.foster [at] inbox [dot] com)

  Permission to use, copy, modify, distribute, and sell this
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of t
/*
    sha1.cpp - source code of

    ============
    SHA-1 in C++
    ============

    100% Public Domain.

    Original C Code
        -- Steve Reid <steve@edmweb.com>
    Small changes to fit into bglibs
        -- Bruce Guenter <bruce@untroubled.org>
    Translation to simpler C++ Code
        -- Volker Grabsch <vog@notjusthosting.com>
    Fixing bugs and improving style
        -- Eugene Hopkinson <slowriot at voxelstorm dot com>
*/

#include "sha1.h"
#include <sstream>
#include <iomanip>
#include <fstream>

/* Help macros */
#define SHA1_ROL(value, bits) (((value) << (bits)) | (((value) & 0xffffffff) >> (32 - (bits))))
#define SHA1_BLK(i) (block[i&15] = SHA1_ROL(block[(i+13)&15] ^ block[(i+8)&15] ^ block[(i+2)&15] ^ block[i&15],1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define SHA1_R0(v,w,x,y,z,i) z += ((w&(x^y))^y)     + block[i]    + 0x5a827999 + SHA1_ROL(v,5); w=SHA1_ROL(w,30);
#define SHA1_R1(v,w,x,y,z,i) z += ((w&(x^y))^y)     + SHA1_BLK(i) + 0x5a827999 + SHA1_ROL(v,5); w=SHA1_ROL(w,30);
#define SHA1_R2(v,w,x,y,z,i) z += (w^x^y)           + SHA1_BLK(i) + 0x6ed9eba1 + SHA1_ROL(v,5); w=SHA1_ROL(w,30);
#define SHA1_R3(v,w,x,y,z,i) z += (((w|x)&y)|(w&x)) + SHA1_BLK(i) + 0x8f1bbcdc + SHA1_ROL(v,5); w=SHA1_ROL(w,30);
#define SHA1_R4(v,w,x,y,z,i) z += (w^x^y)           + SHA1_BLK(i) + 0xca62c1d6 + SHA1_ROL(v,5); w=SHA1_ROL(w,30);

SHA1::SHA1()
{
    reset();
}


void SHA1::update(const std::string &s)
{
    std::istringstream is(s);
    update(is);
}


void SHA1::update(std::istream &is)
{
    std::string rest_of_buffer;
    read(is, rest_of_buffer, BLOCK_BYTES - buffer.size());
    buffer += rest_of_buffer;

    while (is)
    {
        uint32_t block[BLOCK_INTS];
        buffer_to_block(buffer, block);
        transform(block);
        read(is, buffer, BLOCK_BYTES);
    }
}


/*
 * Add padding and return the message digest.
 */

std::string SHA1::final()
{
    /* Total number of hashed bits */
    uint64_t total_bits = (transforms*BLOCK_BYTES + buffer.size()) * 8;

    /* Padding */
    buffer += 0x80;
    unsigned int orig_size = buffer.size();
    while (buffer.size() < BLOCK_BYTES)
    {
        buffer += (char)0x00;
    }

    uint32_t block[BLOCK_INTS];
    buffer_to_block(buffer, block);

    if (orig_size > BLOCK_BYTES - 8)
    {
        transform(block);
        for (unsigned int i = 0; i < BLOCK_INTS - 2; i++)
        {
            block[i] = 0;
        }
    }

    /* Append total_bits, split this uint64_t into two uint32_t */
    block[BLOCK_INTS - 1] = total_bits;
    block[BLOCK_INTS - 2] = (total_bits >> 32);
    transform(block);

    /* Hex std::string */
    std::ostringstream result;
    for (unsigned int i = 0; i < DIGEST_INTS; i++)
    {
        result << std::hex << std::setfill('0') << std::setw(8);
        result << (digest[i] & 0xffffffff);
    }

    /* Reset for next run */
    reset();

    return result.str();
}


std::string SHA1::from_file(const std::string &filename)
{
    std::ifstream stream(filename.c_str(), std::ios::binary);
    SHA1 checksum;
    checksum.update(stream);
    return checksum.final();
}


void SHA1::reset()
{
    /* SHA1 initialization constants */
    digest[0] = 0x67452301;
    digest[1] = 0xefcdab89;
    digest[2] = 0x98badcfe;
    digest[3] = 0x10325476;
    digest[4] = 0xc3d2e1f0;

    /* Reset counters */
    transforms = 0;
    buffer = "";
}


/*
 * Hash a single 512-bit block. This is the core of the algorithm.
 */

void SHA1::transform(uint32_t block[BLOCK_BYTES])
{
    /* Copy digest[] to working vars */
    uint32_t a = digest[0];
    uint32_t b = digest[1];
    uint32_t c = digest[2];
    uint32_t d = digest[3];
    uint32_t e = digest[4];


    /* 4 rounds of 20 operations each. Loop unrolled. */
    SHA1_R0(a,b,c,d,e, 0);
    SHA1_R0(e,a,b,c,d, 1);
    SHA1_R0(d,e,a,b,c, 2);
    SHA1_R0(c,d,e,a,b, 3);
    SHA1_R0(b,c,d,e,a, 4);
    SHA1_R0(a,b,c,d,e, 5);
    SHA1_R0(e,a,b,c,d, 6);
    SHA1_R0(d,e,a,b,c, 7);
    SHA1_R0(c,d,e,a,b, 8);
    SHA1_R0(b,c,d,e,a, 9);
    SHA1_R0(a,b,c,d,e,10);
    SHA1_R0(e,a,b,c,d,11);
    SHA1_R0(d,e,a,b,c,12);
    SHA1_R0(c,d,e,a,b,13);
    SHA1_R0(b,c,d,e,a,14);
    SHA1_R0(a,b,c,d,e,15);
    SHA1_R1(e,a,b,c,d,16);
    SHA1_R1(d,e,a,b,c,17);
    SHA1_R1(c,d,e,a,b,18);
    SHA1_R1(b,c,d,e,a,19);
    SHA1_R2(a,b,c,d,e,20);
    SHA1_R2(e,a,b,c,d,21);
    SHA1_R2(d,e,a,b,c,22);
    SHA1_R2(c,d,e,a,b,23);
    SHA1_R2(b,c,d,e,a,24);
    SHA1_R2(a,b,c,d,e,25);
    SHA1_R2(e,a,b,c,d,26);
    SHA1_R2(d,e,a,b,c,27);
    SHA1_R2(c,d,e,a,b,28);
    SHA1_R2(b,c,d,e,a,29);
    SHA1_R2(a,b,c,d,e,30);
    SHA1_R2(e,a,b,c,d,31);
    SHA1_R2(d,e,a,b,c,32);
    SHA1_R2(c,d,e,a,b,33);
    SHA1_R2(b,c,d,e,a,34);
    SHA1_R2(a,b,c,d,e,35);
    SHA1_R2(e,a,b,c,d,36);
    SHA1_R2(d,e,a,b,c,37);
    SHA1_R2(c,d,e,a,b,38);
    SHA1_R2(b,c,d,e,a,39);
    SHA1_R3(a,b,c,d,e,40);
    SHA1_R3(e,a,b,c,d,41);
    SHA1_R3(d,e,a,b,c,42);
    SHA1_R3(c,d,e,a,b,43);
    SHA1_R3(b,c,d,e,a,44);
    SHA1_R3(a,b,c,d,e,45);
    SHA1_R3(e,a,b,c,d,46);
    SHA1_R3(d,e,a,b,c,47);
    SHA1_R3(c,d,e,a,b,48);
    SHA1_R3(b,c,d,e,a,49);
    SHA1_R3(a,b,c,d,e,50);
    SHA1_R3(e,a,b,c,d,51);
    SHA1_R3(d,e,a,b,c,52);
    SHA1_R3(c,d,e,a,b,53);
    SHA1_R3(b,c,d,e,a,54);
    SHA1_R3(a,b,c,d,e,55);
    SHA1_R3(e,a,b,c,d,56);
    SHA1_R3(d,e,a,b,c,57);
    SHA1_R3(c,d,e,a,b,58);
    SHA1_R3(b,c,d,e,a,59);
    SHA1_R4(a,b,c,d,e,60);
    SHA1_R4(e,a,b,c,d,61);
    SHA1_R4(d,e,a,b,c,62);
    SHA1_R4(c,d,e,a,b,63);
    SHA1_R4(b,c,d,e,a,64);
    SHA1_R4(a,b,c,d,e,65);
    SHA1_R4(e,a,b,c,d,66);
    SHA1_R4(d,e,a,b,c,67);
    SHA1_R4(c,d,e,a,b,68);
    SHA1_R4(b,c,d,e,a,69);
    SHA1_R4(a,b,c,d,e,70);
    SHA1_R4(e,a,b,c,d,71);
    SHA1_R4(d,e,a,b,c,72);
    SHA1_R4(c,d,e,a,b,73);
    SHA1_R4(b,c,d,e,a,74);
    SHA1_R4(a,b,c,d,e,75);
    SHA1_R4(e,a,b,c,d,76);
    SHA1_R4(d,e,a,b,c,77);
    SHA1_R4(c,d,e,a,b,78);
    SHA1_R4(b,c,d,e,a,79);

    /* Add the working vars back into digest[] */
    digest[0] += a;
    digest[1] += b;
    digest[2] += c;
    digest[3] += d;
    digest[4] += e;

    /* Count the number of transformations */
    transforms++;
}


void SHA1::buffer_to_block(const std::string &buffer, uint32_t block[BLOCK_INTS])
{
    /* Convert the std::string (byte buffer) to a uint32_t array (MSB) */
    for (unsigned int i = 0; i < BLOCK_INTS; i++)
    {
        block[i] = (buffer[4*i+3] & 0xff)
                   | (buffer[4*i+2] & 0xff)<<8
                   | (buffer[4*i+1] & 0xff)<<16
                   | (buffer[4*i+0] & 0xff)<<24;
    }
}


void SHA1::read(std::istream &is, std::string &s, size_t max)
{
    char* sbuf = new char[max];

    is.read(sbuf, max);
    s.assign(sbuf, is.gcount());

    delete[] sbuf;
}


std::string sha1(const std::string &string)
{
    SHA1 checksum;
    checksum.update(string);
    return checksum.final();
}