/*
 *  FIPS-180-1 compliant SHA-1 implementation
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
/*
 *  The SHA-1 standard was published by NIST in 1993.
 *
 *  http://www.itl.nist.gov/fipspubs/fip180-1.htm
 */

#include "sha1.h"
#include <string.h>
#include <stdio.h>

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
}

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n,b,i)                            \
{                                                       \
    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
        | ( (uint32_t) (b)[(i) + 3]       );            \
}
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n,b,i)                            \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

void mbedtls_sha1_init( mbedtls_sha1_context *ctx )
{
    memset( ctx, 0, sizeof( mbedtls_sha1_context ) );
}

void mbedtls_sha1_free( mbedtls_sha1_context *ctx )
{
    if( ctx == NULL )
        return;

    mbedtls_zeroize( ctx, sizeof( mbedtls_sha1_context ) );
}

/*
 * SHA-1 context setup
 */
void mbedtls_sha1_starts( mbedtls_sha1_context *ctx )
{
    ctx->total[0] = 0;
    ctx->total[1] = 0;

    ctx->state[0] = 0x67452301;
    ctx->state[1] = 0xEFCDAB89;
    ctx->state[2] = 0x98BADCFE;
    ctx->state[3] = 0x10325476;
    ctx->state[4] = 0xC3D2E1F0;
}

void mbedtls_sha1_process( mbedtls_sha1_context *ctx, const unsigned char data[SHA1_BLOCK_LENGTH] )
{
    uint32_t temp, W[16], A, B, C, D, E;

    GET_UINT32_BE( W[ 0], data,  0 );
    GET_UINT32_BE( W[ 1], data,  4 );
    GET_UINT32_BE( W[ 2], data,  8 );
    GET_UINT32_BE( W[ 3], data, 12 );
    GET_UINT32_BE( W[ 4], data, 16 );
    GET_UINT32_BE( W[ 5], data, 20 );
    GET_UINT32_BE( W[ 6], data, 24 );
    GET_UINT32_BE( W[ 7], data, 28 );
    GET_UINT32_BE( W[ 8], data, 32 );
    GET_UINT32_BE( W[ 9], data, 36 );
    GET_UINT32_BE( W[10], data, 40 );
    GET_UINT32_BE( W[11], data, 44 );
    GET_UINT32_BE( W[12], data, 48 );
    GET_UINT32_BE( W[13], data, 52 );
    GET_UINT32_BE( W[14], data, 56 );
    GET_UINT32_BE( W[15], data, 60 );

#define S(x,n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define R(t)                                            \
(                                                       \
    temp = W[( t -  3 ) & 0x0F] ^ W[( t - 8 ) & 0x0F] ^ \
           W[( t - 14 ) & 0x0F] ^ W[  t       & 0x0F],  \
    ( W[t & 0x0F] = S(temp,1) )                         \
)

#define P(a,b,c,d,e,x)                                  \
{                                                       \
    e += S(a,5) + F(b,c,d) + K + x; b = S(b,30);        \
}

    A = ctx->state[0];
    B = ctx->state[1];
    C = ctx->state[2];
    D = ctx->state[3];
    E = ctx->state[4];

#define F(x,y,z) (z ^ (x & (y ^ z)))
#define K 0x5A827999

    P( A, B, C, D, E, W[0]  );
    P( E, A, B, C, D, W[1]  );
    P( D, E, A, B, C, W[2]  );
    P( C, D, E, A, B, W[3]  );
    P( B, C, D, E, A, W[4]  );
    P( A, B, C, D, E, W[5]  );
    P( E, A, B, C, D, W[6]  );
    P( D, E, A, B, C, W[7]  );
    P( C, D, E, A, B, W[8]  );
    P( B, C, D, E, A, W[9]  );
    P( A, B, C, D, E, W[10] );
    P( E, A, B, C, D, W[11] );
    P( D, E, A, B, C, W[12] );
    P( C, D, E, A, B, W[13] );
    P( B, C, D, E, A, W[14] );
    P( A, B, C, D, E, W[15] );
    P( E, A, B, C, D, R(16) );
    P( D, E, A, B, C, R(17) );
    P( C, D, E, A, B, R(18) );
    P( B, C, D, E, A, R(19) );

#undef K
#undef F

#define F(x,y,z) (x ^ y ^ z)
#define K 0x6ED9EBA1

    P( A, B, C, D, E, R(20) );
    P( E, A, B, C, D, R(21) );
    P( D, E, A, B, C, R(22) );
    P( C, D, E, A, B, R(23) );
    P( B, C, D, E, A, R(24) );
    P( A, B, C, D, E, R(25) );
    P( E, A, B, C, D, R(26) );
    P( D, E, A, B, C, R(27) );
    P( C, D, E, A, B, R(28) );
    P( B, C, D, E, A, R(29) );
    P( A, B, C, D, E, R(30) );
    P( E, A, B, C, D, R(31) );
    P( D, E, A, B, C, R(32) );
    P( C, D, E, A, B, R(33) );
    P( B, C, D, E, A, R(34) );
    P( A, B, C, D, E, R(35) );
    P( E, A, B, C, D, R(36) );
    P( D, E, A, B, C, R(37) );
    P( C, D, E, A, B, R(38) );
    P( B, C, D, E, A, R(39) );

#undef K
#undef F

#define F(x,y,z) ((x & y) | (z & (x | y)))
#define K 0x8F1BBCDC

    P( A, B, C, D, E, R(40) );
    P( E, A, B, C, D, R(41) );
    P( D, E, A, B, C, R(42) );
    P( C, D, E, A, B, R(43) );
    P( B, C, D, E, A, R(44) );
    P( A, B, C, D, E, R(45) );
    P( E, A, B, C, D, R(46) );
    P( D, E, A, B, C, R(47) );
    P( C, D, E, A, B, R(48) );
    P( B, C, D, E, A, R(49) );
    P( A, B, C, D, E, R(50) );
    P( E, A, B, C, D, R(51) );
    P( D, E, A, B, C, R(52) );
    P( C, D, E, A, B, R(53) );
    P( B, C, D, E, A, R(54) );
    P( A, B, C, D, E, R(55) );
    P( E, A, B, C, D, R(56) );
    P( D, E, A, B, C, R(57) );
    P( C, D, E, A, B, R(58) );
    P( B, C, D, E, A, R(59) );

#undef K
#undef F

#define F(x,y,z) (x ^ y ^ z)
#define K 0xCA62C1D6

    P( A, B, C, D, E, R(60) );
    P( E, A, B, C, D, R(61) );
    P( D, E, A, B, C, R(62) );
    P( C, D, E, A, B, R(63) );
    P( B, C, D, E, A, R(64) );
    P( A, B, C, D, E, R(65) );
    P( E, A, B, C, D, R(66) );
    P( D, E, A, B, C, R(67) );
    P( C, D, E, A, B, R(68) );
    P( B, C, D, E, A, R(69) );
    P( A, B, C, D, E, R(70) );
    P( E, A, B, C, D, R(71) );
    P( D, E, A, B, C, R(72) );
    P( C, D, E, A, B, R(73) );
    P( B, C, D, E, A, R(74) );
    P( A, B, C, D, E, R(75) );
    P( E, A, B, C, D, R(76) );
    P( D, E, A, B, C, R(77) );
    P( C, D, E, A, B, R(78) );
    P( B, C, D, E, A, R(79) );

#undef K
#undef F

    ctx->state[0] += A;
    ctx->state[1] += B;
    ctx->state[2] += C;
    ctx->state[3] += D;
    ctx->state[4] += E;
}

/*
 * SHA-1 process buffer
 */
void mbedtls_sha1_update( mbedtls_sha1_context *ctx, const unsigned char *input, size_t ilen )
{
    size_t fill;
    uint32_t left;

    if( ilen == 0 )
        return;

    left = ctx->total[0] & 0x3F;
    fill = 64 - left;

    ctx->total[0] += (uint32_t) ilen;
    ctx->total[0] &= 0xFFFFFFFF;

    if( ctx->total[0] < (uint32_t) ilen )
        ctx->total[1]++;

    if( left && ilen >= fill )
    {
        memcpy( (void *) (ctx->buffer + left), input, fill );
        mbedtls_sha1_process( ctx, ctx->buffer );
        input += fill;
        ilen  -= fill;
        left = 0;
    }

    while( ilen >= 64 )
    {
        mbedtls_sha1_process( ctx, input );
        input += 64;
        ilen  -= 64;
    }

    if( ilen > 0 )
        memcpy( (void *) (ctx->buffer + left), input, ilen );
}

static const unsigned char sha1_padding[SHA1_BLOCK_LENGTH] =
{
 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/*
 * SHA-1 final digest
 */
void mbedtls_sha1_finish( mbedtls_sha1_context *ctx, unsigned char output[SHA1_DIGEST_LENGTH] )
{
    uint32_t last, padn;
    uint32_t high, low;
    unsigned char msglen[8];

    high = ( ctx->total[0] >> 29 )
         | ( ctx->total[1] <<  3 );
    low  = ( ctx->total[0] <<  3 );

    PUT_UINT32_BE( high, msglen, 0 );
    PUT_UINT32_BE( low,  msglen, 4 );

    last = ctx->total[0] & 0x3F;
    padn = ( last < 56 ) ? ( 56 - last ) : ( 120 - last );

    mbedtls_sha1_update( ctx, sha1_padding, padn );
    mbedtls_sha1_update( ctx, msglen, 8 );

    PUT_UINT32_BE( ctx->state[0], output,  0 );
    PUT_UINT32_BE( ctx->state[1], output,  4 );
    PUT_UINT32_BE( ctx->state[2], output,  8 );
    PUT_UINT32_BE( ctx->state[3], output, 12 );
    PUT_UINT32_BE( ctx->state[4], output, 16 );
}

/*
 * output = SHA-1( input buffer )
 */
void mbedtls_sha1( const unsigned char *input, size_t ilen, unsigned char output[SHA1_DIGEST_LENGTH] )
{
    mbedtls_sha1_context ctx;

    mbedtls_sha1_init( &ctx );
    mbedtls_sha1_starts( &ctx );
    mbedtls_sha1_update( &ctx, input, ilen );
    mbedtls_sha1_finish( &ctx, output );
    mbedtls_sha1_free( &ctx );
}

/*
* Compute HMAC_SHA1 using key, key length, text to hash, size of the text, and output buffer
*/
void HMAC_SHA1(const uint8_t* key, size_t key_length, const uint8_t *in, size_t n, uint8_t out[SHA1_DIGEST_LENGTH]){

  uint8_t i;
  uint8_t k_ipad[SHA1_BLOCK_LENGTH]; /* inner padding - key XORd with ipad */
  uint8_t k_opad[SHA1_BLOCK_LENGTH]; /* outer padding - key XORd with opad */
  uint8_t buffer[SHA1_BLOCK_LENGTH + SHA1_DIGEST_LENGTH];

  /* start out by storing key in pads */
  memset(k_ipad, 0, sizeof(k_ipad));
  memset(k_opad, 0, sizeof(k_opad));

  if (key_length <= SHA1_BLOCK_LENGTH) {
      memcpy(k_ipad, key, key_length);
      memcpy(k_opad, key, key_length);
  }

  else {
      mbedtls_sha1(key, key_length, k_ipad);
      memcpy(k_opad, k_ipad, SHA1_BLOCK_LENGTH);
  }

  /* XOR key with ipad and opad values */
  for (i = 0; i < SHA1_BLOCK_LENGTH; i++) {
      k_ipad[i] ^= HMAC_IPAD;
      k_opad[i] ^= HMAC_OPAD;
  }
  
  // perform inner SHA1
  memcpy(buffer, k_ipad, SHA1_BLOCK_LENGTH);
  memcpy(buffer + SHA1_BLOCK_LENGTH, in, n);
  mbedtls_sha1(buffer, SHA1_BLOCK_LENGTH + n, out);
  
  memset(buffer, 0, SHA1_BLOCK_LENGTH + n);

  // perform outer SHA1
  memcpy(buffer, k_opad, SHA1_BLOCK_LENGTH);
  memcpy(buffer + SHA1_BLOCK_LENGTH, out, SHA1_DIGEST_LENGTH);
  mbedtls_sha1(buffer, SHA1_BLOCK_LENGTH + SHA1_DIGEST_LENGTH, out);
}
/*
* Compute TOTP_HMAC_SHA1 using key, key length, text to hash, size of the text
*/
uint32_t TOTP_HMAC_SHA1(const uint8_t* key, size_t key_length, const uint8_t *in, size_t n){
    // STEP 1, get the HMAC-SHA1 hash from counter and key
    uint8_t hash[SHA1_DIGEST_LENGTH];
    HMAC_SHA1(key, key_length, in, n, hash);

    // STEP 2, apply dynamic truncation to obtain a 4-bytes string
    uint32_t truncated_hash = 0;
    uint8_t _offset = hash[SHA1_DIGEST_LENGTH - 1] & 0xF;
    uint8_t j;
    for (j = 0; j < 4; ++j) {
        truncated_hash <<= 8;
        truncated_hash  |= hash[_offset + j];
    }

    // STEP 3, compute the OTP value
    truncated_hash &= 0x7FFFFFFF;    //Disabled
    truncated_hash %= 1000000;

    return truncated_hash;
}
