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// This file is part of a crypto library, exam for the Algorithms class.
// All of these files are under MIT license.
//
// SHA declaration document:
// https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
#ifndef HMACSHA256_SHA256_H_
#define HMACSHA256_SHA256_H_
#include<cstdint>
#include<array>
namespace hmacsha256 {
class SHA256 {
public:
// create a new SHA256 thanks an array of bytes
SHA256(const uint8_t*, uint32_t);
SHA256(const std::string&);
~SHA256();
// get digest as array of bytes
uint8_t* digest();
std::string hexdigest();
private:
uint8_t* digest_;
// work variables: a, b, c, d, e, f, g, h
uint32_t vars_[8];
// data message, in bytes
// M, "message to be hashed"
uint8_t message_[64];
// length L of the original message
uint32_t message_l_;
// lengh of bits
uint64_t bit_len_;
// first 80 costansts 64bit words, paragraph 4.2.2
std::array<uint32_t, 64> K = {
0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,
0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,
0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,
0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,
0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,
0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,
0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,
0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,
0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
};
// the constructor
void init(const uint8_t* data, uint32_t length);
// Ch(x, y, z) = (x | y) ^ (~x & z)
static uint32_t ch(uint32_t, uint32_t, uint32_t);
// Maj(x, y, z) = (x | y) ^ (x & z) ^ (y & z)
static uint32_t maj(uint32_t, uint32_t, uint32_t);
// circular right shift. Takes two params: `x` a w-bit word and `n` an int
// with 0 <= n < w.
// w, in our case is 32
//
// rots is also defined in the NIST document as
// rotr(x) = (x >> n) or (x << w - n)
static uint32_t rotr(uint32_t, uint32_t);
// function defined in 4.4
static uint32_t big_sigma0(uint32_t);
// function defined in 4.5
static uint32_t big_sigma1(uint32_t);
// function defined in 4.6
static uint32_t sigma0(uint32_t);
// function defined in 4.7
static uint32_t sigma1(uint32_t);
// padding
void pad();
// main function
void transform();
// transform bytes in big-endian, because SHA256 wants big endian ordering
// Takes 1 parameter, the array of bytes that we want to reorder
void bigendian(uint8_t*);
};
} // namespace hmacsha256
#endif // HMACSHA256_SHA256_H_
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