HMACSHA256.cpp

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#include "pch.h"
#include "System/Security/Cryptography/HMACSHA256.h"
#include "System/ArgumentNullException.h"
#include <cstring>
 
namespace DotNetDupe {
    namespace System {
        namespace Security {
            namespace Cryptography {
 
                // --- SHA256 Helper Implementation ---
                #define SHA2_SHFR(x, n)    (x >> n)
                #define SHA2_ROTR(x, n)    ((x >> n) | (x << ((sizeof(x) << 3) - n)))
                #define SHA2_CH(x, y, z)   ((x & y) ^ (~x & z))
                #define SHA2_MAJ(x, y, z)  ((x & y) ^ (x & z) ^ (y & z))
                #define SHA256_F1(x)       (SHA2_ROTR(x, 2) ^ SHA2_ROTR(x, 13) ^ SHA2_ROTR(x, 22))
                #define SHA256_F2(x)       (SHA2_ROTR(x, 6) ^ SHA2_ROTR(x, 11) ^ SHA2_ROTR(x, 25))
                #define SHA256_F3(x)       (SHA2_ROTR(x, 7) ^ SHA2_ROTR(x, 18) ^ SHA2_SHFR(x, 3))
                #define SHA256_F4(x)       (SHA2_ROTR(x, 17) ^ SHA2_ROTR(x, 19) ^ SHA2_SHFR(x, 10))
 
                #define SHA2_UNPACK32(x, str)                 \
                {                                             \
                    *((str) + 3) = (unsigned char) ((x)      ); \
                    *((str) + 2) = (unsigned char) ((x) >>  8); \
                    *((str) + 1) = (unsigned char) ((x) >> 16); \
                    *((str) + 0) = (unsigned char) ((x) >> 24); \
                }
 
                #define SHA2_PACK32(str, x)                   \
                {                                             \
                    *(x) =   ((unsigned int) *((str) + 3)      ) \
                           | ((unsigned int) *((str) + 2) <<  8) \
                           | ((unsigned int) *((str) + 1) << 16) \
                           | ((unsigned int) *((str) + 0) << 24);\
                }
 
                static const unsigned int sha256_k[64] = {
                    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
                };
 
                class SHA256Impl {
                public:
                    void Init() {
                        h[0] = 0x6a09e667;
                        h[1] = 0xbb67ae85;
                        h[2] = 0x3c6ef372;
                        h[3] = 0xa54ff53a;
                        h[4] = 0x510e527f;
                        h[5] = 0x9b05688c;
                        h[6] = 0x1f83d9ab;
                        h[7] = 0x5be0cd19;
                        len = 0;
                        tot_len = 0;
                    }
 
                    void Transform(const unsigned char* message, unsigned int block_nb) {
                        unsigned int w[64];
                        unsigned int wv[8];
                        unsigned int t1, t2;
                        const unsigned char* sub_block;
                        for (unsigned int i = 0; i < block_nb; i++) {
                            sub_block = message + (i << 6);
                            for (unsigned int j = 0; j < 16; j++) {
                                SHA2_PACK32(&sub_block[j << 2], &w[j]);
                            }
                            for (unsigned int j = 16; j < 64; j++) {
                                w[j] = SHA256_F4(w[j - 2]) + w[j - 7] + SHA256_F3(w[j - 15]) + w[j - 16];
                            }
                            for (unsigned int j = 0; j < 8; j++) {
                                wv[j] = h[j];
                            }
                            for (unsigned int j = 0; j < 64; j++) {
                                t1 = wv[7] + SHA256_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6]) + sha256_k[j] + w[j];
                                t2 = SHA256_F1(wv[0]) + SHA2_MAJ(wv[0], wv[1], wv[2]);
                                wv[7] = wv[6];
                                wv[6] = wv[5];
                                wv[5] = wv[4];
                                wv[4] = wv[3] + t1;
                                wv[3] = wv[2];
                                wv[2] = wv[1];
                                wv[1] = wv[0];
                                wv[0] = t1 + t2;
                            }
                            for (unsigned int j = 0; j < 8; j++) {
                                h[j] += wv[j];
                            }
                        }
                    }
 
                    void Update(const unsigned char* message, unsigned int message_len) {
                        unsigned int tmp_len = 64 - len;
                        unsigned int rem_len = message_len < tmp_len ? message_len : tmp_len;
                        std::memcpy(&block[len], message, rem_len);
                        if (len + message_len < 64) {
                            len += message_len;
                            return;
                        }
                        Transform(block, 1);
                        unsigned int block_nb = (message_len - rem_len) >> 6;
                        Transform(message + rem_len, block_nb);
                        rem_len += (block_nb << 6);
                        len = message_len - rem_len;
                        std::memcpy(block, message + rem_len, len);
                        tot_len += (block_nb + 1) << 6;
                    }
 
                    void Final(unsigned char* digest) {
                        unsigned int block_nb = (64 - 9 < len) ? 2 : 1;
                        tot_len += len;
                        std::memset(&block[len], 0, 64 - len);
                        block[len] = 0x80;
                        if (block_nb == 2) {
                            Transform(block, 1);
                            std::memset(block, 0, 64);
                        }
                        SHA2_UNPACK32(tot_len << 3, &block[60]);
                        Transform(block, 1);
                        for (int i = 0; i < 8; i++) {
                            SHA2_UNPACK32(h[i], &digest[i << 2]);
                        }
                    }
 
                private:
                    unsigned int tot_len;
                    unsigned int len;
                    unsigned char block[64];
                    unsigned int h[8];
                };
 
                // --- HMACSHA256 implementation ---
 
                HMACSHA256::HMACSHA256() : m_key(0) {
                }
 
                HMACSHA256::HMACSHA256(const Array<char>& key) : m_key(key) {
                }
 
                Array<char> HMACSHA256::ComputeHash(const Array<char>& buffer) {
                    return ComputeHash(buffer, m_key);
                }
 
                static void PrepareHmacPads(const Array<char>& key, unsigned char* k_ipad, unsigned char* k_opad) {
                    unsigned char key_hashed[32];
                    int key_len = key.GetLength();
                    const unsigned char* key_data = reinterpret_cast<const unsigned char*>(key.GetData());
                    if (key_len > 64) {
                        SHA256Impl sha; sha.Init(); sha.Update(key_data, key_len); sha.Final(key_hashed);
                        key_data = key_hashed; key_len = 32;
                    }
                    std::memset(k_ipad, 0, 64); std::memset(k_opad, 0, 64);
                    if (key_len > 0) { std::memcpy(k_ipad, key_data, key_len); std::memcpy(k_opad, key_data, key_len); }
                    for (int i = 0; i < 64; i++) { k_ipad[i] ^= 0x36; k_opad[i] ^= 0x5c; }
                }
 
                static void ComputeHmacDigests(const unsigned char* k_ipad, const unsigned char* k_opad, const Array<char>& buffer, unsigned char* outer_digest) {
                    unsigned char inner_digest[32];
                    SHA256Impl sha_inner; sha_inner.Init(); sha_inner.Update(k_ipad, 64);
                    if (buffer.GetLength() > 0) sha_inner.Update(reinterpret_cast<const unsigned char*>(buffer.GetData()), buffer.GetLength());
                    sha_inner.Final(inner_digest);
 
                    SHA256Impl sha_outer; sha_outer.Init(); sha_outer.Update(k_opad, 64); sha_outer.Update(inner_digest, 32);
                    sha_outer.Final(outer_digest);
                }
 
                Array<char> HMACSHA256::ComputeHash(const Array<char>& buffer, const Array<char>& key) {
                    unsigned char k_ipad[64], k_opad[64], outer_digest[32];
                    PrepareHmacPads(key, k_ipad, k_opad);
                    ComputeHmacDigests(k_ipad, k_opad, buffer, outer_digest);
                    Array<char> result(32);
                    for (int i = 0; i < 32; i++) result[i] = static_cast<char>(outer_digest[i]);
                    return result;
                }
 
            }
        }
    }
}