// This code is public domain, taken from a PD crypto source file on GitHub.

#include "SHA512.hpp"

#include "Utils.hpp"

#include <algorithm>

namespace ZeroTier {

#ifndef ZT_HAVE_NATIVE_SHA512

namespace {

struct sha512_state {
    uint64_t length, state[8];
    unsigned long curlen;
    uint8_t buf[128];
};

static const uint64_t K[80] = { 0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL, 0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL, 0x3956c25bf348b538ULL, 0x59f111f1b605d019ULL, 0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL, 0xd807aa98a3030242ULL,
                                0x12835b0145706fbeULL, 0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL, 0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL, 0x9bdc06a725c71235ULL, 0xc19bf174cf692694ULL, 0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL,
                                0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL, 0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL, 0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL, 0x983e5152ee66dfabULL, 0xa831c66d2db43210ULL, 0xb00327c898fb213fULL,
                                0xbf597fc7beef0ee4ULL, 0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL, 0x06ca6351e003826fULL, 0x142929670a0e6e70ULL, 0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL, 0x4d2c6dfc5ac42aedULL, 0x53380d139d95b3dfULL,
                                0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL, 0x81c2c92e47edaee6ULL, 0x92722c851482353bULL, 0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL, 0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL, 0xd192e819d6ef5218ULL,
                                0xd69906245565a910ULL, 0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL, 0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL, 0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL, 0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL,
                                0x5b9cca4f7763e373ULL, 0x682e6ff3d6b2b8a3ULL, 0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL, 0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL, 0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL, 0xbef9a3f7b2c67915ULL,
                                0xc67178f2e372532bULL, 0xca273eceea26619cULL, 0xd186b8c721c0c207ULL, 0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL, 0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL, 0x113f9804bef90daeULL, 0x1b710b35131c471bULL,
                                0x28db77f523047d84ULL, 0x32caab7b40c72493ULL, 0x3c9ebe0a15c9bebcULL, 0x431d67c49c100d4cULL, 0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL, 0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL };

#define STORE64H(x, y) Utils::storeBigEndian<uint64_t>(y, x)
#define LOAD64H(x, y)  x = Utils::loadBigEndian<uint64_t>(y)
#define ROL64c(x, y)   (((x) << (y)) | ((x) >> (64 - (y))))
#define ROR64c(x, y)   (((x) >> (y)) | ((x) << (64 - (y))))
#define Ch(x, y, z)    (z ^ (x & (y ^ z)))
#define Maj(x, y, z)   (((x | y) & z) | (x & y))
#define S(x, n)        ROR64c(x, n)
#define R(x, n)        ((x) >> (n))
#define Sigma0(x)      (S(x, 28) ^ S(x, 34) ^ S(x, 39))
#define Sigma1(x)      (S(x, 14) ^ S(x, 18) ^ S(x, 41))
#define Gamma0(x)      (S(x, 1) ^ S(x, 8) ^ R(x, 7))
#define Gamma1(x)      (S(x, 19) ^ S(x, 61) ^ R(x, 6))

static ZT_INLINE void sha512_compress(sha512_state* const md, uint8_t* const buf)
{
    uint64_t S[8], W[80], t0, t1;
    int i;

    for (i = 0; i < 8; i++) {
        S[i] = md->state[i];
    }
    for (i = 0; i < 16; i++) {
        LOAD64H(W[i], buf + (8 * i));
    }
    for (i = 16; i < 80; i++) {
        W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];
    }

#define RND(a, b, c, d, e, f, g, h, i)                                                                                                                                                                                                         \
    t0 = h + Sigma1(e) + Ch(e, f, g) + K[i] + W[i];                                                                                                                                                                                            \
    t1 = Sigma0(a) + Maj(a, b, c);                                                                                                                                                                                                             \
    d += t0;                                                                                                                                                                                                                                   \
    h = t0 + t1;

    for (i = 0; i < 80; i += 8) {
        RND(S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7], i + 0);
        RND(S[7], S[0], S[1], S[2], S[3], S[4], S[5], S[6], i + 1);
        RND(S[6], S[7], S[0], S[1], S[2], S[3], S[4], S[5], i + 2);
        RND(S[5], S[6], S[7], S[0], S[1], S[2], S[3], S[4], i + 3);
        RND(S[4], S[5], S[6], S[7], S[0], S[1], S[2], S[3], i + 4);
        RND(S[3], S[4], S[5], S[6], S[7], S[0], S[1], S[2], i + 5);
        RND(S[2], S[3], S[4], S[5], S[6], S[7], S[0], S[1], i + 6);
        RND(S[1], S[2], S[3], S[4], S[5], S[6], S[7], S[0], i + 7);
    }

    for (i = 0; i < 8; i++) {
        md->state[i] = md->state[i] + S[i];
    }
}

static ZT_INLINE void sha384_init(sha512_state* const md)
{
    md->curlen = 0;
    md->length = 0;
    md->state[0] = 0xcbbb9d5dc1059ed8ULL;
    md->state[1] = 0x629a292a367cd507ULL;
    md->state[2] = 0x9159015a3070dd17ULL;
    md->state[3] = 0x152fecd8f70e5939ULL;
    md->state[4] = 0x67332667ffc00b31ULL;
    md->state[5] = 0x8eb44a8768581511ULL;
    md->state[6] = 0xdb0c2e0d64f98fa7ULL;
    md->state[7] = 0x47b5481dbefa4fa4ULL;
}

static ZT_INLINE void sha512_init(sha512_state* const md)
{
    md->curlen = 0;
    md->length = 0;
    md->state[0] = 0x6a09e667f3bcc908ULL;
    md->state[1] = 0xbb67ae8584caa73bULL;
    md->state[2] = 0x3c6ef372fe94f82bULL;
    md->state[3] = 0xa54ff53a5f1d36f1ULL;
    md->state[4] = 0x510e527fade682d1ULL;
    md->state[5] = 0x9b05688c2b3e6c1fULL;
    md->state[6] = 0x1f83d9abfb41bd6bULL;
    md->state[7] = 0x5be0cd19137e2179ULL;
}

static void sha512_process(sha512_state* const md, const uint8_t* in, unsigned long inlen)
{
    while (inlen > 0) {
        if (md->curlen == 0 && inlen >= 128) {
            sha512_compress(md, (uint8_t*)in);
            md->length += 128 * 8;
            in += 128;
            inlen -= 128;
        }
        else {
            unsigned long n = std::min(inlen, (128 - md->curlen));
            Utils::copy(md->buf + md->curlen, in, n);
            md->curlen += n;
            in += n;
            inlen -= n;
            if (md->curlen == 128) {
                sha512_compress(md, md->buf);
                md->length += 8 * 128;
                md->curlen = 0;
            }
        }
    }
}

static ZT_INLINE void sha512_done(sha512_state* const md, uint8_t* out)
{
    int i;

    md->length += md->curlen * 8ULL;
    md->buf[md->curlen++] = (uint8_t)0x80;

    if (md->curlen > 112) {
        while (md->curlen < 128) {
            md->buf[md->curlen++] = (uint8_t)0;
        }
        sha512_compress(md, md->buf);
        md->curlen = 0;
    }

    while (md->curlen < 120) {
        md->buf[md->curlen++] = (uint8_t)0;
    }

    STORE64H(md->length, md->buf + 120);
    sha512_compress(md, md->buf);

    for (i = 0; i < 8; i++) {
        STORE64H(md->state[i], out + (8 * i));
    }
}

}   // anonymous namespace

void SHA512(void* digest, const void* data, unsigned int len)
{
    sha512_state state;
    sha512_init(&state);
    sha512_process(&state, (uint8_t*)data, (unsigned long)len);
    sha512_done(&state, (uint8_t*)digest);
}

void SHA384(void* digest, const void* data, unsigned int len)
{
    uint8_t tmp[64];
    sha512_state state;
    sha384_init(&state);
    sha512_process(&state, (uint8_t*)data, (unsigned long)len);
    sha512_done(&state, tmp);
    Utils::copy<48>(digest, tmp);
}

void SHA384(void* digest, const void* data0, unsigned int len0, const void* data1, unsigned int len1)
{
    uint8_t tmp[64];
    sha512_state state;
    sha384_init(&state);
    sha512_process(&state, (uint8_t*)data0, (unsigned long)len0);
    sha512_process(&state, (uint8_t*)data1, (unsigned long)len1);
    sha512_done(&state, tmp);
    Utils::copy<48>(digest, tmp);
}

#endif   // !ZT_HAVE_NATIVE_SHA512

void HMACSHA384(const uint8_t key[ZT_SYMMETRIC_KEY_SIZE], const void* msg, const unsigned int msglen, uint8_t mac[48])
{
    uint64_t kInPadded[16];   // input padded key
    uint64_t outer[22];       // output padded key | H(input padded key | msg)

    const uint64_t k0 = Utils::loadMachineEndian<uint64_t>(key);
    const uint64_t k1 = Utils::loadMachineEndian<uint64_t>(key + 8);
    const uint64_t k2 = Utils::loadMachineEndian<uint64_t>(key + 16);
    const uint64_t k3 = Utils::loadMachineEndian<uint64_t>(key + 24);
    const uint64_t k4 = Utils::loadMachineEndian<uint64_t>(key + 32);
    const uint64_t k5 = Utils::loadMachineEndian<uint64_t>(key + 40);

    const uint64_t ipad = 0x3636363636363636ULL;
    kInPadded[0] = k0 ^ ipad;
    kInPadded[1] = k1 ^ ipad;
    kInPadded[2] = k2 ^ ipad;
    kInPadded[3] = k3 ^ ipad;
    kInPadded[4] = k4 ^ ipad;
    kInPadded[5] = k5 ^ ipad;
    kInPadded[6] = ipad;
    kInPadded[7] = ipad;
    kInPadded[8] = ipad;
    kInPadded[9] = ipad;
    kInPadded[10] = ipad;
    kInPadded[11] = ipad;
    kInPadded[12] = ipad;
    kInPadded[13] = ipad;
    kInPadded[14] = ipad;
    kInPadded[15] = ipad;

    const uint64_t opad = 0x5c5c5c5c5c5c5c5cULL;
    outer[0] = k0 ^ opad;
    outer[1] = k1 ^ opad;
    outer[2] = k2 ^ opad;
    outer[3] = k3 ^ opad;
    outer[4] = k4 ^ opad;
    outer[5] = k5 ^ opad;
    outer[6] = opad;
    outer[7] = opad;
    outer[8] = opad;
    outer[9] = opad;
    outer[10] = opad;
    outer[11] = opad;
    outer[12] = opad;
    outer[13] = opad;
    outer[14] = opad;
    outer[15] = opad;

    // H(output padded key | H(input padded key | msg))
    SHA384(reinterpret_cast<uint8_t*>(outer) + 128, kInPadded, 128, msg, msglen);
    SHA384(mac, outer, 176);
}

void KBKDFHMACSHA384(const uint8_t key[ZT_SYMMETRIC_KEY_SIZE], const char label, const char context, const uint32_t iter, uint8_t out[ZT_SYMMETRIC_KEY_SIZE])
{
    uint8_t kbkdfMsg[13];

    Utils::storeBigEndian<uint32_t>(kbkdfMsg, (uint32_t)iter);

    kbkdfMsg[4] = (uint8_t)'Z';
    kbkdfMsg[5] = (uint8_t)'T';   // preface our labels with something ZT-specific
    kbkdfMsg[6] = (uint8_t)label;
    kbkdfMsg[7] = 0;

    kbkdfMsg[8] = (uint8_t)context;

    // Output key length: 384 bits (as 32-bit big-endian value)
    kbkdfMsg[9] = 0;
    kbkdfMsg[10] = 0;
    kbkdfMsg[11] = 0x01;
    kbkdfMsg[12] = 0x80;

    static_assert(ZT_SYMMETRIC_KEY_SIZE == ZT_SHA384_DIGEST_SIZE, "sizeof(out) != ZT_SHA384_DIGEST_SIZE");
    HMACSHA384(key, &kbkdfMsg, sizeof(kbkdfMsg), out);
}

}   // namespace ZeroTier

// Internally re-export to included C code, which includes some fast crypto code ported in on some platforms.
// This eliminates the need to link against a third party SHA512() from this code
extern "C" void ZT_sha512internal(void* digest, const void* data, unsigned int len)
{
    ZeroTier::SHA512(digest, data, len);
}