/*
 * Copyright (C) 2016-2019 Alibaba Group Holding Limited
 */

#include "sha256.h"

/* Implementation that should never be optimized out by the compiler */
static void 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)                                              \
    do {                                                                    \
        (n) = ((uint32_t)(b)[(i)] << 24) | ((uint32_t)(b)[(i) + 1] << 16) | \
              ((uint32_t)(b)[(i) + 2] << 8) | ((uint32_t)(b)[(i) + 3]);     \
    } while (0)
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n, b, i)                     \
    do {                                           \
        (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));       \
    } while (0)
#endif

void impl_sha256_init(impl_sha256_context *ctx)
{
    memset(ctx, 0, sizeof(impl_sha256_context));
}

void impl_sha256_free(impl_sha256_context *ctx)
{
    if (ctx == NULL)
        return;

    zeroize(ctx, sizeof(impl_sha256_context));
}

void impl_sha256_clone(impl_sha256_context *      dst,
                      const impl_sha256_context *src)
{
    *dst = *src;
}

/*
 * SHA-256 context setup
 */
void impl_sha256_starts(impl_sha256_context *ctx, int is224)
{
    ctx->total[0] = 0;
    ctx->total[1] = 0;

    if (is224 == 0) {
        /* SHA-256 */
        ctx->state[0] = 0x6A09E667;
        ctx->state[1] = 0xBB67AE85;
        ctx->state[2] = 0x3C6EF372;
        ctx->state[3] = 0xA54FF53A;
        ctx->state[4] = 0x510E527F;
        ctx->state[5] = 0x9B05688C;
        ctx->state[6] = 0x1F83D9AB;
        ctx->state[7] = 0x5BE0CD19;
    } else {
        /* SHA-224 */
        ctx->state[0] = 0xC1059ED8;
        ctx->state[1] = 0x367CD507;
        ctx->state[2] = 0x3070DD17;
        ctx->state[3] = 0xF70E5939;
        ctx->state[4] = 0xFFC00B31;
        ctx->state[5] = 0x68581511;
        ctx->state[6] = 0x64F98FA7;
        ctx->state[7] = 0xBEFA4FA4;
    }

    ctx->is224 = is224;
}

static const uint32_t 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,
};

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

#define S0(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3))
#define S1(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10))

#define S2(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
#define S3(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))

#define F0(x, y, z) ((x & y) | (z & (x | y)))
#define F1(x, y, z) (z ^ (x & (y ^ z)))

#define R(t) (W[t] = S1(W[t - 2]) + W[t - 7] + S0(W[t - 15]) + W[t - 16])

#define P(a, b, c, d, e, f, g, h, x, K)          \
    {                                            \
        temp1 = h + S3(e) + F1(e, f, g) + K + x; \
        temp2 = S2(a) + F0(a, b, c);             \
        d += temp1;                              \
        h = temp1 + temp2;                       \
    }

void impl_sha256_process(impl_sha256_context *ctx,
                        const unsigned char data[64])
{
    uint32_t     temp1, temp2, W[64];
    uint32_t     A[8];
    unsigned int i;

    for (i = 0; i < 8; i++)
        A[i] = ctx->state[i];

#if defined(CONFIG_SHA256_SMALLER)
    for (i = 0; i < 64; i++) {
        if (i < 16)
            GET_UINT32_BE(W[i], data, 4 * i);
        else
            R(i);

        P(A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i], K[i]);

        temp1 = A[7];
        A[7]  = A[6];
        A[6]  = A[5];
        A[5]  = A[4];
        A[4]  = A[3];
        A[3]  = A[2];
        A[2]  = A[1];
        A[1]  = A[0];
        A[0]  = temp1;
    }
#else  /* CONFIG_SHA256_SMALLER */
    for (i = 0; i < 16; i++)
        GET_UINT32_BE(W[i], data, 4 * i);

    for (i = 0; i < 16; i += 8) {
        P(A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i + 0], K[i + 0]);
        P(A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], W[i + 1], K[i + 1]);
        P(A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], W[i + 2], K[i + 2]);
        P(A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], W[i + 3], K[i + 3]);
        P(A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], W[i + 4], K[i + 4]);
        P(A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], W[i + 5], K[i + 5]);
        P(A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], W[i + 6], K[i + 6]);
        P(A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], W[i + 7], K[i + 7]);
    }

    for (i = 16; i < 64; i += 8) {
        P(A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], R(i + 0), K[i + 0]);
        P(A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], R(i + 1), K[i + 1]);
        P(A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], R(i + 2), K[i + 2]);
        P(A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], R(i + 3), K[i + 3]);
        P(A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], R(i + 4), K[i + 4]);
        P(A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], R(i + 5), K[i + 5]);
        P(A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], R(i + 6), K[i + 6]);
        P(A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], R(i + 7), K[i + 7]);
    }
#endif /* CONFIG_SHA256_SMALLER */

    for (i = 0; i < 8; i++)
        ctx->state[i] += A[i];
}

/*
 * SHA-256 process buffer
 */
void impl_sha256_update(impl_sha256_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);
        impl_sha256_process(ctx, ctx->buffer);
        input += fill;
        ilen -= fill;
        left = 0;
    }

    while (ilen >= 64) {
        impl_sha256_process(ctx, input);
        input += 64;
        ilen -= 64;
    }

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

static const unsigned char sha256_padding[64] = {
    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-256 final digest
 */
void impl_sha256_finish(impl_sha256_context *ctx,
                       unsigned char output[32])
{
    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);

    impl_sha256_update(ctx, sha256_padding, padn);
    impl_sha256_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);
    PUT_UINT32_BE(ctx->state[5], output, 20);
    PUT_UINT32_BE(ctx->state[6], output, 24);

    if (ctx->is224 == 0)
        PUT_UINT32_BE(ctx->state[7], output, 28);
}

/*
 * output = SHA-256( input buffer )
 */
void impl_sha256(const unsigned char *input, size_t ilen,
                unsigned char output[32], int is224)
{
    impl_sha256_context ctx;

    impl_sha256_init(&ctx);
    impl_sha256_starts(&ctx, is224);
    impl_sha256_update(&ctx, input, ilen);
    impl_sha256_finish(&ctx, output);
    impl_sha256_free(&ctx);
}
