/*

SHA-1 in C

By Steve Reid <steve@edmweb.com>

100% Public Domain

Test Vectors (from FIPS PUB 180-1)

"abc"

  A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D

"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"

  84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1

A million repetitions of "a"

  34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F

*/

/* #define LITTLE_ENDIAN * This should be #define'd already, if true. */

/* #define SHA1HANDSOFF * Copies data before messing with it. */

#define SHA1HANDSOFF

#if defined(__clang__)

#elif defined(__GNUC__)

#pragma GCC diagnostic push

/* Ignore the case when SHA1Transform() called with 'char *', that code passed

 * buffer of 64 bytes anyway (at least now) */

#pragma GCC diagnostic ignored "-Wstringop-overread"

#endif

#include <stdio.h>

#include <string.h>

/* for uint32_t */

#include <stdint.h>

#include "sha1.h"

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* blk0() and blk() perform the initial expand. */

/* I got the idea of expanding during the round function from SSLeay */

#if defined(LITTLE_ENDIAN)

#define blk0(i)                                                                \

    (block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |                       \

                   (rol(block->l[i], 8) & 0x00FF00FF))

#elif defined(BIG_ENDIAN)

#define blk0(i) block->l[i]

#else

#error "Endianness not defined!"

#endif

#define blk(i)                                                                 \

    (block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15] ^ \

                                block->l[(i + 2) & 15] ^ block->l[i & 15],     \

                            1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */

#define R0(v, w, x, y, z, i)                                                   \

    z += ((w & (x ^ y)) ^ y) + blk0(i) + 0x5A827999 + rol(v, 5);               \

    w = rol(w, 30);

#define R1(v, w, x, y, z, i)                                                   \

    z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5);                \

    w = rol(w, 30);

#define R2(v, w, x, y, z, i)                                                   \

    z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5);                        \

    w = rol(w, 30);

#define R3(v, w, x, y, z, i)                                                   \

    z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5);          \

    w = rol(w, 30);

#define R4(v, w, x, y, z, i)                                                   \

    z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5);                        \

    w = rol(w, 30);

typedef struct {

    uint32_t state[5];

    uint32_t count[2];

    unsigned char buffer[64];

} SHA1_CTX;

static void SHA1Transform(uint32_t state[5], const unsigned char buffer[64]);

static void SHA1Init(SHA1_CTX *context);

static void SHA1Update(SHA1_CTX *context, const unsigned char *data, uint32_t len);

static void SHA1Final(unsigned char digest[20], SHA1_CTX *context);

/* Hash a single 512-bit block. This is the core of the algorithm. */

static void SHA1Transform(uint32_t state[5], const unsigned char buffer[64]) {

    uint32_t a, b, c, d, e;

    typedef union {

        unsigned char c[64];

        uint32_t l[16];

    } CHAR64LONG16;

#ifdef SHA1HANDSOFF

    CHAR64LONG16 block[1]; /* use array to appear as a pointer */

    memcpy(block, buffer, 64);

#else

    /* The following had better never be used because it causes the

     * pointer-to-const buffer to be cast into a pointer to non-const.

     * And the result is written through.  I threw a "const" in, hoping

     * this will cause a diagnostic.

     */

    CHAR64LONG16 *block = (const CHAR64LONG16 *)buffer;

#endif

    /* Copy context->state[] to working vars */

    a = state[0];

    b = state[1];

    c = state[2];

    d = state[3];

    e = state[4];

    /* 4 rounds of 20 operations each. Loop unrolled. */

    R0(a, b, c, d, e, 0);

    R0(e, a, b, c, d, 1);

    R0(d, e, a, b, c, 2);

    R0(c, d, e, a, b, 3);

    R0(b, c, d, e, a, 4);

    R0(a, b, c, d, e, 5);

    R0(e, a, b, c, d, 6);

    R0(d, e, a, b, c, 7);

    R0(c, d, e, a, b, 8);

    R0(b, c, d, e, a, 9);

    R0(a, b, c, d, e, 10);

    R0(e, a, b, c, d, 11);

    R0(d, e, a, b, c, 12);

    R0(c, d, e, a, b, 13);

    R0(b, c, d, e, a, 14);

    R0(a, b, c, d, e, 15);

    R1(e, a, b, c, d, 16);

    R1(d, e, a, b, c, 17);

    R1(c, d, e, a, b, 18);

    R1(b, c, d, e, a, 19);

    R2(a, b, c, d, e, 20);

    R2(e, a, b, c, d, 21);

    R2(d, e, a, b, c, 22);

    R2(c, d, e, a, b, 23);

    R2(b, c, d, e, a, 24);

    R2(a, b, c, d, e, 25);

    R2(e, a, b, c, d, 26);

    R2(d, e, a, b, c, 27);

    R2(c, d, e, a, b, 28);

    R2(b, c, d, e, a, 29);

    R2(a, b, c, d, e, 30);

    R2(e, a, b, c, d, 31);

    R2(d, e, a, b, c, 32);

    R2(c, d, e, a, b, 33);

    R2(b, c, d, e, a, 34);

    R2(a, b, c, d, e, 35);

    R2(e, a, b, c, d, 36);

    R2(d, e, a, b, c, 37);

    R2(c, d, e, a, b, 38);

    R2(b, c, d, e, a, 39);

    R3(a, b, c, d, e, 40);

    R3(e, a, b, c, d, 41);

    R3(d, e, a, b, c, 42);

    R3(c, d, e, a, b, 43);

    R3(b, c, d, e, a, 44);

    R3(a, b, c, d, e, 45);

    R3(e, a, b, c, d, 46);

    R3(d, e, a, b, c, 47);

    R3(c, d, e, a, b, 48);

    R3(b, c, d, e, a, 49);

    R3(a, b, c, d, e, 50);

    R3(e, a, b, c, d, 51);

    R3(d, e, a, b, c, 52);

    R3(c, d, e, a, b, 53);

    R3(b, c, d, e, a, 54);

    R3(a, b, c, d, e, 55);

    R3(e, a, b, c, d, 56);

    R3(d, e, a, b, c, 57);

    R3(c, d, e, a, b, 58);

    R3(b, c, d, e, a, 59);

    R4(a, b, c, d, e, 60);

    R4(e, a, b, c, d, 61);

    R4(d, e, a, b, c, 62);

    R4(c, d, e, a, b, 63);

    R4(b, c, d, e, a, 64);

    R4(a, b, c, d, e, 65);

    R4(e, a, b, c, d, 66);

    R4(d, e, a, b, c, 67);

    R4(c, d, e, a, b, 68);

    R4(b, c, d, e, a, 69);

    R4(a, b, c, d, e, 70);

    R4(e, a, b, c, d, 71);

    R4(d, e, a, b, c, 72);

    R4(c, d, e, a, b, 73);

    R4(b, c, d, e, a, 74);

    R4(a, b, c, d, e, 75);

    R4(e, a, b, c, d, 76);

    R4(d, e, a, b, c, 77);

    R4(c, d, e, a, b, 78);

    R4(b, c, d, e, a, 79);

    /* Add the working vars back into context.state[] */

    state[0] += a;

    state[1] += b;

    state[2] += c;

    state[3] += d;

    state[4] += e;

#ifdef SHA1HANDSOFF

    memset(block, '\0', sizeof(block));

#endif

}

/* SHA1Init - Initialize new context */

static void SHA1Init(SHA1_CTX *context) {

    /* SHA1 initialization constants */

    context->state[0] = 0x67452301;

    context->state[1] = 0xEFCDAB89;

    context->state[2] = 0x98BADCFE;

    context->state[3] = 0x10325476;

    context->state[4] = 0xC3D2E1F0;

    context->count[0] = context->count[1] = 0;

}

/* Run your data through this. */

static void SHA1Update(SHA1_CTX *context, const unsigned char *data, uint32_t len) {

    uint32_t i;

    uint32_t j;

    j = context->count[0];

    if ((context->count[0] += len << 3) < j)

        context->count[1]++;

    context->count[1] += (len >> 29);

    j = (j >> 3) & 63;

    if ((j + len) > 63) {

        memcpy(&context->buffer[j], data, (i = 64 - j));

        SHA1Transform(context->state, context->buffer);

        for (; i + 63 < len; i += 64) {

            SHA1Transform(context->state, &data[i]);

        }

        j = 0;

    } else

        i = 0;

    memcpy(&context->buffer[j], &data[i], len - i);

}

/* Add padding and return the message digest. */

static void SHA1Final(unsigned char digest[20], SHA1_CTX *context) {

    unsigned i;

    unsigned char finalcount[8];

    unsigned char c;

#if 0 /* untested "improvement" by DHR */

    /* Convert context->count to a sequence of bytes

     * in finalcount.  Second element first, but

     * big-endian order within element.

     * But we do it all backwards.

     */

    unsigned char *fcp = &finalcount[8];

    for (i = 0; i < 2; i++)

    {

        uint32_t t = context->count[i];

        int j;

        for (j = 0; j < 4; t >>= 8, j++)

            *--fcp = (unsigned char) t}

#else

    for (i = 0; i < 8; i++) {

        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)] >>

                                         ((3 - (i & 3)) * 8)) &

                                        255); /* Endian independent */

    }

#endif

    c = 0200;

    SHA1Update(context, &c, 1);

    while ((context->count[0] & 504) != 448) {

        c = 0000;

        SHA1Update(context, &c, 1);

    }

    SHA1Update(context, finalcount, 8); /* Should cause a SHA1Transform() */

    for (i = 0; i < 20; i++) {

        digest[i] =

            (unsigned char)((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) &

                            255);

    }

    /* Wipe variables */

    memset(context, '\0', sizeof(*context));

    memset(&finalcount, '\0', sizeof(finalcount));

}

void builtin_SHA1(char *hash_out, const char *str, int len) {

    SHA1_CTX ctx;

    int ii;

    SHA1Init(&ctx);

    for (ii = 0; ii < len; ii += 1)

        SHA1Update(&ctx, (const unsigned char *)str + ii, 1);

    SHA1Final((unsigned char *)hash_out, &ctx);

}