/*
 *  Copyright (C) 2021 - This file is part of libecc project
 *
 *  Authors:
 *      Ryad BENADJILA <ryadbenadjila@gmail.com>
 *      Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr>
 *
 *  This software is licensed under a dual BSD and GPL v2 license.
 *  See LICENSE file at the root folder of the project.
 */
#include "sha1.h"

#define ROTL_SHA1(x, n)      ((((u32)(x)) << (n)) | (((u32)(x)) >> (32-(n))))

/* All the inner SHA-1 operations */
#define K1_SHA1 0x5a827999
#define K2_SHA1 0x6ed9eba1
#define K3_SHA1 0x8f1bbcdc
#define K4_SHA1 0xca62c1d6

#define F1_SHA1(x, y, z)   ((z) ^ ((x) & ((y) ^ (z))))
#define F2_SHA1(x, y, z)   ((x) ^ (y) ^ (z))
#define F3_SHA1(x, y, z)   (((x) & (y)) | ((z) & ((x) | (y))))
#define F4_SHA1(x, y, z)   ((x) ^ (y) ^ (z))

#define SHA1_EXPAND(W, i) (W[i & 15] = ROTL_SHA1((W[i & 15] ^ W[(i - 14) & 15] ^ W[(i - 8) & 15] ^ W[(i - 3) & 15]), 1))

#define SHA1_SUBROUND(a, b, c, d, e, F, K, data) do { \
        u32 A_, B_, C_, D_, E_; \
        A_ = (e + ROTL_SHA1(a, 5) + F(b, c, d) + K + data); \
        B_ = a; \
        C_ = ROTL_SHA1(b, 30); \
        D_ = c; \
        E_ = d; \
        /**/ \
        a = A_; b = B_; c = C_; d = D_; e = E_; \
} while(0)

/* SHA-1 core processing. Returns 0 on success, -1 on error. */
ATTRIBUTE_WARN_UNUSED_RET static inline int sha1_process(sha1_context *ctx,
                           const u8 data[SHA1_BLOCK_SIZE])
{
        u32 A, B, C, D, E;
        u32 W[16];
        int ret;
        unsigned int i;

        MUST_HAVE((data != NULL), ret, err);
        SHA1_HASH_CHECK_INITIALIZED(ctx, ret, err);

        /* Init our inner variables */
        A = ctx->sha1_state[0];
        B = ctx->sha1_state[1];
        C = ctx->sha1_state[2];
        D = ctx->sha1_state[3];
        E = ctx->sha1_state[4];

        /* Load data */
        for (i = 0; i < 16; i++) {
                GET_UINT32_BE(W[i], data, (4 * i));
        }
        for (i = 0; i < 80; i++) {
                if(i <= 15){
                        SHA1_SUBROUND(A, B, C, D, E, F1_SHA1, K1_SHA1, W[i]);
                }
                else if((i >= 16) && (i <= 19)){
                        SHA1_SUBROUND(A, B, C, D, E, F1_SHA1, K1_SHA1, SHA1_EXPAND(W, i));
                }
                else if((i >= 20) && (i <= 39)){
                        SHA1_SUBROUND(A, B, C, D, E, F2_SHA1, K2_SHA1, SHA1_EXPAND(W, i));
                }
                else if((i >= 40) && (i <= 59)){
                        SHA1_SUBROUND(A, B, C, D, E, F3_SHA1, K3_SHA1, SHA1_EXPAND(W, i));
                }
                else{
                        SHA1_SUBROUND(A, B, C, D, E, F4_SHA1, K4_SHA1, SHA1_EXPAND(W, i));
                }
        }

        /* Update state */
        ctx->sha1_state[0] += A;
        ctx->sha1_state[1] += B;
        ctx->sha1_state[2] += C;
        ctx->sha1_state[3] += D;
        ctx->sha1_state[4] += E;

        ret = 0;

err:
        return ret;
}

/* Init hash function. Returns 0 on success, -1 on error. */
ATTRIBUTE_WARN_UNUSED_RET int sha1_init(sha1_context *ctx)
{
        int ret;

        MUST_HAVE((ctx != NULL), ret, err);

        /* Sanity check on size */
        MUST_HAVE((SHA1_DIGEST_SIZE <= MAX_DIGEST_SIZE), ret, err);

        ctx->sha1_total = 0;
        ctx->sha1_state[0] = 0x67452301;
        ctx->sha1_state[1] = 0xefcdab89;
        ctx->sha1_state[2] = 0x98badcfe;
        ctx->sha1_state[3] = 0x10325476;
        ctx->sha1_state[4] = 0xc3d2e1f0;

        /* Tell that we are initialized */
        ctx->magic = SHA1_HASH_MAGIC;

        ret = 0;

err:
        return ret;
}

ATTRIBUTE_WARN_UNUSED_RET int sha1_update(sha1_context *ctx, const u8 *input, u32 ilen)
{
        const u8 *data_ptr = input;
        u32 remain_ilen = ilen;
        u16 fill;
        u8 left;
        int ret;

        MUST_HAVE((input != NULL) || (ilen == 0), ret, err);
        SHA1_HASH_CHECK_INITIALIZED(ctx, ret, err);

        /* Nothing to process, return */
        if (ilen == 0) {
                ret = 0;
                goto err;
        }

        /* Get what's left in our local buffer */
        left = (ctx->sha1_total & 0x3F);
        fill = (u16)(SHA1_BLOCK_SIZE - left);

        ctx->sha1_total += ilen;

        if ((left > 0) && (remain_ilen >= fill)) {
                /* Copy data at the end of the buffer */
                ret = local_memcpy(ctx->sha1_buffer + left, data_ptr, fill); EG(ret, err);
                ret = sha1_process(ctx, ctx->sha1_buffer); EG(ret, err);
                data_ptr += fill;
                remain_ilen -= fill;
                left = 0;
        }

        while (remain_ilen >= SHA1_BLOCK_SIZE) {
                ret = sha1_process(ctx, data_ptr); EG(ret, err);
                data_ptr += SHA1_BLOCK_SIZE;
                remain_ilen -= SHA1_BLOCK_SIZE;
        }

        if (remain_ilen > 0) {
                ret = local_memcpy(ctx->sha1_buffer + left, data_ptr, remain_ilen); EG(ret, err);
        }

        ret = 0;

err:
        return ret;
}

/* Finalize. Returns 0 on success, -1 on error.*/
ATTRIBUTE_WARN_UNUSED_RET int sha1_final(sha1_context *ctx, u8 output[SHA1_DIGEST_SIZE])
{
        unsigned int block_present = 0;
        u8 last_padded_block[2 * SHA1_BLOCK_SIZE];
        int ret;

        MUST_HAVE((output != NULL), ret, err);
        SHA1_HASH_CHECK_INITIALIZED(ctx, ret, err);

        /* Fill in our last block with zeroes */
        ret = local_memset(last_padded_block, 0, sizeof(last_padded_block)); EG(ret, err);

        /* This is our final step, so we proceed with the padding */
        block_present = ctx->sha1_total % SHA1_BLOCK_SIZE;
        if (block_present != 0) {
                /* Copy what's left in our temporary context buffer */
                ret = local_memcpy(last_padded_block, ctx->sha1_buffer,
                             block_present); EG(ret, err);
        }

        /* Put the 0x80 byte, beginning of padding  */
        last_padded_block[block_present] = 0x80;

        /* Handle possible additional block */
        if (block_present > (SHA1_BLOCK_SIZE - 1 - sizeof(u64))) {
                /* We need an additional block */
                PUT_UINT64_BE(8 * ctx->sha1_total, last_padded_block,
                              (2 * SHA1_BLOCK_SIZE) - sizeof(u64));
                ret = sha1_process(ctx, last_padded_block); EG(ret, err);
                ret = sha1_process(ctx, last_padded_block + SHA1_BLOCK_SIZE); EG(ret, err);
        } else {
                /* We do not need an additional block */
                PUT_UINT64_BE(8 * ctx->sha1_total, last_padded_block,
                              SHA1_BLOCK_SIZE - sizeof(u64));
                ret = sha1_process(ctx, last_padded_block); EG(ret, err);
        }

        /* Output the hash result */
        PUT_UINT32_BE(ctx->sha1_state[0], output, 0);
        PUT_UINT32_BE(ctx->sha1_state[1], output, 4);
        PUT_UINT32_BE(ctx->sha1_state[2], output, 8);
        PUT_UINT32_BE(ctx->sha1_state[3], output, 12);
        PUT_UINT32_BE(ctx->sha1_state[4], output, 16);

        /* Tell that we are uninitialized */
        ctx->magic = WORD(0);

        ret = 0;

err:
        return ret;
}


/*
 * Scattered version performing init/update/finalize on a vector of buffers
 * 'inputs' with the length of each buffer passed via 'ilens'. The function
 * loops on pointers in 'inputs' until it finds a NULL pointer. The function
 * returns 0 on success, -1 on error.
 */
ATTRIBUTE_WARN_UNUSED_RET int sha1_scattered(const u8 **inputs, const u32 *ilens,
                      u8 output[SHA1_DIGEST_SIZE])
{
        sha1_context ctx;
        int ret, pos = 0;

        MUST_HAVE((inputs != NULL) && (ilens != NULL) && (output != NULL), ret, err);

        ret = sha1_init(&ctx); EG(ret, err);

        while (inputs[pos] != NULL) {
                ret = sha1_update(&ctx, inputs[pos], ilens[pos]); EG(ret, err);
                pos += 1;
        }

        ret = sha1_final(&ctx, output);

err:
        return ret;
}

/*
 * Single call version performing init/update/final on given input.
 * Returns 0 on success, -1 on error.
 */
ATTRIBUTE_WARN_UNUSED_RET int sha1(const u8 *input, u32 ilen, u8 output[SHA1_DIGEST_SIZE])
{
        sha1_context ctx;
        int ret;

        ret = sha1_init(&ctx); EG(ret, err);
        ret = sha1_update(&ctx, input, ilen); EG(ret, err);
        ret = sha1_final(&ctx, output);

err:
        return ret;
}