/*

 * Copyright 2010-2018 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "internal/cryptlib.h"

#include <openssl/cmac.h>

#include <openssl/err.h>

struct CMAC_CTX_st {

    /* Cipher context to use */

    EVP_CIPHER_CTX *cctx;

    /* Keys k1 and k2 */

    unsigned char k1[EVP_MAX_BLOCK_LENGTH];

    unsigned char k2[EVP_MAX_BLOCK_LENGTH];

    /* Temporary block */

    unsigned char tbl[EVP_MAX_BLOCK_LENGTH];

    /* Last (possibly partial) block */

    unsigned char last_block[EVP_MAX_BLOCK_LENGTH];

    /* Number of bytes in last block: -1 means context not initialised */

    int nlast_block;

};

/* Make temporary keys K1 and K2 */

static void make_kn(unsigned char *k1, const unsigned char *l, int bl)

{

    int i;

    unsigned char c = l[0], carry = c >> 7, cnext;

    /* Shift block to left, including carry */

    for (i = 0; i < bl - 1; i++, c = cnext)

        k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);

    /* If MSB set fixup with R */

    k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));

}

CMAC_CTX *CMAC_CTX_new(void)

{

    CMAC_CTX *ctx;

    if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) {

        CRYPTOerr(CRYPTO_F_CMAC_CTX_NEW, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    ctx->cctx = EVP_CIPHER_CTX_new();

    if (ctx->cctx == NULL) {

        OPENSSL_free(ctx);

        return NULL;

    }

    ctx->nlast_block = -1;

    return ctx;

}

void CMAC_CTX_cleanup(CMAC_CTX *ctx)

{

    EVP_CIPHER_CTX_reset(ctx->cctx);

    OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);

    OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);

    OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);

    OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);

    ctx->nlast_block = -1;

}

EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)

{

    return ctx->cctx;

}

void CMAC_CTX_free(CMAC_CTX *ctx)

{

    if (!ctx)

        return;

    CMAC_CTX_cleanup(ctx);

    EVP_CIPHER_CTX_free(ctx->cctx);

    OPENSSL_free(ctx);

}

int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)

{

    int bl;

    if (in->nlast_block == -1)

        return 0;

    if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))

        return 0;

    bl = EVP_CIPHER_CTX_block_size(in->cctx);

    memcpy(out->k1, in->k1, bl);

    memcpy(out->k2, in->k2, bl);

    memcpy(out->tbl, in->tbl, bl);

    memcpy(out->last_block, in->last_block, bl);

    out->nlast_block = in->nlast_block;

    return 1;

}

int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,

              const EVP_CIPHER *cipher, ENGINE *impl)

{

    static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };

    /* All zeros means restart */

    if (!key && !cipher && !impl && keylen == 0) {

        /* Not initialised */

        if (ctx->nlast_block == -1)

            return 0;

        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))

            return 0;

        memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));

        ctx->nlast_block = 0;

        return 1;

    }

    /* Initialise context */

    if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))

        return 0;

    /* Non-NULL key means initialisation complete */

    if (key) {

        int bl;

        if (!EVP_CIPHER_CTX_cipher(ctx->cctx))

            return 0;

        if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))

            return 0;

        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))

            return 0;

        bl = EVP_CIPHER_CTX_block_size(ctx->cctx);

        if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl))

            return 0;

        make_kn(ctx->k1, ctx->tbl, bl);

        make_kn(ctx->k2, ctx->k1, bl);

        OPENSSL_cleanse(ctx->tbl, bl);

        /* Reset context again ready for first data block */

        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))

            return 0;

        /* Zero tbl so resume works */

        memset(ctx->tbl, 0, bl);

        ctx->nlast_block = 0;

    }

    return 1;

}

int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)

{

    const unsigned char *data = in;

    size_t bl;

    if (ctx->nlast_block == -1)

        return 0;

    if (dlen == 0)

        return 1;

    bl = EVP_CIPHER_CTX_block_size(ctx->cctx);

    /* Copy into partial block if we need to */

    if (ctx->nlast_block > 0) {

        size_t nleft;

        nleft = bl - ctx->nlast_block;

        if (dlen < nleft)

            nleft = dlen;

        memcpy(ctx->last_block + ctx->nlast_block, data, nleft);

        dlen -= nleft;

        ctx->nlast_block += nleft;

        /* If no more to process return */

        if (dlen == 0)

            return 1;

        data += nleft;

        /* Else not final block so encrypt it */

        if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl))

            return 0;

    }

    /* Encrypt all but one of the complete blocks left */

    while (dlen > bl) {

        if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl))

            return 0;

        dlen -= bl;

        data += bl;

    }

    /* Copy any data left to last block buffer */

    memcpy(ctx->last_block, data, dlen);

    ctx->nlast_block = dlen;

    return 1;

}

int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)

{

    int i, bl, lb;

    if (ctx->nlast_block == -1)

        return 0;

    bl = EVP_CIPHER_CTX_block_size(ctx->cctx);

    *poutlen = (size_t)bl;

    if (!out)

        return 1;

    lb = ctx->nlast_block;

    /* Is last block complete? */

    if (lb == bl) {

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

            out[i] = ctx->last_block[i] ^ ctx->k1[i];

    } else {

        ctx->last_block[lb] = 0x80;

        if (bl - lb > 1)

            memset(ctx->last_block + lb + 1, 0, bl - lb - 1);

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

            out[i] = ctx->last_block[i] ^ ctx->k2[i];

    }

    if (!EVP_Cipher(ctx->cctx, out, out, bl)) {

        OPENSSL_cleanse(out, bl);

        return 0;

    }

    return 1;

}

int CMAC_resume(CMAC_CTX *ctx)

{

    if (ctx->nlast_block == -1)

        return 0;

    /*

     * The buffer "tbl" contains the last fully encrypted block which is the

     * last IV (or all zeroes if no last encrypted block). The last block has

     * not been modified since CMAC_final(). So reinitialising using the last

     * decrypted block will allow CMAC to continue after calling

     * CMAC_Final().

     */

    return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);

}