path: root/crypto/modes/siv128.c

/*
 * Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (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 <string.h>
#include <stdlib.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/core_names.h>
#include <openssl/params.h>
#include "internal/endian.h"
#include "crypto/modes.h"
#include "crypto/siv.h"

#ifndef OPENSSL_NO_SIV

__owur static ossl_inline uint32_t rotl8(uint32_t x)
{
    return (x << 8) | (x >> 24);
}

__owur static ossl_inline uint32_t rotr8(uint32_t x)
{
    return (x >> 8) | (x << 24);
}

__owur static ossl_inline uint64_t byteswap8(uint64_t x)
{
    uint32_t high = (uint32_t)(x >> 32);
    uint32_t low = (uint32_t)x;

    high = (rotl8(high) & 0x00ff00ff) | (rotr8(high) & 0xff00ff00);
    low = (rotl8(low) & 0x00ff00ff) | (rotr8(low) & 0xff00ff00);
    return ((uint64_t)low) << 32 | (uint64_t)high;
}

__owur static ossl_inline uint64_t siv128_getword(SIV_BLOCK const *b, size_t i)
{
    DECLARE_IS_ENDIAN;

    if (IS_LITTLE_ENDIAN)
        return byteswap8(b->word[i]);
    return b->word[i];
}

static ossl_inline void siv128_putword(SIV_BLOCK *b, size_t i, uint64_t x)
{
    DECLARE_IS_ENDIAN;

    if (IS_LITTLE_ENDIAN)
        b->word[i] = byteswap8(x);
    else
        b->word[i] = x;
}

static ossl_inline void siv128_xorblock(SIV_BLOCK *x,
                                        SIV_BLOCK const *y)
{
    x->word[0] ^= y->word[0];
    x->word[1] ^= y->word[1];
}

/*
 * Doubles |b|, which is 16 bytes representing an element
 * of GF(2**128) modulo the irreducible polynomial
 * x**128 + x**7 + x**2 + x + 1.
 * Assumes two's-complement arithmetic
 */
static ossl_inline void siv128_dbl(SIV_BLOCK *b)
{
    uint64_t high = siv128_getword(b, 0);
    uint64_t low = siv128_getword(b, 1);
    uint64_t high_carry = high & (((uint64_t)1) << 63);
    uint64_t low_carry = low & (((uint64_t)1) << 63);
    int64_t low_mask = -((int64_t)(high_carry >> 63)) & 0x87;
    uint64_t high_mask = low_carry >> 63;

    high = (high << 1) | high_mask;
    low = (low << 1) ^ (uint64_t)low_mask;
    siv128_putword(b, 0, high);
    siv128_putword(b, 1, low);
}

__owur static ossl_inline int siv128_do_s2v_p(SIV128_CONTEXT *ctx, SIV_BLOCK *out,
                                              unsigned char const* in, size_t len)
{
    SIV_BLOCK t;
    size_t out_len = sizeof(out->byte);
    EVP_MAC_CTX *mac_ctx;
    int ret = 0;

    mac_ctx = EVP_MAC_CTX_dup(ctx->mac_ctx_init);
    if (mac_ctx == NULL)
        return 0;

    if (len >= SIV_LEN) {
        if (!EVP_MAC_update(mac_ctx, in, len - SIV_LEN))
            goto err;
        memcpy(&t, in + (len-SIV_LEN), SIV_LEN);
        siv128_xorblock(&t, &ctx->d);
        if (!EVP_MAC_update(mac_ctx, t.byte, SIV_LEN))
            goto err;
    } else {
        memset(&t, 0, sizeof(t));
        memcpy(&t, in, len);
        t.byte[len] = 0x80;
        siv128_dbl(&ctx->d);
        siv128_xorblock(&t, &ctx->d);
        if (!EVP_MAC_update(mac_ctx, t.byte, SIV_LEN))
            goto err;
    }
    if (!EVP_MAC_final(mac_ctx, out->byte, &out_len, sizeof(out->byte))
        || out_len != SIV_LEN)
        goto err;

    ret = 1;

err:
    EVP_MAC_CTX_free(mac_ctx);
    return ret;
}


__owur static ossl_inline int siv128_do_encrypt(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                             unsigned char const *in, size_t len,
                                             SIV_BLOCK *icv)
{
    int out_len = (int)len;

    if (!EVP_CipherInit_ex(ctx, NULL, NULL, NULL, icv->byte, 1))
        return 0;
    return EVP_EncryptUpdate(ctx, out, &out_len, in, out_len);
}

/*
 * Create a new SIV128_CONTEXT
 */
SIV128_CONTEXT *ossl_siv128_new(const unsigned char *key, int klen,
                                  EVP_CIPHER *cbc, EVP_CIPHER *ctr,
                                  OSSL_LIB_CTX *libctx, const char *propq)
{
    SIV128_CONTEXT *ctx;
    int ret;

    if ((ctx = OPENSSL_malloc(sizeof(*ctx))) != NULL) {
        ret = ossl_siv128_init(ctx, key, klen, cbc, ctr, libctx, propq);
        if (ret)
            return ctx;
        OPENSSL_free(ctx);
    }

    return NULL;
}

/*
 * Initialise an existing SIV128_CONTEXT
 */
int ossl_siv128_init(SIV128_CONTEXT *ctx, const unsigned char *key, int klen,
                       const EVP_CIPHER *cbc, const EVP_CIPHER *ctr,
                       OSSL_LIB_CTX *libctx, const char *propq)
{
    static const unsigned char zero[SIV_LEN] = { 0 };
    size_t out_len = SIV_LEN;
    EVP_MAC_CTX *mac_ctx = NULL;
    OSSL_PARAM params[3];
    const char *cbc_name;

    if (ctx == NULL)
        return 0;

    memset(&ctx->d, 0, sizeof(ctx->d));
    EVP_CIPHER_CTX_free(ctx->cipher_ctx);
    EVP_MAC_CTX_free(ctx->mac_ctx_init);
    EVP_MAC_free(ctx->mac);
    ctx->mac = NULL;
    ctx->cipher_ctx = NULL;
    ctx->mac_ctx_init = NULL;

    if (key == NULL || cbc == NULL || ctr == NULL)
        return 0;

    cbc_name = EVP_CIPHER_name(cbc);
    params[0] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_CIPHER,
                                                 (char *)cbc_name, 0);
    params[1] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
                                                  (void *)key, klen);
    params[2] = OSSL_PARAM_construct_end();

    if ((ctx->cipher_ctx = EVP_CIPHER_CTX_new()) == NULL
            || (ctx->mac =
                EVP_MAC_fetch(libctx, OSSL_MAC_NAME_CMAC, propq)) == NULL
            || (ctx->mac_ctx_init = EVP_MAC_CTX_new(ctx->mac)) == NULL
            || !EVP_MAC_CTX_set_params(ctx->mac_ctx_init, params)
            || !EVP_EncryptInit_ex(ctx->cipher_ctx, ctr, NULL, key