480 lines
13 KiB
C
480 lines
13 KiB
C
/*
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* Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* See SP800-185 "Appendix A - KMAC, .... in Terms of Keccak[c]"
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*
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* Inputs are:
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* K = Key (len(K) < 2^2040 bits)
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* X = Input
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* L = Output length (0 <= L < 2^2040 bits)
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* S = Customization String Default="" (len(S) < 2^2040 bits)
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*
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* KMAC128(K, X, L, S)
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* {
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* newX = bytepad(encode_string(K), 168) || X || right_encode(L).
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* T = bytepad(encode_string("KMAC") || encode_string(S), 168).
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* return KECCAK[256](T || newX || 00, L).
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* }
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*
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* KMAC256(K, X, L, S)
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* {
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* newX = bytepad(encode_string(K), 136) || X || right_encode(L).
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* T = bytepad(encode_string("KMAC") || encode_string(S), 136).
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* return KECCAK[512](T || newX || 00, L).
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* }
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*
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* KMAC128XOF(K, X, L, S)
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* {
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* newX = bytepad(encode_string(K), 168) || X || right_encode(0).
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* T = bytepad(encode_string("KMAC") || encode_string(S), 168).
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* return KECCAK[256](T || newX || 00, L).
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* }
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*
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* KMAC256XOF(K, X, L, S)
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* {
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* newX = bytepad(encode_string(K), 136) || X || right_encode(0).
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* T = bytepad(encode_string("KMAC") || encode_string(S), 136).
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* return KECCAK[512](T || newX || 00, L).
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* }
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*
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*/
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#include <stdlib.h>
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#include <openssl/evp.h>
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#include "internal/cryptlib.h"
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#include "internal/evp_int.h"
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#define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
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#define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
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/* Length encoding will be a 1 byte size + length in bits (2 bytes max) */
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#define KMAC_MAX_ENCODED_HEADER_LEN 3
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/*
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* Custom string max size is chosen such that:
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* len(encoded_string(custom) + len(kmac_encoded_string) <= KMAC_MIN_BLOCKSIZE
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* i.e: (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_LEN) + 6 <= 136
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*/
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#define KMAC_MAX_CUSTOM 127
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/* Maximum size of encoded custom string */
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#define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
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/* Maximum key size in bytes = 2040 / 8 */
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#define KMAC_MAX_KEY 255
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/*
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* Maximum Encoded Key size will be padded to a multiple of the blocksize
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* i.e KMAC_MAX_KEY + KMAC_MAX_ENCODED_LEN = 258
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* Padded to a multiple of KMAC_MAX_BLOCKSIZE
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*/
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#define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
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/* Fixed value of encode_string("KMAC") */
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static const unsigned char kmac_string[] = {
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0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
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};
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#define KMAC_FLAG_XOF_MODE 1
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/* typedef EVP_MAC_IMPL */
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struct evp_mac_impl_st {
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EVP_MD_CTX *ctx;
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const EVP_MD *md;
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size_t out_len;
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int key_len;
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int custom_len;
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/* If xof_mode = 1 then we use right_encode(0) */
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int xof_mode;
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/* key and custom are stored in encoded form */
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unsigned char key[KMAC_MAX_KEY_ENCODED];
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unsigned char custom[KMAC_MAX_CUSTOM_ENCODED];
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};
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static int encode_string(unsigned char *out, int *out_len,
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const unsigned char *in, int in_len);
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static int right_encode(unsigned char *out, int *out_len, size_t bits);
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static int bytepad(unsigned char *out, int *out_len,
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const unsigned char *in1, int in1_len,
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const unsigned char *in2, int in2_len,
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int w);
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static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
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const unsigned char *in, int in_len,
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int w);
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static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
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const char *value);
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static void kmac_free(EVP_MAC_IMPL *kctx)
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{
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if (kctx != NULL) {
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EVP_MD_CTX_free(kctx->ctx);
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OPENSSL_cleanse(kctx->key, kctx->key_len);
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OPENSSL_cleanse(kctx->custom, kctx->custom_len);
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OPENSSL_free(kctx);
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}
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}
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static EVP_MAC_IMPL *kmac_new(const EVP_MD *md)
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{
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EVP_MAC_IMPL *kctx = NULL;
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if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
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|| (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
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kmac_free(kctx);
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return NULL;
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}
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kctx->md = md;
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kctx->out_len = md->md_size;
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return kctx;
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}
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static EVP_MAC_IMPL *kmac128_new(void)
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{
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return kmac_new(evp_keccak_kmac128());
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}
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static EVP_MAC_IMPL *kmac256_new(void)
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{
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return kmac_new(evp_keccak_kmac256());
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}
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static EVP_MAC_IMPL *kmac_dup(const EVP_MAC_IMPL *gsrc)
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{
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EVP_MAC_IMPL *gdst;
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gdst = kmac_new(gsrc->md);
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if (gdst == NULL)
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return NULL;
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if (!EVP_MD_CTX_copy(gdst->ctx, gsrc->ctx)) {
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kmac_free(gdst);
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return NULL;
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}
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gdst->md = gsrc->md;
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gdst->out_len = gsrc->out_len;
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gdst->key_len = gsrc->key_len;
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gdst->custom_len = gsrc->custom_len;
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gdst->xof_mode = gsrc->xof_mode;
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memcpy(gdst->key, gsrc->key, gsrc->key_len);
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memcpy(gdst->custom, gsrc->custom, gdst->custom_len);
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return gdst;
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}
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/*
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* The init() assumes that any ctrl methods are set beforehand for
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* md, key and custom. Setting the fields afterwards will have no
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* effect on the output mac.
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*/
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static int kmac_init(EVP_MAC_IMPL *kctx)
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{
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EVP_MD_CTX *ctx = kctx->ctx;
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unsigned char out[KMAC_MAX_BLOCKSIZE];
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int out_len, block_len;
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/* Check key has been set */
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if (kctx->key_len == 0) {
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EVPerr(EVP_F_KMAC_INIT, EVP_R_NO_KEY_SET);
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return 0;
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}
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if (!EVP_DigestInit_ex(kctx->ctx, kctx->md, NULL))
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return 0;
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block_len = EVP_MD_block_size(kctx->md);
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/* Set default custom string if it is not already set */
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if (kctx->custom_len == 0)
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(void)kmac_ctrl_str(kctx, "custom", "");
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return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
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kctx->custom, kctx->custom_len, block_len)
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&& EVP_DigestUpdate(ctx, out, out_len)
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&& EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
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}
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static size_t kmac_size(EVP_MAC_IMPL *kctx)
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{
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return kctx->out_len;
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}
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static int kmac_update(EVP_MAC_IMPL *kctx, const unsigned char *data,
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size_t datalen)
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{
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return EVP_DigestUpdate(kctx->ctx, data, datalen);
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}
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static int kmac_final(EVP_MAC_IMPL *kctx, unsigned char *out)
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{
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EVP_MD_CTX *ctx = kctx->ctx;
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int lbits, len;
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unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
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/* KMAC XOF mode sets the encoded length to 0 */
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lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
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return right_encode(encoded_outlen, &len, lbits)
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&& EVP_DigestUpdate(ctx, encoded_outlen, len)
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&& EVP_DigestFinalXOF(ctx, out, kctx->out_len);
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}
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/*
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* The following Ctrl functions can be set any time before final():
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* - EVP_MAC_CTRL_SET_SIZE: The requested output length.
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* - EVP_MAC_CTRL_SET_XOF: If set, this indicates that right_encoded(0) is
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* part of the digested data, otherwise it uses
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* right_encoded(requested output length).
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* All other Ctrl functions should be set before init().
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*/
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static int kmac_ctrl(EVP_MAC_IMPL *kctx, int cmd, va_list args)
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{
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const unsigned char *p;
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size_t len;
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size_t size;
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switch (cmd) {
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case EVP_MAC_CTRL_SET_XOF:
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kctx->xof_mode = va_arg(args, int);
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return 1;
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case EVP_MAC_CTRL_SET_SIZE:
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size = va_arg(args, size_t);
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kctx->out_len = size;
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return 1;
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case EVP_MAC_CTRL_SET_KEY:
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p = va_arg(args, const unsigned char *);
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len = va_arg(args, size_t);
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if (len < 4 || len > KMAC_MAX_KEY) {
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EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_KEY_LENGTH);
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return 0;
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}
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return kmac_bytepad_encode_key(kctx->key, &kctx->key_len, p, len,
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EVP_MD_block_size(kctx->md));
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case EVP_MAC_CTRL_SET_CUSTOM:
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p = va_arg(args, const unsigned char *);
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len = va_arg(args, size_t);
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if (len > KMAC_MAX_CUSTOM) {
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EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_CUSTOM_LENGTH);
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return 0;
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}
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return encode_string(kctx->custom, &kctx->custom_len, p, len);
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default:
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return -2;
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}
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}
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static int kmac_ctrl_int(EVP_MAC_IMPL *kctx, int cmd, ...)
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{
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int rv;
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va_list args;
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va_start(args, cmd);
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rv = kmac_ctrl(kctx, cmd, args);
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va_end(args);
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return rv;
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}
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static int kmac_ctrl_str_cb(void *kctx, int cmd, void *buf, size_t buflen)
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{
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return kmac_ctrl_int(kctx, cmd, buf, buflen);
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}
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static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
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const char *value)
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{
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if (value == NULL)
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return 0;
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if (strcmp(type, "outlen") == 0)
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return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_SIZE, (size_t)atoi(value));
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if (strcmp(type, "xof") == 0)
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return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_XOF, atoi(value));
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if (strcmp(type, "key") == 0)
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return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
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value);
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if (strcmp(type, "hexkey") == 0)
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return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
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value);
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if (strcmp(type, "custom") == 0)
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return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
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value);
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if (strcmp(type, "hexcustom") == 0)
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return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
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value);
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return -2;
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}
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/*
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* Encoding/Padding Methods.
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*/
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/* Returns the number of bytes required to store 'bits' into a byte array */
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static unsigned int get_encode_size(size_t bits)
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{
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unsigned int cnt = 0, sz = sizeof(size_t);
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while (bits && (cnt < sz)) {
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++cnt;
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bits >>= 8;
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}
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/* If bits is zero 1 byte is required */
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if (cnt == 0)
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cnt = 1;
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return cnt;
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}
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/*
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* Convert an integer into bytes . The number of bytes is appended
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* to the end of the buffer. Returns an array of bytes 'out' of size
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* *out_len.
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*
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* e.g if bits = 32, out[2] = { 0x20, 0x01 }
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*
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*/
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static int right_encode(unsigned char *out, int *out_len, size_t bits)
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{
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unsigned int len = get_encode_size(bits);
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int i;
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/* The length is constrained to a single byte: 2040/8 = 255 */
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if (len > 0xFF)
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return 0;
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/* MSB's are at the start of the bytes array */
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for (i = len - 1; i >= 0; --i) {
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out[i] = (unsigned char)(bits & 0xFF);
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bits >>= 8;
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}
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/* Tack the length onto the end */
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out[len] = (unsigned char)len;
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/* The Returned length includes the tacked on byte */
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*out_len = len + 1;
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return 1;
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}
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/*
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* Encodes a string with a left encoded length added. Note that the
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* in_len is converted to bits (*8).
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*
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* e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
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* len bits K M A C
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*/
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static int encode_string(unsigned char *out, int *out_len,
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const unsigned char *in, int in_len)
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{
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if (in == NULL) {
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*out_len = 0;
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} else {
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int i, bits, len;
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bits = 8 * in_len;
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len = get_encode_size(bits);
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if (len > 0xFF)
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return 0;
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out[0] = len;
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for (i = len; i > 0; --i) {
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out[i] = (bits & 0xFF);
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bits >>= 8;
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}
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memcpy(out + len + 1, in, in_len);
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*out_len = (1 + len + in_len);
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}
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return 1;
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}
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/*
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* Returns a zero padded encoding of the inputs in1 and an optional
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* in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
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* The value of w is in bytes (< 256).
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*
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* The returned output is:
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* zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
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*/
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static int bytepad(unsigned char *out, int *out_len,
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const unsigned char *in1, int in1_len,
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const unsigned char *in2, int in2_len, int w)
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{
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int len;
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unsigned char *p = out;
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int sz = w;
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/* Left encoded w */
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*p++ = 1;
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*p++ = w;
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/* || in1 */
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memcpy(p, in1, in1_len);
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p += in1_len;
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/* [ || in2 ] */
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if (in2 != NULL && in2_len > 0) {
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memcpy(p, in2, in2_len);
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p += in2_len;
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}
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/* Figure out the pad size (divisible by w) */
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len = p - out;
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while (len > sz) {
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sz += w;
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}
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/* zero pad the end of the buffer */
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memset(p, 0, sz - len);
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*out_len = sz;
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return 1;
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}
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/*
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* Returns out = bytepad(encode_string(in), w)
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*/
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static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
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const unsigned char *in, int in_len,
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int w)
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{
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unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
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int tmp_len;
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if (!encode_string(tmp, &tmp_len, in, in_len))
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return 0;
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return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
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}
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const EVP_MAC kmac128_meth = {
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EVP_MAC_KMAC128,
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kmac128_new,
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kmac_dup,
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kmac_free,
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kmac_size,
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kmac_init,
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kmac_update,
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kmac_final,
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kmac_ctrl,
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kmac_ctrl_str
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};
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const EVP_MAC kmac256_meth = {
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EVP_MAC_KMAC256,
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kmac256_new,
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kmac_dup,
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kmac_free,
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kmac_size,
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kmac_init,
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kmac_update,
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kmac_final,
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kmac_ctrl,
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kmac_ctrl_str
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};
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