kmac_prov.c
/*
* Copyright 2018-2020 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
*/
/*
* See SP800-185 "Appendix A - KMAC, .... in Terms of Keccak[c]"
*
* Inputs are:
* K = Key (len(K) < 2^2040 bits)
* X = Input
* L = Output length (0 <= L < 2^2040 bits)
* S = Customization String Default="" (len(S) < 2^2040 bits)
*
* KMAC128(K, X, L, S)
* {
* newX = bytepad(encode_string(K), 168) || X || right_encode(L).
* T = bytepad(encode_string("KMAC") || encode_string(S), 168).
* return KECCAK[256](T || newX || 00, L).
* }
*
* KMAC256(K, X, L, S)
* {
* newX = bytepad(encode_string(K), 136) || X || right_encode(L).
* T = bytepad(encode_string("KMAC") || encode_string(S), 136).
* return KECCAK[512](T || newX || 00, L).
* }
*
* KMAC128XOF(K, X, L, S)
* {
* newX = bytepad(encode_string(K), 168) || X || right_encode(0).
* T = bytepad(encode_string("KMAC") || encode_string(S), 168).
* return KECCAK[256](T || newX || 00, L).
* }
*
* KMAC256XOF(K, X, L, S)
* {
* newX = bytepad(encode_string(K), 136) || X || right_encode(0).
* T = bytepad(encode_string("KMAC") || encode_string(S), 136).
* return KECCAK[512](T || newX || 00, L).
* }
*
*/
#include <stdlib.h>
#include <string.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/params.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include "prov/providercommonerr.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/provider_util.h"
#include "prov/providercommon.h"
/*
* Forward declaration of everything implemented here. This is not strictly
* necessary for the compiler, but provides an assurance that the signatures
* of the functions in the dispatch table are correct.
*/
static OSSL_FUNC_mac_newctx_fn kmac128_new;
static OSSL_FUNC_mac_newctx_fn kmac256_new;
static OSSL_FUNC_mac_dupctx_fn kmac_dup;
static OSSL_FUNC_mac_freectx_fn kmac_free;
static OSSL_FUNC_mac_gettable_ctx_params_fn kmac_gettable_ctx_params;
static OSSL_FUNC_mac_get_ctx_params_fn kmac_get_ctx_params;
static OSSL_FUNC_mac_settable_ctx_params_fn kmac_settable_ctx_params;
static OSSL_FUNC_mac_set_ctx_params_fn kmac_set_ctx_params;
static OSSL_FUNC_mac_size_fn kmac_size;
static OSSL_FUNC_mac_init_fn kmac_init;
static OSSL_FUNC_mac_update_fn kmac_update;
static OSSL_FUNC_mac_final_fn kmac_final;
#define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
#define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
/* Length encoding will be a 1 byte size + length in bits (2 bytes max) */
#define KMAC_MAX_ENCODED_HEADER_LEN 3
/*
* Custom string max size is chosen such that:
* len(encoded_string(custom) + len(kmac_encoded_string) <= KMAC_MIN_BLOCKSIZE
* i.e: (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_LEN) + 6 <= 136
*/
#define KMAC_MAX_CUSTOM 127
/* Maximum size of encoded custom string */
#define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
/* Maximum key size in bytes = 2040 / 8 */
#define KMAC_MAX_KEY 255
/*
* Maximum Encoded Key size will be padded to a multiple of the blocksize
* i.e KMAC_MAX_KEY + KMAC_MAX_ENCODED_LEN = 258
* Padded to a multiple of KMAC_MAX_BLOCKSIZE
*/
#define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
/* Fixed value of encode_string("KMAC") */
static const unsigned char kmac_string[] = {
0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
};
#define KMAC_FLAG_XOF_MODE 1
struct kmac_data_st {
void *provctx;
EVP_MD_CTX *ctx;
PROV_DIGEST digest;
size_t out_len;
int key_len;
int custom_len;
/* If xof_mode = 1 then we use right_encode(0) */
int xof_mode;
/* key and custom are stored in encoded form */
unsigned char key[KMAC_MAX_KEY_ENCODED];
unsigned char custom[KMAC_MAX_CUSTOM_ENCODED];
};
static int encode_string(unsigned char *out, int *out_len,
const unsigned char *in, int in_len);
static int right_encode(unsigned char *out, int *out_len, size_t bits);
static int bytepad(unsigned char *out, int *out_len,
const unsigned char *in1, int in1_len,
const unsigned char *in2, int in2_len,
int w);
static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
const unsigned char *in, int in_len,
int w);
static void kmac_free(void *vmacctx)
{
struct kmac_data_st *kctx = vmacctx;
if (kctx != NULL) {
EVP_MD_CTX_free(kctx->ctx);
ossl_prov_digest_reset(&kctx->digest);
OPENSSL_cleanse(kctx->key, kctx->key_len);
OPENSSL_cleanse(kctx->custom, kctx->custom_len);
OPENSSL_free(kctx);
}
}
/*
* We have KMAC implemented as a hash, which we can use instead of
* reimplementing the EVP functionality with direct use of
* keccak_mac_init() and friends.
*/
static struct kmac_data_st *kmac_new(void *provctx)
{
struct kmac_data_st *kctx;
if (!ossl_prov_is_running())
return NULL;
if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
|| (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
kmac_free(kctx);
return NULL;
}
kctx->provctx = provctx;
return kctx;
}
static void *kmac_fetch_new(void *provctx, const OSSL_PARAM *params)
{
struct kmac_data_st *kctx = kmac_new(provctx);
if (kctx == NULL)
return 0;
if (!ossl_prov_digest_load_from_params(&kctx->digest, params,
PROV_LIBCTX_OF(provctx))) {
kmac_free(kctx);
return 0;
}
kctx->out_len = EVP_MD_size(ossl_prov_digest_md(&kctx->digest));
return kctx;
}
static void *kmac128_new(void *provctx)
{
static const OSSL_PARAM kmac128_params[] = {
OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC128,
sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC128)),
OSSL_PARAM_END
};
return kmac_fetch_new(provctx, kmac128_params);
}
static void *kmac256_new(void *provctx)
{
static const OSSL_PARAM kmac256_params[] = {
OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC256,
sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC256)),
OSSL_PARAM_END
};
return kmac_fetch_new(provctx, kmac256_params);
}
static void *kmac_dup(void *vsrc)
{
struct kmac_data_st *src = vsrc;
struct kmac_data_st *dst;
if (!ossl_prov_is_running())
return NULL;
dst = kmac_new(src->provctx);
if (dst == NULL)
return NULL;
if (!EVP_MD_CTX_copy(dst->ctx, src->ctx)
|| !ossl_prov_digest_copy(&dst->digest, &src->digest)) {
kmac_free(dst);
return NULL;
}
dst->out_len = src->out_len;
dst->key_len = src->key_len;
dst->custom_len = src->custom_len;
dst->xof_mode = src->xof_mode;
memcpy(dst->key, src->key, src->key_len);
memcpy(dst->custom, src->custom, dst->custom_len);
return dst;
}
/*
* The init() assumes that any ctrl methods are set beforehand for
* md, key and custom. Setting the fields afterwards will have no
* effect on the output mac.
*/
static int kmac_init(void *vmacctx)
{
struct kmac_data_st *kctx = vmacctx;
EVP_MD_CTX *ctx = kctx->ctx;
unsigned char out[KMAC_MAX_BLOCKSIZE];
int out_len, block_len;
if (!ossl_prov_is_running())
return 0;
/* Check key has been set */
if (kctx->key_len == 0) {
ERR_raise(ERR_LIB_EVP, EVP_R_NO_KEY_SET);
return 0;
}
if (!EVP_DigestInit_ex(kctx->ctx, ossl_prov_digest_md(&kctx->digest),
NULL))
return 0;
block_len = EVP_MD_block_size(ossl_prov_digest_md(&kctx->digest));
if (block_len < 0)
return 0;
/* Set default custom string if it is not already set */
if (kctx->custom_len == 0) {
const OSSL_PARAM params[] = {
OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, "", 0),
OSSL_PARAM_END
};
(void)kmac_set_ctx_params(kctx, params);
}
return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
kctx->custom, kctx->custom_len, block_len)
&& EVP_DigestUpdate(ctx, out, out_len)
&& EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
}
static size_t kmac_size(void *vmacctx)
{
struct kmac_data_st *kctx = vmacctx;
return kctx->out_len;
}
static int kmac_update(void *vmacctx, const unsigned char *data,
size_t datalen)
{
struct kmac_data_st *kctx = vmacctx;
return EVP_DigestUpdate(kctx->ctx, data, datalen);
}
static int kmac_final(void *vmacctx, unsigned char *out, size_t *outl,
size_t outsize)
{
struct kmac_data_st *kctx = vmacctx;
EVP_MD_CTX *ctx = kctx->ctx;
int lbits, len;
unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
int ok;
if (!ossl_prov_is_running())
return 0;
/* KMAC XOF mode sets the encoded length to 0 */
lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
ok = right_encode(encoded_outlen, &len, lbits)
&& EVP_DigestUpdate(ctx, encoded_outlen, len)
&& EVP_DigestFinalXOF(ctx, out, kctx->out_len);
*outl = kctx->out_len;
return ok;
}
static const OSSL_PARAM known_gettable_ctx_params[] = {
OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
OSSL_PARAM_END
};
static const OSSL_PARAM *kmac_gettable_ctx_params(ossl_unused void *provctx)
{
return known_gettable_ctx_params;
}
static int kmac_get_ctx_params(void *vmacctx, OSSL_PARAM params[])
{
OSSL_PARAM *p;
if ((p = OSSL_PARAM_locate(params, OSSL_MAC_PARAM_SIZE)) != NULL)
return OSSL_PARAM_set_size_t(p, kmac_size(vmacctx));
return 1;
}
static const OSSL_PARAM known_settable_ctx_params[] = {
OSSL_PARAM_int(OSSL_MAC_PARAM_XOF, NULL),
OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
OSSL_PARAM_octet_string(OSSL_MAC_PARAM_KEY, NULL, 0),
OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, NULL, 0),
OSSL_PARAM_END
};
static const OSSL_PARAM *kmac_settable_ctx_params(ossl_unused void *provctx)
{
return known_settable_ctx_params;
}
/*
* The following params can be set any time before final():
* - "outlen" or "size": The requested output length.
* - "xof": If set, this indicates that right_encoded(0)
* is part of the digested data, otherwise it
* uses right_encoded(requested output length).
*
* All other params should be set before init().
*/
static int kmac_set_ctx_params(void *vmacctx, const OSSL_PARAM *params)
{
struct kmac_data_st *kctx = vmacctx;
const OSSL_PARAM *p;
const EVP_MD *digest = ossl_prov_digest_md(&kctx->digest);
if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_XOF)) != NULL
&& !OSSL_PARAM_get_int(p, &kctx->xof_mode))
return 0;
if (((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_SIZE)) != NULL)
&& !OSSL_PARAM_get_size_t(p, &kctx->out_len))
return 0;
if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_KEY)) != NULL) {
if (p->data_size < 4 || p->data_size > KMAC_MAX_KEY) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
return 0;
}
if (!kmac_bytepad_encode_key(kctx->key, &kctx->key_len,
p->data, p->data_size,
EVP_MD_block_size(digest)))
return 0;
}
if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_CUSTOM))
!= NULL) {
if (p->data_size > KMAC_MAX_CUSTOM) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CUSTOM_LENGTH);
return 0;
}
if (!encode_string(kctx->custom, &kctx->custom_len,
p->data, p->data_size))
return 0;
}
return 1;
}
/*
* Encoding/Padding Methods.
*/
/* Returns the number of bytes required to store 'bits' into a byte array */
static unsigned int get_encode_size(size_t bits)
{
unsigned int cnt = 0, sz = sizeof(size_t);
while (bits && (cnt < sz)) {
++cnt;
bits >>= 8;
}
/* If bits is zero 1 byte is required */
if (cnt == 0)
cnt = 1;
return cnt;
}
/*
* Convert an integer into bytes . The number of bytes is appended
* to the end of the buffer. Returns an array of bytes 'out' of size
* *out_len.
*
* e.g if bits = 32, out[2] = { 0x20, 0x01 }
*
*/
static int right_encode(unsigned char *out, int *out_len, size_t bits)
{
unsigned int len = get_encode_size(bits);
int i;
/* The length is constrained to a single byte: 2040/8 = 255 */
if (len > 0xFF)
return 0;
/* MSB's are at the start of the bytes array */
for (i = len - 1; i >= 0; --i) {
out[i] = (unsigned char)(bits & 0xFF);
bits >>= 8;
}
/* Tack the length onto the end */
out[len] = (unsigned char)len;
/* The Returned length includes the tacked on byte */
*out_len = len + 1;
return 1;
}
/*
* Encodes a string with a left encoded length added. Note that the
* in_len is converted to bits (*8).
*
* e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
* len bits K M A C
*/
static int encode_string(unsigned char *out, int *out_len,
const unsigned char *in, int in_len)
{
if (in == NULL) {
*out_len = 0;
} else {
int i, bits, len;
bits = 8 * in_len;
len = get_encode_size(bits);
if (len > 0xFF)
return 0;
out[0] = len;
for (i = len; i > 0; --i) {
out[i] = (bits & 0xFF);
bits >>= 8;
}
memcpy(out + len + 1, in, in_len);
*out_len = (1 + len + in_len);
}
return 1;
}
/*
* Returns a zero padded encoding of the inputs in1 and an optional
* in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
* The value of w is in bytes (< 256).
*
* The returned output is:
* zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
*/
static int bytepad(unsigned char *out, int *out_len,
const unsigned char *in1, int in1_len,
const unsigned char *in2, int in2_len, int w)
{
int len;
unsigned char *p = out;
int sz = w;
/* Left encoded w */
*p++ = 1;
*p++ = w;
/* || in1 */
memcpy(p, in1, in1_len);
p += in1_len;
/* [ || in2 ] */
if (in2 != NULL && in2_len > 0) {
memcpy(p, in2, in2_len);
p += in2_len;
}
/* Figure out the pad size (divisible by w) */
len = p - out;
while (len > sz) {
sz += w;
}
/* zero pad the end of the buffer */
memset(p, 0, sz - len);
*out_len = sz;
return 1;
}
/*
* Returns out = bytepad(encode_string(in), w)
*/
static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
const unsigned char *in, int in_len,
int w)
{
unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
int tmp_len;
if (!encode_string(tmp, &tmp_len, in, in_len))
return 0;
return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
}
const OSSL_DISPATCH ossl_kmac128_functions[] = {
{ OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac128_new },
{ OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
{ OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
{ OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
{ OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
{ OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
{ OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
(void (*)(void))kmac_gettable_ctx_params },
{ OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
{ OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
(void (*)(void))kmac_settable_ctx_params },
{ OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
{ 0, NULL }
};
const OSSL_DISPATCH ossl_kmac256_functions[] = {
{ OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac256_new },
{ OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
{ OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
{ OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
{ OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
{ OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
{ OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
(void (*)(void))kmac_gettable_ctx_params },
{ OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
{ OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
(void (*)(void))kmac_settable_ctx_params },
{ OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
{ 0, NULL }
};
