sskdf.c
/*
* Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2019, Oracle and/or its affiliates. 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
*/
/*
* Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
* Section 4.1.
*
* The Single Step KDF algorithm is given by:
*
* Result(0) = empty bit string (i.e., the null string).
* For i = 1 to reps, do the following:
* Increment counter by 1.
* Result(i) = Result(i - 1) || H(counter || Z || FixedInfo).
* DKM = LeftmostBits(Result(reps), L))
*
* NOTES:
* Z is a shared secret required to produce the derived key material.
* counter is a 4 byte buffer.
* FixedInfo is a bit string containing context specific data.
* DKM is the output derived key material.
* L is the required size of the DKM.
* reps = [L / H_outputBits]
* H(x) is the auxiliary function that can be either a hash, HMAC or KMAC.
* H_outputBits is the length of the output of the auxiliary function H(x).
*
* Currently there is not a comprehensive list of test vectors for this
* algorithm, especially for H(x) = HMAC and H(x) = KMAC.
* Test vectors for H(x) = Hash are indirectly used by CAVS KAS tests.
*/
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
#include <openssl/core_names.h>
#include <openssl/params.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include "crypto/evp.h"
#include "prov/provider_ctx.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_util.h"
#include "internal/params.h"
typedef struct {
void *provctx;
EVP_MAC_CTX *macctx; /* H(x) = HMAC_hash OR H(x) = KMAC */
PROV_DIGEST digest; /* H(x) = hash(x) */
unsigned char *secret;
size_t secret_len;
unsigned char *info;
size_t info_len;
unsigned char *salt;
size_t salt_len;
size_t out_len; /* optional KMAC parameter */
int is_kmac;
} KDF_SSKDF;
#define SSKDF_MAX_INLEN (1<<30)
#define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)
#define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)
/* KMAC uses a Customisation string of 'KDF' */
static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };
static OSSL_FUNC_kdf_newctx_fn sskdf_new;
static OSSL_FUNC_kdf_dupctx_fn sskdf_dup;
static OSSL_FUNC_kdf_freectx_fn sskdf_free;
static OSSL_FUNC_kdf_reset_fn sskdf_reset;
static OSSL_FUNC_kdf_derive_fn sskdf_derive;
static OSSL_FUNC_kdf_derive_fn x963kdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;
/*
* Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
* Section 4. One-Step Key Derivation using H(x) = hash(x)
* Note: X9.63 also uses this code with the only difference being that the
* counter is appended to the secret 'z'.
* i.e.
* result[i] = Hash(counter || z || info) for One Step OR
* result[i] = Hash(z || counter || info) for X9.63.
*/
static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
const unsigned char *z, size_t z_len,
const unsigned char *info, size_t info_len,
unsigned int append_ctr,
unsigned char *derived_key, size_t derived_key_len)
{
int ret = 0, hlen;
size_t counter, out_len, len = derived_key_len;
unsigned char c[4];
unsigned char mac[EVP_MAX_MD_SIZE];
unsigned char *out = derived_key;
EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
|| derived_key_len > SSKDF_MAX_INLEN
|| derived_key_len == 0)
return 0;
hlen = EVP_MD_get_size(kdf_md);
if (hlen <= 0)
return 0;
out_len = (size_t)hlen;
ctx = EVP_MD_CTX_create();
ctx_init = EVP_MD_CTX_create();
if (ctx == NULL || ctx_init == NULL)
goto end;
if (!EVP_DigestInit(ctx_init, kdf_md))
goto end;
for (counter = 1;; counter++) {
c[0] = (unsigned char)((counter >> 24) & 0xff);
c[1] = (unsigned char)((counter >> 16) & 0xff);
c[2] = (unsigned char)((counter >> 8) & 0xff);
c[3] = (unsigned char)(counter & 0xff);
if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
&& (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
&& EVP_DigestUpdate(ctx, z, z_len)
&& (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
&& EVP_DigestUpdate(ctx, info, info_len)))
goto end;
if (len >= out_len) {
if (!EVP_DigestFinal_ex(ctx, out, NULL))
goto end;
out += out_len;
len -= out_len;
if (len == 0)
break;
} else {
if (!EVP_DigestFinal_ex(ctx, mac, NULL))
goto end;
memcpy(out, mac, len);
break;
}
}
ret = 1;
end:
EVP_MD_CTX_destroy(ctx);
EVP_MD_CTX_destroy(ctx_init);
OPENSSL_cleanse(mac, sizeof(mac));
return ret;
}
static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
size_t custom_len, size_t kmac_out_len,
size_t derived_key_len, unsigned char **out)
{
OSSL_PARAM params[2];
/* Only KMAC has custom data - so return if not KMAC */
if (custom == NULL)
return 1;
params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
(void *)custom, custom_len);
params[1] = OSSL_PARAM_construct_end();
if (!EVP_MAC_CTX_set_params(ctx, params))
return 0;
/* By default only do one iteration if kmac_out_len is not specified */
if (kmac_out_len == 0)
kmac_out_len = derived_key_len;
/* otherwise check the size is valid */
else if (!(kmac_out_len == derived_key_len
|| kmac_out_len == 20
|| kmac_out_len == 28
|| kmac_out_len == 32
|| kmac_out_len == 48
|| kmac_out_len == 64))
return 0;
params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
&kmac_out_len);
if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
return 0;
/*
* For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so
* alloc a buffer for this case.
*/
if (kmac_out_len > EVP_MAX_MD_SIZE) {
*out = OPENSSL_zalloc(kmac_out_len);
if (*out == NULL)
return 0;
}
return 1;
}
/*
* Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
* Section 4. One-Step Key Derivation using MAC: i.e either
* H(x) = HMAC-hash(salt, x) OR
* H(x) = KMAC#(salt, x, outbits, CustomString='KDF')
*/
static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,
const unsigned char *kmac_custom,
size_t kmac_custom_len, size_t kmac_out_len,
const unsigned char *salt, size_t salt_len,
const unsigned char *z, size_t z_len,
const unsigned char *info, size_t info_len,
unsigned char *derived_key, size_t derived_key_len)
{
int ret = 0;
size_t counter, out_len, len;
unsigned char c[4];
unsigned char mac_buf[EVP_MAX_MD_SIZE];
unsigned char *out = derived_key;
EVP_MAC_CTX *ctx = NULL;
unsigned char *mac = mac_buf, *kmac_buffer = NULL;
if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
|| derived_key_len > SSKDF_MAX_INLEN
|| derived_key_len == 0)
return 0;
if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
derived_key_len, &kmac_buffer))
goto end;
if (kmac_buffer != NULL)
mac = kmac_buffer;
if (!EVP_MAC_init(ctx_init, salt, salt_len, NULL))
goto end;
out_len = EVP_MAC_CTX_get_mac_size(ctx_init); /* output size */
if (out_len <= 0 || (mac == mac_buf && out_len > sizeof(mac_buf)))
goto end;
len = derived_key_len;
for (counter = 1;; counter++) {
c[0] = (unsigned char)((counter >> 24) & 0xff);
c[1] = (unsigned char)((counter >> 16) & 0xff);
c[2] = (unsigned char)((counter >> 8) & 0xff);
c[3] = (unsigned char)(counter & 0xff);
ctx = EVP_MAC_CTX_dup(ctx_init);
if (!(ctx != NULL
&& EVP_MAC_update(ctx, c, sizeof(c))
&& EVP_MAC_update(ctx, z, z_len)
&& EVP_MAC_update(ctx, info, info_len)))
goto end;
if (len >= out_len) {
if (!EVP_MAC_final(ctx, out, NULL, len))
goto end;
out += out_len;
len -= out_len;
if (len == 0)
break;
} else {
if (!EVP_MAC_final(ctx, mac, NULL, out_len))
goto end;
memcpy(out, mac, len);
break;
}
EVP_MAC_CTX_free(ctx);
ctx = NULL;
}
ret = 1;
end:
if (kmac_buffer != NULL)
OPENSSL_clear_free(kmac_buffer, kmac_out_len);
else
OPENSSL_cleanse(mac_buf, sizeof(mac_buf));
EVP_MAC_CTX_free(ctx);
return ret;
}
static void *sskdf_new(void *provctx)
{
KDF_SSKDF *ctx;
if (!ossl_prov_is_running())
return NULL;
if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
ctx->provctx = provctx;
return ctx;
}
static void sskdf_reset(void *vctx)
{
KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
void *provctx = ctx->provctx;
EVP_MAC_CTX_free(ctx->macctx);
ossl_prov_digest_reset(&ctx->digest);
OPENSSL_clear_free(ctx->secret, ctx->secret_len);
OPENSSL_clear_free(ctx->info, ctx->info_len);
OPENSSL_clear_free(ctx->salt, ctx->salt_len);
memset(ctx, 0, sizeof(*ctx));
ctx->provctx = provctx;
}
static void sskdf_free(void *vctx)
{
KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
if (ctx != NULL) {
sskdf_reset(ctx);
OPENSSL_free(ctx);
}
}
static void *sskdf_dup(void *vctx)
{
const KDF_SSKDF *src = (const KDF_SSKDF *)vctx;
KDF_SSKDF *dest;
dest = sskdf_new(src->provctx);
if (dest != NULL) {
if (src->macctx != NULL) {
dest->macctx = EVP_MAC_CTX_dup(src->macctx);
if (dest->macctx == NULL)
goto err;
}
if (!ossl_prov_memdup(src->info, src->info_len,
&dest->info, &dest->info_len)
|| !ossl_prov_memdup(src->salt, src->salt_len,
&dest->salt , &dest->salt_len)
|| !ossl_prov_memdup(src->secret, src->secret_len,
&dest->secret, &dest->secret_len)
|| !ossl_prov_digest_copy(&dest->digest, &src->digest))
goto err;
dest->out_len = src->out_len;
dest->is_kmac = src->is_kmac;
}
return dest;
err:
sskdf_free(dest);
return NULL;
}
static size_t sskdf_size(KDF_SSKDF *ctx)
{
int len;
const EVP_MD *md = NULL;
if (ctx->is_kmac)
return SIZE_MAX;
md = ossl_prov_digest_md(&ctx->digest);
if (md == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
return 0;
}
len = EVP_MD_get_size(md);
return (len <= 0) ? 0 : (size_t)len;
}
static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,
const OSSL_PARAM params[])
{
KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
const EVP_MD *md;
if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
return 0;
if (ctx->secret == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
return 0;
}
md = ossl_prov_digest_md(&ctx->digest);
if (ctx->macctx != NULL) {
/* H(x) = KMAC or H(x) = HMAC */
int ret;
const unsigned char *custom = NULL;
size_t custom_len = 0;
int default_salt_len;
EVP_MAC *mac = EVP_MAC_CTX_get0_mac(ctx->macctx);
if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {
/* H(x) = HMAC(x, salt, hash) */
if (md == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
return 0;
}
default_salt_len = EVP_MD_get_size(md);
if (default_salt_len <= 0)
return 0;
} else if (ctx->is_kmac) {
/* H(x) = KMACzzz(x, salt, custom) */
custom = kmac_custom_str;
custom_len = sizeof(kmac_custom_str);
if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))
default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
else
default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
} else {
ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
return 0;
}
/* If no salt is set then use a default_salt of zeros */
if (ctx->salt == NULL || ctx->salt_len <= 0) {
ctx->salt = OPENSSL_zalloc(default_salt_len);
if (ctx->salt == NULL)
return 0;
ctx->salt_len = default_salt_len;
}
ret = SSKDF_mac_kdm(ctx->macctx,
custom, custom_len, ctx->out_len,
ctx->salt, ctx->salt_len,
ctx->secret, ctx->secret_len,
ctx->info, ctx->info_len, key, keylen);
return ret;
} else {
/* H(x) = hash */
if (md == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
return 0;
}
return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
ctx->info, ctx->info_len, 0, key, keylen);
}
}
static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen,
const OSSL_PARAM params[])
{
KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
const EVP_MD *md;
if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
return 0;
if (ctx->secret == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
return 0;
}
if (ctx->macctx != NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
return 0;
}
/* H(x) = hash */
md = ossl_prov_digest_md(&ctx->digest);
if (md == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
return 0;
}
return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
ctx->info, ctx->info_len, 1, key, keylen);
}
static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
const OSSL_PARAM *p;
KDF_SSKDF *ctx = vctx;
OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
size_t sz;
int r;
if (params == NULL)
return 1;
if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
NULL, NULL, NULL, libctx))
return 0;
if (ctx->macctx != NULL) {
if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
OSSL_MAC_NAME_KMAC128)
|| EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
OSSL_MAC_NAME_KMAC256)) {
ctx->is_kmac = 1;
}
}
if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
return 0;
r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SECRET,
&ctx->secret, &ctx->secret_len);
if (r == -1)
r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_KEY,
&ctx->secret, &ctx->secret_len);
if (r == 0)
return 0;
if (ossl_param_get1_concat_octet_string(params, OSSL_KDF_PARAM_INFO,
&ctx->info, &ctx->info_len, 0) == 0)
return 0;
if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SALT,
&ctx->salt, &ctx->salt_len) == 0)
return 0;
if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
!= NULL) {
if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
return 0;
ctx->out_len = sz;
}
return 1;
}
static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *ctx,
ossl_unused void *provctx)
{
static const OSSL_PARAM known_settable_ctx_params[] = {
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),
OSSL_PARAM_END
};
return known_settable_ctx_params;
}
static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
OSSL_PARAM *p;
if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));
return -2;
}
static const OSSL_PARAM *sskdf_gettable_ctx_params(ossl_unused void *ctx,
ossl_unused void *provctx)
{
static const OSSL_PARAM known_gettable_ctx_params[] = {
OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
OSSL_PARAM_END
};
return known_gettable_ctx_params;
}
const OSSL_DISPATCH ossl_kdf_sskdf_functions[] = {
{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
{ OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
(void(*)(void))sskdf_settable_ctx_params },
{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
(void(*)(void))sskdf_gettable_ctx_params },
{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
OSSL_DISPATCH_END
};
const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {
{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
{ OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
(void(*)(void))sskdf_settable_ctx_params },
{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
(void(*)(void))sskdf_gettable_ctx_params },
{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
OSSL_DISPATCH_END
};
