kbkdf.c
/*
* Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2019 Red Hat, Inc.
*
* 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
*/
/*
* This implements https://csrc.nist.gov/publications/detail/sp/800-108/final
* section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC
* and CMAC. That document does not name the KDFs it defines; the name is
* derived from
* https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation
*
* Note that section 5.3 ("double-pipeline mode") is not implemented, though
* it would be possible to do so in the future.
*
* These versions all assume the counter is used. It would be relatively
* straightforward to expose a configuration handle should the need arise.
*
* Variable names attempt to match those of SP800-108.
*/
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/core_names.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/kdf.h>
#include <openssl/params.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "crypto/evp.h"
#include "internal/numbers.h"
#include "internal/endian.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/provider_util.h"
#include "prov/providercommon.h"
#include "internal/e_os.h"
#include "internal/params.h"
#define ossl_min(a, b) ((a) < (b)) ? (a) : (b)
typedef enum {
COUNTER = 0,
FEEDBACK
} kbkdf_mode;
/* Our context structure. */
typedef struct {
void *provctx;
kbkdf_mode mode;
EVP_MAC_CTX *ctx_init;
/* Names are lowercased versions of those found in SP800-108. */
int r;
unsigned char *ki;
size_t ki_len;
unsigned char *label;
size_t label_len;
unsigned char *context;
size_t context_len;
unsigned char *iv;
size_t iv_len;
int use_l;
int is_kmac;
int use_separator;
} KBKDF;
/* Definitions needed for typechecking. */
static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
static OSSL_FUNC_kdf_dupctx_fn kbkdf_dup;
static OSSL_FUNC_kdf_freectx_fn kbkdf_free;
static OSSL_FUNC_kdf_reset_fn kbkdf_reset;
static OSSL_FUNC_kdf_derive_fn kbkdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params;
/* Not all platforms have htobe32(). */
static uint32_t be32(uint32_t host)
{
uint32_t big = 0;
DECLARE_IS_ENDIAN;
if (!IS_LITTLE_ENDIAN)
return host;
big |= (host & 0xff000000) >> 24;
big |= (host & 0x00ff0000) >> 8;
big |= (host & 0x0000ff00) << 8;
big |= (host & 0x000000ff) << 24;
return big;
}
static void init(KBKDF *ctx)
{
ctx->r = 32;
ctx->use_l = 1;
ctx->use_separator = 1;
ctx->is_kmac = 0;
}
static void *kbkdf_new(void *provctx)
{
KBKDF *ctx;
if (!ossl_prov_is_running())
return NULL;
ctx = OPENSSL_zalloc(sizeof(*ctx));
if (ctx == NULL)
return NULL;
ctx->provctx = provctx;
init(ctx);
return ctx;
}
static void kbkdf_free(void *vctx)
{
KBKDF *ctx = (KBKDF *)vctx;
if (ctx != NULL) {
kbkdf_reset(ctx);
OPENSSL_free(ctx);
}
}
static void kbkdf_reset(void *vctx)
{
KBKDF *ctx = (KBKDF *)vctx;
void *provctx = ctx->provctx;
EVP_MAC_CTX_free(ctx->ctx_init);
OPENSSL_clear_free(ctx->context, ctx->context_len);
OPENSSL_clear_free(ctx->label, ctx->label_len);
OPENSSL_clear_free(ctx->ki, ctx->ki_len);
OPENSSL_clear_free(ctx->iv, ctx->iv_len);
memset(ctx, 0, sizeof(*ctx));
ctx->provctx = provctx;
init(ctx);
}
static void *kbkdf_dup(void *vctx)
{
const KBKDF *src = (const KBKDF *)vctx;
KBKDF *dest;
dest = kbkdf_new(src->provctx);
if (dest != NULL) {
dest->ctx_init = EVP_MAC_CTX_dup(src->ctx_init);
if (dest->ctx_init == NULL
|| !ossl_prov_memdup(src->ki, src->ki_len,
&dest->ki, &dest->ki_len)
|| !ossl_prov_memdup(src->label, src->label_len,
&dest->label, &dest->label_len)
|| !ossl_prov_memdup(src->context, src->context_len,
&dest->context, &dest->context_len)
|| !ossl_prov_memdup(src->iv, src->iv_len,
&dest->iv, &dest->iv_len))
goto err;
dest->mode = src->mode;
dest->r = src->r;
dest->use_l = src->use_l;
dest->use_separator = src->use_separator;
dest->is_kmac = src->is_kmac;
}
return dest;
err:
kbkdf_free(dest);
return NULL;
}
/* SP800-108 section 5.1 or section 5.2 depending on mode. */
static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,
size_t iv_len, unsigned char *label, size_t label_len,
unsigned char *context, size_t context_len,
unsigned char *k_i, size_t h, uint32_t l, int has_separator,
unsigned char *ko, size_t ko_len, int r)
{
int ret = 0;
EVP_MAC_CTX *ctx = NULL;
size_t written = 0, to_write, k_i_len = iv_len;
const unsigned char zero = 0;
uint32_t counter, i;
/*
* From SP800-108:
* The fixed input data is a concatenation of a Label,
* a separation indicator 0x00, the Context, and L.
* One or more of these fixed input data fields may be omitted.
*
* has_separator == 0 means that the separator is omitted.
* Passing a value of l == 0 means that L is omitted.
* The Context and L are omitted automatically if a NULL buffer is passed.
*/
int has_l = (l != 0);
/* Setup K(0) for feedback mode. */
if (iv_len > 0)
memcpy(k_i, iv, iv_len);
for (counter = 1; written < ko_len; counter++) {
i = be32(counter);
ctx = EVP_MAC_CTX_dup(ctx_init);
if (ctx == NULL)
goto done;
/* Perform feedback, if appropriate. */
if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))
goto done;
if (!EVP_MAC_update(ctx, 4 - (r / 8) + (unsigned char *)&i, r / 8)
|| !EVP_MAC_update(ctx, label, label_len)
|| (has_separator && !EVP_MAC_update(ctx, &zero, 1))
|| !EVP_MAC_update(ctx, context, context_len)
|| (has_l && !EVP_MAC_update(ctx, (unsigned char *)&l, 4))
|| !EVP_MAC_final(ctx, k_i, NULL, h))
goto done;
to_write = ko_len - written;
memcpy(ko + written, k_i, ossl_min(to_write, h));
written += h;
k_i_len = h;
EVP_MAC_CTX_free(ctx);
ctx = NULL;
}
ret = 1;
done:
EVP_MAC_CTX_free(ctx);
return ret;
}
/* This must be run before the key is set */
static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom, size_t customlen)
{
OSSL_PARAM params[2];
if (custom == NULL || customlen == 0)
return 1;
params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
(void *)custom, customlen);
params[1] = OSSL_PARAM_construct_end();
return EVP_MAC_CTX_set_params(ctx, params) > 0;
}
static int kmac_derive(EVP_MAC_CTX *ctx, unsigned char *out, size_t outlen,
const unsigned char *context, size_t contextlen)
{
OSSL_PARAM params[2];
params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE, &outlen);
params[1] = OSSL_PARAM_construct_end();
return EVP_MAC_CTX_set_params(ctx, params) > 0
&& EVP_MAC_update(ctx, context, contextlen)
&& EVP_MAC_final(ctx, out, NULL, outlen);
}
static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen,
const OSSL_PARAM params[])
{
KBKDF *ctx = (KBKDF *)vctx;
int ret = 0;
unsigned char *k_i = NULL;
uint32_t l = 0;
size_t h = 0;
uint64_t counter_max;
if (!ossl_prov_is_running() || !kbkdf_set_ctx_params(ctx, params))
return 0;
/* label, context, and iv are permitted to be empty. Check everything
* else. */
if (ctx->ctx_init == NULL) {
if (ctx->ki_len == 0 || ctx->ki == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
return 0;
}
/* Could either be missing MAC or missing message digest or missing
* cipher - arbitrarily, I pick this one. */
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);
return 0;
}
/* Fail if the output length is zero */
if (keylen == 0) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
return 0;
}
if (ctx->is_kmac) {
ret = kmac_derive(ctx->ctx_init, key, keylen,
ctx->context, ctx->context_len);
goto done;
}
h = EVP_MAC_CTX_get_mac_size(ctx->ctx_init);
if (h == 0)
goto done;
if (ctx->iv_len != 0 && ctx->iv_len != h) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);
goto done;
}
if (ctx->mode == COUNTER) {
/* Fail if keylen is too large for r */
counter_max = (uint64_t)1 << (uint64_t)ctx->r;
if ((uint64_t)(keylen / h) >= counter_max) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
goto done;
}
}
if (ctx->use_l != 0)
l = be32(keylen * 8);
k_i = OPENSSL_zalloc(h);
if (k_i == NULL)
goto done;
ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,
ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,
ctx->use_separator, key, keylen, ctx->r);
done:
if (ret != 1)
OPENSSL_cleanse(key, keylen);
OPENSSL_clear_free(k_i, h);
return ret;
}
static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
KBKDF *ctx = (KBKDF *)vctx;
OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
const OSSL_PARAM *p;
if (params == NULL)
return 1;
if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,
NULL, NULL, libctx))
return 0;
else if (ctx->ctx_init != NULL) {
if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
OSSL_MAC_NAME_KMAC128)
|| EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
OSSL_MAC_NAME_KMAC256)) {
ctx->is_kmac = 1;
} else if (!EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
OSSL_MAC_NAME_HMAC)
&& !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),
OSSL_MAC_NAME_CMAC)) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);
return 0;
}
}
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);
if (p != NULL
&& OPENSSL_strncasecmp("counter", p->data, p->data_size) == 0) {
ctx->mode = COUNTER;
} else if (p != NULL
&& OPENSSL_strncasecmp("feedback", p->data, p->data_size) == 0) {
ctx->mode = FEEDBACK;
} else if (p != NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
return 0;
}
if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_KEY,
&ctx->ki, &ctx->ki_len) == 0)
return 0;
if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SALT,
&ctx->label, &ctx->label_len) == 0)
return 0;
if (ossl_param_get1_concat_octet_string(params, OSSL_KDF_PARAM_INFO,
&ctx->context, &ctx->context_len,
0) == 0)
return 0;
if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SEED,
&ctx->iv, &ctx->iv_len) == 0)
return 0;
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L);
if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_l))
return 0;
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_R);
if (p != NULL) {
int new_r = 0;
if (!OSSL_PARAM_get_int(p, &new_r))
return 0;
if (new_r != 8 && new_r != 16 && new_r != 24 && new_r != 32)
return 0;
ctx->r = new_r;
}
p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR);
if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_separator))
return 0;
/* Set up digest context, if we can. */
if (ctx->ctx_init != NULL && ctx->ki_len != 0) {
if ((ctx->is_kmac && !kmac_init(ctx->ctx_init, ctx->label, ctx->label_len))
|| !EVP_MAC_init(ctx->ctx_init, ctx->ki, ctx->ki_len, NULL))
return 0;
}
return 1;
}
static const OSSL_PARAM *kbkdf_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_INFO, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL),
OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, NULL),
OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_R, NULL),
OSSL_PARAM_END,
};
return known_settable_ctx_params;
}
static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
OSSL_PARAM *p;
p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);
if (p == NULL)
return -2;
/* KBKDF can produce results as large as you like. */
return OSSL_PARAM_set_size_t(p, SIZE_MAX);
}
static const OSSL_PARAM *kbkdf_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_kbkdf_functions[] = {
{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },
{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kbkdf_dup },
{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },
{ OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },
{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },
{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
(void(*)(void))kbkdf_settable_ctx_params },
{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },
{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
(void(*)(void))kbkdf_gettable_ctx_params },
{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },
OSSL_DISPATCH_END,
};
