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/*
* Copyright 2019-2020 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 "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 "prov/providercommonerr.h"
#include "e_os.h"
#define 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. */
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 use_separator;
} KBKDF;
/* Definitions needed for typechecking. */
static OSSL_FUNC_kdf_newctx_fn kbkdf_new;
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->use_l = 1;
ctx->use_separator = 1;
}
static void *kbkdf_new(void *provctx)
{
KBKDF *ctx;
if (!ossl_prov_is_running())
return NULL;
ctx = OPENSSL_zalloc(sizeof(*ctx));
if (ctx == NULL) {
ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
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);
}
/* 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 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, (unsigned char *)&i, 4)
|| !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, 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;
}
static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen)
{
KBKDF *ctx = (KBKDF *)vctx;
int ret = 0;
unsigned char *k_i = NULL;
uint32_t l = 0;
size_t h = 0;
if (!ossl_prov_is_running())
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;
}
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->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
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