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openssl/crypto/rand/drbg_hmac.c

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/*
* Copyright 2011-2018 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
*/
#include <stdlib.h>
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "internal/thread_once.h"
#include "rand_lcl.h"
/*
* Called twice by SP800-90Ar1 10.1.2.2 HMAC_DRBG_Update_Process.
*
* hmac is an object that holds the input/output Key and Value (K and V).
* inbyte is 0x00 on the first call and 0x01 on the second call.
* in1, in2, in3 are optional inputs that can be NULL.
* in1len, in2len, in3len are the lengths of the input buffers.
*
* The returned K,V is:
* hmac->K = HMAC(hmac->K, hmac->V || inbyte || [in1] || [in2] || [in3])
* hmac->V = HMAC(hmac->K, hmac->V)
*
* Returns zero if an error occurs otherwise it returns 1.
*/
static int do_hmac(RAND_DRBG_HMAC *hmac, unsigned char inbyte,
const unsigned char *in1, size_t in1len,
const unsigned char *in2, size_t in2len,
const unsigned char *in3, size_t in3len)
{
HMAC_CTX *ctx = hmac->ctx;
return HMAC_Init_ex(ctx, hmac->K, hmac->blocklen, hmac->md, NULL)
/* K = HMAC(K, V || inbyte || [in1] || [in2] || [in3]) */
&& HMAC_Update(ctx, hmac->V, hmac->blocklen)
&& HMAC_Update(ctx, &inbyte, 1)
&& (in1 == NULL || in1len == 0 || HMAC_Update(ctx, in1, in1len))
&& (in2 == NULL || in2len == 0 || HMAC_Update(ctx, in2, in2len))
&& (in3 == NULL || in3len == 0 || HMAC_Update(ctx, in3, in3len))
&& HMAC_Final(ctx, hmac->K, NULL)
/* V = HMAC(K, V) */
&& HMAC_Init_ex(ctx, hmac->K, hmac->blocklen, hmac->md, NULL)
&& HMAC_Update(ctx, hmac->V, hmac->blocklen)
&& HMAC_Final(ctx, hmac->V, NULL);
}
/*
* SP800-90Ar1 10.1.2.2 HMAC_DRBG_Update_Process
*
*
* Updates the drbg objects Key(K) and Value(V) using the following algorithm:
* K,V = do_hmac(hmac, 0, in1, in2, in3)
* if (any input is not NULL)
* K,V = do_hmac(hmac, 1, in1, in2, in3)
*
* where in1, in2, in3 are optional input buffers that can be NULL.
* in1len, in2len, in3len are the lengths of the input buffers.
*
* Returns zero if an error occurs otherwise it returns 1.
*/
static int drbg_hmac_update(RAND_DRBG *drbg,
const unsigned char *in1, size_t in1len,
const unsigned char *in2, size_t in2len,
const unsigned char *in3, size_t in3len)
{
RAND_DRBG_HMAC *hmac = &drbg->data.hmac;
/* (Steps 1-2) K = HMAC(K, V||0x00||provided_data). V = HMAC(K,V) */
if (!do_hmac(hmac, 0x00, in1, in1len, in2, in2len, in3, in3len))
return 0;
/* (Step 3) If provided_data == NULL then return (K,V) */
if (in1len == 0 && in2len == 0 && in3len == 0)
return 1;
/* (Steps 4-5) K = HMAC(K, V||0x01||provided_data). V = HMAC(K,V) */
return do_hmac(hmac, 0x01, in1, in1len, in2, in2len, in3, in3len);
}
/*
* SP800-90Ar1 10.1.2.3 HMAC_DRBG_Instantiate_Process:
*
* This sets the drbg Key (K) to all zeros, and Value (V) to all 1's.
* and then calls (K,V) = drbg_hmac_update() with input parameters:
* ent = entropy data (Can be NULL) of length ent_len.
* nonce = nonce data (Can be NULL) of length nonce_len.
* pstr = personalization data (Can be NULL) of length pstr_len.
*
* Returns zero if an error occurs otherwise it returns 1.
*/
static int drbg_hmac_instantiate(RAND_DRBG *drbg,
const unsigned char *ent, size_t ent_len,
const unsigned char *nonce, size_t nonce_len,
const unsigned char *pstr, size_t pstr_len)
{
RAND_DRBG_HMAC *hmac = &drbg->data.hmac;
/* (Step 2) Key = 0x00 00...00 */
memset(hmac->K, 0x00, hmac->blocklen);
/* (Step 3) V = 0x01 01...01 */
memset(hmac->V, 0x01, hmac->blocklen);
/* (Step 4) (K,V) = HMAC_DRBG_Update(entropy||nonce||pers string, K, V) */
return drbg_hmac_update(drbg, ent, ent_len, nonce, nonce_len, pstr,
pstr_len);
}
/*
* SP800-90Ar1 10.1.2.4 HMAC_DRBG_Reseed_Process:
*
* Reseeds the drbg's Key (K) and Value (V) by calling
* (K,V) = drbg_hmac_update() with the following input parameters:
* ent = entropy input data (Can be NULL) of length ent_len.
* adin = additional input data (Can be NULL) of length adin_len.
*
* Returns zero if an error occurs otherwise it returns 1.
*/
static int drbg_hmac_reseed(RAND_DRBG *drbg,
const unsigned char *ent, size_t ent_len,
const unsigned char *adin, size_t adin_len)
{
/* (Step 2) (K,V) = HMAC_DRBG_Update(entropy||additional_input, K, V) */
return drbg_hmac_update(drbg, ent, ent_len, adin, adin_len, NULL, 0);
}
/*
* SP800-90Ar1 10.1.2.5 HMAC_DRBG_Generate_Process:
*
* Generates pseudo random bytes and updates the internal K,V for the drbg.
* out is a buffer to fill with outlen bytes of pseudo random data.
* adin is an additional_input string of size adin_len that may be NULL.
*
* Returns zero if an error occurs otherwise it returns 1.
*/
static int drbg_hmac_generate(RAND_DRBG *drbg,
unsigned char *out, size_t outlen,
const unsigned char *adin, size_t adin_len)
{
RAND_DRBG_HMAC *hmac = &drbg->data.hmac;
HMAC_CTX *ctx = hmac->ctx;
const unsigned char *temp = hmac->V;
/* (Step 2) if adin != NULL then (K,V) = HMAC_DRBG_Update(adin, K, V) */
if (adin != NULL
&& adin_len > 0
&& !drbg_hmac_update(drbg, adin, adin_len, NULL, 0, NULL, 0))
return 0;
/*
* (Steps 3-5) temp = NULL
* while (len(temp) < outlen) {
* V = HMAC(K, V)
* temp = temp || V
* }
*/
for (;;) {
if (!HMAC_Init_ex(ctx, hmac->K, hmac->blocklen, hmac->md, NULL)
|| !HMAC_Update(ctx, temp, hmac->blocklen))
return 0;
if (outlen > hmac->blocklen) {
if (!HMAC_Final(ctx, out, NULL))
return 0;
temp = out;
} else {
if (!HMAC_Final(ctx, hmac->V, NULL))
return 0;
memcpy(out, hmac->V, outlen);
break;
}
out += hmac->blocklen;
outlen -= hmac->blocklen;
}
/* (Step 6) (K,V) = HMAC_DRBG_Update(adin, K, V) */
if (!drbg_hmac_update(drbg, adin, adin_len, NULL, 0, NULL, 0))
return 0;
return 1;
}
static int drbg_hmac_uninstantiate(RAND_DRBG *drbg)
{
HMAC_CTX_free(drbg->data.hmac.ctx);
OPENSSL_cleanse(&drbg->data.hmac, sizeof(drbg->data.hmac));
return 1;
}
static RAND_DRBG_METHOD drbg_hmac_meth = {
drbg_hmac_instantiate,
drbg_hmac_reseed,
drbg_hmac_generate,
drbg_hmac_uninstantiate
};
int drbg_hmac_init(RAND_DRBG *drbg)
{
const EVP_MD *md = NULL;
RAND_DRBG_HMAC *hmac = &drbg->data.hmac;
/* Any approved digest is allowed - assume we pass digest (not NID_hmac*) */
md = EVP_get_digestbynid(drbg->type);
if (md == NULL)
return 0;
drbg->meth = &drbg_hmac_meth;
if (hmac->ctx == NULL) {
hmac->ctx = HMAC_CTX_new();
if (hmac->ctx == NULL)
return 0;
}
/* These are taken from SP 800-90 10.1 Table 2 */
hmac->md = md;
hmac->blocklen = EVP_MD_size(md);
/* See SP800-57 Part1 Rev4 5.6.1 Table 3 */
drbg->strength = 64 * (int)(hmac->blocklen >> 3);
if (drbg->strength > 256)
drbg->strength = 256;
drbg->seedlen = hmac->blocklen;
drbg->min_entropylen = drbg->strength / 8;
drbg->max_entropylen = DRBG_MAX_LENGTH;
drbg->min_noncelen = drbg->min_entropylen / 2;
drbg->max_noncelen = DRBG_MAX_LENGTH;
drbg->max_perslen = DRBG_MAX_LENGTH;
drbg->max_adinlen = DRBG_MAX_LENGTH;
/* Maximum number of bits per request = 2^19 = 2^16 bytes*/
drbg->max_request = 1 << 16;
return 1;
}
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