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28bdbe1aaa
Optimize the the AES-based implementation of the CTR_DRBG construction, see 10.2.1 in [1]. Due to the optimizations, the code may deviate (more) from the pseudocode in [1], but it is functional equivalence being decisive for compliance: "All DRBG mechanisms and algorithms are described in this document in pseudocode, which is intended to explain functionality. The pseudocode is not intended to constrain real-world implementations." [9 in [1]]. The following optimizations are done: - Replace multiple plain AES encryptions by a single AES-ECB encryption of a corresponding pre-initialized buffer, where possible. This allows platform-specific AES-ECB support to be used and reduces the overhead of multiple EVP calls. - Replace the generate operation loop (which is a counter increment followed by a plain AES encryption) by a loop which does a plain AES encryption followed by a counter increment. The latter loop is just a description of AES-CTR, so we replace it by a single AES-CTR encryption. This allows for platform-specific AES-CTR support to be used and reduces the overhead of multiple EVP calls. This change, that is, going from a pre- to a post- counter increment, requires the counter in the internal state to be kept at "+1" (compared to the pseudocode in [1]) such that it is in the correct state, when a generate operation is called. That in turn also requires all other operations to be changed from pre- to post-increment to keep functional equivalence. [1] NIST SP 800-90A Revision 1 Signed-off-by: Patrick Steuer <patrick.steuer@de.ibm.com> Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org> (Merged from https://github.com/openssl/openssl/pull/10457)
506 lines
14 KiB
C
506 lines
14 KiB
C
/*
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* Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <openssl/crypto.h>
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#include <openssl/err.h>
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#include <openssl/rand.h>
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#include "crypto/modes.h"
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#include "internal/thread_once.h"
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#include "rand_local.h"
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/*
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* Implementation of NIST SP 800-90A CTR DRBG.
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*/
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static void inc_128(RAND_DRBG_CTR *ctr)
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{
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int i;
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unsigned char c;
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unsigned char *p = &ctr->V[15];
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for (i = 0; i < 16; i++, p--) {
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c = *p;
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c++;
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*p = c;
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if (c != 0) {
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/* If we didn't wrap around, we're done. */
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break;
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}
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}
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}
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static void ctr_XOR(RAND_DRBG_CTR *ctr, const unsigned char *in, size_t inlen)
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{
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size_t i, n;
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if (in == NULL || inlen == 0)
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return;
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/*
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* Any zero padding will have no effect on the result as we
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* are XORing. So just process however much input we have.
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*/
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n = inlen < ctr->keylen ? inlen : ctr->keylen;
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for (i = 0; i < n; i++)
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ctr->K[i] ^= in[i];
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if (inlen <= ctr->keylen)
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return;
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n = inlen - ctr->keylen;
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if (n > 16) {
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/* Should never happen */
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n = 16;
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}
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for (i = 0; i < n; i++)
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ctr->V[i] ^= in[i + ctr->keylen];
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}
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/*
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* Process a complete block using BCC algorithm of SP 800-90A 10.3.3
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*/
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__owur static int ctr_BCC_block(RAND_DRBG_CTR *ctr, unsigned char *out,
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const unsigned char *in, int len)
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{
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int i, outlen = AES_BLOCK_SIZE;
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for (i = 0; i < len; i++)
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out[i] ^= in[i];
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if (!EVP_CipherUpdate(ctr->ctx_df, out, &outlen, out, len)
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|| outlen != len)
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return 0;
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return 1;
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}
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/*
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* Handle several BCC operations for as much data as we need for K and X
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*/
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__owur static int ctr_BCC_blocks(RAND_DRBG_CTR *ctr, const unsigned char *in)
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{
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unsigned char in_tmp[48];
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unsigned char num_of_blk = 2;
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memcpy(in_tmp, in, 16);
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memcpy(in_tmp + 16, in, 16);
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if (ctr->keylen != 16) {
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memcpy(in_tmp + 32, in, 16);
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num_of_blk = 3;
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}
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return ctr_BCC_block(ctr, ctr->KX, in_tmp, AES_BLOCK_SIZE * num_of_blk);
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}
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/*
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* Initialise BCC blocks: these have the value 0,1,2 in leftmost positions:
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* see 10.3.1 stage 7.
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*/
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__owur static int ctr_BCC_init(RAND_DRBG_CTR *ctr)
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{
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unsigned char bltmp[48] = {0};
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unsigned char num_of_blk;
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memset(ctr->KX, 0, 48);
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num_of_blk = ctr->keylen == 16 ? 2 : 3;
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bltmp[(AES_BLOCK_SIZE * 1) + 3] = 1;
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bltmp[(AES_BLOCK_SIZE * 2) + 3] = 2;
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return ctr_BCC_block(ctr, ctr->KX, bltmp, num_of_blk * AES_BLOCK_SIZE);
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}
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/*
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* Process several blocks into BCC algorithm, some possibly partial
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*/
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__owur static int ctr_BCC_update(RAND_DRBG_CTR *ctr,
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const unsigned char *in, size_t inlen)
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{
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if (in == NULL || inlen == 0)
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return 1;
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/* If we have partial block handle it first */
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if (ctr->bltmp_pos) {
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size_t left = 16 - ctr->bltmp_pos;
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/* If we now have a complete block process it */
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if (inlen >= left) {
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memcpy(ctr->bltmp + ctr->bltmp_pos, in, left);
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if (!ctr_BCC_blocks(ctr, ctr->bltmp))
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return 0;
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ctr->bltmp_pos = 0;
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inlen -= left;
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in += left;
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}
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}
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/* Process zero or more complete blocks */
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for (; inlen >= 16; in += 16, inlen -= 16) {
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if (!ctr_BCC_blocks(ctr, in))
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return 0;
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}
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/* Copy any remaining partial block to the temporary buffer */
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if (inlen > 0) {
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memcpy(ctr->bltmp + ctr->bltmp_pos, in, inlen);
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ctr->bltmp_pos += inlen;
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}
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return 1;
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}
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__owur static int ctr_BCC_final(RAND_DRBG_CTR *ctr)
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{
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if (ctr->bltmp_pos) {
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memset(ctr->bltmp + ctr->bltmp_pos, 0, 16 - ctr->bltmp_pos);
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if (!ctr_BCC_blocks(ctr, ctr->bltmp))
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return 0;
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}
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return 1;
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}
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__owur static int ctr_df(RAND_DRBG_CTR *ctr,
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const unsigned char *in1, size_t in1len,
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const unsigned char *in2, size_t in2len,
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const unsigned char *in3, size_t in3len)
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{
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static unsigned char c80 = 0x80;
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size_t inlen;
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unsigned char *p = ctr->bltmp;
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int outlen = AES_BLOCK_SIZE;
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if (!ctr_BCC_init(ctr))
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return 0;
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if (in1 == NULL)
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in1len = 0;
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if (in2 == NULL)
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in2len = 0;
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if (in3 == NULL)
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in3len = 0;
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inlen = in1len + in2len + in3len;
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/* Initialise L||N in temporary block */
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*p++ = (inlen >> 24) & 0xff;
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*p++ = (inlen >> 16) & 0xff;
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*p++ = (inlen >> 8) & 0xff;
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*p++ = inlen & 0xff;
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/* NB keylen is at most 32 bytes */
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*p++ = 0;
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*p++ = 0;
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*p++ = 0;
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*p = (unsigned char)((ctr->keylen + 16) & 0xff);
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ctr->bltmp_pos = 8;
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if (!ctr_BCC_update(ctr, in1, in1len)
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|| !ctr_BCC_update(ctr, in2, in2len)
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|| !ctr_BCC_update(ctr, in3, in3len)
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|| !ctr_BCC_update(ctr, &c80, 1)
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|| !ctr_BCC_final(ctr))
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return 0;
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/* Set up key K */
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if (!EVP_CipherInit_ex(ctr->ctx_ecb, NULL, NULL, ctr->KX, NULL, -1))
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return 0;
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/* X follows key K */
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if (!EVP_CipherUpdate(ctr->ctx_ecb, ctr->KX, &outlen, ctr->KX + ctr->keylen,
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AES_BLOCK_SIZE)
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|| outlen != AES_BLOCK_SIZE)
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return 0;
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if (!EVP_CipherUpdate(ctr->ctx_ecb, ctr->KX + 16, &outlen, ctr->KX,
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AES_BLOCK_SIZE)
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|| outlen != AES_BLOCK_SIZE)
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return 0;
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if (ctr->keylen != 16)
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if (!EVP_CipherUpdate(ctr->ctx_ecb, ctr->KX + 32, &outlen,
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ctr->KX + 16, AES_BLOCK_SIZE)
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|| outlen != AES_BLOCK_SIZE)
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return 0;
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return 1;
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}
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/*
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* NB the no-df Update in SP800-90A specifies a constant input length
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* of seedlen, however other uses of this algorithm pad the input with
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* zeroes if necessary and have up to two parameters XORed together,
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* so we handle both cases in this function instead.
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*/
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__owur static int ctr_update(RAND_DRBG *drbg,
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const unsigned char *in1, size_t in1len,
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const unsigned char *in2, size_t in2len,
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const unsigned char *nonce, size_t noncelen)
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{
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RAND_DRBG_CTR *ctr = &drbg->data.ctr;
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int outlen = AES_BLOCK_SIZE;
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unsigned char V_tmp[48], out[48];
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unsigned char len;
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/* correct key is already set up. */
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memcpy(V_tmp, ctr->V, 16);
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inc_128(ctr);
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memcpy(V_tmp + 16, ctr->V, 16);
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if (ctr->keylen == 16) {
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len = 32;
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} else {
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inc_128(ctr);
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memcpy(V_tmp + 32, ctr->V, 16);
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len = 48;
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}
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if (!EVP_CipherUpdate(ctr->ctx_ecb, out, &outlen, V_tmp, len)
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|| outlen != len)
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return 0;
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memcpy(ctr->K, out, ctr->keylen);
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memcpy(ctr->V, out + ctr->keylen, 16);
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if ((drbg->flags & RAND_DRBG_FLAG_CTR_NO_DF) == 0) {
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/* If no input reuse existing derived value */
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if (in1 != NULL || nonce != NULL || in2 != NULL)
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if (!ctr_df(ctr, in1, in1len, nonce, noncelen, in2, in2len))
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return 0;
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/* If this a reuse input in1len != 0 */
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if (in1len)
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ctr_XOR(ctr, ctr->KX, drbg->seedlen);
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} else {
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ctr_XOR(ctr, in1, in1len);
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ctr_XOR(ctr, in2, in2len);
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}
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if (!EVP_CipherInit_ex(ctr->ctx_ecb, NULL, NULL, ctr->K, NULL, -1)
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|| !EVP_CipherInit_ex(ctr->ctx_ctr, NULL, NULL, ctr->K, NULL, -1))
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return 0;
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return 1;
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}
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__owur static int drbg_ctr_instantiate(RAND_DRBG *drbg,
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const unsigned char *entropy, size_t entropylen,
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const unsigned char *nonce, size_t noncelen,
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const unsigned char *pers, size_t perslen)
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{
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RAND_DRBG_CTR *ctr = &drbg->data.ctr;
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if (entropy == NULL)
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return 0;
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memset(ctr->K, 0, sizeof(ctr->K));
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memset(ctr->V, 0, sizeof(ctr->V));
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if (!EVP_CipherInit_ex(ctr->ctx_ecb, NULL, NULL, ctr->K, NULL, -1))
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return 0;
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inc_128(ctr);
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if (!ctr_update(drbg, entropy, entropylen, pers, perslen, nonce, noncelen))
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return 0;
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return 1;
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}
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__owur static int drbg_ctr_reseed(RAND_DRBG *drbg,
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const unsigned char *entropy, size_t entropylen,
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const unsigned char *adin, size_t adinlen)
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{
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RAND_DRBG_CTR *ctr = &drbg->data.ctr;
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if (entropy == NULL)
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return 0;
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inc_128(ctr);
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if (!ctr_update(drbg, entropy, entropylen, adin, adinlen, NULL, 0))
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return 0;
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return 1;
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}
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static void ctr96_inc(unsigned char *counter)
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{
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u32 n = 12, c = 1;
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do {
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--n;
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c += counter[n];
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counter[n] = (u8)c;
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c >>= 8;
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} while (n);
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}
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__owur static int drbg_ctr_generate(RAND_DRBG *drbg,
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unsigned char *out, size_t outlen,
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const unsigned char *adin, size_t adinlen)
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{
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RAND_DRBG_CTR *ctr = &drbg->data.ctr;
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unsigned int ctr32, blocks;
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int outl, buflen;
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if (adin != NULL && adinlen != 0) {
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inc_128(ctr);
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if (!ctr_update(drbg, adin, adinlen, NULL, 0, NULL, 0))
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return 0;
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/* This means we reuse derived value */
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if ((drbg->flags & RAND_DRBG_FLAG_CTR_NO_DF) == 0) {
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adin = NULL;
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adinlen = 1;
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}
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} else {
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adinlen = 0;
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}
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inc_128(ctr);
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if (outlen == 0) {
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inc_128(ctr);
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if (!ctr_update(drbg, adin, adinlen, NULL, 0, NULL, 0))
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return 0;
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return 1;
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}
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memset(out, 0, outlen);
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do {
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if (!EVP_CipherInit_ex(ctr->ctx_ctr,
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NULL, NULL, NULL, ctr->V, -1))
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return 0;
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/*-
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* outlen has type size_t while EVP_CipherUpdate takes an
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* int argument and thus cannot be guaranteed to process more
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* than 2^31-1 bytes at a time. We process such huge generate
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* requests in 2^30 byte chunks, which is the greatest multiple
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* of AES block size lower than or equal to 2^31-1.
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*/
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buflen = outlen > (1U << 30) ? (1U << 30) : outlen;
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blocks = (buflen + 15) / 16;
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ctr32 = GETU32(ctr->V + 12) + blocks;
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if (ctr32 < blocks) {
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/* 32-bit counter overflow into V. */
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blocks -= ctr32;
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buflen = blocks * 16;
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ctr32 = 0;
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ctr96_inc(ctr->V);
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}
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PUTU32(ctr->V + 12, ctr32);
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if (!EVP_CipherUpdate(ctr->ctx_ctr, out, &outl, out, buflen)
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|| outl != buflen)
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return 0;
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out += buflen;
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outlen -= buflen;
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} while (outlen);
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if (!ctr_update(drbg, adin, adinlen, NULL, 0, NULL, 0))
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return 0;
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return 1;
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}
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static int drbg_ctr_uninstantiate(RAND_DRBG *drbg)
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{
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EVP_CIPHER_CTX_free(drbg->data.ctr.ctx_ecb);
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EVP_CIPHER_CTX_free(drbg->data.ctr.ctx_ctr);
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EVP_CIPHER_CTX_free(drbg->data.ctr.ctx_df);
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EVP_CIPHER_free(drbg->data.ctr.cipher_ecb);
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EVP_CIPHER_free(drbg->data.ctr.cipher_ctr);
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OPENSSL_cleanse(&drbg->data.ctr, sizeof(drbg->data.ctr));
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return 1;
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}
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static RAND_DRBG_METHOD drbg_ctr_meth = {
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drbg_ctr_instantiate,
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drbg_ctr_reseed,
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drbg_ctr_generate,
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drbg_ctr_uninstantiate
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};
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int drbg_ctr_init(RAND_DRBG *drbg)
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{
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RAND_DRBG_CTR *ctr = &drbg->data.ctr;
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size_t keylen;
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EVP_CIPHER *cipher_ecb = NULL;
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EVP_CIPHER *cipher_ctr = NULL;
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switch (drbg->type) {
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default:
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/* This can't happen, but silence the compiler warning. */
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return 0;
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case NID_aes_128_ctr:
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keylen = 16;
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cipher_ecb = EVP_CIPHER_fetch(drbg->libctx, "AES-128-ECB", "");
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cipher_ctr = EVP_CIPHER_fetch(drbg->libctx, "AES-128-CTR", "");
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break;
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case NID_aes_192_ctr:
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keylen = 24;
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cipher_ecb = EVP_CIPHER_fetch(drbg->libctx, "AES-192-ECB", "");
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cipher_ctr = EVP_CIPHER_fetch(drbg->libctx, "AES-192-CTR", "");
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break;
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case NID_aes_256_ctr:
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keylen = 32;
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cipher_ecb = EVP_CIPHER_fetch(drbg->libctx, "AES-256-ECB", "");
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cipher_ctr = EVP_CIPHER_fetch(drbg->libctx, "AES-256-CTR", "");
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break;
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}
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if (cipher_ecb == NULL || cipher_ctr == NULL)
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return 0;
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EVP_CIPHER_free(ctr->cipher_ecb);
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ctr->cipher_ecb = cipher_ecb;
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EVP_CIPHER_free(ctr->cipher_ctr);
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ctr->cipher_ctr = cipher_ctr;
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ctr->keylen = keylen;
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if (ctr->ctx_ecb == NULL)
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ctr->ctx_ecb = EVP_CIPHER_CTX_new();
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if (ctr->ctx_ctr == NULL)
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ctr->ctx_ctr = EVP_CIPHER_CTX_new();
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if (ctr->ctx_ecb == NULL || ctr->ctx_ctr == NULL
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|| !EVP_CipherInit_ex(ctr->ctx_ecb,
|
|
ctr->cipher_ecb, NULL, NULL, NULL, 1)
|
|
|| !EVP_CipherInit_ex(ctr->ctx_ctr,
|
|
ctr->cipher_ctr, NULL, NULL, NULL, 1))
|
|
return 0;
|
|
|
|
drbg->meth = &drbg_ctr_meth;
|
|
drbg->strength = keylen * 8;
|
|
drbg->seedlen = keylen + 16;
|
|
|
|
if ((drbg->flags & RAND_DRBG_FLAG_CTR_NO_DF) == 0) {
|
|
/* df initialisation */
|
|
static const unsigned char df_key[32] = {
|
|
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
|
|
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
|
|
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
|
|
0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
|
|
};
|
|
|
|
if (ctr->ctx_df == NULL)
|
|
ctr->ctx_df = EVP_CIPHER_CTX_new();
|
|
if (ctr->ctx_df == NULL)
|
|
return 0;
|
|
/* Set key schedule for df_key */
|
|
if (!EVP_CipherInit_ex(ctr->ctx_df,
|
|
ctr->cipher_ecb, NULL, df_key, NULL, 1))
|
|
return 0;
|
|
|
|
drbg->min_entropylen = ctr->keylen;
|
|
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;
|
|
} else {
|
|
#ifdef FIPS_MODE
|
|
RANDerr(RAND_F_DRBG_CTR_INIT,
|
|
RAND_R_DERIVATION_FUNCTION_MANDATORY_FOR_FIPS);
|
|
return 0;
|
|
#else
|
|
drbg->min_entropylen = drbg->seedlen;
|
|
drbg->max_entropylen = drbg->seedlen;
|
|
/* Nonce not used */
|
|
drbg->min_noncelen = 0;
|
|
drbg->max_noncelen = 0;
|
|
drbg->max_perslen = drbg->seedlen;
|
|
drbg->max_adinlen = drbg->seedlen;
|
|
#endif
|
|
}
|
|
|
|
drbg->max_request = 1 << 16;
|
|
|
|
return 1;
|
|
}
|