diff options
Diffstat (limited to 'crypto/rand/drbg_hash.c')
| -rw-r--r-- | crypto/rand/drbg_hash.c | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/crypto/rand/drbg_hash.c b/crypto/rand/drbg_hash.c new file mode 100644 index 0000000000..9caf5b27be --- /dev/null +++ b/crypto/rand/drbg_hash.c @@ -0,0 +1,347 @@ +/* + * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the OpenSSL license (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 <assert.h> +#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" + +/* 440 bits from SP800-90Ar1 10.1 table 2 */ +#define HASH_PRNG_SMALL_SEEDLEN (440/8) +/* Determine what seedlen to use based on the block length */ +#define MAX_BLOCKLEN_USING_SMALL_SEEDLEN (256/8) +#define INBYTE_IGNORE ((unsigned char)0xFF) + + +/* + * SP800-90Ar1 10.3.1 Derivation function using a Hash Function (Hash_df). + * The input string used is composed of: + * inbyte - An optional leading byte (ignore if equal to INBYTE_IGNORE) + * in - input string 1 (A Non NULL value). + * in2 - optional input string (Can be NULL). + * in3 - optional input string (Can be NULL). + * These are concatenated as part of the DigestUpdate process. + */ +static int hash_df(RAND_DRBG *drbg, unsigned char *out, + const unsigned char inbyte, + const unsigned char *in, size_t inlen, + const unsigned char *in2, size_t in2len, + const unsigned char *in3, size_t in3len) +{ + RAND_DRBG_HASH *hash = &drbg->data.hash; + EVP_MD_CTX *ctx = hash->ctx; + unsigned char *vtmp = hash->vtmp; + /* tmp = counter || num_bits_returned || [inbyte] */ + unsigned char tmp[1 + 4 + 1]; + int tmp_sz = 0; + size_t outlen = drbg->seedlen; + size_t num_bits_returned = outlen * 8; + /* + * No need to check outlen size here, as the standard only ever needs + * seedlen bytes which is always less than the maximum permitted. + */ + + /* (Step 3) counter = 1 (tmp[0] is the 8 bit counter) */ + tmp[tmp_sz++] = 1; + /* tmp[1..4] is the fixed 32 bit no_of_bits_to_return */ + tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 24) & 0xff); + tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 16) & 0xff); + tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 8) & 0xff); + tmp[tmp_sz++] = (unsigned char)(num_bits_returned & 0xff); + /* Tack the additional input byte onto the end of tmp if it exists */ + if (inbyte != INBYTE_IGNORE) + tmp[tmp_sz++] = inbyte; + + /* (Step 4) */ + for (;;) { + /* + * (Step 4.1) out = out || Hash(tmp || in || [in2] || [in3]) + * (where tmp = counter || num_bits_returned || [inbyte]) + */ + if (!(EVP_DigestInit_ex(ctx, hash->md, NULL) + && EVP_DigestUpdate(ctx, tmp, tmp_sz) + && EVP_DigestUpdate(ctx, in, inlen) + && (in2 == NULL || EVP_DigestUpdate(ctx, in2, in2len)) + && (in3 == NULL || EVP_DigestUpdate(ctx, in3, in3len)))) + return 0; + + if (outlen < hash->blocklen) { + if (!EVP_DigestFinal(ctx, vtmp, NULL)) + return 0; + memcpy(out, vtmp, outlen); + OPENSSL_cleanse(vtmp, hash->blocklen); + break; + } else if(!EVP_DigestFinal(ctx, out, NULL)) { + return 0; + } + + outlen -= hash->blocklen; + if (outlen == 0) + break; + /* (Step 4.2) counter++ */ + tmp[0]++; + out += hash->blocklen; + } + return 1; +} + +/* Helper function that just passes 2 input parameters to hash_df() */ +static int hash_df1(RAND_DRBG *drbg, unsigned char *out, + const unsigned char in_byte, + const unsigned char *in1, size_t in1len) +{ + return hash_df(drbg, out, in_byte, in1, in1len, NULL, 0, NULL, 0); +} + +/* + * Add 2 byte buffers together. The first elements in each buffer are the top + * most bytes. The result is stored in the dst buffer. + * The final carry is ignored i.e: dst = (dst + in) mod (2^seedlen_bits). + * where dst size is drbg->seedlen, and inlen <= drbg->seedlen. + */ +static int add_bytes(RAND_DRBG *drbg, unsigned char *dst, + unsigned char *in, size_t inlen) +{ + size_t i; + int result; + const unsigned char *add; + unsigned char carry = 0, *d; + + assert(drbg->seedlen >= 1 && inlen >= 1 && inlen <= drbg->seedlen); + + d = &dst[drbg->seedlen - 1]; + add = &in[inlen - 1]; + + for (i = inlen; i > 0; i--, d--, add--) { + result = *d + *add + carry; + carry = (unsigned char)(result >> 8); + *d = (unsigned char)(result & 0xff); + } + + if (carry != 0) { + /* Add the carry to the top of the dst if inlen is not the same size */ + for (i = drbg->seedlen - inlen; i > 0; --i, d--) { + *d += 1; /* Carry can only be 1 */ + if (*d != 0) /* exit if carry doesnt propagate to the next byte */ + break; + } + } + return 1; +} + +/* V = (V + Hash(inbyte || V || [additional_input]) mod (2^seedlen) */ +static int add_hash_to_v(RAND_DRBG *drbg, unsigned char inbyte, + const unsigned char *adin, size_t adinlen) +{ + RAND_DRBG_HASH *hash = &drbg->data.hash; + EVP_MD_CTX *ctx = hash->ctx; + + return EVP_DigestInit_ex(ctx, hash->md, NULL) + && EVP_DigestUpdate(ctx, &inbyte, 1) + && EVP_DigestUpdate(ctx, hash->V, drbg->seedlen) + && (adin == NULL || EVP_DigestUpdate(ctx, adin, adinlen)) + && EVP_DigestFinal(ctx, hash->vtmp, NULL) + && add_bytes(drbg, hash->V, hash->vtmp, hash->blocklen); +} + +/* + * The Hashgen() as listed in SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process. + * + * drbg contains the current value of V. + * outlen is the requested number of bytes. + * out is a buffer to return the generated bits. + * + * The algorithm to generate the bits is: + * data = V + * w = NULL + * for (i = 1 to m) { + * W = W || Hash(data) + * data = (data + 1) mod (2^seedlen) + * } + * out = Leftmost(W, outlen) + * + * Returns zero if an error occurs otherwise it returns 1. + */ +static int hash_gen(RAND_DRBG *drbg, unsigned char *out, size_t outlen) +{ + RAND_DRBG_HASH *hash = &drbg->data.hash; + unsigned char one = 1; + + if (outlen == 0) + return 1; + memcpy(hash->vtmp, hash->V, drbg->seedlen); + for(;;) { + if (!EVP_DigestInit_ex(hash->ctx, hash->md, NULL) + || !EVP_DigestUpdate(hash->ctx, hash->vtmp, drbg->seedlen)) + return 0; + + if (outlen < hash->blocklen) { + if (!EVP_DigestFinal(hash->ctx, hash->vtmp, NULL)) + return 0; + memcpy(out, hash->vtmp, outlen); + return 1; + } else { + if (!EVP_DigestFinal(hash->ctx, out, NULL)) + return 0; + outlen -= hash->blocklen; + if (outlen == 0) + break; + out += hash->blocklen; + } + add_bytes(drbg, hash->vtmp, &one, 1); + } + return 1; +} + +/* + * SP800-90Ar1 10.1.1.2 Hash_DRBG_Instantiate_Process: + * + * ent is entropy input obtained from a randomness source of length ent_len. + * nonce is a string of bytes of length nonce_len. + * pstr is a personalization string received from an application. May be NULL. + * + * Returns zero if an error occurs otherwise it returns 1. + */ +static int drbg_hash_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_HASH *hash = &drbg->data.hash; + + /* (Step 1-3) V = Hash_df(entropy||nonce||pers, seedlen) */ + return hash_df(drbg, hash->V, INBYTE_IGNORE, + ent, ent_len, nonce, nonce_len, pstr, pstr_len) + /* (Step 4) C = Hash_df(0x00||V, seedlen) */ + && hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen); +} + +/* + * SP800-90Ar1 10.1.1.3 Hash_DRBG_Reseed_Process: + * + * ent is entropy input bytes obtained from a randomness source. + * addin is additional input received from an application. May be NULL. + * + * Returns zero if an error occurs otherwise it returns 1. + */ +static int drbg_hash_reseed(RAND_DRBG *drbg, + const unsigned char *ent, size_t ent_len, + const unsigned char *adin, size_t adin_len) +{ + RAND_DRBG_HASH *hash = &drbg->data.hash; + + /* (Step 1-2) V = Hash_df(0x01 || V || entropy_input || additional_input)*/ + /* V about to be updated so use C as output instead */ + if (!hash_df(drbg, hash->C, 0x01, hash->V, drbg->seedlen, ent, ent_len, + adin, adin_len)) + return 0; + memcpy(hash->V, hash->C, drbg->seedlen); + /* (Step 4) C = Hash_df(0x00||V, seedlen) */ + return hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen); +} + +/* + * SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process: + * + * Generates pseudo random bytes using the drbg. + * out is a buffer to fill with outlen bytes of pseudo random data. + * addin is additional input received from an application. May be NULL. + * + * Returns zero if an error occurs otherwise it returns 1. + */ +static int drbg_hash_generate(RAND_DRBG *drbg, + unsigned char *out, size_t outlen, + const unsigned char *adin, size_t adin_len) +{ + RAND_DRBG_HASH *hash = &drbg->data.hash; + unsigned char counter[4]; + int reseed_counter = drbg->reseed_gen_counter; + + counter[0] = (unsigned char)((reseed_counter >> 24) & 0xff); + counter[1] = (unsigned char)((reseed_counter >> 16) & 0xff); + counter[2] = (unsigned char)((reseed_counter >> 8) & 0xff); + counter[3] = (unsigned char)(reseed_counter & 0xff); + + return (adin == NULL + /* (Step 2) if adin != NULL then V = V + Hash(0x02||V||adin) */ + || adin_len == 0 + || add_hash_to_v(drbg, 0x02, adin, adin_len)) + /* (Step 3) Hashgen(outlen, V) */ + && hash_gen(drbg, out, outlen) + /* (Step 4/5) H = V = (V + Hash(0x03||V) mod (2^seedlen_bits) */ + && add_hash_to_v(drbg, 0x03, NULL, 0) + /* (Step 5) V = (V + H + C + reseed_counter) mod (2^seedlen_bits) */ + /* V = (V + C) mod (2^seedlen_bits) */ + && add_bytes(drbg, hash->V, hash->C, drbg->seedlen) + /* V = (V + reseed_counter) mod (2^seedlen_bits) */ + && add_bytes(drbg, hash->V, counter, 4); +} + +static int drbg_hash_uninstantiate(RAND_DRBG *drbg) +{ + EVP_MD_CTX_free(drbg->data.hash.ctx); + OPENSSL_cleanse(&drbg->data.hash, sizeof(drbg->data.hash)); + return 1; +} + +static RAND_DRBG_METHOD drbg_hash_meth = { + drbg_hash_instantiate, + drbg_hash_reseed, + drbg_hash_generate, + drbg_hash_uninstantiate +}; + +int drbg_hash_init(RAND_DRBG *drbg) +{ + const EVP_MD *md; + RAND_DRBG_HASH *hash = &drbg->data.hash; + + /* Any approved digest is allowed */ + md = EVP_get_digestbynid(drbg->type); + if (md == NULL) + return 0; + + drbg->meth = &drbg_hash_meth; + hash->md = md; + + if (hash->ctx == NULL) { + hash->ctx = EVP_MD_CTX_new(); + if (hash->ctx == NULL) + return 0; + } + + /* These are taken from SP 800-90 10.1 Table 2 */ + hash->blocklen = EVP_MD_size(md); + /* See SP800-57 Part1 Rev4 5.6.1 Table 3 */ + drbg->strength = 64 * (hash->blocklen >> 3); + if (drbg->strength > 256) + drbg->strength = 256; + if (hash->blocklen > MAX_BLOCKLEN_USING_SMALL_SEEDLEN) + drbg->seedlen = HASH_PRNG_MAX_SEEDLEN; + else + drbg->seedlen = HASH_PRNG_SMALL_SEEDLEN; + + drbg->min_entropylen = drbg->strength / 8; + drbg->max_entropylen = DRBG_MINMAX_FACTOR * drbg->min_entropylen; + + drbg->min_noncelen = drbg->min_entropylen / 2; + drbg->max_noncelen = DRBG_MINMAX_FACTOR * drbg->min_noncelen; + + 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; +} |