/* * 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 #include #include #include #include #include #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_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; }