Implemented bitspender based on the MGF1 mask generator function
This commit is contained in:
Andreas Steffen
parent
c3664d8ee1
commit
988d477145
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@ -11,7 +11,8 @@ crypto/prfs/prf.c crypto/prfs/mac_prf.c crypto/pkcs5.c \
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crypto/rngs/rng.c crypto/prf_plus.c crypto/signers/signer.c \
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crypto/signers/mac_signer.c crypto/crypto_factory.c crypto/crypto_tester.c \
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crypto/diffie_hellman.c crypto/aead.c crypto/transform.c \
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crypto/iv/iv_gen_rand.c crypto/iv/iv_gen_seq.c crypto/mgf1/mgf1.c \
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crypto/iv/iv_gen_rand.c crypto/iv/iv_gen_seq.c \
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crypto/mgf1/mgf1.c crypto/mgf1/mgf1_bitspender.c \
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credentials/credential_factory.c credentials/builder.c \
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credentials/cred_encoding.c credentials/keys/private_key.c \
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credentials/keys/public_key.c credentials/keys/shared_key.c \
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@ -66,7 +67,8 @@ crypto/prfs/prf.h crypto/prfs/mac_prf.h crypto/rngs/rng.h crypto/nonce_gen.h \
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crypto/prf_plus.h crypto/signers/signer.h crypto/signers/mac_signer.h \
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crypto/crypto_factory.h crypto/crypto_tester.h crypto/diffie_hellman.h \
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crypto/aead.h crypto/transform.h crypto/pkcs5.h crypto/iv/iv_gen.h \
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crypto/iv/iv_gen_rand.h crypto/iv/iv_gen_seq.h crypto/mgf1/mgf1.h \
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crypto/iv/iv_gen_rand.h crypto/iv/iv_gen_seq.h \
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crypto/mgf1/mgf1.h crypto/mgf1/mgf1_bitspender.h \
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credentials/credential_factory.h credentials/builder.h \
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credentials/cred_encoding.h credentials/keys/private_key.h \
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credentials/keys/public_key.h credentials/keys/shared_key.h \
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@ -68,7 +68,7 @@ struct mgf1_t {
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*
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* @param alg hash algorithm to be used by MGF1
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* @param seed seed used by MGF1 to generate mask from
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* @param hash_seed hash seed before using it as a seed from MGF1
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* @param hash_seed hash seed before using it as a seed for MGF1
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*/
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mgf1_t *mgf1_create(hash_algorithm_t alg, chunk_t seed,
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bool hash_seed);
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@ -0,0 +1,158 @@
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/*
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* Copyright (C) 2014 Andreas Steffen
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* HSR Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include "mgf1_bitspender.h"
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#include <crypto/mgf1/mgf1.h>
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typedef struct private_mgf1_bitspender_t private_mgf1_bitspender_t;
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/**
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* Private data structure for mgf1_bitspender_t object
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*/
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struct private_mgf1_bitspender_t {
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/**
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* Public interface.
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*/
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mgf1_bitspender_t public;
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/**
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* MGF1 bit mask generator
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*/
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mgf1_t *mgf1;
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/**
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* Octet storage (accommodates up to 64 octets)
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*/
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uint8_t octets[HASH_SIZE_SHA512];
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/**
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* Length of the returned hash value in octets
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*/
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int hash_len;
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/**
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* Number of generated octets
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*/
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int octets_count;
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/**
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* Number of available octets
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*/
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int octets_left;
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/**
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* Bit storage (accomodates up to 32 bits)
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*/
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uint32_t bits;
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/**
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* Number of available bits
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*/
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int bits_left;
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};
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METHOD(mgf1_bitspender_t, get_bits, uint32_t,
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private_mgf1_bitspender_t *this, int bits_needed)
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{
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uint32_t bits = 0x00000000;
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int bits_now;
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if (bits_needed > 31)
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{
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/* too many bits requested */
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return MGF1_BITSPENDER_ERROR;
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}
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while (bits_needed)
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{
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if (this->bits_left == 0)
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{
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if (this->octets_left == 0)
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{
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/* get another block from MGF1 */
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if (!this->mgf1->get_mask(this->mgf1, this->hash_len,
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this->octets))
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{
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/* no block available */
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return MGF1_BITSPENDER_ERROR;
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}
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this->octets_left = this->hash_len;
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this->octets_count += this->hash_len;
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}
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this->bits = untoh32(this->octets + this->hash_len -
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this->octets_left);
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this->bits_left = 32;
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this->octets_left -= 4;
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}
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if (bits_needed > this->bits_left)
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{
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bits_now = this->bits_left;
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this->bits_left = 0;
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bits_needed -= bits_now;
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bits <<= bits_now;
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bits |= this->bits;
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}
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else
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{
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bits_now = bits_needed;
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this->bits_left -= bits_needed;
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bits_needed = 0;
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bits <<= bits_now;
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bits |= this->bits >> this->bits_left;
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this->bits &= 0xffffffff >> (32 - this->bits_left);
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}
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}
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return bits;
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}
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METHOD(mgf1_bitspender_t, destroy, void,
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private_mgf1_bitspender_t *this)
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{
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DBG2(DBG_LIB, "mgf1 generated %u octets", this->octets_count);
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memwipe(this->octets, sizeof(this->octets));
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this->mgf1->destroy(this->mgf1);
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free(this);
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}
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/**
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* See header.
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*/
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mgf1_bitspender_t *mgf1_bitspender_create(hash_algorithm_t alg, chunk_t seed,
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bool hash_seed)
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{
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private_mgf1_bitspender_t *this;
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mgf1_t *mgf1;
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mgf1 = mgf1_create(alg, seed, hash_seed);
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if (!mgf1)
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{
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return NULL;
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}
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DBG2(DBG_LIB, "mgf1 based on %N is seeded with %u octets",
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hash_algorithm_short_names, alg, seed.len);
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INIT(this,
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.public = {
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.get_bits = _get_bits,
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.destroy = _destroy,
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},
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.mgf1 = mgf1,
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.hash_len = mgf1->get_hash_size(mgf1),
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);
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return &this->public;
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}
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@ -0,0 +1,60 @@
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/*
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* Copyright (C) 2014 Andreas Steffen
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* HSR Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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/**
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* @defgroup mgf1_bitspender mgf1_bitspender
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* @{ @ingroup bliss_p
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*/
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#ifndef MGF1_BITSPENDER_H_
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#define MGF1_BITSPENDER_H_
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#include <library.h>
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#include <crypto/hashers/hasher.h>
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typedef struct mgf1_bitspender_t mgf1_bitspender_t;
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#define MGF1_BITSPENDER_ERROR 0xffffffff
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/**
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* Generates a given number of pseudo-random bits at a time using MFG1
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*/
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struct mgf1_bitspender_t {
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/**
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* Get pseudo-random bits
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*
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* @param bits_needed Number of needed bits (1..31)
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* @result Return between 1 and 31 pseudo-random bits
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*/
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uint32_t (*get_bits)(mgf1_bitspender_t *this, int bits_needed);
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/**
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* Destroy mgf1_bitspender_t object
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*/
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void (*destroy)(mgf1_bitspender_t *this);
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};
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/**
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* Create a mgf1_bitspender_t object
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*
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* @param alg Hash algorithm to be used with MGF1
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* @param seed Seed used to initialize MGF1
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* @param hash_seed Hash seed before using it as a seed for MFG1
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*/
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mgf1_bitspender_t *mgf1_bitspender_create(hash_algorithm_t alg, chunk_t seed,
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bool hash_seed);
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#endif /** MGF1_BITSPENDER_H_ @}*/
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