345 lines
10 KiB
C
345 lines
10 KiB
C
/*
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* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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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
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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/** @file
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*
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* HMAC_DRBG algorithm
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*
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* This algorithm is designed to comply with ANS X9.82 Part 3-2007
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* Section 10.2.2.2. This standard is not freely available, but most
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* of the text appears to be shared with NIST SP 800-90, which can be
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* downloaded from
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*
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* http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
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*
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* Where possible, references are given to both documents. In the
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* case of any disagreement, ANS X9.82 takes priority over NIST SP
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* 800-90. (In particular, note that some algorithms that are
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* Approved by NIST SP 800-90 are not Approved by ANS X9.82.)
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*/
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#include <stdint.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <ipxe/crypto.h>
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#include <ipxe/hmac.h>
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#include <ipxe/hmac_drbg.h>
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/**
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* Update the HMAC_DRBG key
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*
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* @v state HMAC_DRBG internal state
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* @v data Provided data
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* @v len Length of provided data
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* @v single Single byte used in concatenation
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*
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* This function carries out the operation
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*
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* K = HMAC ( K, V || single || provided_data )
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*
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* as used by hmac_drbg_update()
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*/
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static void hmac_drbg_update_key ( struct hmac_drbg_state *state,
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const void *data, size_t len,
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const uint8_t single ) {
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uint8_t context[HMAC_DRBG_CTX_SIZE];
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size_t key_len = sizeof ( state->key );
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DBGC ( state, "HMAC_DRBG %p provided data :\n", state );
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DBGC_HDA ( state, 0, data, len );
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/* Sanity checks */
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assert ( state != NULL );
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assert ( ( data != NULL ) || ( len == 0 ) );
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assert ( ( single == 0x00 ) || ( single == 0x01 ) );
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/* K = HMAC ( K, V || single || provided_data ) */
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hmac_init ( &hmac_drbg_algorithm, context, state->key, &key_len );
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assert ( key_len == sizeof ( state->key ) );
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hmac_update ( &hmac_drbg_algorithm, context,
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state->value, sizeof ( state->value ) );
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hmac_update ( &hmac_drbg_algorithm, context,
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&single, sizeof ( single ) );
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hmac_update ( &hmac_drbg_algorithm, context, data, len );
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hmac_final ( &hmac_drbg_algorithm, context, state->key, &key_len,
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state->key );
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assert ( key_len == sizeof ( state->key ) );
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DBGC ( state, "HMAC_DRBG %p K = HMAC ( K, V || %#02x || "
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"provided_data ) :\n", state, single );
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DBGC_HDA ( state, 0, state->key, sizeof ( state->key ) );
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}
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/**
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* Update the HMAC_DRBG value
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*
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* @v state HMAC_DRBG internal state
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* @v data Provided data
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* @v len Length of provided data
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* @v single Single byte used in concatenation
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*
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* This function carries out the operation
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*
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* V = HMAC ( K, V )
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*
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* as used by hmac_drbg_update() and hmac_drbg_generate()
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*/
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static void hmac_drbg_update_value ( struct hmac_drbg_state *state ) {
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uint8_t context[HMAC_DRBG_CTX_SIZE];
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size_t key_len = sizeof ( state->key );
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/* Sanity checks */
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assert ( state != NULL );
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/* V = HMAC ( K, V ) */
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hmac_init ( &hmac_drbg_algorithm, context, state->key, &key_len );
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assert ( key_len == sizeof ( state->key ) );
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hmac_update ( &hmac_drbg_algorithm, context,
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state->value, sizeof ( state->value ) );
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hmac_final ( &hmac_drbg_algorithm, context, state->key, &key_len,
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state->value );
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assert ( key_len == sizeof ( state->key ) );
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DBGC ( state, "HMAC_DRBG %p V = HMAC ( K, V ) :\n", state );
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DBGC_HDA ( state, 0, state->value, sizeof ( state->value ) );
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}
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/**
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* Update HMAC_DRBG internal state
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*
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* @v state HMAC_DRBG internal state
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* @v data Provided data
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* @v len Length of provided data
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*
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* This is the HMAC_DRBG_Update function defined in ANS X9.82 Part
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* 3-2007 Section 10.2.2.2.2 (NIST SP 800-90 Section 10.1.2.2).
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*
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* The key and value are updated in-place within the HMAC_DRBG
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* internal state.
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*/
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static void hmac_drbg_update ( struct hmac_drbg_state *state,
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const void *data, size_t len ) {
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DBGC ( state, "HMAC_DRBG %p update\n", state );
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/* Sanity checks */
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assert ( state != NULL );
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assert ( ( data != NULL ) || ( len == 0 ) );
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/* 1. K = HMAC ( K, V || 0x00 || provided_data ) */
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hmac_drbg_update_key ( state, data, len, 0x00 );
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/* 2. V = HMAC ( K, V ) */
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hmac_drbg_update_value ( state );
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/* 3. If ( provided_data = Null ), then return K and V */
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if ( ! len )
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return;
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/* 4. K = HMAC ( K, V || 0x01 || provided_data ) */
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hmac_drbg_update_key ( state, data, len, 0x01 );
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/* 5. V = HMAC ( K, V ) */
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hmac_drbg_update_value ( state );
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/* 6. Return K and V */
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}
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/**
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* Instantiate HMAC_DRBG
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*
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* @v state HMAC_DRBG internal state to be initialised
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* @v entropy Entropy input
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* @v entropy_len Length of entropy input
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* @v personal Personalisation string
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* @v personal_len Length of personalisation string
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*
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* This is the HMAC_DRBG_Instantiate_algorithm function defined in ANS
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* X9.82 Part 3-2007 Section 10.2.2.2.3 (NIST SP 800-90 Section
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* 10.1.2.3).
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*
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* The nonce must be included within the entropy input (i.e. the
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* entropy input must contain at least 3/2 * security_strength bits of
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* entropy, as per ANS X9.82 Part 3-2007 Section 8.4.2 (NIST SP 800-90
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* Section 8.6.7).
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*
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* The key, value and reseed counter are updated in-place within the
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* HMAC_DRBG internal state.
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*/
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void hmac_drbg_instantiate ( struct hmac_drbg_state *state,
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const void *entropy, size_t entropy_len,
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const void *personal, size_t personal_len ){
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DBGC ( state, "HMAC_DRBG %p instantiate\n", state );
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/* Sanity checks */
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assert ( state != NULL );
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assert ( entropy != NULL );
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assert ( ( 8 * entropy_len ) >=
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( 3 * HMAC_DRBG_SECURITY_STRENGTH / 2 ) );
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assert ( ( personal != NULL ) || ( personal_len == 0 ) );
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/* 1. seed_material = entropy_input || nonce ||
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* personalisation_string
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*/
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/* 2. Key = 0x00 00..00 */
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memset ( state->key, 0x00, sizeof ( state->key ) );
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/* 3. V = 0x01 01...01 */
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memset ( state->value, 0x01, sizeof ( state->value ) );
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/* 4. ( Key, V ) = HMAC_DBRG_Update ( seed_material, Key, V )
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* 5. reseed_counter = 1
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* 6. Return V, Key and reseed_counter as the
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* initial_working_state
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*/
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hmac_drbg_reseed ( state, entropy, entropy_len,
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personal, personal_len );
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}
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/**
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* Reseed HMAC_DRBG
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*
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* @v state HMAC_DRBG internal state
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* @v entropy Entropy input
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* @v entropy_len Length of entropy input
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* @v additional Additional input
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* @v additional_len Length of additional input
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*
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* This is the HMAC_DRBG_Reseed_algorithm function defined in ANS X9.82
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* Part 3-2007 Section 10.2.2.2.4 (NIST SP 800-90 Section 10.1.2.4).
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*
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* The key, value and reseed counter are updated in-place within the
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* HMAC_DRBG internal state.
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*/
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void hmac_drbg_reseed ( struct hmac_drbg_state *state,
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const void *entropy, size_t entropy_len,
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const void *additional, size_t additional_len ) {
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uint8_t seed_material[ entropy_len + additional_len ];
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DBGC ( state, "HMAC_DRBG %p (re)seed\n", state );
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/* Sanity checks */
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assert ( state != NULL );
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assert ( entropy != NULL );
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assert ( ( 8 * entropy_len ) >= HMAC_DRBG_SECURITY_STRENGTH );
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assert ( ( additional != NULL ) || ( additional_len == 0 ) );
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/* 1. seed_material = entropy_input || additional_input */
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memcpy ( seed_material, entropy, entropy_len );
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memcpy ( ( seed_material + entropy_len ), additional, additional_len );
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DBGC ( state, "HMAC_DRBG %p seed material :\n", state );
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DBGC_HDA ( state, 0, seed_material, sizeof ( seed_material ) );
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/* 2. ( Key, V ) = HMAC_DBRG_Update ( seed_material, Key, V ) */
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hmac_drbg_update ( state, seed_material, sizeof ( seed_material ) );
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/* 3. reseed_counter = 1 */
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state->reseed_counter = 1;
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/* 4. Return V, Key and reseed_counter as the new_working_state */
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}
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/**
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* Generate pseudorandom bits using HMAC_DRBG
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*
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* @v state HMAC_DRBG internal state
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* @v additional Additional input
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* @v additional_len Length of additional input
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* @v data Output buffer
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* @v len Length of output buffer
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* @ret rc Return status code
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*
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* This is the HMAC_DRBG_Generate_algorithm function defined in ANS X9.82
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* Part 3-2007 Section 10.2.2.2.5 (NIST SP 800-90 Section 10.1.2.5).
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*
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* Requests must be for an integral number of bytes.
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*
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* The key, value and reseed counter are updated in-place within the
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* HMAC_DRBG internal state.
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*
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* Note that the only permitted error is "reseed required".
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*/
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int hmac_drbg_generate ( struct hmac_drbg_state *state,
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const void *additional, size_t additional_len,
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void *data, size_t len ) {
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void *orig_data = data;
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size_t orig_len = len;
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size_t frag_len;
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DBGC ( state, "HMAC_DRBG %p generate\n", state );
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/* Sanity checks */
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assert ( state != NULL );
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assert ( data != NULL );
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assert ( ( additional != NULL ) || ( additional_len == 0 ) );
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/* 1. If reseed_counter > reseed_interval, then return an
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* indication that a reseed is required
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*/
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if ( state->reseed_counter > HMAC_DRBG_RESEED_INTERVAL ) {
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DBGC ( state, "HMAC_DRBG %p reseed interval exceeded\n",
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state );
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return -ESTALE;
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}
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/* 2. If additional_input != Null, then
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* ( Key, V ) = HMAC_DRBG_Update ( additional_input, Key, V )
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*/
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if ( additional_len )
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hmac_drbg_update ( state, additional, additional_len );
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/* 3. temp = Null
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* 4. While ( len ( temp ) < requested_number_of_bits ) do:
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*/
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while ( len ) {
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/* 4.1 V = HMAC ( Key, V ) */
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hmac_drbg_update_value ( state );
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/* 4.2. temp = temp || V
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* 5. returned_bits = Leftmost requested_number_of_bits
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* of temp
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*/
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frag_len = len;
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if ( frag_len > sizeof ( state->value ) )
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frag_len = sizeof ( state->value );
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memcpy ( data, state->value, frag_len );
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data += frag_len;
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len -= frag_len;
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}
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/* 6. ( Key, V ) = HMAC_DRBG_Update ( additional_input, Key, V ) */
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hmac_drbg_update ( state, additional, additional_len );
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/* 7. reseed_counter = reseed_counter + 1 */
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state->reseed_counter++;
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DBGC ( state, "HMAC_DRBG %p generated :\n", state );
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DBGC_HDA ( state, 0, orig_data, orig_len );
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/* 8. Return SUCCESS, returned_bits, and the new values of
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* Key, V and reseed_counter as the new_working_state
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*/
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return 0;
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}
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