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author | Michael Brown <mcb30@ipxe.org> | 2012-01-23 14:52:56 +0000 |
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committer | Michael Brown <mcb30@ipxe.org> | 2012-01-23 15:03:43 +0000 |
commit | 5c2d6fa3997f5ad82527914c5e2e35ef423c3119 (patch) | |
tree | 5c4fe8da0c9b2ef2ba7e48c522e0d6f2d0cb1402 /src/crypto/hmac_drbg.c | |
parent | f5bbe7ec4a4b31ad197947b025c54a8e87402436 (diff) | |
download | ipxe-5c2d6fa3997f5ad82527914c5e2e35ef423c3119.zip ipxe-5c2d6fa3997f5ad82527914c5e2e35ef423c3119.tar.gz ipxe-5c2d6fa3997f5ad82527914c5e2e35ef423c3119.tar.bz2 |
[rng] Add ANS X9.82 Approved HMAC_DRBG algorithm
ANS X9.82 specifies several Approved algorithms for use in a
Deterministic Random Bit Generator (DRBG). One such algorithm is
HMAC_DRBG, which can be implemented using the existing iPXE SHA-1 and
HMAC functionality. This algorithm provides a maximum security
strength of 128 bits.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/crypto/hmac_drbg.c')
-rw-r--r-- | src/crypto/hmac_drbg.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/src/crypto/hmac_drbg.c b/src/crypto/hmac_drbg.c new file mode 100644 index 0000000..64613d0 --- /dev/null +++ b/src/crypto/hmac_drbg.c @@ -0,0 +1,342 @@ +/* + * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** @file + * + * HMAC_DRBG algorithm + * + * This algorithm is designed to comply with ANS X9.82 Part 3-2007 + * Section 10.2.2.2. This standard is not freely available, but most + * of the text appears to be shared with NIST SP 800-90, which can be + * downloaded from + * + * http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf + * + * Where possible, references are given to both documents. In the + * case of any disagreement, ANS X9.82 takes priority over NIST SP + * 800-90. (In particular, note that some algorithms that are + * Approved by NIST SP 800-90 are not Approved by ANS X9.82.) + */ + +#include <stdint.h> +#include <errno.h> +#include <ipxe/crypto.h> +#include <ipxe/hmac.h> +#include <ipxe/hmac_drbg.h> + +/** + * Update the HMAC_DRBG key + * + * @v state HMAC_DRBG internal state + * @v data Provided data + * @v len Length of provided data + * @v single Single byte used in concatenation + * + * This function carries out the operation + * + * K = HMAC ( K, V || single || provided_data ) + * + * as used by hmac_drbg_update() + */ +static void hmac_drbg_update_key ( struct hmac_drbg_state *state, + const void *data, size_t len, + const uint8_t single ) { + uint8_t context[HMAC_DRBG_CTX_SIZE]; + size_t key_len = sizeof ( state->key ); + + DBGC ( state, "HMAC_DRBG %p provided data :\n", state ); + DBGC_HDA ( state, 0, data, len ); + + /* Sanity checks */ + assert ( state != NULL ); + assert ( ( data != NULL ) || ( len == 0 ) ); + assert ( ( single == 0x00 ) || ( single == 0x01 ) ); + + /* K = HMAC ( K, V || single || provided_data ) */ + hmac_init ( &hmac_drbg_algorithm, context, state->key, &key_len ); + assert ( key_len == sizeof ( state->key ) ); + hmac_update ( &hmac_drbg_algorithm, context, + state->value, sizeof ( state->value ) ); + hmac_update ( &hmac_drbg_algorithm, context, + &single, sizeof ( single ) ); + hmac_update ( &hmac_drbg_algorithm, context, data, len ); + hmac_final ( &hmac_drbg_algorithm, context, state->key, &key_len, + state->key ); + assert ( key_len == sizeof ( state->key ) ); + + DBGC ( state, "HMAC_DRBG %p K = HMAC ( K, V || %#02x || " + "provided_data ) :\n", state, single ); + DBGC_HDA ( state, 0, state->key, sizeof ( state->key ) ); +} + +/** + * Update the HMAC_DRBG value + * + * @v state HMAC_DRBG internal state + * @v data Provided data + * @v len Length of provided data + * @v single Single byte used in concatenation + * + * This function carries out the operation + * + * V = HMAC ( K, V ) + * + * as used by hmac_drbg_update() and hmac_drbg_generate() + */ +static void hmac_drbg_update_value ( struct hmac_drbg_state *state ) { + uint8_t context[HMAC_DRBG_CTX_SIZE]; + size_t key_len = sizeof ( state->key ); + + /* Sanity checks */ + assert ( state != NULL ); + + /* V = HMAC ( K, V ) */ + hmac_init ( &hmac_drbg_algorithm, context, state->key, &key_len ); + assert ( key_len == sizeof ( state->key ) ); + hmac_update ( &hmac_drbg_algorithm, context, + state->value, sizeof ( state->value ) ); + hmac_final ( &hmac_drbg_algorithm, context, state->key, &key_len, + state->value ); + assert ( key_len == sizeof ( state->key ) ); + + DBGC ( state, "HMAC_DRBG %p V = HMAC ( K, V ) :\n", state ); + DBGC_HDA ( state, 0, state->value, sizeof ( state->value ) ); +} + +/** + * Update HMAC_DRBG internal state + * + * @v state HMAC_DRBG internal state + * @v data Provided data + * @v len Length of provided data + * + * This is the HMAC_DRBG_Update function defined in ANS X9.82 Part + * 3-2007 Section 10.2.2.2.2 (NIST SP 800-90 Section 10.1.2.2). + * + * The key and value are updated in-place within the HMAC_DRBG + * internal state. + */ +static void hmac_drbg_update ( struct hmac_drbg_state *state, + const void *data, size_t len ) { + + DBGC ( state, "HMAC_DRBG %p update\n", state ); + + /* Sanity checks */ + assert ( state != NULL ); + assert ( ( data != NULL ) || ( len == 0 ) ); + + /* 1. K = HMAC ( K, V || 0x00 || provided_data ) */ + hmac_drbg_update_key ( state, data, len, 0x00 ); + + /* 2. V = HMAC ( K, V ) */ + hmac_drbg_update_value ( state ); + + /* 3. If ( provided_data = Null ), then return K and V */ + if ( ! len ) + return; + + /* 4. K = HMAC ( K, V || 0x01 || provided_data ) */ + hmac_drbg_update_key ( state, data, len, 0x01 ); + + /* 5. V = HMAC ( K, V ) */ + hmac_drbg_update_value ( state ); + + /* 6. Return K and V */ +} + +/** + * Instantiate HMAC_DRBG + * + * @v state HMAC_DRBG internal state to be initialised + * @v entropy Entropy input + * @v entropy_len Length of entropy input + * @v personal Personalisation string + * @v personal_len Length of personalisation string + * + * This is the HMAC_DRBG_Instantiate_algorithm function defined in ANS + * X9.82 Part 3-2007 Section 10.2.2.2.3 (NIST SP 800-90 Section + * 10.1.2.3). + * + * The nonce must be included within the entropy input (i.e. the + * entropy input must contain at least 3/2 * security_strength bits of + * entropy, as per ANS X9.82 Part 3-2007 Section 8.4.2 (NIST SP 800-90 + * Section 8.6.7). + * + * The key, value and reseed counter are updated in-place within the + * HMAC_DRBG internal state. + */ +void hmac_drbg_instantiate ( struct hmac_drbg_state *state, + const void *entropy, size_t entropy_len, + const void *personal, size_t personal_len ){ + + DBGC ( state, "HMAC_DRBG %p instantiate\n", state ); + + /* Sanity checks */ + assert ( state != NULL ); + assert ( entropy != NULL ); + assert ( ( 8 * entropy_len ) >= + ( 3 * HMAC_DRBG_SECURITY_STRENGTH / 2 ) ); + assert ( ( personal != NULL ) || ( personal_len == 0 ) ); + + /* 1. seed_material = entropy_input || nonce || + * personalisation_string + */ + + /* 2. Key = 0x00 00..00 */ + memset ( state->key, 0x00, sizeof ( state->key ) ); + + /* 3. V = 0x01 01...01 */ + memset ( state->value, 0x01, sizeof ( state->value ) ); + + /* 4. ( Key, V ) = HMAC_DBRG_Update ( seed_material, Key, V ) + * 5. reseed_counter = 1 + * 6. Return V, Key and reseed_counter as the + * initial_working_state + */ + hmac_drbg_reseed ( state, entropy, entropy_len, + personal, personal_len ); +} + +/** + * Reseed HMAC_DRBG + * + * @v state HMAC_DRBG internal state + * @v entropy Entropy input + * @v entropy_len Length of entropy input + * @v additional Additional input + * @v additional_len Length of additional input + * + * This is the HMAC_DRBG_Reseed_algorithm function defined in ANS X9.82 + * Part 3-2007 Section 10.2.2.2.4 (NIST SP 800-90 Section 10.1.2.4). + * + * The key, value and reseed counter are updated in-place within the + * HMAC_DRBG internal state. + */ +void hmac_drbg_reseed ( struct hmac_drbg_state *state, + const void *entropy, size_t entropy_len, + const void *additional, size_t additional_len ) { + uint8_t seed_material[ entropy_len + additional_len ]; + + DBGC ( state, "HMAC_DRBG %p (re)seed\n", state ); + + /* Sanity checks */ + assert ( state != NULL ); + assert ( entropy != NULL ); + assert ( ( 8 * entropy_len ) >= HMAC_DRBG_SECURITY_STRENGTH ); + assert ( ( additional != NULL ) || ( additional_len == 0 ) ); + + /* 1. seed_material = entropy_input || additional_input */ + memcpy ( seed_material, entropy, entropy_len ); + memcpy ( ( seed_material + entropy_len ), additional, additional_len ); + DBGC ( state, "HMAC_DRBG %p seed material :\n", state ); + DBGC_HDA ( state, 0, seed_material, sizeof ( seed_material ) ); + + /* 2. ( Key, V ) = HMAC_DBRG_Update ( seed_material, Key, V ) */ + hmac_drbg_update ( state, seed_material, sizeof ( seed_material ) ); + + /* 3. reseed_counter = 1 */ + state->reseed_counter = 1; + + /* 4. Return V, Key and reseed_counter as the new_working_state */ +} + +/** + * Generate pseudorandom bits using HMAC_DRBG + * + * @v state HMAC_DRBG internal state + * @v additional Additional input + * @v additional_len Length of additional input + * @v data Output buffer + * @v len Length of output buffer + * @ret rc Return status code + * + * This is the HMAC_DRBG_Generate_algorithm function defined in ANS X9.82 + * Part 3-2007 Section 10.2.2.2.5 (NIST SP 800-90 Section 10.1.2.5). + * + * Requests must be for an integral number of bytes. + * + * The key, value and reseed counter are updated in-place within the + * HMAC_DRBG internal state. + * + * Note that the only permitted error is "reseed required". + */ +int hmac_drbg_generate ( struct hmac_drbg_state *state, + const void *additional, size_t additional_len, + void *data, size_t len ) { + void *orig_data = data; + size_t orig_len = len; + size_t frag_len; + + DBGC ( state, "HMAC_DRBG %p generate\n", state ); + + /* Sanity checks */ + assert ( state != NULL ); + assert ( data != NULL ); + assert ( ( additional != NULL ) || ( additional_len == 0 ) ); + + /* 1. If reseed_counter > reseed_interval, then return an + * indication that a reseed is required + */ + if ( state->reseed_counter > HMAC_DRBG_RESEED_INTERVAL ) { + DBGC ( state, "HMAC_DRBG %p reseed interval exceeded\n", + state ); + return -ESTALE; + } + + /* 2. If additional_input != Null, then + * ( Key, V ) = HMAC_DRBG_Update ( additional_input, Key, V ) + */ + if ( additional_len ) + hmac_drbg_update ( state, additional, additional_len ); + + /* 3. temp = Null + * 4. While ( len ( temp ) < requested_number_of_bits ) do: + */ + while ( len ) { + + /* 4.1 V = HMAC ( Key, V ) */ + hmac_drbg_update_value ( state ); + + /* 4.2. temp = temp || V + * 5. returned_bits = Leftmost requested_number_of_bits + * of temp + */ + frag_len = len; + if ( frag_len > sizeof ( state->value ) ) + frag_len = sizeof ( state->value ); + memcpy ( data, state->value, frag_len ); + data += frag_len; + len -= frag_len; + } + + /* 6. ( Key, V ) = HMAC_DRBG_Update ( additional_input, Key, V ) */ + hmac_drbg_update ( state, additional, additional_len ); + + /* 7. reseed_counter = reseed_counter + 1 */ + state->reseed_counter++; + + DBGC ( state, "HMAC_DRBG %p generated :\n", state ); + DBGC_HDA ( state, 0, orig_data, orig_len ); + + /* 8. Return SUCCESS, returned_bits, and the new values of + * Key, V and reseed_counter as the new_working_state + */ + return 0; +} |