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implementation. Rewrite pseudodevice code to use cprng_strong(9). The new pseudodevice is cloning, so each caller gets bits from a stream generated with its own key. Users of /dev/urandom get their generators keyed on a "best effort" basis -- the kernel will rekey generators whenever the entropy pool hits the high water mark -- while users of /dev/random get their generators rekeyed every time key-length bits are output. The underlying cprng_strong API can use AES-256 or AES-128, but we use AES-128 because of concerns about related-key attacks on AES-256. This improves performance (and reduces entropy pool depletion) significantly for users of /dev/urandom but does cause users of /dev/random to rekey twice as often. Also fixes various bugs (including some missing locking and a reseed-counter overflow in the CTR_DRBG code) found while testing this. For long reads, this generator is approximately 20 times as fast as the old generator (dd with bs=64K yields 53MB/sec on 2Ghz Core2 instead of 2.5MB/sec) and also uses a separate mutex per instance so concurrency is greatly improved. For reads of typical key sizes for modern cryptosystems (16-32 bytes) performance is about the same as the old code: a little better for 32 bytes, a little worse for 16 bytes.
81 lines
3.4 KiB
C
81 lines
3.4 KiB
C
/* $NetBSD: nist_ctr_drbg_aes128.h,v 1.2 2011/12/17 20:05:38 tls Exp $ */
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/*-
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* Copyright (c) 2011 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Thor Lancelot Simon.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 2007 Henric Jungheim <software@henric.info>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* NIST SP 800-90 CTR_DRBG (Random Number Generator)
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*/
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#ifndef NIST_CTR_DRBG_AES128_H
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#define NIST_CTR_DRBG_AES128_H
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/* Choose AES-128 as the underlying block cipher */
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#define NIST_BLOCK_KEYLEN (128)
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#define NIST_BLOCK_KEYLEN_BYTES (NIST_BLOCK_KEYLEN / 8)
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#define NIST_BLOCK_KEYLEN_INTS (NIST_BLOCK_KEYLEN_BYTES / sizeof(int))
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#define NIST_BLOCK_OUTLEN (NIST_AES_BLOCKSIZEBITS)
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#define NIST_BLOCK_OUTLEN_BYTES (NIST_BLOCK_OUTLEN / 8)
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#define NIST_BLOCK_OUTLEN_INTS (NIST_BLOCK_OUTLEN_BYTES / sizeof(int))
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#define NIST_BLOCK_OUTLEN_LONGS (NIST_BLOCK_OUTLEN_BYTES / sizeof(long))
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typedef NIST_AES_ENCRYPT_CTX NIST_Key;
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#define Block_Encrypt(ctx, src, dst) NIST_AES_ECB_Encrypt(ctx, src, dst)
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#define Block_Schedule_Encryption(ctx, key) \
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NIST_AES_Schedule_Encryption(ctx, key, NIST_BLOCK_KEYLEN)
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/*
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* NIST SP 800-90 March 2007
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* 10.2 DRBG Mechanism Based on Block Ciphers
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*
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* Table 3 specifies the reseed interval as
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* <= 2^48. We use 2^31 so we can always be sure it'll fit in an int.
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*/
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#define NIST_CTR_DRBG_RESEED_INTERVAL (0x7fffffffU)
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#endif /* NIST_CTR_DRBG_AES128_H */
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