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Diffstat (limited to 'src/cc20rng/cc20_prng.c')
| -rw-r--r-- | src/cc20rng/cc20_prng.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/src/cc20rng/cc20_prng.c b/src/cc20rng/cc20_prng.c new file mode 100644 index 0000000..3d52fc6 --- /dev/null +++ b/src/cc20rng/cc20_prng.c @@ -0,0 +1,219 @@ +/* + * Simple implementation of chacha20 used as a CSPRNG. + * + * Copyright (c) 2016 NORDUnet A/S + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * 3. Neither the name of the NORDUnet nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER + * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include "cc20_prng.h" + +/* "expand 32-byte k" */ +#define CHACHA20_CONSTANT0 0x61707865 +#define CHACHA20_CONSTANT1 0x3320646e +#define CHACHA20_CONSTANT2 0x79622d32 +#define CHACHA20_CONSTANT3 0x6b206574 + +#ifdef CHACHA20_PRNG_DEBUG +void _dump(struct cc20_state *cc, char *str); +#endif + +inline uint32_t rotl32 (uint32_t x, uint32_t n) +{ + return (x << n) | (x >> (32 - n)); +} + +inline void _qr(struct cc20_state *cc, uint32_t a, uint32_t b, uint32_t c, uint32_t d) +{ + cc->i[a] += cc->i[b]; + cc->i[d] ^= cc->i[a]; + cc->i[d] = rotl32(cc->i[d], 16); + + cc->i[c] += cc->i[d]; + cc->i[b] ^= cc->i[c]; + cc->i[b] = rotl32(cc->i[b], 12); + + cc->i[a] += cc->i[b]; + cc->i[d] ^= cc->i[a]; + cc->i[d] = rotl32(cc->i[d], 8); + + cc->i[c] += cc->i[d]; + cc->i[b] ^= cc->i[c]; + cc->i[b] = rotl32(cc->i[b], 7); +} + +void chacha20_prng_reseed(struct cc20_state *cc, uint32_t *entropy) +{ + uint32_t i = 256 / 8 / 4; + while (i--) { + cc->i[i] = entropy[i]; + } +} + +void chacha20_prng_block(struct cc20_state *cc, uint32_t block_counter, struct cc20_state *out) +{ + uint32_t i; + + out->i[0] = CHACHA20_CONSTANT0; + out->i[1] = CHACHA20_CONSTANT1; + out->i[2] = CHACHA20_CONSTANT2; + out->i[3] = CHACHA20_CONSTANT3; + + cc->i[12] = block_counter; + + for (i = 4; i < CHACHA20_NUM_WORDS; i++) { + out->i[i] = cc->i[i]; + } + + for (i = 10; i; i--) { + _qr(out, 0, 4, 8,12); + _qr(out, 1, 5, 9,13); + _qr(out, 2, 6,10,14); + _qr(out, 3, 7,11,15); + _qr(out, 0, 5,10,15); + _qr(out, 1, 6,11,12); + _qr(out, 2, 7, 8,13); + _qr(out, 3, 4, 9,14); + } + + for (i = 0; i < CHACHA20_NUM_WORDS; i++) { + out->i[i] += cc->i[i]; + } +} + +int chacha20_prng_self_test1() +{ + /* Test vector from RFC7539, section 2.3.2. + * https://tools.ietf.org/html/rfc7539#section-2.3.2 + */ + struct cc20_state test = { + {0x61707865, 0x3320646e, 0x79622d32, 0x6b206574, + 0x03020100, 0x07060504, 0x0b0a0908, 0x0f0e0d0c, + 0x13121110, 0x17161514, 0x1b1a1918, 0x1f1e1d1c, + 0x00000001, 0x09000000, 0x4a000000, 0x00000000, + }}; + struct cc20_state expected = { + {0xe4e7f110, 0x15593bd1, 0x1fdd0f50, 0xc47120a3, + 0xc7f4d1c7, 0x0368c033, 0x9aaa2204, 0x4e6cd4c3, + 0x466482d2, 0x09aa9f07, 0x05d7c214, 0xa2028bd9, + 0xd19c12b5, 0xb94e16de, 0xe883d0cb, 0x4e3c50a2, + }}; + uint32_t i; + struct cc20_state out; + +#ifdef CHACHA20_PRNG_DEBUG + _dump(&test, "Test vector from RFC7539, section 2.3.2. Input:"); +#endif + + chacha20_prng_block(&test, 1, &out); +#ifdef CHACHA20_PRNG_DEBUG + _dump(&out, "Test vector from RFC7539, section 2.3.2. Output:"); +#endif + + for (i = 0; i < CHACHA20_NUM_WORDS; i++) { + if (out.i[i] != expected.i[i]) return 0; + } + + return 1; +} + +int chacha20_prng_self_test2() +{ + /* Two-block test vector from RFC7539, section 2.4.2. + * https://tools.ietf.org/html/rfc7539#section-2.4.2 + */ + struct cc20_state test = { + {0x61707865, 0x3320646e, 0x79622d32, 0x6b206574, + 0x03020100, 0x07060504, 0x0b0a0908, 0x0f0e0d0c, + 0x13121110, 0x17161514, 0x1b1a1918, 0x1f1e1d1c, + 0x00000001, 0x00000000, 0x4a000000, 0x00000000, + }}; + struct cc20_state expected1 = { + {0xf3514f22, 0xe1d91b40, 0x6f27de2f, 0xed1d63b8, + 0x821f138c, 0xe2062c3d, 0xecca4f7e, 0x78cff39e, + 0xa30a3b8a, 0x920a6072, 0xcd7479b5, 0x34932bed, + 0x40ba4c79, 0xcd343ec6, 0x4c2c21ea, 0xb7417df0, + }}; + struct cc20_state expected2 = { + {0x9f74a669, 0x410f633f, 0x28feca22, 0x7ec44dec, + 0x6d34d426, 0x738cb970, 0x3ac5e9f3, 0x45590cc4, + 0xda6e8b39, 0x892c831a, 0xcdea67c1, 0x2b7e1d90, + 0x037463f3, 0xa11a2073, 0xe8bcfb88, 0xedc49139, + }}; + struct cc20_state out; + uint32_t i; + +#ifdef CHACHA20_PRNG_DEBUG + _dump(&test, "Test vector from RFC7539, section 2.4.2. Input:"); +#endif + + chacha20_prng_block(&test, 1, &out); +#ifdef CHACHA20_PRNG_DEBUG + _dump(&out, "First block"); +#endif + for (i = 0; i < CHACHA20_NUM_WORDS; i++) { + if (out.i[i] != expected1.i[i]) return 0; + } + + chacha20_prng_block(&test, 2, &out); +#ifdef CHACHA20_PRNG_DEBUG + _dump(&out, "Second block"); +#endif + for (i = 0; i < CHACHA20_NUM_WORDS; i++) { + if (out.i[i] != expected2.i[i]) return 0; + } + + return 1; +} + +#ifdef CHACHA20_PRNG_DEBUG +#include <stdio.h> +void _dump(struct cc20_state *cc, char *str) +{ + uint32_t i; + + printf("%s\n", str); + + for (i = 0; i < 4; i++) { + printf("%02i %08x %08x %08x %08x\n", i * 4, cc->i[i * 4 + 0], + cc->i[i * 4 + 1], cc->i[i * 4 + 2], cc->i[i * 4 + 3]); + } + printf("\n"); +} +#endif + +/* Test vector from RFC, used as simple power-on self-test of ability to compute + * a block correctly. + */ +int chacha20_prng_self_test() +{ + return \ + chacha20_prng_self_test1() && \ + chacha20_prng_self_test2(); +} |