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55 lines
2.3 KiB
C
55 lines
2.3 KiB
C
/*
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* This file is part of the Trezor project, https://trezor.io/
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*
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* Copyright (c) SatoshiLabs
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __CHACHA_DRBG__
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#define __CHACHA_DRBG__
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#include "chacha20poly1305/chacha20poly1305.h"
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#include "sha2.h"
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// A very fast deterministic random bit generator based on CTR_DRBG in NIST SP
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// 800-90A. Chacha is used instead of a block cipher in the counter mode, SHA256
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// is used as a derivation function. The highest supported security strength is
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// at least 256 bits. Reseeding is left up to caller.
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// Length of inputs of chacha_drbg_init (entropy and nonce) or
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// chacha_drbg_reseed (entropy and additional_input) that fill exactly
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// block_count blocks of hash function in derivation_function. There is no need
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// the input to have this length, it's just an optimalization.
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#define CHACHA_DRBG_OPTIMAL_RESEED_LENGTH(block_count) \
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((block_count) * SHA256_BLOCK_LENGTH - 1 - 4 - 9)
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// 1 = sizeof(counter), 4 = sizeof(output_length) in
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// derivation_function, 9 is length of SHA256 padding of message
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// aligned to bytes
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typedef struct _CHACHA_DRBG_CTX {
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ECRYPT_ctx chacha_ctx;
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uint32_t reseed_counter;
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} CHACHA_DRBG_CTX;
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void chacha_drbg_init(CHACHA_DRBG_CTX *ctx, const uint8_t *entropy,
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size_t entropy_length, const uint8_t *nonce,
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size_t nonce_length);
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void chacha_drbg_generate(CHACHA_DRBG_CTX *ctx, uint8_t *output,
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size_t output_length);
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void chacha_drbg_reseed(CHACHA_DRBG_CTX *ctx, const uint8_t *entropy,
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size_t entropy_length, const uint8_t *additional_input,
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size_t additional_input_length);
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#endif // __CHACHA_DRBG__
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