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91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
/*
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* Copyright 2014-2021 The GmSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <gmssl/chacha20.h>
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#include "endian.h"
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void chacha20_set_key(CHACHA20_STATE *state,
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const unsigned char key[CHACHA20_KEY_SIZE],
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const unsigned char nonce[CHACHA20_NONCE_SIZE],
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uint32_t counter)
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{
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state->d[ 0] = 0x61707865;
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state->d[ 1] = 0x3320646e;
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state->d[ 2] = 0x79622d32;
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state->d[ 3] = 0x6b206574;
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state->d[ 4] = GETU32_LE(key );
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state->d[ 5] = GETU32_LE(key + 4);
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state->d[ 6] = GETU32_LE(key + 8);
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state->d[ 7] = GETU32_LE(key + 12);
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state->d[ 8] = GETU32_LE(key + 16);
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state->d[ 9] = GETU32_LE(key + 20);
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state->d[10] = GETU32_LE(key + 24);
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state->d[11] = GETU32_LE(key + 28);
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state->d[12] = counter;
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state->d[13] = GETU32_LE(nonce);
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state->d[14] = GETU32_LE(nonce + 4);
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state->d[15] = GETU32_LE(nonce + 8);
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}
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/* quarter round */
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#define QR(A, B, C, D) \
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A += B; D ^= A; D = ROL32(D, 16); \
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C += D; B ^= C; B = ROL32(B, 12); \
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A += B; D ^= A; D = ROL32(D, 8); \
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C += D; B ^= C; B = ROL32(B, 7)
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/* double round on state 4x4 matrix:
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* four column rounds and and four diagonal rounds
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*
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* 0 1 2 3
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* 4 5 6 7
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* 8 9 10 11
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* 12 13 14 15
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*
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*/
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#define DR(S) \
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QR(S[0], S[4], S[ 8], S[12]); \
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QR(S[1], S[5], S[ 9], S[13]); \
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QR(S[2], S[6], S[10], S[14]); \
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QR(S[3], S[7], S[11], S[15]); \
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QR(S[0], S[5], S[10], S[15]); \
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QR(S[1], S[6], S[11], S[12]); \
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QR(S[2], S[7], S[ 8], S[13]); \
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QR(S[3], S[4], S[ 9], S[14])
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void chacha20_generate_keystream(CHACHA20_STATE *state, unsigned int counts, unsigned char *out)
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{
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uint32_t working_state[16];
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int i;
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while (counts-- > 0) {
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memcpy(working_state, state->d, sizeof(working_state));
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for (i = 0; i < 10; i++) {
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DR(working_state);
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}
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for (i = 0; i < 16; i++) {
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working_state[i] += state->d[i];
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PUTU32_LE(out, working_state[i]);
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out += sizeof(uint32_t);
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}
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state->d[12]++;
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}
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}
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