forked from lthn/blockchain
115 lines
No EOL
2.9 KiB
C
115 lines
No EOL
2.9 KiB
C
/*
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chacha-ref.c version 20080118
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D. J. Bernstein
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Public domain.
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*/
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#include "ecrypt-sync.h"
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#define ROTATE(v,c) (ROTL32(v,c))
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#define XOR(v,w) ((v) ^ (w))
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#define PLUS(v,w) (U32V((v) + (w)))
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#define PLUSONE(v) (PLUS((v),1))
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#define QUARTERROUND(a,b,c,d) \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]),16); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]),12); \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]), 8); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]), 7);
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static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
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{
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u32 x[16];
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int i;
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for (i = 0; i < 16; ++i) x[i] = input[i];
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for (i = 8; i > 0; i -= 2) {
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QUARTERROUND(0, 4, 8, 12)
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QUARTERROUND(1, 5, 9, 13)
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QUARTERROUND(2, 6, 10, 14)
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QUARTERROUND(3, 7, 11, 15)
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QUARTERROUND(0, 5, 10, 15)
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QUARTERROUND(1, 6, 11, 12)
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QUARTERROUND(2, 7, 8, 13)
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QUARTERROUND(3, 4, 9, 14)
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}
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for (i = 0; i < 16; ++i) x[i] = PLUS(x[i], input[i]);
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for (i = 0; i < 16; ++i) U32TO8_LITTLE(output + 4 * i, x[i]);
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}
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void ECRYPT_init(void)
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{
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return;
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}
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static const char sigma[16] = "expand 32-byte k";
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static const char tau[16] = "expand 16-byte k";
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void ECRYPT_keysetup(ECRYPT_ctx *x, const u8 *k, u32 kbits, u32 ivbits)
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{
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const char *constants;
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x->input[4] = U8TO32_LITTLE(k + 0);
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x->input[5] = U8TO32_LITTLE(k + 4);
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x->input[6] = U8TO32_LITTLE(k + 8);
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x->input[7] = U8TO32_LITTLE(k + 12);
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if (kbits == 256) { /* recommended */
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k += 16;
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constants = sigma;
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}
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else { /* kbits == 128 */
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constants = tau;
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}
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x->input[8] = U8TO32_LITTLE(k + 0);
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x->input[9] = U8TO32_LITTLE(k + 4);
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x->input[10] = U8TO32_LITTLE(k + 8);
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x->input[11] = U8TO32_LITTLE(k + 12);
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x->input[0] = U8TO32_LITTLE(constants + 0);
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x->input[1] = U8TO32_LITTLE(constants + 4);
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x->input[2] = U8TO32_LITTLE(constants + 8);
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x->input[3] = U8TO32_LITTLE(constants + 12);
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}
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void ECRYPT_ivsetup(ECRYPT_ctx *x, const u8 *iv)
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{
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x->input[12] = 0;
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x->input[13] = 0;
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x->input[14] = U8TO32_LITTLE(iv + 0);
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x->input[15] = U8TO32_LITTLE(iv + 4);
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}
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void ECRYPT_encrypt_bytes(ECRYPT_ctx *x, const u8 *m, u8 *c, u32 bytes)
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{
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u8 output[64];
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int i;
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if (!bytes) return;
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for (;;) {
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salsa20_wordtobyte(output, x->input);
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x->input[12] = PLUSONE(x->input[12]);
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if (!x->input[12]) {
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x->input[13] = PLUSONE(x->input[13]);
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/* stopping at 2^70 bytes per nonce is user's responsibility */
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}
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if (bytes <= 64) {
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for (i = 0; i < bytes; ++i) c[i] = m[i] ^ output[i];
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return;
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}
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for (i = 0; i < 64; ++i) c[i] = m[i] ^ output[i];
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bytes -= 64;
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c += 64;
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m += 64;
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}
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}
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void ECRYPT_decrypt_bytes(ECRYPT_ctx *x, const u8 *c, u8 *m, u32 bytes)
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{
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ECRYPT_encrypt_bytes(x, c, m, bytes);
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}
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void ECRYPT_keystream_bytes(ECRYPT_ctx *x, u8 *stream, u32 bytes)
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{
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u32 i;
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for (i = 0; i < bytes; ++i) stream[i] = 0;
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ECRYPT_encrypt_bytes(x, stream, stream, bytes);
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} |