2018-10-19 23:07:30 +02:00
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// Based on chacha-merged.c version 20080118
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// D. J. Bernstein
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// Public domain.
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2018-08-26 05:00:00 +02:00
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#include "chacha.h"
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#define U8C(v) (v##U)
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#define U32C(v) (v##U)
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#define U8V(v) ((u8)(v) & U8C(0xFF))
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#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
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#define ROTL32(v, n) \
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2018-10-19 23:07:30 +02:00
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(U32V((v) << (n)) | ((v) >> (32 - (n))))
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2018-08-26 05:00:00 +02:00
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#define U8TO32_LITTLE(p) \
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2018-10-19 23:07:30 +02:00
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(((u32)((p)[0])) | \
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((u32)((p)[1]) << 8) | \
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((u32)((p)[2]) << 16) | \
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((u32)((p)[3]) << 24))
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2018-08-26 05:00:00 +02:00
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#define U32TO8_LITTLE(p, v) \
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2018-10-19 23:07:30 +02:00
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do { \
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(p)[0] = U8V((v)); \
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(p)[1] = U8V((v) >> 8); \
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(p)[2] = U8V((v) >> 16); \
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(p)[3] = U8V((v) >> 24); \
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} while (0)
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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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a = PLUS(a, b); d = ROTATE(XOR(d, a), 16); \
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c = PLUS(c, d); b = ROTATE(XOR(b, c), 12); \
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a = PLUS(a, b); d = ROTATE(XOR(d, a), 8); \
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c = PLUS(c, d); b = ROTATE(XOR(b, c), 7);
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2018-08-26 05:00:00 +02:00
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static const char sigma[16] = "expand 32-byte k";
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2018-10-19 23:07:30 +02:00
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void chacha_keysetup(chacha_ctx *x, const u8 *k) {
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x->input[0] = U8TO32_LITTLE(sigma + 0);
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x->input[1] = U8TO32_LITTLE(sigma + 4);
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x->input[2] = U8TO32_LITTLE(sigma + 8);
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x->input[3] = U8TO32_LITTLE(sigma + 12);
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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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x->input[8] = U8TO32_LITTLE(k + 16);
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x->input[9] = U8TO32_LITTLE(k + 20);
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x->input[10] = U8TO32_LITTLE(k + 24);
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x->input[11] = U8TO32_LITTLE(k + 28);
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2018-08-26 05:00:00 +02:00
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}
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2018-10-19 23:07:30 +02:00
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void chacha_ivsetup(chacha_ctx *x, const u8 *iv) {
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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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2018-08-26 05:00:00 +02:00
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}
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2018-10-19 23:07:30 +02:00
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void chacha_keystream_bytes(chacha_ctx *x, u8 *c, u32 bytes) {
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if (!bytes) {
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return;
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2018-08-26 05:00:00 +02:00
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}
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2019-04-09 06:15:41 +02:00
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u8 *ctarget;
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u8 tmp[64];
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u32 j0 = x->input[0];
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u32 j1 = x->input[1];
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u32 j2 = x->input[2];
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u32 j3 = x->input[3];
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u32 j4 = x->input[4];
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u32 j5 = x->input[5];
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u32 j6 = x->input[6];
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u32 j7 = x->input[7];
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u32 j8 = x->input[8];
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u32 j9 = x->input[9];
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u32 j10 = x->input[10];
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u32 j11 = x->input[11];
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u32 j12 = x->input[12];
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u32 j13 = x->input[13];
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u32 j14 = x->input[14];
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u32 j15 = x->input[15];
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2018-10-19 23:07:30 +02:00
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for (;;) {
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if (bytes < 64) {
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ctarget = c;
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c = tmp;
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}
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2019-04-09 06:15:41 +02:00
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u32 x0 = j0;
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u32 x1 = j1;
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u32 x2 = j2;
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u32 x3 = j3;
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u32 x4 = j4;
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u32 x5 = j5;
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u32 x6 = j6;
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u32 x7 = j7;
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u32 x8 = j8;
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u32 x9 = j9;
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u32 x10 = j10;
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u32 x11 = j11;
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u32 x12 = j12;
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u32 x13 = j13;
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u32 x14 = j14;
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u32 x15 = j15;
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for (unsigned i = 8; i > 0; i -= 2) {
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2018-10-19 23:07:30 +02:00
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QUARTERROUND(x0, x4, x8, x12)
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QUARTERROUND(x1, x5, x9, x13)
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QUARTERROUND(x2, x6, x10, x14)
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QUARTERROUND(x3, x7, x11, x15)
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QUARTERROUND(x0, x5, x10, x15)
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QUARTERROUND(x1, x6, x11, x12)
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QUARTERROUND(x2, x7, x8, x13)
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QUARTERROUND(x3, x4, x9, x14)
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}
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x0 = PLUS(x0, j0);
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x1 = PLUS(x1, j1);
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x2 = PLUS(x2, j2);
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x3 = PLUS(x3, j3);
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x4 = PLUS(x4, j4);
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x5 = PLUS(x5, j5);
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x6 = PLUS(x6, j6);
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x7 = PLUS(x7, j7);
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x8 = PLUS(x8, j8);
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x9 = PLUS(x9, j9);
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x10 = PLUS(x10, j10);
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x11 = PLUS(x11, j11);
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x12 = PLUS(x12, j12);
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x13 = PLUS(x13, j13);
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x14 = PLUS(x14, j14);
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x15 = PLUS(x15, j15);
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j12 = PLUSONE(j12);
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if (!j12) {
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j13 = PLUSONE(j13);
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// stopping at 2^70 bytes per nonce is user's responsibility
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}
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U32TO8_LITTLE(c + 0, x0);
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U32TO8_LITTLE(c + 4, x1);
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U32TO8_LITTLE(c + 8, x2);
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U32TO8_LITTLE(c + 12, x3);
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U32TO8_LITTLE(c + 16, x4);
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U32TO8_LITTLE(c + 20, x5);
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U32TO8_LITTLE(c + 24, x6);
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U32TO8_LITTLE(c + 28, x7);
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U32TO8_LITTLE(c + 32, x8);
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U32TO8_LITTLE(c + 36, x9);
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U32TO8_LITTLE(c + 40, x10);
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U32TO8_LITTLE(c + 44, x11);
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U32TO8_LITTLE(c + 48, x12);
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U32TO8_LITTLE(c + 52, x13);
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U32TO8_LITTLE(c + 56, x14);
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U32TO8_LITTLE(c + 60, x15);
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if (bytes <= 64) {
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if (bytes < 64) {
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2019-04-09 06:15:41 +02:00
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for (unsigned i = 0; i < bytes; ++i) {
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2018-10-19 23:07:30 +02:00
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ctarget[i] = c[i];
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}
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}
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x->input[12] = j12;
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x->input[13] = j13;
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return;
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}
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bytes -= 64;
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c += 64;
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2018-08-26 05:00:00 +02:00
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}
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}
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