use ChaCha8-based CSPRNG
Daniel Micay
parent
2b7c9362bb
commit
c41e659383
5
Makefile
5
Makefile
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@ -2,14 +2,15 @@ CPPFLAGS := -D_GNU_SOURCE
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CFLAGS := -std=c11 -Wall -Wextra -O2 -flto -fPIC -fvisibility=hidden -pedantic
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LDFLAGS := -Wl,--as-needed
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LDLIBS := -lpthread
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OBJECTS := malloc.o random.o util.o
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OBJECTS := chacha.o malloc.o random.o util.o
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hardened_malloc.so: $(OBJECTS)
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$(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@
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malloc.o: malloc.c malloc.h random.h util.h
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random.o: random.c random.h util.h
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random.o: random.c random.h chacha.h util.h
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util.o: util.c util.h
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chacha.o: chacha.c chacha.h
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clean:
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rm -f hardened_malloc.so $(OBJECTS)
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@ -0,0 +1,188 @@
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/*
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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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*/
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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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(U32V((v) << (n)) | ((v) >> (32 - (n))))
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#define U8TO32_LITTLE(p) \
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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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#define U32TO8_LITTLE(p, v) \
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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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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 chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits)
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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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} 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 chacha_ivsetup(chacha_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
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chacha_keystream_bytes(chacha_ctx *x,u8 *c,u32 bytes)
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{
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u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
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u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
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u8 *ctarget;
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u8 tmp[64];
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unsigned i;
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if (!bytes) return;
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j0 = x->input[0];
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j1 = x->input[1];
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j2 = x->input[2];
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j3 = x->input[3];
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j4 = x->input[4];
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j5 = x->input[5];
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j6 = x->input[6];
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j7 = x->input[7];
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j8 = x->input[8];
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j9 = x->input[9];
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j10 = x->input[10];
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j11 = x->input[11];
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j12 = x->input[12];
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j13 = x->input[13];
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j14 = x->input[14];
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j15 = x->input[15];
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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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x0 = j0;
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x1 = j1;
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x2 = j2;
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x3 = j3;
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x4 = j4;
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x5 = j5;
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x6 = j6;
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x7 = j7;
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x8 = j8;
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x9 = j9;
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x10 = j10;
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x11 = j11;
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x12 = j12;
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x13 = j13;
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x14 = j14;
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x15 = j15;
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for (i = 8;i > 0;i -= 2) {
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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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for (i = 0;i < bytes;++i) ctarget[i] = c[i];
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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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}
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}
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@ -0,0 +1,18 @@
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#ifndef CHACHA_H
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#define CHACHA_H
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#include <stdint.h>
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typedef uint8_t u8;
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typedef uint32_t u32;
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typedef struct
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{
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u32 input[16];
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} chacha_ctx;
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void chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits);
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void chacha_ivsetup(chacha_ctx *x,const u8 *iv);
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void chacha_keystream_bytes(chacha_ctx *x,u8 *c,u32 bytes);
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#endif
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22
random.c
22
random.c
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@ -16,6 +16,8 @@ static ssize_t getrandom(void *buf, size_t buflen, unsigned int flags) {
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}
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#endif
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#include "chacha.h"
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static void get_random_seed(void *buf, size_t size) {
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while (size > 0) {
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ssize_t r;
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@ -33,20 +35,34 @@ static void get_random_seed(void *buf, size_t size) {
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}
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}
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#define KEY_SIZE 32
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#define IV_SIZE 8
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void random_state_init(struct random_state *state) {
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state->index = RANDOM_CACHE_SIZE;
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uint8_t rnd[KEY_SIZE + IV_SIZE];
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get_random_seed(rnd, sizeof(rnd));
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chacha_keysetup(&state->ctx, rnd, KEY_SIZE * 8);
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chacha_ivsetup(&state->ctx, rnd + KEY_SIZE);
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chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
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state->index = 0;
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state->reseed = 0;
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}
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void get_random_bytes(struct random_state *state, void *buf, size_t size) {
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if (size > RANDOM_CACHE_SIZE / 2) {
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get_random_seed(buf, size);
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chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
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return;
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}
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while (size) {
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if (state->index == RANDOM_CACHE_SIZE) {
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if (state->reseed >= RANDOM_RESEED_SIZE) {
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random_state_init(state);
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} else {
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chacha_keystream_bytes(&state->ctx, state->cache, RANDOM_CACHE_SIZE);
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state->index = 0;
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get_random_seed(state->cache, RANDOM_CACHE_SIZE);
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state->reseed += RANDOM_CACHE_SIZE;
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}
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}
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size_t remaining = RANDOM_CACHE_SIZE - state->index;
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size_t copy_size = size < remaining ? size : remaining;
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