Attachment 112357 Details for Bug 85827 – patch to add chacha20 support, taken from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=747671#10

[patch] patch to add chacha20 support, taken from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=747671#10

chacha20.patch (text/plain), 12.39 KB, created by thepouar on 2015-01-16 18:46:39 UTC

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Creator: thepouar

Created: 2015-01-16 18:46:39 UTC

Size: 12.39 KB

patch

obsolete

>diff --git a/src/arc4random.c b/src/arc4random.c
>index 20fce09..b7abb35 100644
>--- a/src/arc4random.c
>+++ b/src/arc4random.c
>@@ -1,6 +1,7 @@
> /*
>  * Copyright (c) 1996, David Mazieres <dm@uun.org>
>  * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
>+ * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
>  *
>  * Permission to use, copy, modify, and distribute this software for any
>  * purpose with or without fee is hereby granted, provided that the above
>@@ -16,20 +17,7 @@
>  */
> 
> /*
>- * Arc4 random number generator for OpenBSD.
>- *
>- * This code is derived from section 17.1 of Applied Cryptography,
>- * second edition, which describes a stream cipher allegedly
>- * compatible with RSA Labs "RC4" cipher (the actual description of
>- * which is a trade secret).  The same algorithm is used as a stream
>- * cipher called "arcfour" in Tatu Ylonen's ssh package.
>- *
>- * Here the stream cipher has been modified always to include the time
>- * when initializing the state.  That makes it impossible to
>- * regenerate the same random sequence twice, so this can't be used
>- * for encryption, but will generate good random numbers.
>- *
>- * RC4 is a registered trademark of RSA Laboratories.
>+ * ChaCha based random number generator for OpenBSD.
>  */
> 
> #include <sys/cdefs.h>
>@@ -41,15 +29,19 @@ __FBSDID("$FreeBSD$");
> #include <fcntl.h>
> #include <unistd.h>
> #include <pthread.h>
>+#include <string.h>
>+
>+#define KEYSTREAM_ONLY
>+#include "chacha_private.h"
> 
>-struct arc4_stream {
>-	u_int8_t i;
>-	u_int8_t j;
>-	u_int8_t s[256];
>-};
>+/* "min" in arc4random_uniform() */
>+#define MIN(a, b) ((a) < (b) ? (a) : (b))
> 
> #define	RANDOMDEV	"/dev/urandom"
>-#define KEYSIZE		128
>+#define KEYSZ	32
>+#define IVSZ	8
>+#define BLOCKSZ	64
>+#define RSBUFSZ	(16*BLOCKSZ)
> 
> #ifdef __REENTRANT
> static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
>@@ -60,45 +52,42 @@ static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
> #define	THREAD_UNLOCK()
> #endif
> 
>-static struct arc4_stream rs;
>+/*
>+ * XXX rs, rsx should be pointers, keeping them this way to reduce diff size;
>+ * http://openbsd.cs.toronto.edu/cgi-bin/cvsweb/src/lib/libc/crypt/arc4random.c.diff?r1=1.27&r2=1.28
>+ */
>+static struct _rs {
>+	size_t		rs_have;	/* valid bytes at end of rs_buf */
>+	size_t		rs_count;	/* bytes till reseed */
>+} rs[1];
>+static struct _rsx {
>+	chacha_ctx	rs_chacha;	/* chacha context for random keystream */
>+	u_char		rs_buf[RSBUFSZ];	/* keystream blocks */
>+} rsx[1];
> static int rs_initialized;
> static int rs_stired;
>-static int arc4_count;
> 
>-static inline u_int8_t arc4_getbyte(void);
> static void arc4_stir(void);
> 
> static inline void
> arc4_init(void)
> {
>-	int     n;
>-
>-	for (n = 0; n < 256; n++)
>-		rs.s[n] = n;
>-	rs.i = 0;
>-	rs.j = 0;
>+	/* NOP - chacha only needs key/iv setup */
> }
> 
> static inline void
>-arc4_addrandom(u_char *dat, int datlen)
>+arc4_addrandom(uint8_t *buf, int datlen)
> {
>-	int     n;
>-	u_int8_t si;
>-
>-	rs.i--;
>-	for (n = 0; n < 256; n++) {
>-		rs.i = (rs.i + 1);
>-		si = rs.s[rs.i];
>-		rs.j = (rs.j + si + dat[n % datlen]);
>-		rs.s[rs.i] = rs.s[rs.j];
>-		rs.s[rs.j] = si;
>-	}
>-	rs.j = rs.i;
>+	if (datlen != KEYSZ + IVSZ)
>+		abort();	/* canthappen - this is an assertion. */
>+	chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8, 0);
>+	chacha_ivsetup(&rsx->rs_chacha, buf + KEYSZ);
> }
> 
> static void
> arc4_stir(void)
> {
>+	enum { KEYSIZE = KEYSZ + IVSZ };
> 	int done, fd, n;
> 	struct {
> 		struct timeval	tv;
>@@ -121,62 +110,82 @@ arc4_stir(void)
> 
> 	arc4_addrandom((u_char *)&rdat, KEYSIZE);
> 
>-	/*
>-	 * Throw away the first N bytes of output, as suggested in the
>-	 * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
>-	 * by Fluher, Mantin, and Shamir.  N=1024 is based on
>-	 * suggestions in the paper "(Not So) Random Shuffles of RC4"
>-	 * by Ilya Mironov.
>-	 */
>-	for (n = 0; n < 1024; n++)
>-		(void) arc4_getbyte();
>-	arc4_count = 1600000;
>+	/* invalidate rs_buf */
>+	rs->rs_have = 0;
>+	memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
>+
>+	/* Chacha doesn't need to discard anything */
>+	rs->rs_count = 1600000;
> }
> 
>-static inline u_int8_t
>-arc4_getbyte(void)
>+static void
>+arc4_check_init(void)
> {
>-	u_int8_t si, sj;
>+	if (!rs_initialized) {
>+		arc4_init();
>+		rs_initialized = 1;
>+	}
>+}
> 
>-	rs.i = (rs.i + 1);
>-	si = rs.s[rs.i];
>-	rs.j = (rs.j + si);
>-	sj = rs.s[rs.j];
>-	rs.s[rs.i] = sj;
>-	rs.s[rs.j] = si;
>+static inline void
>+arc4_check_stir(void)
>+{
>+	if (!rs_stired || rs->rs_count <= 0) {
>+		arc4_stir();
>+		rs_stired = 1;
>+	}
>+}
> 
>-	return (rs.s[(si + sj) & 0xff]);
>+static inline void
>+_rs_rekey(u_char *dat, size_t datlen)
>+{
>+#ifndef KEYSTREAM_ONLY
>+	memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
>+#endif
>+	/* fill rs_buf with the keystream */
>+	chacha_encrypt_bytes(&rsx->rs_chacha, rsx->rs_buf,
>+	    rsx->rs_buf, sizeof(rsx->rs_buf));
>+	/* mix in optional user provided data */
>+	if (dat) {
>+		size_t i, m;
>+
>+		m = MIN(datlen, KEYSZ + IVSZ);
>+		for (i = 0; i < m; i++)
>+			rsx->rs_buf[i] ^= dat[i];
>+	}
>+	/* immediately reinit for backtracking resistance */
>+	arc4_addrandom(rsx->rs_buf, KEYSZ + IVSZ);
>+	memset(rsx->rs_buf, 0, KEYSZ + IVSZ);
>+	rs->rs_have = sizeof(rsx->rs_buf) - KEYSZ - IVSZ;
> }
> 
> static inline u_int32_t
> arc4_getword(void)
> {
> 	u_int32_t val;
>+	u_char *keystream;
> 
>-	val = arc4_getbyte() << 24;
>-	val |= arc4_getbyte() << 16;
>-	val |= arc4_getbyte() << 8;
>-	val |= arc4_getbyte();
>+	arc4_check_stir();
>+	if (rs->rs_have < sizeof(val))
>+		_rs_rekey(NULL, 0);
>+	keystream = rsx->rs_buf + sizeof(rsx->rs_buf) - rs->rs_have;
>+	memcpy(&val, keystream, sizeof(val));
>+	memset(keystream, 0, sizeof(val));
>+	rs->rs_have -= sizeof(val);
> 
> 	return (val);
> }
> 
>-static void
>-arc4_check_init(void)
>-{
>-	if (!rs_initialized) {
>-		arc4_init();
>-		rs_initialized = 1;
>-	}
>-}
>-
> static inline void
>-arc4_check_stir(void)
>+_rs_stir_if_needed(size_t len)
> {
>-	if (!rs_stired || arc4_count <= 0) {
>+	arc4_check_stir();
>+	if (rs->rs_count <= len)
> 		arc4_stir();
>-		rs_stired = 1;
>-	}
>+	if (rs->rs_count <= len)
>+		rs->rs_count = 0;
>+	else
>+		rs->rs_count -= len;
> }
> 
> void
>@@ -208,24 +217,41 @@ arc4random(void)
> 	arc4_check_init();
> 	arc4_check_stir();
> 	rnd = arc4_getword();
>-	arc4_count -= 4;
>+	rs->rs_count -= 4;
> 	THREAD_UNLOCK();
> 
> 	return (rnd);
> }
> 
>-void
>-arc4random_buf(void *_buf, size_t n)
>+static inline void
>+_rs_random_buf(void *_buf, size_t n)
> {
> 	u_char *buf = (u_char *)_buf;
>+	u_char *keystream;
>+	size_t m;
>+
>+	_rs_stir_if_needed(n);
>+	while (n > 0) {
>+		if (rs->rs_have > 0) {
>+			m = MIN(n, rs->rs_have);
>+			keystream = rsx->rs_buf + sizeof(rsx->rs_buf)
>+			    - rs->rs_have;
>+			memcpy(buf, keystream, m);
>+			memset(keystream, 0, m);
>+			buf += m;
>+			n -= m;
>+			rs->rs_have -= m;
>+		}
>+		if (rs->rs_have == 0)
>+			_rs_rekey(NULL, 0);
>+	}
>+}
> 
>+void
>+arc4random_buf(void *_buf, size_t n)
>+{
> 	THREAD_LOCK();
>-	arc4_check_init();
>-	while (n--) {
>-		arc4_check_stir();
>-		buf[n] = arc4_getbyte();
>-		arc4_count--;
>-	}
>+	_rs_random_buf(_buf, n);
> 	THREAD_UNLOCK();
> }
> 
>diff --git a/src/chacha_private.h b/src/chacha_private.h
>new file mode 100644
>index 0000000..b720d93
>--- /dev/null
>+++ b/src/chacha_private.h
>@@ -0,0 +1,222 @@
>+/*
>+chacha-merged.c version 20080118
>+D. J. Bernstein
>+Public domain.
>+*/
>+
>+/* $OpenBSD$ */
>+
>+typedef unsigned char u8;
>+typedef unsigned int u32;
>+
>+typedef struct
>+{
>+  u32 input[16]; /* could be compressed */
>+} chacha_ctx;
>+
>+#define U8C(v) (v##U)
>+#define U32C(v) (v##U)
>+
>+#define U8V(v) ((u8)(v) & U8C(0xFF))
>+#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
>+
>+#define ROTL32(v, n) \
>+  (U32V((v) << (n)) | ((v) >> (32 - (n))))
>+
>+#define U8TO32_LITTLE(p) \
>+  (((u32)((p)[0])      ) | \
>+   ((u32)((p)[1]) <<  8) | \
>+   ((u32)((p)[2]) << 16) | \
>+   ((u32)((p)[3]) << 24))
>+
>+#define U32TO8_LITTLE(p, v) \
>+  do { \
>+    (p)[0] = U8V((v)      ); \
>+    (p)[1] = U8V((v) >>  8); \
>+    (p)[2] = U8V((v) >> 16); \
>+    (p)[3] = U8V((v) >> 24); \
>+  } while (0)
>+
>+#define ROTATE(v,c) (ROTL32(v,c))
>+#define XOR(v,w) ((v) ^ (w))
>+#define PLUS(v,w) (U32V((v) + (w)))
>+#define PLUSONE(v) (PLUS((v),1))
>+
>+#define QUARTERROUND(a,b,c,d) \
>+  a = PLUS(a,b); d = ROTATE(XOR(d,a),16); \
>+  c = PLUS(c,d); b = ROTATE(XOR(b,c),12); \
>+  a = PLUS(a,b); d = ROTATE(XOR(d,a), 8); \
>+  c = PLUS(c,d); b = ROTATE(XOR(b,c), 7);
>+
>+static const char sigma[16] = "expand 32-byte k";
>+static const char tau[16] = "expand 16-byte k";
>+
>+static void
>+chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits,u32 ivbits)
>+{
>+  const char *constants;
>+
>+  x->input[4] = U8TO32_LITTLE(k + 0);
>+  x->input[5] = U8TO32_LITTLE(k + 4);
>+  x->input[6] = U8TO32_LITTLE(k + 8);
>+  x->input[7] = U8TO32_LITTLE(k + 12);
>+  if (kbits == 256) { /* recommended */
>+    k += 16;
>+    constants = sigma;
>+  } else { /* kbits == 128 */
>+    constants = tau;
>+  }
>+  x->input[8] = U8TO32_LITTLE(k + 0);
>+  x->input[9] = U8TO32_LITTLE(k + 4);
>+  x->input[10] = U8TO32_LITTLE(k + 8);
>+  x->input[11] = U8TO32_LITTLE(k + 12);
>+  x->input[0] = U8TO32_LITTLE(constants + 0);
>+  x->input[1] = U8TO32_LITTLE(constants + 4);
>+  x->input[2] = U8TO32_LITTLE(constants + 8);
>+  x->input[3] = U8TO32_LITTLE(constants + 12);
>+}
>+
>+static void
>+chacha_ivsetup(chacha_ctx *x,const u8 *iv)
>+{
>+  x->input[12] = 0;
>+  x->input[13] = 0;
>+  x->input[14] = U8TO32_LITTLE(iv + 0);
>+  x->input[15] = U8TO32_LITTLE(iv + 4);
>+}
>+
>+static void
>+chacha_encrypt_bytes(chacha_ctx *x,const u8 *m,u8 *c,u32 bytes)
>+{
>+  u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
>+  u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
>+  u8 *ctarget = NULL;
>+  u8 tmp[64];
>+  u_int i;
>+
>+  if (!bytes) return;
>+
>+  j0 = x->input[0];
>+  j1 = x->input[1];
>+  j2 = x->input[2];
>+  j3 = x->input[3];
>+  j4 = x->input[4];
>+  j5 = x->input[5];
>+  j6 = x->input[6];
>+  j7 = x->input[7];
>+  j8 = x->input[8];
>+  j9 = x->input[9];
>+  j10 = x->input[10];
>+  j11 = x->input[11];
>+  j12 = x->input[12];
>+  j13 = x->input[13];
>+  j14 = x->input[14];
>+  j15 = x->input[15];
>+
>+  for (;;) {
>+    if (bytes < 64) {
>+      for (i = 0;i < bytes;++i) tmp[i] = m[i];
>+      m = tmp;
>+      ctarget = c;
>+      c = tmp;
>+    }
>+    x0 = j0;
>+    x1 = j1;
>+    x2 = j2;
>+    x3 = j3;
>+    x4 = j4;
>+    x5 = j5;
>+    x6 = j6;
>+    x7 = j7;
>+    x8 = j8;
>+    x9 = j9;
>+    x10 = j10;
>+    x11 = j11;
>+    x12 = j12;
>+    x13 = j13;
>+    x14 = j14;
>+    x15 = j15;
>+    for (i = 20;i > 0;i -= 2) {
>+      QUARTERROUND( x0, x4, x8,x12)
>+      QUARTERROUND( x1, x5, x9,x13)
>+      QUARTERROUND( x2, x6,x10,x14)
>+      QUARTERROUND( x3, x7,x11,x15)
>+      QUARTERROUND( x0, x5,x10,x15)
>+      QUARTERROUND( x1, x6,x11,x12)
>+      QUARTERROUND( x2, x7, x8,x13)
>+      QUARTERROUND( x3, x4, x9,x14)
>+    }
>+    x0 = PLUS(x0,j0);
>+    x1 = PLUS(x1,j1);
>+    x2 = PLUS(x2,j2);
>+    x3 = PLUS(x3,j3);
>+    x4 = PLUS(x4,j4);
>+    x5 = PLUS(x5,j5);
>+    x6 = PLUS(x6,j6);
>+    x7 = PLUS(x7,j7);
>+    x8 = PLUS(x8,j8);
>+    x9 = PLUS(x9,j9);
>+    x10 = PLUS(x10,j10);
>+    x11 = PLUS(x11,j11);
>+    x12 = PLUS(x12,j12);
>+    x13 = PLUS(x13,j13);
>+    x14 = PLUS(x14,j14);
>+    x15 = PLUS(x15,j15);
>+
>+#ifndef KEYSTREAM_ONLY
>+    x0 = XOR(x0,U8TO32_LITTLE(m + 0));
>+    x1 = XOR(x1,U8TO32_LITTLE(m + 4));
>+    x2 = XOR(x2,U8TO32_LITTLE(m + 8));
>+    x3 = XOR(x3,U8TO32_LITTLE(m + 12));
>+    x4 = XOR(x4,U8TO32_LITTLE(m + 16));
>+    x5 = XOR(x5,U8TO32_LITTLE(m + 20));
>+    x6 = XOR(x6,U8TO32_LITTLE(m + 24));
>+    x7 = XOR(x7,U8TO32_LITTLE(m + 28));
>+    x8 = XOR(x8,U8TO32_LITTLE(m + 32));
>+    x9 = XOR(x9,U8TO32_LITTLE(m + 36));
>+    x10 = XOR(x10,U8TO32_LITTLE(m + 40));
>+    x11 = XOR(x11,U8TO32_LITTLE(m + 44));
>+    x12 = XOR(x12,U8TO32_LITTLE(m + 48));
>+    x13 = XOR(x13,U8TO32_LITTLE(m + 52));
>+    x14 = XOR(x14,U8TO32_LITTLE(m + 56));
>+    x15 = XOR(x15,U8TO32_LITTLE(m + 60));
>+#endif
>+
>+    j12 = PLUSONE(j12);
>+    if (!j12) {
>+      j13 = PLUSONE(j13);
>+      /* stopping at 2^70 bytes per nonce is user's responsibility */
>+    }
>+
>+    U32TO8_LITTLE(c + 0,x0);
>+    U32TO8_LITTLE(c + 4,x1);
>+    U32TO8_LITTLE(c + 8,x2);
>+    U32TO8_LITTLE(c + 12,x3);
>+    U32TO8_LITTLE(c + 16,x4);
>+    U32TO8_LITTLE(c + 20,x5);
>+    U32TO8_LITTLE(c + 24,x6);
>+    U32TO8_LITTLE(c + 28,x7);
>+    U32TO8_LITTLE(c + 32,x8);
>+    U32TO8_LITTLE(c + 36,x9);
>+    U32TO8_LITTLE(c + 40,x10);
>+    U32TO8_LITTLE(c + 44,x11);
>+    U32TO8_LITTLE(c + 48,x12);
>+    U32TO8_LITTLE(c + 52,x13);
>+    U32TO8_LITTLE(c + 56,x14);
>+    U32TO8_LITTLE(c + 60,x15);
>+
>+    if (bytes <= 64) {
>+      if (bytes < 64) {
>+        for (i = 0;i < bytes;++i) ctarget[i] = c[i];
>+      }
>+      x->input[12] = j12;
>+      x->input[13] = j13;
>+      return;
>+    }
>+    bytes -= 64;
>+    c += 64;
>+#ifndef KEYSTREAM_ONLY
>+    m += 64;
>+#endif
>+  }
>+}
>-- 
>2.1.4

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