libsec: add chacha cipher (from charles forsyth)

sys/include/libsec.h

@@ -70,6 +70,37 @@ void	bfCBCdecrypt(uchar*, int, BFstate*);
 void	bfECBencrypt(uchar*, int, BFstate*);
 void	bfECBdecrypt(uchar*, int, BFstate*);
 
+/*
+ * Chacha definitions
+ */
+
+enum
+{
+	ChachaBsize=	64,
+	ChachaKeylen=	256/8,
+	ChachaIVlen=	96/8,
+};
+
+typedef struct Chachastate Chachastate;
+struct Chachastate
+{
+	union{
+		u32int	input[16];
+		struct {
+			u32int	constant[4];
+			u32int	key[8];
+			u32int	counter;
+			u32int	iv[3];
+		};
+	};
+	int	rounds;
+};
+
+void	setupChachastate(Chachastate*, uchar*, ulong, uchar*, int);
+void	chacha_setblock(Chachastate*, u32int);
+void	chacha_encrypt(uchar*, ulong, Chachastate*);
+void	chacha_encrypt2(uchar*, uchar*, ulong, Chachastate*);
+
 /*
  * DES definitions
  */

sys/man/2/chacha

@@ -0,0 +1,93 @@
+.TH CHACHA 2
+.SH NAME
+setupChachastate, chacha_setblock, chacha_encrypt, chacha_encrypt2  - chacha encryption
+.SH SYNOPSIS
+.B #include <u.h>
+.br
+.B #include <libc.h>
+.br
+.B #include <mp.h>
+.br
+.B #include <libsec.h>
+.PP
+.B
+void setupChachastate(Chachastate *s, uchar key[], ulong keylen, uchar *nonce, int rounds)
+.PP
+.B
+void chacha_encrypt(uchar *data, ulong len, Chachastate *s)
+.PP
+.B
+void chacha_encrypt2(uchar *src, uchar *dst, ulong len, Chachastate *s)
+.PP
+.B
+void chacha_setblock(Chachastate *s, u32int blockno)
+.SH DESCRIPTION
+.PP
+Chacha is D J Berstein's symmetric stream cipher, as modified by RFC7539. It supports
+keys of 256 bits (128 bits is supported here for special purposes). It has an underlying block size of 64 bytes
+(named as constant
+.BR ChachaBsize ).
+.PP
+.I SetupChachastate
+takes a reference to a
+.B Chachastate
+structure, a
+.I key
+of
+.I keylen
+bytes, which should normally be
+.BR ChachaKeylen ,
+a
+.I nonce
+or initialisation vector of
+.B ChachaIVlen
+bytes (set to all zeros if the argument is nil),
+and the number of
+.I rounds
+(set to the default of 20 if the argument is zero).
+With a keylength of 256 bits (32 bytes) and 20
+.IR rounds ,
+the function implements the Chacha20 encryption function of RFC7539.
+.PP
+.I Chacha_encrypt
+encrypts
+.I len
+bytes of
+.I buf
+in place using the
+.B Chachastate
+in
+.IR s .
+.I Len
+can be any byte length.
+Encryption and decryption are the same operation given the same starting state
+.IR s .
+.PP
+.I Chacha_encrypt2
+is similar, but encrypts
+.I len
+bytes of
+.I src
+into
+.I dst
+without modifying
+.IR src .
+.PP
+.I Chacha_setblock
+sets the Chacha block counter for the next encryption to
+.IR blockno ,
+allowing seeking in an encrypted stream.
+.SH SOURCE
+.B /sys/src/libsec
+.SH SEE ALSO
+.IR mp (2),
+.IR aes (2),
+.IR blowfish (2),
+.IR des (2),
+.IR dsa (2),
+.IR elgamal (2),
+.IR rc4 (2),
+.IR rsa (2),
+.IR sechash (2),
+.IR prime (2),
+.IR rand (2)

sys/src/libsec/port/chacha.c

@@ -0,0 +1,175 @@
+/*
+Adapted from chacha-merged.c version 20080118
+D. J. Bernstein
+Public domain.
+
+modified for use in Plan 9 and Inferno (no algorithmic changes),
+and including the changes to block number and nonce defined in RFC7539
+*/
+
+#include <u.h>
+#include <libc.h>
+#include <libsec.h>
+
+enum{
+	Blockwords=	ChachaBsize/sizeof(u32int)
+};
+
+/* little-endian data order */
+#define GET4(p)	((((((p)[3]<<8) | (p)[2])<<8) | (p)[1])<<8 | (p)[0])
+#define PUT4(p, v)	(((p)[0]=v), (v>>=8), ((p)[1]=v), (v>>=8), ((p)[2]=v), (v>>=8), ((p)[3]=v))
+
+#define ROTATE(v,c) ((u32int)((v) << (c)) | ((v) >> (32 - (c))))
+
+#define QUARTERROUND(ia,ib,ic,id) { \
+	u32int a, b, c, d, t;\
+	a = x[ia]; b = x[ib]; c = x[ic]; d = x[id]; \
+	a += b; t = d^a; d = ROTATE(t,16); \
+	c += d; t = b^c; b = ROTATE(t,12); \
+	a += b; t = d^a; d = ROTATE(t, 8); \
+	c += d; t = b^c; b = ROTATE(t, 7); \
+	x[ia] = a; x[ib] = b; x[ic] = c; x[id] = d; \
+}
+
+#define ENCRYPT(s, x, y, d) {\
+	u32int v; \
+	uchar *sp, *dp; \
+	sp = (s); \
+	v = GET4(sp); \
+	v ^= (x)+(y); \
+	dp = (d); \
+	PUT4(dp, v); \
+}
+
+static uchar sigma[16] = "expand 32-byte k";
+static uchar tau[16] = "expand 16-byte k";
+
+static void
+load(u32int *d, uchar *s, int nw)
+{
+	int i;
+
+	for(i = 0; i < nw; i++, s+=4)
+		d[i] = GET4(s);
+}
+
+void
+setupChachastate(Chachastate *s, uchar *key, ulong keylen, uchar *iv, int rounds)
+{
+	if(keylen != 256/8 && keylen != 128/8)
+		sysfatal("invalid chacha key length");
+	if(rounds == 0)
+		rounds = 20;
+	s->rounds = rounds;
+	if(keylen == 256/8) { /* recommended */
+		load(&s->input[0], sigma, 4);
+		load(&s->input[4], key, 8);
+	}else{
+		load(&s->input[0], tau, 4);
+		load(&s->input[4], key, 4);
+		load(&s->input[8], key, 4);
+	}
+	s->input[12] = 0;
+	if(iv == nil){
+		s->input[13] = 0;
+		s->input[14] = 0;
+		s->input[15] = 0;
+	}else
+		load(&s->input[13], iv, 3);
+}
+
+void
+chacha_setblock(Chachastate *s, u32int blockno)
+{
+	s->input[12] = blockno;
+}
+
+static void
+encryptblock(Chachastate *s, uchar *src, uchar *dst)
+{
+	u32int x[Blockwords];
+	int i, rounds;
+
+	rounds = s->rounds;
+	x[0] = s->input[0];
+	x[1] = s->input[1];
+	x[2] = s->input[2];
+	x[3] = s->input[3];
+	x[4] = s->input[4];
+	x[5] = s->input[5];
+	x[6] = s->input[6];
+	x[7] = s->input[7];
+	x[8] = s->input[8];
+	x[9] = s->input[9];
+	x[10] = s->input[10];
+	x[11] = s->input[11];
+	x[12] = s->input[12];
+	x[13] = s->input[13];
+	x[14] = s->input[14];
+	x[15] = s->input[15];
+
+	for(i = rounds; i > 0; i -= 2) {
+		QUARTERROUND(0, 4, 8,12)
+		QUARTERROUND(1, 5, 9,13)
+		QUARTERROUND(2, 6,10,14)
+		QUARTERROUND(3, 7,11,15)
+
+		QUARTERROUND(0, 5,10,15)
+		QUARTERROUND(1, 6,11,12)
+		QUARTERROUND(2, 7, 8,13)
+		QUARTERROUND(3, 4, 9,14)
+	}
+
+#ifdef FULL_UNROLL
+	ENCRYPT(src+0*4, x[0], s->input[0], dst+0*4);
+	ENCRYPT(src+1*4, x[1], s->input[1], dst+1*4);
+	ENCRYPT(src+2*4, x[2], s->input[2], dst+2*4);
+	ENCRYPT(src+3*4, x[3], s->input[3], dst+3*4);
+	ENCRYPT(src+4*4, x[4], s->input[4], dst+4*4);
+	ENCRYPT(src+5*4, x[5], s->input[5], dst+5*4);
+	ENCRYPT(src+6*4, x[6], s->input[6], dst+6*4);
+	ENCRYPT(src+7*4, x[7], s->input[7], dst+7*4);
+	ENCRYPT(src+8*4, x[8], s->input[8], dst+8*4);
+	ENCRYPT(src+9*4, x[9], s->input[9], dst+9*4);
+	ENCRYPT(src+10*4, x[10], s->input[10], dst+10*4);
+	ENCRYPT(src+11*4, x[11], s->input[11], dst+11*4);
+	ENCRYPT(src+12*4, x[12], s->input[12], dst+12*4);
+	ENCRYPT(src+13*4, x[13], s->input[13], dst+13*4);
+	ENCRYPT(src+14*4, x[14], s->input[14], dst+14*4);
+	ENCRYPT(src+15*4, x[15], s->input[15], dst+15*4);
+#else
+	for(i=0; i<nelem(x); i+=4){
+		ENCRYPT(src, x[i], s->input[i], dst);
+		ENCRYPT(src+4, x[i+1], s->input[i+1], dst+4);
+		ENCRYPT(src+8, x[i+2], s->input[i+2], dst+8);
+		ENCRYPT(src+12, x[i+3], s->input[i+3], dst+12);
+		src += 16;
+		dst += 16;
+	}
+#endif
+
+	s->input[12]++;
+}
+
+void
+chacha_encrypt2(uchar *src, uchar *dst, ulong bytes, Chachastate *s)
+{
+	uchar tmp[ChachaBsize];
+
+	for(; bytes >= ChachaBsize; bytes -= ChachaBsize){
+		encryptblock(s, src, dst);
+		src += ChachaBsize;
+		dst += ChachaBsize;
+	}
+	if(bytes > 0){
+		memmove(tmp, src, bytes);
+		encryptblock(s, tmp, tmp);
+		memmove(dst, tmp, bytes);
+	}
+}
+
+void
+chacha_encrypt(uchar *buf, ulong bytes, Chachastate *s)
+{
+	chacha_encrypt2(buf, buf, bytes, s);
+}

sys/src/libsec/port/chachatest.c

@@ -0,0 +1,70 @@
+#include <u.h>
+#include <libc.h>
+#include <libsec.h>
+
+static void
+printblock(uchar *b, usize n)
+{
+	int i;
+
+	for(i=0; i+8<=n; i+=8){
+		print("%#.2ux %#.2ux %#.2ux %#.2ux %#.2ux %#.2ux %#.2ux %#.2ux\n",
+			b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7]);
+		b += 8;
+	}
+	if(i < n){
+		print("%#.2ux", *b++);
+		while(++i < n)
+			print(" %#.2ux", *b++);
+		print("\n");
+	}
+}
+
+/* test vector from RFC7539 */
+uchar	rfckey[] = {
+	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f};
+uchar	rfcnonce[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x00, 0x00};
+u32int	rfccount = 1;
+char	rfctext[] = "Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, "
+	"sunscreen would be it.";
+uchar	rfcout[3*ChachaBsize];
+uchar	rfcref[3*ChachaBsize] = {
+	0x6e, 0x2e, 0x35, 0x9a, 0x25, 0x68, 0xf9, 0x80, 0x41, 0xba, 0x07, 0x28, 0xdd, 0x0d, 0x69, 0x81,
+	0xe9, 0x7e, 0x7a, 0xec, 0x1d, 0x43, 0x60, 0xc2, 0x0a, 0x27, 0xaf, 0xcc, 0xfd, 0x9f, 0xae, 0x0b,
+	0xf9, 0x1b, 0x65, 0xc5, 0x52, 0x47, 0x33, 0xab, 0x8f, 0x59, 0x3d, 0xab, 0xcd, 0x62, 0xb3, 0x57,
+	0x16, 0x39, 0xd6, 0x24, 0xe6, 0x51, 0x52, 0xab, 0x8f, 0x53, 0x0c, 0x35, 0x9f, 0x08, 0x61, 0xd8,
+	0x07, 0xca, 0x0d, 0xbf, 0x50, 0x0d, 0x6a, 0x61, 0x56, 0xa3, 0x8e, 0x08, 0x8a, 0x22, 0xb6, 0x5e,
+	0x52, 0xbc, 0x51, 0x4d, 0x16, 0xcc, 0xf8, 0x06, 0x81, 0x8c, 0xe9, 0x1a, 0xb7, 0x79, 0x37, 0x36,
+	0x5a, 0xf9, 0x0b, 0xbf, 0x74, 0xa3, 0x5b, 0xe6, 0xb4, 0x0b, 0x8e, 0xed, 0xf2, 0x78, 0x5e, 0x42,
+	0x87, 0x4d
+};
+
+void
+main(int argc, char **argv)
+{
+	Chachastate s;
+	int n;
+
+	ARGBEGIN{
+	}ARGEND
+	print("rfc7539:\n");
+	print("key:\n");
+	printblock(rfckey, sizeof(rfckey));
+	n = strlen(rfctext);
+	setupChachastate(&s, rfckey, sizeof(rfckey), rfcnonce, 0);
+	chacha_setblock(&s, rfccount);
+	print("rfc in:\n");
+	printblock((uchar*)rfctext, n);
+	chacha_encrypt2((uchar*)rfctext, rfcout, n, &s);
+	print("rfc out:\n");
+	printblock(rfcout, n);
+	if(memcmp(rfcout, rfcref, sizeof(rfcout)) != 0){
+		print("failure of vision\n");
+		exits("wrong");
+	}
+	print("passed\n");
+	exits(nil);
+}

sys/src/libsec/port/mkfile

@@ -9,6 +9,7 @@ CFILES = des.c desmodes.c desECB.c desCBC.c des3ECB.c des3CBC.c\
 	sha1pickle.c md5pickle.c\
 	poly1305.c\
 	rc4.c\
+	chacha.c\
 	genrandom.c prng.c fastrand.c nfastrand.c\
 	probably_prime.c smallprimetest.c genprime.c dsaprimes.c\
 	gensafeprime.c genstrongprime.c\