ref: 847f3a0cf54ac6aaafaeda7f6c6a4422e2f14700
parent: 7effba9d98e8a39ee1504192d02d40e86d90b19a
author: cinap_lenrek <[email protected]>
date: Thu Oct 22 03:48:26 EDT 2015
libsec: add chacha cipher (from charles forsyth)
--- a/sys/include/libsec.h
+++ b/sys/include/libsec.h
@@ -71,6 +71,37 @@
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
*/
--- /dev/null
+++ b/sys/man/2/chacha
@@ -1,0 +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)
--- /dev/null
+++ b/sys/src/libsec/port/chacha.c
@@ -1,0 +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);
+}
--- /dev/null
+++ b/sys/src/libsec/port/chachatest.c
@@ -1,0 +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);
+}
--- a/sys/src/libsec/port/mkfile
+++ b/sys/src/libsec/port/mkfile
@@ -9,6 +9,7 @@
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\