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libsec: add chacha20
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Add ChaCha20 stream cipher (RFC7539).
http://9legacy.org/9legacy/patch/libsec-chacha.diff
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adriangrigore committed Jun 23, 2024
1 parent 074f81b commit 9cd2994
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36 changes: 36 additions & 0 deletions include/libsec.h
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,42 @@ 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
{
/*
* 0-3: a constant (sigma or tau)
* 4-11: the key
* 12: block counter
* 13-15: IV
*/
union{
u32int input[16];
struct{
u32int constant[4];
u32int key[8];
u32int counter;
u32int iv[3];
};
};
int rounds;
};

void setupChachastate(Chachastate*, uchar*, usize, uchar*, int);
void chacha_setblock(Chachastate*, u32int);
void chacha_encrypt(uchar*, usize, Chachastate*);
void chacha_encrypt2(uchar*, uchar*, usize, Chachastate*);

/*
* DES definitions
*/
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1 change: 1 addition & 0 deletions libsec/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ LIB=libsec.a
OFILES=\
aes.$O\
blowfish.$O\
chacha.$O\
decodepem.$O\
des.$O\
des3CBC.$O\
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175 changes: 175 additions & 0 deletions libsec/chacha.c
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@@ -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, usize 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, usize 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, usize bytes, Chachastate *s)
{
chacha_encrypt2(buf, buf, bytes, s);
}
70 changes: 70 additions & 0 deletions libsec/chachatest.c
Original file line number Diff line number Diff line change
@@ -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);
}

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