add ccm mode from cinap

Reference: /n/atom/patch/applied/aesccm
Date: Thu May 15 00:46:00 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libsec/port/aesccm.c	Thu Jan  1 00:00:00 1970
+++ /sys/src/libsec/port/aesccm.c	Thu May 15 00:45:59 2014
@@ -0,0 +1,125 @@
+#include <u.h>
+#include <libc.h>
+#include <mp.h>
+#include <libsec.h>
+
+static uchar*
+putbe32(uchar *p, u32int v, int L)
+{
+	while(--L >= 0)
+		*p++ = v >> L*8;
+	return p;
+}
+
+static void
+xblock(int L, int M, uchar *N, uchar *a, int la, int lm, uchar t[16], AESstate *s)
+{
+	uchar l[8], *p, *x, *e;
+
+	assert(M >= 4 && M <= 16);
+	assert(L >= 2 && L <= 4);
+
+	t[0] = ((la > 0)<<6) | ((M-2)/2)<<3 | (L-1);	/* flags */
+	memmove(&t[1], N, 15-L);
+	putbe32(&t[16-L], lm, L);
+	aes_encrypt(s->ekey, s->rounds, t, t);
+	
+	if(la > 0){
+		assert(la < 0xFF00);
+		for(p = l, e = putbe32(l, la, 2), x = t; p < e; x++, p++)
+			*x ^= *p;
+		for(e = a + la; a < e; x = t){
+			for(; a < e && x < &t[16]; x++, a++)
+				*x ^= *a;
+			aes_encrypt(s->ekey, s->rounds, t, t);
+		}
+	}
+}
+
+static uchar*
+sblock(int L, uchar *N, uint i, uchar b[16], AESstate *s)
+{
+	b[0] = L-1;	/* flags */
+	memmove(&b[1], N, 15-L);
+	putbe32(&b[16-L], i, L);
+	aes_encrypt(s->ekey, s->rounds, b, b);
+	return b;
+};
+
+void
+aesCCMencrypt(int L, int M, uchar *N /* N[15-L] */,
+	uchar *a /* a[la] */, int la,
+	uchar *m /* m[lm+M] */, int lm,
+	AESstate *s)
+{
+	uchar t[16], b[16], *p, *x;
+	uint i;
+
+	xblock(L, M, N, a, la, lm, t, s);
+
+	for(i = 1; lm >= 16; i++, m += 16, lm -= 16){
+		sblock(L, N, i, b, s);
+
+		*((u32int*)&t[0]) ^= *((u32int*)&m[0]);
+		*((u32int*)&m[0]) ^= *((u32int*)&b[0]);
+		*((u32int*)&t[4]) ^= *((u32int*)&m[4]);
+		*((u32int*)&m[4]) ^= *((u32int*)&b[4]);
+		*((u32int*)&t[8]) ^= *((u32int*)&m[8]);
+		*((u32int*)&m[8]) ^= *((u32int*)&b[8]);
+		*((u32int*)&t[12]) ^= *((u32int*)&m[12]);
+		*((u32int*)&m[12]) ^= *((u32int*)&b[12]);
+
+		aes_encrypt(s->ekey, s->rounds, t, t);
+	}
+	if(lm > 0){
+		for(p = sblock(L, N, i, b, s), x = t; p < &b[lm]; x++, m++, p++){
+			*x ^= *m;
+			*m ^= *p;
+		}
+		aes_encrypt(s->ekey, s->rounds, t, t);
+	}
+
+	for(p = sblock(L, N, 0, b, s), x = t; p < &b[M]; x++, p++)
+		*x ^= *p;
+
+	memmove(m, t, M);
+}
+
+int
+aesCCMdecrypt(int L, int M, uchar *N /* N[15-L] */,
+	uchar *a /* a[la] */, int la,
+	uchar *m /* m[lm+M] */, int lm,
+	AESstate *s)
+{
+	uchar t[16], b[16], *p, *x;
+	uint i;
+
+	xblock(L, M, N, a, la, lm, t, s);
+
+	for(i = 1; lm >= 16; i++, m += 16, lm -= 16){
+		sblock(L, N, i, b, s);
+
+		*((u32int*)&m[0]) ^= *((u32int*)&b[0]);
+		*((u32int*)&t[0]) ^= *((u32int*)&m[0]);
+		*((u32int*)&m[4]) ^= *((u32int*)&b[4]);
+		*((u32int*)&t[4]) ^= *((u32int*)&m[4]);
+		*((u32int*)&m[8]) ^= *((u32int*)&b[8]);
+		*((u32int*)&t[8]) ^= *((u32int*)&m[8]);
+		*((u32int*)&m[12]) ^= *((u32int*)&b[12]);
+		*((u32int*)&t[12]) ^= *((u32int*)&m[12]);
+
+		aes_encrypt(s->ekey, s->rounds, t, t);
+	}
+	if(lm > 0){
+		for(p = sblock(L, N, i, b, s), x = t; p < &b[lm]; x++, m++, p++){
+			*m ^= *p;
+			*x ^= *m;
+		}
+		aes_encrypt(s->ekey, s->rounds, t, t);
+	}
+
+	for(p = sblock(L, N, 0, b, s), x = t; p < &b[M]; x++, p++)
+		*x ^= *p;
+
+	return memcmp(m, t, M) != 0;
+}
--- /sys/src/libsec/port/mkfile	Thu May 15 00:45:59 2014
+++ /sys/src/libsec/port/mkfile	Thu May 15 00:45:59 2014
@@ -3,7 +3,7 @@
 LIB=/$objtype/lib/libsec.a
 
 CFILES = des.c desmodes.c desECB.c desCBC.c des3ECB.c des3CBC.c\
-	aes.c blowfish.c \
+	aes.c aesccm blowfish.c \
 	hmac.c md5.c md5block.c md4.c sha1.c sha1block.c\
 	sha2_64.c sha2_128.c sha2block64.c sha2block128.c\
 	sha1pickle.c md5pickle.c\
--- /sys/include/libsec.h	Thu May 15 00:45:59 2014
+++ /sys/include/libsec.h	Thu May 15 00:45:59 2014
@@ -41,6 +41,9 @@
 void	aesCTRdecrypt(uchar *p, int len, AESstate *s);
 void	aesCTRencrypt(uchar *p, int len, AESstate *s);
 
+void	aesCCMencrypt(int, int, uchar*, uchar *, int, uchar*, int, AESstate*);
+int	aesCCMdecrypt(int, int, uchar*, uchar *, int, uchar*, int, AESstate*);
+
 void	setupAESXCBCstate(AESstate *s);
 uchar*	aesXCBCmac(uchar *p, int len, AESstate *s);