devfs crypto code - alpha version

2 files changed, 70 insertions, 0 deletions

diff --git a/sys/src/libsec/port/aes_xts.c b/sys/src/libsec/port/aes_xts.c
new file mode 100644
index 000000000..f200e4db2
--- /dev/null
+++ b/sys/src/libsec/port/aes_xts.c
@@ -0,0 +1,69 @@
+// Author Taru Karttunen <taruti@taruti.net>
+// This file can be used as both Public Domain or Creative Commons CC0.
+#include <u.h>
+#include <libsec.h>
+
+#define AesBlockSize 16
+
+static void xor128(uchar* o,uchar* i1,uchar* i2) {
+	((ulong*)o)[0] = ((ulong*)i1)[0] ^ ((ulong*)i2)[0];
+	((ulong*)o)[1] = ((ulong*)i1)[1] ^ ((ulong*)i2)[1];
+	((ulong*)o)[2] = ((ulong*)i1)[2] ^ ((ulong*)i2)[2];
+	((ulong*)o)[3] = ((ulong*)i1)[3] ^ ((ulong*)i2)[3];
+}
+
+static void gf_mulx(uchar* x) {
+    ulong t = ((((ulong*)(x))[3] & 0x80000000u) ? 0x00000087u : 0);;
+    ((ulong*)(x))[3] = (((ulong*)(x))[3] << 1) | (((ulong*)(x))[2] & 0x80000000u ? 1 : 0);
+    ((ulong*)(x))[2] = (((ulong*)(x))[2] << 1) | (((ulong*)(x))[1] & 0x80000000u ? 1 : 0);
+    ((ulong*)(x))[1] = (((ulong*)(x))[1] << 1) | (((ulong*)(x))[0] & 0x80000000u ? 1 : 0);
+    ((ulong*)(x))[0] = (((ulong*)(x))[0] << 1) ^ t;
+
+}
+
+int aes_xts_encrypt(ulong tweak[], ulong ecb[],  vlong sectorNumber, uchar *input, uchar *output, ulong len) {
+	uchar T[16], x[16];
+	int i;
+	
+	if(len % 16 != 0)
+		return -1;
+
+	for(i=0; i<AesBlockSize; i++) {
+		T[i] = (uchar)(sectorNumber & 0xFF);
+		sectorNumber = sectorNumber >> 8;
+	}
+	
+	aes_encrypt(tweak, 10, T, T);
+
+	for (i=0; i<len; i+=AesBlockSize) {
+		xor128(&x[0], &input[i], &T[0]);
+		aes_encrypt(ecb, 10, x, x);
+		xor128(&output[i], &x[0], &T[0]);
+		gf_mulx(&T[0]);
+	}
+	return 0;
+}
+
+int aes_xts_decrypt(ulong tweak[], ulong ecb[], vlong sectorNumber, uchar *input, uchar *output, ulong len) {
+	uchar T[16], x[16];
+	int i;
+	
+	if(len % 16 != 0)
+		return -1;
+
+	for(i=0; i<AesBlockSize; i++) {
+		T[i] = (uchar)(sectorNumber & 0xFF);
+		sectorNumber = sectorNumber >> 8;
+	}
+	
+	aes_encrypt(tweak, 10, T, T);
+
+	for (i=0; i<len; i+=AesBlockSize) {
+		xor128(&x[0], &input[i], &T[0]);
+		aes_decrypt(ecb, 10, x, x);
+		xor128(&output[i], &x[0], &T[0]);
+		gf_mulx(&T[0]);
+	}
+	return 0;
+}
+
diff --git a/sys/src/libsec/port/mkfile b/sys/src/libsec/port/mkfile
index 41d1f0c78..b14df90a4 100644
--- a/sys/src/libsec/port/mkfile
+++ b/sys/src/libsec/port/mkfile
@@ -17,6 +17,7 @@ CFILES = des.c desmodes.c desECB.c desCBC.c des3ECB.c des3CBC.c\
 	egsign.c egverify.c \
 	dsagen.c dsaalloc.c dsaprivtopub.c dsasign.c dsaverify.c \
 	tlshand.c thumb.c readcert.c \
+	aes_xts.c  \
 
 ALLOFILES=${CFILES:%.c=%.$O}