auth: release dp9ik implementation and reentrant factotum

1 files changed, 40 insertions, 0 deletions

diff --git a/sys/src/libauthsrv/edwards.mp b/sys/src/libauthsrv/edwards.mp
new file mode 100644
index 000000000..33305b71a
--- /dev/null
+++ b/sys/src/libauthsrv/edwards.mp
@@ -0,0 +1,40 @@
+# Edwards curve arithmetic
+edwards_add(p,a,d, X1,Y1,Z1,T1, X2,Y2,Z2,T2, X3,Y3,Z3,T3) mod(p) {
+	A = X1*X2;
+	B = Y1*Y2;
+	C = d*T1*T2;
+	D = Z1*Z2;
+	E = (X1+Y1)*(X2+Y2);
+	E = E - A - B;
+	F = D - C;
+	G = D + C;
+	H = B - a*A;
+	X3 = E*F;
+	Y3 = G*H;
+	Z3 = F*G;
+	T3 = E*H;
+}
+edwards_sel(s, X1,Y1,Z1,T1, X2,Y2,Z2,T2, X3,Y3,Z3,T3){
+	X3 = s != 0 ? X1 : X2;
+	Y3 = s != 0 ? Y1 : Y2;
+	Z3 = s != 0 ? Z1 : Z2;
+	T3 = s != 0 ? T1 : T2;
+}
+edwards_new(x,y,z,t, X,Y,Z,T) {
+	X = x;
+	Y = y;
+	Z = z;
+	T = t;
+}
+edwards_scale(p,a,d, s, X1,Y1,Z1,T1, X3,Y3,Z3,T3) {
+	X2,Y2,Z2,T2 = edwards_new(X1,Y1,Z1,T1);
+	X4,Y4,Z4,T4 = edwards_new( 0, 1, 1, 0);
+	X3,Y3,Z3,T3 = edwards_sel(s % 2, X2,Y2,Z2,T2, X4,Y4,Z4,T4);
+	k = s >> 1; j = p >> 1;
+	while(j != 0){
+		X2,Y2,Z2,T2 = edwards_add(p,a,d, X2,Y2,Z2,T2, X2,Y2,Z2,T2);
+		X4,Y4,Z4,T4 = edwards_add(p,a,d, X2,Y2,Z2,T2, X3,Y3,Z3,T3);
+		X3,Y3,Z3,T3 = edwards_sel(k % 2, X4,Y4,Z4,T4, X3,Y3,Z3,T3);
+		k = k >> 1; j = j >> 1;
+	}
+}