First iteration sha256

circuits/sha256/maj.circom

@@ -0,0 +1,25 @@
+/* Maj function for sha256
+
+out = a&b ^ a&c ^ b&c  =>
+
+out = a*b   +  a*c  +  b*c  -  2*a*b*c  =>
+
+out = a*( b + c - 2*b*c ) + b*c =>
+
+mid = b*c
+out = a*( b + c - 2*mid ) + mid
+
+*/
+
+template Maj(n) {
+    signal input a[n];
+    signal input b[n];
+    signal input c[n];
+    signal output out[n];
+    signal mid[n];
+
+    for (var k=0; k<n; k++) {
+        mid[k] <== b[k]*c[k];
+        out[k] <== a[k] * (b[k]+c[k]-2*mid[k]) + mid[k];
+    }
+}