Merge branch 'master' of ssh://gitlab.hasufell.de:22022/Goldi/quantumcrypto

Fixed .gitignore with .project

.gitignore

@@ -20,4 +20,6 @@ latex/
 src/main.c
 src/main
 
-./.settings/org.eclipse*
+./.settings/org.eclipse*
+
+.project

.project

@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>Semesterprojekt2014</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-	</buildSpec>
-	<natures>
-	</natures>
-</projectDescription>

src/ntru_decrypt.c

@@ -19,6 +19,49 @@
  * MA  02110-1301  USA
  */
 
+#include "ntru_decrypt.h"
+
+/*
+ * Legend
+ *
+ * N : highest degree of the polynom
+ * q : "is given" (... mod q)
+ * p : "is given" (... mod p)
+ * f : private key
+ * Fp: inverse of "modulo p"
+ * e : encrypted message
+ * a : result of first multiplication (StarMultiply(f, e, a, N, q))
+ * d : result of second multiplication (StarMultiply(a, Fp , d, N, p)), decrypted message
+ * */
+
+// Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
-	return 0;
+	// toDo q = ?, p = ?, fp = ?
+
+	pb_poly *a = first_multiply(private_key, encr_msg, q);// StarMultiply(f, e, a, N, q)
+
+	for(int i = 0, i < N, i++){
+		if(a[i] < 0 ) {
+			a[i] = a[i] + q; // Make all coefficients positive
+		}
+		if(a[i] > q/2) {
+			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
+		}
+	}
+	char* d = second_multiply(a, fp, p)// StarMultiply(a, Fp , d, N, p)
+
+	// {Decode returns the decrypted message, d, through the argument list.}
+	return d;
+}
+
+// toDo fix header file definition and types if needed!
+pb_poly* first_multiply(pb_poly *private_key, char *encr_msg, int q) {
+	// toDo a= f*e mod q
+	return NULL;
+}
+
+// toDo fix header file definition and types if needed!
+char* second_multiply(pb_poly *a, pb_poly *fp, int p) {
+	//toDo a*Fp mod p
+	return NULL;
 }

src/ntru_decrypt.h

@@ -26,5 +26,7 @@
 #include "context.h"
 
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
+pb_poly* first_multiply(pb_poly*, char*, int);
+char* first_multiply(pb_poly*, pb_poly*, int);
 
 #endif /* NTRU_DECRYPT */