Add files via upload

Project3-main/Project3/src/module-info.java

@@ -0,0 +1,2 @@
+module Project3 {
+}

Project3-main/Project3/src/v1/Person.java

@@ -0,0 +1,51 @@
+package v1;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+/**
+ * 
+ * @author Matt Abrams
+ * 
+ * A class that encrypts a message using RSA and with 2 character blocks
+ *
+ */
+public class Person {
+
+	long e;
+	long m;
+	long d;
+
+
+	public Person() {
+		int p = RSA.randomPrime(256, 65536);
+		int q = RSA.randomPrime(256,  65536);
+		m = p * q;
+		long n = (p-1) * (q-1);
+		e = RSA.relPrime(n);
+		d = RSA.getInverse(e, n);
+	}
+
+	public long[] encryptTo(String msg, Person recipient) {
+		ArrayList<Long> cipher = new ArrayList<Long>();
+		char[] msgArr = msg.toCharArray();
+		//Pad if necessary
+		if (msgArr.length % 2 != 0) {
+			msgArr = Arrays.copyOf(msgArr, msgArr.length + 1);
+		}
+		for (int i = 0; i < msgArr.length; i += 2) {
+			long textVal = RSA.toLong(msg, i);
+			cipher.add(RSA.power(textVal, e, m));
+		}
+		return cipher.stream().mapToLong(i -> i).toArray();
+	}
+
+	public String decrypt(long[] message) {
+		StringBuilder msg = new StringBuilder();
+		for (long block : message) {  
+			long decryptBlock = RSA.power(block, d, m);
+			msg.append(RSA.longTo2Chars(decryptBlock));
+		}
+		return msg.toString();
+
+	}
+}

Project3-main/Project3/src/v1/RSA.java

@@ -0,0 +1,128 @@
+package v1;
+import java.util.*;
+
+public class RSA {
+
+	public static final String DELIMITER = "00";
+
+	public static void main (String args[]) {
+		Person Alice = new Person();
+		Person Bob = new Person();
+
+		String msg = "Bob, let's have lunch";
+		long[] cipher = Alice.encryptTo(msg, Bob);
+
+		System.out.println("Message is: " + msg);
+		System.out.println("Alice sends:");
+		show(cipher);
+
+		System.out.println("Bob decodes and reads: " + Bob.decrypt(cipher));
+
+		System.out.println();
+	}
+
+	public static long getInverse(long n, long m){
+		for (long k = 1; k < m; k++) { 
+	        if (((n%m) * (k%m)) % m == 1) { 
+	            return k;
+	        }
+		}
+		return -1;
+	}
+
+	/* @author Riley Miller
+	 * @param  a base value, a power for that base, and a mod value
+	 * @return the result of the equation
+	 */
+
+	public static long power(long base, long power, long mod) {
+		if (mod == 1)
+			return 0;
+
+		long result = 1;
+		base = base % mod;
+
+		while (power > 0)
+		{
+			if (power % 2 == 1)
+				result = (result * base) % mod;
+
+			power/=2;
+			base = (base*base)%mod;
+		}
+		return result;
+	}
+
+	/*  @author Riley Miller
+	 * 	@param minimum value and maximum value for the random number
+	 *  @return a random prime number
+	 */
+	public static long randomPrime(long min, long max) {
+		Random random = new Random();
+		long randNum;
+		boolean done = false;
+
+		do {
+			randNum = (long)(random.nextDouble() * (max-min + 1)) + min;
+			for (int i = 2; i < max; i++)
+			{
+				if (randNum % i == 0)
+					done = true;
+			}
+		} while (!done)
+
+		return randNum;
+	}
+
+	static long relPrime(long n) {
+
+		Random random = new Random();
+		long candidate;
+
+		do {
+			candidate = random.nextLong() % n;
+			//Handle negatives
+			if (candidate < n) {
+				candidate += n;
+			}
+		} while (gcd(candidate, n) != 1) ;
+
+		return candidate;
+	}
+
+	private static long  gcd(long a, long b) {
+		while (b != 0) {
+			long temp = b;
+			b = a % b;
+			a = temp;
+		}
+		return a;
+	}
+
+	static long toLong(String msg, int p) {
+		if (p > msg.length() - 2) {
+			return 0;
+		}
+		char[] msgArr = msg.toCharArray(); 
+		String concat = (int) msgArr[p] +  DELIMITER + (int) msgArr[p+1];
+		return (long) Integer.parseInt(concat);
+	}
+
+	static String longTo2Chars(long x) {
+		String[] charStrings = Long.toString(x).split(DELIMITER);
+		StringBuilder result = new StringBuilder();
+		for (String charString : charStrings) {
+			char msg = (char) Integer.parseInt(charString);
+			result.append(msg);
+		}
+		return result.toString();
+	}
+
+	static void show(long[] cipher) {
+		System.out.print("[ ");
+		for (long val: cipher) {
+			System.out.print(val + " ");
+		}
+		System.out.print("\b]");
+	}
+}