Des (#4172)

* Update directory

* Add DES Encryption algorithm

* Update directory

---------

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

src/test/java/com/thealgorithms/ciphers/DESTest.java

@@ -0,0 +1,51 @@
+package com.thealgorithms.ciphers;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+//Test example taken from https://page.math.tu-berlin.de/~kant/teaching/hess/krypto-ws2006/des.htm
+public class DESTest {
+
+    DES des;
+
+    @BeforeEach
+    public void setUp() {
+        des = new DES("0000111000110010100100100011001011101010011011010000110101110011");
+    }
+
+    @Test
+    void testEncrypt() {
+        //given
+        String plainText = "Your lips are smoother than vaseline\r\n";
+        //This is equal to c0999fdde378d7ed727da00bca5a84ee47f269a4d6438190d9d52f78f5358499828ac9b453e0e653 in hexadecimal
+        String expectedOutput = "11000000100110011001111111011101111000110111100011010111111" +
+        "011010111001001111101101000000000101111001010010110101000010011101110010001111111001" +
+        "001101001101001001101011001000011100000011001000011011001110101010010111101111000111" +
+        "101010011010110000100100110011000001010001010110010011011010001010011111000001110011001010011";
+
+        //when
+        String cipherText = des.encrypt(plainText);
+
+        //then
+        assertEquals(expectedOutput, cipherText);
+    }
+
+    @Test
+    void testDecrypt() {
+        //given
+       //This is equal to c0999fdde378d7ed727da00bca5a84ee47f269a4d6438190d9d52f78f5358499828ac9b453e0e653 in hexadecimal
+       String cipherText = "11000000100110011001111111011101111000110111100011010111111" +
+       "011010111001001111101101000000000101111001010010110101000010011101110010001111111001" +
+       "001101001101001001101011001000011100000011001000011011001110101010010111101111000111" +
+       "101010011010110000100100110011000001010001010110010011011010001010011111000001110011001010011";
+        String expectedOutput = "Your lips are smoother than vaseline\r\n";;
+
+        //when
+        String plainText = des.decrypt(cipherText);
+
+        //then
+        assertEquals(expectedOutput, plainText);
+    }
+}