diff --git a/DIRECTORY.md b/DIRECTORY.md index fb49d163e..6f246ff12 100644 --- a/DIRECTORY.md +++ b/DIRECTORY.md @@ -30,6 +30,7 @@ * [Blowfish](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/Blowfish.java) * [Caesar](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/Caesar.java) * [ColumnarTranspositionCipher](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/ColumnarTranspositionCipher.java) + * [DES](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/DES.java) * [HillCipher](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/HillCipher.java) * [Polybius](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/Polybius.java) * [ProductCipher](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/ciphers/ProductCipher.java) @@ -151,14 +152,15 @@ * [AVLSimple](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/AVLSimple.java) * [AVLTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/AVLTree.java) * [BinaryTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/BinaryTree.java) + * [BSTFromSortedArray](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/BSTFromSortedArray.java) * [BSTIterative](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/BSTIterative.java) * [BSTRecursive](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/BSTRecursive.java) * [BSTRecursiveGeneric](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/BSTRecursiveGeneric.java) * [CeilInBinarySearchTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CeilInBinarySearchTree.java) + * [CheckBinaryTreeIsValidBST](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CheckBinaryTreeIsValidBST.java) * [CheckIfBinaryTreeBalanced](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CheckIfBinaryTreeBalanced.java) * [CheckTreeIsSymmetric](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CheckTreeIsSymmetric.java) * [CreateBinaryTreeFromInorderPreorder](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CreateBinaryTreeFromInorderPreorder.java) - * [CreateBSTFromSortedArray](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/CreateBSTFromSortedArray.java) * [FenwickTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/FenwickTree.java) * [GenericTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/GenericTree.java) * [InorderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/InorderTraversal.java) @@ -166,7 +168,6 @@ * [LazySegmentTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/LazySegmentTree.java) * [LCA](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/LCA.java) * [LevelOrderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/LevelOrderTraversal.java) - * [LevelOrderTraversalHelper](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/LevelOrderTraversalHelper.java) * [nearestRightKey](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/nearestRightKey.java) * [PostOrderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/PostOrderTraversal.java) * [PreOrderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/PreOrderTraversal.java) @@ -175,9 +176,7 @@ * [SameTreesCheck](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/SameTreesCheck.java) * [SegmentTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/SegmentTree.java) * [TreeRandomNode](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/TreeRandomNode.java) - * [TreeTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/TreeTraversal.java) * [TrieImp](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/TrieImp.java) - * [ValidBSTOrNot](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/ValidBSTOrNot.java) * [VerticalOrderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/VerticalOrderTraversal.java) * [ZigzagTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/ZigzagTraversal.java) * devutils @@ -202,6 +201,7 @@ * [BoundaryFill](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/BoundaryFill.java) * [BruteForceKnapsack](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/BruteForceKnapsack.java) * [CatalanNumber](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/CatalanNumber.java) + * [ClimbingStairs](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/ClimbingStairs.java) * [CoinChange](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/CoinChange.java) * [CountFriendsPairing](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/CountFriendsPairing.java) * [DiceThrow](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/dynamicprogramming/DiceThrow.java) @@ -382,6 +382,7 @@ * [KochSnowflake](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/KochSnowflake.java) * [Krishnamurthy](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/Krishnamurthy.java) * [LinearCongruentialGenerator](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/LinearCongruentialGenerator.java) + * [LineSweep](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/LineSweep.java) * [LowestBasePalindrome](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/LowestBasePalindrome.java) * [Luhn](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/Luhn.java) * [Mandelbrot](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/Mandelbrot.java) @@ -403,7 +404,6 @@ * [StackPostfixNotation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/StackPostfixNotation.java) * [StringMatchFiniteAutomata](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java) * [Sudoku](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/Sudoku.java) - * [ThreeSum](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/ThreeSum.java) * [TopKWords](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/TopKWords.java) * [TowerOfHanoi](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/TowerOfHanoi.java) * [TwoPointers](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/TwoPointers.java) @@ -526,6 +526,7 @@ * [LFSRTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/a5/LFSRTest.java) * [BlowfishTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/BlowfishTest.java) * [CaesarTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/CaesarTest.java) + * [DESTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/DESTest.java) * [PolybiusTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/PolybiusTest.java) * [RSATest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/RSATest.java) * [SimpleSubCipherTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/SimpleSubCipherTest.java) @@ -575,7 +576,10 @@ * [PriorityQueuesTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java) * trees * [BinaryTreeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/BinaryTreeTest.java) + * [BSTFromSortedArrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/BSTFromSortedArrayTest.java) + * [BSTIterativeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/BSTIterativeTest.java) * [CeilInBinarySearchTreeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/CeilInBinarySearchTreeTest.java) + * [CheckBinaryTreeIsValidBSTTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/CheckBinaryTreeIsValidBSTTest.java) * [CheckTreeIsSymmetricTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/CheckTreeIsSymmetricTest.java) * [InorderTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/InorderTraversalTest.java) * [KDTreeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/KDTreeTest.java) @@ -585,7 +589,6 @@ * [PreOrderTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/PreOrderTraversalTest.java) * [SameTreesCheckTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/SameTreesCheckTest.java) * [TreeTestUtils](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/TreeTestUtils.java) - * [ValidBSTOrNotTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/ValidBSTOrNotTest.java) * [VerticalOrderTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/VerticalOrderTraversalTest.java) * [ZigzagTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/ZigzagTraversalTest.java) * divideandconquer @@ -593,6 +596,7 @@ * [StrassenMatrixMultiplicationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/divideandconquer/StrassenMatrixMultiplicationTest.java) * dynamicprogramming * [CatalanNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/CatalanNumberTest.java) + * [climbStairsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/climbStairsTest.java) * [EggDroppingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/EggDroppingTest.java) * [KnapsackMemoizationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/KnapsackMemoizationTest.java) * [LevenshteinDistanceTests](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/dynamicprogramming/LevenshteinDistanceTests.java) @@ -674,6 +678,7 @@ * [CRCAlgorithmTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/CRCAlgorithmTest.java) * [FirstFitCPUTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/FirstFitCPUTest.java) * [KadaneAlogrithmTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/KadaneAlogrithmTest.java) + * [LineSweepTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/LineSweepTest.java) * [LinkListSortTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/LinkListSortTest.java) * [NewManShanksPrimeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/NewManShanksPrimeTest.java) * [NextFitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/NextFitTest.java) @@ -731,6 +736,7 @@ * [CheckAnagramsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CheckAnagramsTest.java) * [CheckVowelsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java) * [HammingDistanceTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/HammingDistanceTest.java) + * [HorspoolSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/HorspoolSearchTest.java) * [IsomorphicTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/IsomorphicTest.java) * [LetterCombinationsOfPhoneNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LetterCombinationsOfPhoneNumberTest.java) * [longestNonRepeativeSubstringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/longestNonRepeativeSubstringTest.java) diff --git a/src/main/java/com/thealgorithms/ciphers/DES.java b/src/main/java/com/thealgorithms/ciphers/DES.java new file mode 100644 index 000000000..8b226e284 --- /dev/null +++ b/src/main/java/com/thealgorithms/ciphers/DES.java @@ -0,0 +1,344 @@ +package com.thealgorithms.ciphers; + +/** + * This class is build to demonstrate the application of the DES-algorithm on a + * plain English message. The supplied key must be in form of a 64 bit binary String. + */ +public class DES { + + private String key; + private String subKeys[]; + + private void sanitize(String key) { + int length = key.length(); + if (length != 64) { + throw new IllegalArgumentException("DES key must be supplied as a 64 character binary string"); + } + } + + DES(String key) { + sanitize(key); + this.key = key; + subKeys = getSubkeys(key); + } + + public String getKey() { + return this.key; + } + + public void setKey(String key) { + sanitize(key); + this.key = key; + } + + //Permutation table to convert initial 64 bit key to 56 bit key + private static int[] PC1 = + { + 57, 49, 41, 33, 25, 17, 9, + 1, 58, 50, 42, 34, 26, 18, + 10, 2, 59, 51, 43, 35, 27, + 19, 11, 3, 60, 52, 44, 36, + 63, 55, 47, 39, 31, 23, 15, + 7, 62, 54, 46, 38, 30, 22, + 14, 6, 61, 53, 45, 37, 29, + 21, 13, 5, 28, 20, 12, 4 + }; + + //Lookup table used to shift the initial key, in order to generate the subkeys + private static int[] KEY_SHIFTS = + { + 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 + }; + + //Table to convert the 56 bit subkeys to 48 bit subkeys + private static int[] PC2 = + { + 14, 17, 11, 24, 1, 5, + 3, 28, 15, 6, 21, 10, + 23, 19, 12, 4, 26, 8, + 16, 7, 27, 20, 13, 2, + 41, 52, 31, 37, 47, 55, + 30, 40, 51, 45, 33, 48, + 44, 49, 39, 56, 34, 53, + 46, 42, 50, 36, 29, 32 + }; + + //Initial permutatation of each 64 but message block + private static int[] IP = + { + 58, 50, 42, 34, 26, 18, 10 , 2, + 60, 52, 44, 36, 28, 20, 12, 4, + 62, 54, 46, 38, 30, 22, 14, 6, + 64, 56, 48, 40, 32, 24, 16, 8, + 57, 49, 41, 33, 25, 17, 9, 1, + 59, 51, 43, 35, 27, 19, 11, 3, + 61, 53, 45, 37, 29, 21, 13, 5, + 63, 55, 47, 39, 31, 23, 15, 7 + }; + + //Expansion table to convert right half of message blocks from 32 bits to 48 bits + private static int[] expansion = + { + 32, 1, 2, 3, 4, 5, + 4, 5, 6, 7, 8, 9, + 8, 9, 10, 11, 12, 13, + 12, 13, 14, 15, 16, 17, + 16, 17, 18, 19, 20, 21, + 20, 21, 22, 23, 24, 25, + 24, 25, 26, 27, 28, 29, + 28, 29, 30, 31, 32, 1 + }; + + //The eight substitution boxes are defined below + private static int[][] s1 = { + {14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7}, + {0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8}, + {4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0}, + {15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13} + }; + + private static int[][] s2 = { + {15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10}, + {3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5}, + {0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15}, + {13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9} + }; + + private static int[][] s3 = { + {10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8}, + {13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1}, + {13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7}, + {1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12} + }; + + private static int[][] s4 = { + {7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15}, + {13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9}, + {10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4}, + {3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14} + }; + + private static int[][] s5 = { + {2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9}, + {14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6}, + {4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14}, + {11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3} + }; + + private static int[][] s6 = { + {12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11}, + {10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8}, + {9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6}, + {4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13} + }; + + private static int[][] s7 = { + {4, 11, 2, 14, 15, 0, 8, 13 , 3, 12, 9 , 7, 5, 10, 6, 1}, + {13 , 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6}, + {1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2}, + {6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12} + }; + + private static int[][] s8 = { + {13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7}, + {1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6 ,11, 0, 14, 9, 2}, + {7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10 ,13, 15, 3, 5, 8}, + {2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6 ,11} + }; + + private static int[][][] s = {s1, s2, s3, s4, s5, s6, s7, s8}; + + //Permutation table, used in the feistel function post s-box usage + static int[] permutation = + { + 16, 7, 20, 21, + 29, 12, 28, 17, + 1, 15, 23, 26, + 5, 18, 31, 10, + 2, 8, 24, 14, + 32, 27, 3, 9, + 19, 13, 30, 6, + 22, 11, 4, 25 + }; + + //Table used for final inversion of the message box after 16 rounds of Feistel Function + static int[] IPinverse = + { + 40, 8, 48, 16, 56, 24, 64, 32, + 39, 7, 47, 15, 55, 23, 63, 31, + 38, 6, 46, 14, 54, 22, 62, 30, + 37, 5, 45, 13, 53, 21, 61, 29, + 36, 4, 44, 12, 52, 20, 60, 28, + 35, 3, 43 ,11, 51, 19, 59, 27, + 34, 2, 42, 10, 50, 18, 58, 26, + 33, 1, 41, 9, 49, 17, 57, 25 + }; + + private String[] getSubkeys(String originalKey) { + StringBuilder permutedKey = new StringBuilder(); //Initial permutation of keys via PC1 + int i, j; + for (i = 0; i < 56; i++) { + permutedKey.append(originalKey.charAt(PC1[i] - 1)); + } + String subKeys[] = new String[16]; + String initialPermutedKey = permutedKey.toString(); + String C0 = initialPermutedKey.substring(0, 28), D0 = initialPermutedKey.substring(28); + + //We will now operate on the left and right halves of the permutedKey + for (i = 0; i < 16; i++) { + String Cn = C0.substring(KEY_SHIFTS[i]) + C0.substring(0, KEY_SHIFTS[i]); + String Dn = D0.substring(KEY_SHIFTS[i]) + D0.substring(0, KEY_SHIFTS[i]); + subKeys[i] = Cn + Dn; + C0 = Cn; //Re-assign the values to create running permutation + D0 = Dn; + } + + //Let us shrink the keys to 48 bits (well, characters here) using PC2 + for (i = 0; i < 16; i++) { + String key = subKeys[i]; + permutedKey.setLength(0); + for (j = 0; j < 48; j++) { + permutedKey.append(key.charAt(PC2[j] - 1)); + } + subKeys[i] = permutedKey.toString(); + } + + return subKeys; + } + + private String XOR(String a, String b) { + int i, l = a.length(); + StringBuilder xor = new StringBuilder(); + for (i = 0; i < l; i++) { + int firstBit = a.charAt(i) - 48; // 48 is '0' in ascii + int secondBit = b.charAt(i) - 48; + xor.append((firstBit ^ secondBit)); + } + return xor.toString(); + } + + private String createPaddedString(String s, int desiredLength, char pad) { + int i, l = s.length(); + StringBuilder paddedString = new StringBuilder(); + int diff = desiredLength - l; + for (i = 0; i < diff; i++) { + paddedString.append(pad); + } + return paddedString.toString(); + } + + private String pad(String s, int desiredLength) { + return createPaddedString(s, desiredLength, '0') + s; + } + + private String padLast(String s, int desiredLength) { + return s + createPaddedString(s, desiredLength, '\u0000'); + } + + private String feistel(String messageBlock, String key) { + int i; + StringBuilder expandedKey = new StringBuilder(); + for (i = 0; i < 48; i++) { + expandedKey.append(messageBlock.charAt(expansion[i] - 1)); + } + String mixedKey = XOR(expandedKey.toString(), key); + StringBuilder substitutedString = new StringBuilder(); + + //Let us now use the s-boxes to transform each 6 bit (length here) block to 4 bits + for (i = 0; i < 48; i += 6) { + String block = mixedKey.substring(i, i + 6); + int row = (block.charAt(0) - 48) * 2 + (block.charAt(5) - 48); + int col = (block.charAt(1) - 48) * 8 + (block.charAt(2) - 48) * 4 + (block.charAt(3) - 48) * 2 + (block.charAt(4) - 48); + String substitutedBlock = pad(Integer.toBinaryString(s[i / 6][row][col]), 4); + substitutedString.append(substitutedBlock); + } + + StringBuilder permutedString = new StringBuilder(); + for (i = 0; i < 32; i++) { + permutedString.append(substitutedString.charAt(permutation[i] - 1)); + } + + return permutedString.toString(); + } + + private String encryptBlock(String message, String keys[]) { + StringBuilder permutedMessage = new StringBuilder(); + int i; + for (i = 0; i < 64; i++) { + permutedMessage.append(message.charAt(IP[i] - 1)); + } + String L0 = permutedMessage.substring(0, 32), R0 = permutedMessage.substring(32); + + //Iterate 16 times + for (i = 0; i < 16; i++) { + String Ln = R0; // Previous Right block + String Rn = XOR(L0, feistel(R0, keys[i])); + L0 = Ln; + R0 = Rn; + } + + String combinedBlock = R0 + L0; //Reverse the 16th block + permutedMessage.setLength(0); + for (i = 0; i < 64; i++) { + permutedMessage.append(combinedBlock.charAt(IPinverse[i] - 1)); + } + return permutedMessage.toString(); + } + + //To decode, we follow the same process as encoding, but with reversed keys + private String decryptBlock(String message, String keys[]) { + String reversedKeys[] = new String[keys.length]; + for (int i = 0; i < keys.length; i++) { + reversedKeys[i] = keys[keys.length - i - 1]; + } + return encryptBlock(message, reversedKeys); + } + + /** + * @param message Message to be encrypted + * @return The encrypted message, as a binary string + */ + public String encrypt(String message) { + StringBuilder encryptedMessage = new StringBuilder(); + int l = message.length(), i, j; + if (l % 8 != 0) { + int desiredLength = (l / 8 + 1) * 8; + l = desiredLength; + message = padLast(message, desiredLength); + } + + for (i = 0; i < l; i+= 8) { + String block = message.substring(i, i + 8); + StringBuilder bitBlock = new StringBuilder(); + byte[] bytes = block.getBytes(); + for (j = 0; j < 8; j++) { + bitBlock.append(pad(Integer.toBinaryString(bytes[j]), 8)); + } + encryptedMessage.append(encryptBlock(bitBlock.toString(), subKeys)); + } + return encryptedMessage.toString(); + } + + /** + * @param message The encrypted string. Expects it to be a multiple of 64 bits, in binary format + * @return The decrypted String, in plain English + */ + public String decrypt(String message) { + StringBuilder decryptedMessage = new StringBuilder(); + int l = message.length(), i, j; + if (l % 64 != 0) { + throw new IllegalArgumentException("Encrypted message should be a multiple of 64 characters in length"); + } + for (i = 0; i < l; i+= 64) { + String block = message.substring(i, i + 64); + String result = decryptBlock(block.toString(), subKeys); + byte res[] = new byte[8]; + for (j = 0; j < 64; j+=8) { + res[j / 8] = (byte)Integer.parseInt(result.substring(j, j + 8), 2); + } + decryptedMessage.append(new String(res)); + } + return decryptedMessage.toString().replace("\0", ""); // Get rid of the null bytes used for padding + } + +} \ No newline at end of file diff --git a/src/test/java/com/thealgorithms/ciphers/DESTest.java b/src/test/java/com/thealgorithms/ciphers/DESTest.java new file mode 100644 index 000000000..a0c529d5f --- /dev/null +++ b/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); + } +}