SimpleDES 算法 java 实现

SimpleDES是为讲解DES算法而简化了的算法。

算法文本说明请在正面链接下载

http://homepage.smc.edu/morgan_david/vpn/C-SDES.pdf

算法来自参考资料1，为方便学习，我加了注释说明。

将文件中的截图也上传上来，方便查看。

图1(Figure C.1 Simplified DES Scheme)：

图2(Figure C.2 Key Generation for Simplified DES)：

图3(Figure C.3 Simplified DES Encryption Detail)：

SimpleDESTest.java 代码如下：

import java.io.IOException;import java.util.Arrays;public class SimpleDESTest {// two keys K1 and K2static int K1 = 0;static int K2 = 0;/* some parameters */static int P10[] = new int[] { 3, 5, 2, 7, 4, 10, 1, 9, 8, 6 };static int P8[] = new int[] { 6, 3, 7, 4, 8, 5, 10, 9 };static int P4[] = new int[] { 2, 4, 3, 1 };static int IP[] = new int[] { 2, 6, 3, 1, 4, 8, 5, 7 };static int IPI[] = new int[] { 4, 1, 3, 5, 7, 2, 8, 6 };static int EP[] = new int[] { 4, 1, 2, 3, 2, 3, 4, 1 };static int S0[][] = { { 1, 0, 3, 2 }, { 3, 2, 1, 0 }, { 0, 2, 1, 3 },{ 3, 1, 3, 2 }, };static int S1[][] = { { 0, 1, 2, 3 }, { 2, 0, 1, 3 }, { 3, 0, 1, 0 },{ 2, 1, 0, 3 }, };// 根据数组交换static int Permute(int num, int p[], int pmax) {int result = 0;System.out.println("start Permute");System.out.println("num:" + Integer.toString(num, 2));System.out.println("p:" + Arrays.toString(p));System.out.println("pmax:" + Integer.toString(pmax, 2));for (int i = 0; i < p.length; i++) {result <<= 1;// System.out.println("" + i + ":result <<= 1," +// Integer.toString(result, 2) + "," + Integer.toString(p[i], 2));result |= (num >> (pmax - p[i])) & 1;// System.out.println("result |= (num >> (pmax - p[i])) & 1," +// Integer.toString(result, 2));}System.out.println("result:" + Integer.toString(result, 2));System.out.println("end Permute");return result;}// 生成k1,k2static void SDES(String Key) {int K = Integer.parseInt(Key, 2);System.out.println("start generate K1");K = Permute(K, P10, 10);System.out.println("K:" + Integer.toString(K, 2));int th = 0, tl = 0;th = (K >> 5) & 0x1f;// 取Key的高5位tl = K & 0x1f; // 取Key的低5位System.out.println("K top 5:" + Integer.toString(th, 2));System.out.println("K low 5:" + Integer.toString(tl, 2));// LS-1th = ((th & 0xf) << 1) | ((th & 0x10) >> 4);// 循环左移一位tl = ((tl & 0xf) << 1) | ((tl & 0x10) >> 4);// 循环左移一位System.out.println("K top 5 LS-1:" + Integer.toString(th, 2));System.out.println("K low 5 LS-1:" + Integer.toString(tl, 2));K1 = Permute((th << 5) | tl, P8, 10); // 生成K1System.out.println("K1:" + Integer.toString(K1, 2));System.out.println("end generate K1");System.out.println("start generate K2");// LS-2System.out.println("K top 5:" + Integer.toString(th, 2));System.out.println("K low 5:" + Integer.toString(tl, 2));th = ((th & 0x07) << 2) | ((th & 0x18) >> 3);// 循环左移二位tl = ((tl & 0x07) << 2) | ((tl & 0x18) >> 3);// 循环左移二位System.out.println("K top 5 LS-2:" + Integer.toString(th, 2));System.out.println("K low 5 LS-2:" + Integer.toString(tl, 2));K2 = Permute((th << 5) | tl, P8, 10); // 生成K2System.out.println("K2:" + Integer.toString(K2, 2));System.out.println("end generate K2");}// f函数static int F(int R, int K) {System.out.println("start F");System.out.println("R:" + Integer.toString(R, 2));System.out.println("K:" + Integer.toString(K, 2));int t = Permute(R, EP, 4) ^ K;System.out.println("Permute(R, EP, 4) ^ K:" + Integer.toString(t, 2));int t0 = (t >> 4) & 0xf;int t1 = t & 0xf;System.out.println("F top 4:" + Integer.toString(t0, 2));System.out.println("F low 4:" + Integer.toString(t1, 2));int x1 = ((t0 & 0x8) >> 2) | (t0 & 1);int y1 = (t0 >> 1) & 0x3;int x2 = ((t1 & 0x8) >> 2) | (t1 & 1);int y2 = (t1 >> 1) & 0x3;t0 = S0[x1][y1];t1 = S1[x2][y2];System.out.println("F top 4 S0[" + Integer.toString(x1, 2) + "]["+ Integer.toString(y1, 2) + "]:" + Integer.toString(t0, 2));System.out.println("F low 4 S1[" + Integer.toString(x2, 2) + "]["+ Integer.toString(y2, 2) + "]:" + Integer.toString(t1, 2));t = Permute((t0 << 2) | t1, P4, 4);System.out.println("Permute((t0 << 2) | t1, P4, 4):"+ Integer.toString(t, 2));System.out.println("end F");return t;}// fk函数static int fk(int input, int k) {System.out.println("input:" + Integer.toString(input, 2));System.out.println("k:" + Integer.toString(k, 2));int l = (input >> 4) & 0xf;int r = input & 0xf;System.out.println("fk top 4:" + Integer.toString(l, 2));System.out.println("fk low 4:" + Integer.toString(r, 2));return ((l ^ F(r, k)) << 4) | r;}// switch functionstatic int SW(int x) {return ((x & 0xf) << 4) | ((x >> 4) & 0xf);}// 加密static String encrypt(String input) {int m = Integer.parseInt(input, 2);m = Permute(m, IP, 8);System.out.println("Permute(m, IP, 8)=" + Integer.toString(m, 2));m = fk(m, K1);System.out.println("fk(m, K1)=" + Integer.toString(m, 2));m = SW(m);System.out.println("SW(m)=" + Integer.toString(m, 2));m = fk(m, K2);System.out.println("fk(m, K2)=" + Integer.toString(m, 2));m = Permute(m, IPI, 8);System.out.println("Permute(m, IPI, 8)=" + Integer.toString(m, 2));return Integer.toString(m, 2);}// 解密static String decrypt(String input) {int m = Integer.parseInt(input, 2);System.out.println("start IP");m = Permute(m, IP, 8);System.out.println("Permute(m, IP, 8)=" + Integer.toString(m, 2));System.out.println("end IP");System.out.println("start fk K2");m = fk(m, K2);System.out.println("fk(m, K2)=" + Integer.toString(m, 2));System.out.println("end fk K2");System.out.println("start SW");m = SW(m);System.out.println("SW(m)=" + Integer.toString(m, 2));System.out.println("end SW");System.out.println("start fk K1");m = fk(m, K1);System.out.println("fk(m, K1)=" + Integer.toString(m, 2));System.out.println("end fk K1");System.out.println("start IIP");m = Permute(m, IPI, 8);System.out.println("Permute(m, IPI, 8)=" + Integer.toString(m, 2));System.out.println("end IIP");System.out.println("end decrypt");return Integer.toString(m, 2);}public static void main(String[] args) throws IOException {String plaintext, ciphertext, key;java.util.Scanner scan = new java.util.Scanner(System.in);String command = "1:加密(encrypt),2:解密(decrypt),3:退出(exit),请输入一个数字来选择:";String inputPlainText = "请输入明文(8 bit plaintext):";String inputCipherText = "请输入密文(8 bit ciphertext):";String inputKey = "请输入密钥(10 bit key):";System.out.println(command);int mode = scan.nextInt();while (true) {if (mode == 1) {System.out.println(inputPlainText);plaintext = scan.next();System.out.println(inputKey);key = scan.next();SDES(key);ciphertext = encrypt(plaintext);// 如果密文不足8位，补足8位if (ciphertext.length() < 8) {for (int i = 0; i < 8 - ciphertext.length(); i++)ciphertext = "0" + ciphertext;}System.out.println("加密后的密文(8 bit ciphertext)为:" + ciphertext);} else if (mode == 2) {System.out.println(inputCipherText);ciphertext = scan.next();System.out.println(inputKey);key = scan.next();SDES(key);plaintext = decrypt(ciphertext);if (plaintext.length() < 8) {for (int i = 0; i < 8 - plaintext.length(); i++)plaintext = "0" + plaintext;}System.out.println("解密后的明文(8 bit plaintext)为:" + plaintext);} else if (mode == 3)break;System.out.println(command);mode = scan.nextInt();}}}

对密文10100010，密钥0111111101解密的过程如下：

1:加密(encrypt),2:解密(decrypt),3:退出(exit),请输入一个数字来选择:2请输入密文(8 bit ciphertext):10100010请输入密钥(10 bit key):0111111101start generate K1start Permutenum:111111101p:[3, 5, 2, 7, 4, 10, 1, 9, 8, 6]pmax:1010result:1111110011end PermuteK:1111110011K top 5:11111K low 5:10011K top 5 LS-1:11111K low 5 LS-1:111start Permutenum:1111100111p:[6, 3, 7, 4, 8, 5, 10, 9]pmax:1010result:1011111end PermuteK1:1011111end generate K1start generate K2K top 5:11111K low 5:111K top 5 LS-2:11111K low 5 LS-2:11100start Permutenum:1111111100p:[6, 3, 7, 4, 8, 5, 10, 9]pmax:1010result:11111100end PermuteK2:11111100end generate K2start IPstart Permutenum:10100010p:[2, 6, 3, 1, 4, 8, 5, 7]pmax:1000result:110001end PermutePermute(m, IP, 8)=110001end IPstart fk K2input:110001k:11111100fk top 4:11fk low 4:1start FR:1K:11111100start Permutenum:1p:[4, 1, 2, 3, 2, 3, 4, 1]pmax:100result:10000010end PermutePermute(R, EP, 4) ^ K:1111110F top 4:111F low 4:1110F top 4 S0[1][11]:0F low 4 S1[10][11]:0start Permutenum:0p:[2, 4, 3, 1]pmax:100result:0end PermutePermute((t0 << 2) | t1, P4, 4):0end Ffk(m, K2)=110001end fk K2start SWSW(m)=10011end SWstart fk K1input:10011k:1011111fk top 4:1fk low 4:11start FR:11K:1011111start Permutenum:11p:[4, 1, 2, 3, 2, 3, 4, 1]pmax:100result:10010110end PermutePermute(R, EP, 4) ^ K:11001001F top 4:1100F low 4:1001F top 4 S0[10][10]:1F low 4 S1[11][0]:10start Permutenum:110p:[2, 4, 3, 1]pmax:100result:1010end PermutePermute((t0 << 2) | t1, P4, 4):1010end Ffk(m, K1)=10110011end fk K1start IIPstart Permutenum:10110011p:[4, 1, 3, 5, 7, 2, 8, 6]pmax:1000result:11101010end PermutePermute(m, IPI, 8)=11101010end IIPend decrypt解密后的明文(8 bit plaintext)为:111010101:加密(encrypt),2:解密(decrypt),3:退出(exit),请输入一个数字来选择:

对明文11101010，密钥011111101的加密过程如下：

1:加密(encrypt),2:解密(decrypt),3:退出(exit),请输入一个数字来选择:1请输入明文(8 bit plaintext):11101010请输入密钥(10 bit key):0111111101start generate K1start Permutenum:111111101p:[3, 5, 2, 7, 4, 10, 1, 9, 8, 6]pmax:1010result:1111110011end PermuteK:1111110011K top 5:11111K low 5:10011K top 5 LS-1:11111K low 5 LS-1:111start Permutenum:1111100111p:[6, 3, 7, 4, 8, 5, 10, 9]pmax:1010result:1011111end PermuteK1:1011111end generate K1start generate K2K top 5:11111K low 5:111K top 5 LS-2:11111K low 5 LS-2:11100start Permutenum:1111111100p:[6, 3, 7, 4, 8, 5, 10, 9]pmax:1010result:11111100end PermuteK2:11111100end generate K2start Permutenum:11101010p:[2, 6, 3, 1, 4, 8, 5, 7]pmax:1000result:10110011end PermutePermute(m, IP, 8)=10110011input:10110011k:1011111fk top 4:1011fk low 4:11start FR:11K:1011111start Permutenum:11p:[4, 1, 2, 3, 2, 3, 4, 1]pmax:100result:10010110end PermutePermute(R, EP, 4) ^ K:11001001F top 4:1100F low 4:1001F top 4 S0[10][10]:1F low 4 S1[11][0]:10start Permutenum:110p:[2, 4, 3, 1]pmax:100result:1010end PermutePermute((t0 << 2) | t1, P4, 4):1010end Ffk(m, K1)=10011SW(m)=110001input:110001k:11111100fk top 4:11fk low 4:1start FR:1K:11111100start Permutenum:1p:[4, 1, 2, 3, 2, 3, 4, 1]pmax:100result:10000010end PermutePermute(R, EP, 4) ^ K:1111110F top 4:111F low 4:1110F top 4 S0[1][11]:0F low 4 S1[10][11]:0start Permutenum:0p:[2, 4, 3, 1]pmax:100result:0end PermutePermute((t0 << 2) | t1, P4, 4):0end Ffk(m, K2)=110001start Permutenum:110001p:[4, 1, 3, 5, 7, 2, 8, 6]pmax:1000result:10100010end PermutePermute(m, IPI, 8)=10100010加密后的密文(8 bit ciphertext)为:101000101:加密(encrypt),2:解密(decrypt),3:退出(exit),请输入一个数字来选择:

参考资料
1.simple-des算法的java实现.http://blog.csdn.net/jason314/article/details/5425248

2.《Cryptography and Network Security Principles and Practice》.appendix C Simplified DES.http://homepage.smc.edu/morgan_david/vpn/C-SDES.pdf