仿射密码和置换密码.doc

福州大学数学与计算机科学学院计算机密码学上机实验报告专业和班级数学2班姓名吴少敦成绩学号030801212实验名称古典密码学实验实验目的和要求（1）练习古典密码学的加密和解密；（2）练习仿射密码和置换密码的加密和解密实验任务(1)熟悉仿射密码。(2)熟悉置换密码。实验内容仿射密码：import java.util.Scanner;public class FangsheMima public FangsheMima() System.out.println(请输入两个密钥：);Scanner sacn1 = new Scanner(System.in);int k1 = sacn1.nextInt();int k2 = sacn1.nextInt();if (gcd(k1, 26) != 1) System.out.println(密钥 错误！); else boolean boo = true;do System.out.print(请选择功能：);System.out.print(1：加密 );System.out.print(2：解密 );System.out.println(3：退出 );int t = sacn1.nextInt();switch (t) case 1:System.out.println(请输入明文：);Scanner sacn2 = new Scanner(System.in);String mingwen = sacn2.nextLine();System.out.println(明文： + mingwen);System.out.println(密钥：k1= + k1 + ,k2= + k2);System.out.println(密文： + jiaMi(mingwen, k1, k2);break;case 2:System.out.println(请输入密文：);Scanner sacn3 = new Scanner(System.in);String miwen = sacn3.nextLine();System.out.println(密文： + miwen);System.out.println(密钥：k1= + k1 + ,k2= + k2);System.out.println(明文： + jieMi(miwen, k1, k2);break;case 3:boo = false;System.out.println(已经退出！);break; while (boo);public int gcd(int a, int b) int k = 0;do k = a % b;a = b;b = k; while (k != 0);return a;/ 辗转相除球最大公约数public int ni(int a, int b) int i = 1;while (a * i % b != 1) i+;return i;/ a相对b的逆public String jiaMi(String mingwen, int k1, int k2) String miwen = ;char c = new charmingwen.length();for (int i = 0; i = a & ci = A & ci = Z) ci = (char) (k1 * (ci - A) + k2) % 26 + A);miwen += ci;return miwen;/ 加密public String jieMi(String miwen, int k1, int k2) String mingwen = ;char c = new charmiwen.length();int tem = 0;for (int i = 0; i 64 & ci 91) tem = (ni(k1, 26) * (ci - 65) - k2) % 26;if (tem 97 & ci 123) tem = (ni(k1, 26) * (ci - 97) - k2) % 26;if (tem 0) ci = (char) (tem % 26 + 26 + 97); else ci = (char) (tem % 26 + 97);mingwen += ci;return mingwen;/ 解密public static void main(String args) new FangsheMima();置换密码：package zhihua;import java.util.Scanner;import java.util.Vector;public class ZhihuanMama private Scanner scan = new Scanner(System.in);private int m;private int x;private int y;public ZhihuanMama() System.out.println(请输M：);m = scan.nextInt();System.out.println(请输入密钥：);System.out.print(x);for (int i = 0; i m; i+) System.out.print(t);System.out.print(i + 1);System.out.println();y = new intm;int min = 0;Vector vector = new Vector();for (int i = 0; i = m) System.out.println(密钥超出 M ！);min = scan.nextInt() - 1; else if (min 0) System.out.println(密钥超出 M ！);min = scan.nextInt() - 1;yi = min;vector.add(min);x = new intm;init(y);boolean boo = true;do System.out.print(请选择功能：t);System.out.print(1：加密 t);System.out.print(2：解密 t);System.out.println(3：退出 t);int t = scan.nextInt();if (t 3) System.out.println(请选择正确的功能：);t = scan.nextInt();switch (t) case 1:System.out.println(请输入明文：);Scanner scan1 = new Scanner(System.in);String mingwen = scan1.nextLine();String str1 = trim(mingwen);jaMi(str1);break;case 2:System.out.println(请输入密文：);Scanner scan2 = new Scanner(System.in);String miwen = scan2.nextLine();String str2 = trim(miwen);jieMi(str2);break;case 3:boo = false;System.out.println(已经退出！);break; while (boo);/ 加密密钥xpublic void init(int y) for (int i = 0; i y.length; i+) for (int j = 0; j y.length; j+) if (yj = i) xi = j;public String trim(String wen) String str = ;for (int i = 0; i wen.length(); i+) if (wen.charAt(i) != ) str += wen.charAt(i);return str;/ 去空格/ 加密public void jaMi(String mingWen) String miWen = ;String jmingwen = jieduan(mingWen, m);for (int i = 0; i jmingwen.length; i+) miWen += zhihuan(x, jmingweni);System.out.println(加密后密文：);miWen = miWen.toUpperCase();System.out.println(miWen);/ 解密public void jieMi(String miWen) String mingWen = ;String jmingwen = jieduan(miWen, m);for (int i = 0; i jmingwen.length; i+) mingWen += zhihuan(y, jmingweni);System.out.println(解密后密文：);mingWen = mingWen.toLowerCase();System.out.println(mingWen);/ 截断原文public String jieduan(String wen, int m) Vector vector = new Vector();String s = ;int i = 0;for (; i wen.length(); i += m) if (i + m wen.length() s = wen.substring(i, i + m); else s = wen.substring(i, wen.length();vector.add(s);String str = new Stringvector.size();for (int j = 0; j str.length; j+) strj = vector.get(j);return str;/ 置换public String zhihuan(int miyao, Stri