java矩阵换位加密，java矩阵换位,package sun.

java矩阵换位加密，java矩阵换位,package sun.

package sun.netsecurity.matrixtran;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.math.BigInteger;public class MatrixTransposition {    private static BufferedReader br;    static {        InputStreamReader reader = new InputStreamReader(System.in);        br = new BufferedReader(reader);    }    /**     * @param args     * @throws IOException      */    public static void main(String[] args) throws IOException {        char[] plaintext = inputPlaintext();        Integer key = inputKey();        br.close();        String ciphertext = encrypt(plaintext, key);        System.out.println("明文加密后为: " + ciphertext);        String plaintextStr = decrypt(ciphertext.toCharArray(), plaintext, key);        System.out.println("密文解密后为: " + plaintextStr);    }    /**     * 将明文字符数组分组     *      * @param plaintext     *            明文字符数组     * @param key     *            密钥     * @return     */    static char[][] groupPlaintext(char[] plaintext, Integer key) {        char[][] plaintextGroup = null;        Integer length = plaintext.length;        if (length % key != 0) {// 当字符数组的长度不是密钥的整数倍时，用字符'$'填补            String plaintextStr = new String(plaintext);            BigInteger lengthBI = new BigInteger(length.toString());            BigInteger keyBI = new BigInteger(key.toString());            BigInteger mod = lengthBI.mod(keyBI);            int fillNumber = keyBI.intValue() - mod.intValue();            for (int i = 0; i < fillNumber; i++) {                plaintextStr = plaintextStr + "$";            }            plaintext = plaintextStr.toCharArray();            length = plaintext.length;        }        int groupAmount = length / key;        plaintextGroup = new char[groupAmount][key];        for (int i = 0; i < groupAmount; i++) {            for (int j = 0; j < key; j++) {                // 将明文字符数组分割为二维数组                plaintextGroup[i][j] = plaintext[i * key + j];            }        }        return plaintextGroup;    }    /**     * 将密文分组     *      * @param ciphertext     *            密文     * @param key     *            密钥     * @return     */    static char[][] groupCiphertext(char[] ciphertext, Integer key) {        char[][] ciphertextGroup = null;        int length = ciphertext.length;        int groupAmount = length / key;        ciphertextGroup = new char[groupAmount][key];        for (int i = 0; i < groupAmount; i++) {            for (int j = 0; j < key; j++) {                ciphertextGroup[i][j] = ciphertext[i * key + j];            }        }        return ciphertextGroup;    }    /**     * 按照加密规则，将分割后的各个子字符数组分别进行移位     *      * @param group     *            每一个子字符数组     * @return     */    static char[] changePlaintext(char[] group) {        char[] newGroup = new char[group.length];        for (int i = 0; i < group.length; i++) {            if (i == 0) {                newGroup[0] = group[group.length - 1];                continue;            }            newGroup[i] = group[i - 1];        }        return newGroup;    }    /**     *      * @param group     *            按照加密规则,将密文分割后的各个子字符数组按照相反的方式分别进行移位     * @return     */    static char[] changeCiphertext(char[] group) {        char[] newGroup = new char[group.length];        for (int i = 0; i < group.length; i++) {            if (i == group.length - 1) {                newGroup[group.length - 1] = group[0];                break;            }            newGroup[i] = group[i + 1];        }        return newGroup;    }    static String getCipherFromGroup(char[][] plaintextGroup) {        String ciphertext = "";        int rowAccount = plaintextGroup.length;        int lowAccount = plaintextGroup[0].length;        for (int i = 0; i < rowAccount; i++) {            char[] rowChar = new char[lowAccount];            for (int j = 0; j < lowAccount; j++) {                rowChar[j] = plaintextGroup[i][j];            }            ciphertext = ciphertext + new String(rowChar);        }        return ciphertext;    }    static String getPlaintextFromGroup(char[][] ciphertextGroup) {        String plaintext = "";        int rowAccount = ciphertextGroup.length;        int lowAccount = ciphertextGroup[0].length;        for (int i = 0; i < rowAccount; i++) {            char[] rowChar = new char[lowAccount];            for (int j = 0; j < lowAccount; j++) {                rowChar[j] = ciphertextGroup[i][j];            }            plaintext = plaintext + new String(rowChar);        }        return plaintext;    }    // 从键盘输入明文    static char[] inputPlaintext() {        System.out.println("请输入明文:");        char[] plaintextChar = null;        try {            String plaintext = null;            plaintext = br.readLine();            plaintextChar = plaintext.toCharArray();        } catch (Exception e) {            e.printStackTrace();        }        return plaintextChar;    }    // 从键盘获得密钥    static Integer inputKey() {        System.out.println("请输入密钥:");        Integer key = null;        try {            String keyString = null;            keyString = br.readLine();            key = new Integer(keyString);        } catch (Exception e) {            e.printStackTrace();        }        return key;    }    /**     * 对明文进行加密     *      * @param plaintext     *            明文     * @param key     *            密钥     * @return     */    static String encrypt(char[] plaintext, Integer key) {        String ciphertext;        char[][] plaintextGroup;        // 调用groupPlaintext(plaintext, key)方法对明文分组        plaintextGroup = groupPlaintext(plaintext, key);        for (int i = 0; i < plaintextGroup.length; i++) {            // 调用changePlaintext(char[])进行位变换            char[] rowText = changePlaintext(plaintextGroup[i]);            plaintextGroup[i] = rowText;        }        //        ciphertext = getCipherFromGroup(plaintextGroup);        return ciphertext;    }    /**     * 对密文进行解密     * @param ciphertext 密文     * @param plaintext  明文     * @param key        密钥     * @return     */    static String decrypt(char[] ciphertext, char[] plaintext, Integer key) {        String plaintextStr;        char[][] ciphertextGroup;        ciphertextGroup = groupCiphertext(ciphertext, key);        for (int i = 0; i < ciphertextGroup.length; i++) {            char[] rowText = changeCiphertext(ciphertextGroup[i]);            ciphertextGroup[i] = rowText;        }        plaintextStr = getPlaintextFromGroup(ciphertextGroup);        Integer plaintextLength = plaintext.length;        BigInteger pLenghBI = new BigInteger(plaintextLength.toString());        BigInteger keyBI = new BigInteger(key.toString());        BigInteger mod = pLenghBI.mod(keyBI);        if (mod.intValue() != 0) {            plaintextStr = plaintextStr.substring(0, plaintextStr.length()                    - (key - mod.intValue()));        }        return plaintextStr;    }}