androidRSA加密解密算法

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;import javax.crypto.Cipher;public class RSAUtils {/*** 生成公钥和私钥* &＃64;throws NoSuchAlgorithmException**/public static HashMap getKeys() throws NoSuchAlgorithmException{HashMap map &＃61; new HashMap();KeyPairGenerator keyPairGen &＃61; KeyPairGenerator.getInstance("RSA");keyPairGen.initialize(1024);KeyPair keyPair &＃61; keyPairGen.generateKeyPair();RSAPublicKey publicKey &＃61; (RSAPublicKey) keyPair.getPublic();RSAPrivateKey privateKey &＃61; (RSAPrivateKey) keyPair.getPrivate();map.put("public", publicKey);map.put("private", privateKey);return map;}/*** 使用模和指数生成RSA公钥* 注意&＃xff1a;【此代码用了默认补位方式&＃xff0c;为RSA/None/PKCS1Padding&＃xff0c;不同JDK默认的补位方式可能不同&＃xff0c;如Android默认是RSA* /None/NoPadding】** &＃64;param modulus* 模* &＃64;param exponent* 指数* &＃64;return*/public static RSAPublicKey getPublicKey(String modulus, String exponent) {try {BigInteger b1 &＃61; new BigInteger(modulus);BigInteger b2 &＃61; new BigInteger(exponent);KeyFactory keyFactory &＃61; KeyFactory.getInstance("RSA");RSAPublicKeySpec keySpec &＃61; new RSAPublicKeySpec(b1, b2);return (RSAPublicKey) keyFactory.generatePublic(keySpec);} catch (Exception e) {e.printStackTrace();return null;}}/*** 使用模和指数生成RSA私钥* 注意&＃xff1a;【此代码用了默认补位方式&＃xff0c;为RSA/None/PKCS1Padding&＃xff0c;不同JDK默认的补位方式可能不同&＃xff0c;如Android默认是RSA* /None/NoPadding】** &＃64;param modulus* 模* &＃64;param exponent* 指数* &＃64;return*/public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {try {BigInteger b1 &＃61; new BigInteger(modulus);BigInteger b2 &＃61; new BigInteger(exponent);KeyFactory keyFactory &＃61; KeyFactory.getInstance("RSA");RSAPrivateKeySpec keySpec &＃61; new RSAPrivateKeySpec(b1, b2);return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);} catch (Exception e) {e.printStackTrace();return null;}}/*** 公钥加密** &＃64;param data* &＃64;param publicKey* &＃64;return* &＃64;throws Exception*/public static String encryptByPublicKey(String data, RSAPublicKey publicKey)throws Exception {Cipher cipher &＃61; Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE, publicKey);// 模长int key_len &＃61; publicKey.getModulus().bitLength() / 8;// 加密数据长度 <&＃61; 模长-11String[] datas &＃61; splitString(data, key_len - 11);String mi &＃61; "";//如果明文长度大于模长-11则要分组加密for (String s : datas) {mi &＃43;&＃61; bcd2Str(cipher.doFinal(s.getBytes()));}return mi;}/*** 私钥解密** &＃64;param data* &＃64;param privateKey* &＃64;return* &＃64;throws Exception*/public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)throws Exception {Cipher cipher &＃61; Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE, privateKey);//模长int key_len &＃61; privateKey.getModulus().bitLength() / 8;byte[] bytes &＃61; data.getBytes();byte[] bcd &＃61; ASCII_To_BCD(bytes, bytes.length);System.err.println(bcd.length);//如果密文长度大于模长则要分组解密String ming &＃61; "";byte[][] arrays &＃61; splitArray(bcd, key_len);for(byte[] arr : arrays){ming &＃43;&＃61; new String(cipher.doFinal(arr));}return ming;}/*** ASCII码转BCD码**/public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {byte[] bcd &＃61; new byte[asc_len / 2];int j &＃61; 0;for (int i &＃61; 0; i <(asc_len &＃43; 1) / 2; i&＃43;&＃43;) {bcd[i] &＃61; asc_to_bcd(ascii[j&＃43;&＃43;]);bcd[i] &＃61; (byte) (((j >&＃61; asc_len) ? 0x00 : asc_to_bcd(ascii[j&＃43;&＃43;])) &＃43; (bcd[i] <<4));}return bcd;}public static byte asc_to_bcd(byte asc) {byte bcd;if ((asc >&＃61; &＃39;0&＃39;) && (asc <&＃61; &＃39;9&＃39;))bcd &＃61; (byte) (asc - &＃39;0&＃39;);else if ((asc >&＃61; &＃39;A&＃39;) && (asc <&＃61; &＃39;F&＃39;))bcd &＃61; (byte) (asc - &＃39;A&＃39; &＃43; 10);else if ((asc >&＃61; &＃39;a&＃39;) && (asc <&＃61; &＃39;f&＃39;))bcd &＃61; (byte) (asc - &＃39;a&＃39; &＃43; 10);elsebcd &＃61; (byte) (asc - 48);return bcd;}/*** BCD转字符串*/public static String bcd2Str(byte[] bytes) {char temp[] &＃61; new char[bytes.length * 2], val;for (int i &＃61; 0; i ) {val &＃61; (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);temp[i * 2] &＃61; (char) (val > 9 ? val &＃43; &＃39;A&＃39; - 10 : val &＃43; &＃39;0&＃39;);val &＃61; (char) (bytes[i] & 0x0f);temp[i * 2 &＃43; 1] &＃61; (char) (val > 9 ? val &＃43; &＃39;A&＃39; - 10 : val &＃43; &＃39;0&＃39;);}return new String(temp);}/*** 拆分字符串*/public static String[] splitString(String string, int len) {int x &＃61; string.length() / len;int y &＃61; string.length() % len;int z &＃61; 0;if (y !&＃61; 0) {z &＃61; 1;}String[] strings &＃61; new String[x &＃43; z];String str &＃61; "";for (int i&＃61;0; i) {if (i&＃61;&＃61;x&＃43;z-1 && y!&＃61;0) {str &＃61; string.substring(i*len, i*len&＃43;y);}else{str &＃61; string.substring(i*len, i*len&＃43;len);}strings[i] &＃61; str;}return strings;}/***拆分数组*/public static byte[][] splitArray(byte[] data,int len){int x &＃61; data.length / len;int y &＃61; data.length % len;int z &＃61; 0;if(y!&＃61;0){z &＃61; 1;}byte[][] arrays &＃61; new byte[x&＃43;z][];byte[] arr;for(int i&＃61;0; i){arr &＃61; new byte[len];if(i&＃61;&＃61;x&＃43;z-1 && y!&＃61;0){System.arraycopy(data, i*len, arr, 0, y);}else{System.arraycopy(data, i*len, arr, 0, len);}arrays[i] &＃61; arr;}return arrays;}
}

public static void main(String[] args) throws Exception {// TODO Auto-generated method stubHashMap map &＃61; RSAUtils.getKeys();//生成公钥和私钥RSAPublicKey publicKey &＃61; (RSAPublicKey) map.get("public");RSAPrivateKey privateKey &＃61; (RSAPrivateKey) map.get("private");//模String modulus &＃61; publicKey.getModulus().toString();System.out.println(modulus);//公钥指数String public_exponent &＃61; publicKey.getPublicExponent().toString();//私钥指数String private_exponent &＃61; privateKey.getPrivateExponent().toString();System.out.println("公钥指数:"&＃43;public_exponent);System.out.println("私钥指数:"&＃43;private_exponent);//明文String ming &＃61; "123456789 Hello 小笨蛋";//使用模和指数生成公钥和私钥RSAPublicKey pubKey &＃61; RSAUtils.getPublicKey(modulus, public_exponent);RSAPrivateKey priKey &＃61; RSAUtils.getPrivateKey(modulus, private_exponent);//加密后的密文String mi &＃61; RSAUtils.encryptByPublicKey(ming, pubKey);System.out.println("加密后的密文"&＃43;mi);//解密后的明文String mingn &＃61; RSAUtils.decryptByPrivateKey(mi, priKey);System.out.println("解密后的明文"&＃43;mingn);}