該工具類中用到了BASE64，需要借助第三方類庫：javabase64-1.3.1.jar

下載地址：http://download.csdn.net/detail/centralperk/5025595

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注意：
RSA加密明文最大長度117字節，解密要求密文最大長度為128字節，所以在加密和解密的過程中需要分塊進行。
RSA加密對明文的長度是有限制的，如果加密數據過大會拋出如下異常：

Exception in thread "main" javax.crypto.IllegalBlockSizeException: Data must not be longer than 117 bytes at com.sun.crypto.provider.RSACipher.a(DashoA13*..) at com.sun.crypto.provider.RSACipher.engineDoFinal(DashoA13*..) at javax.crypto.Cipher.doFinal(DashoA13*..)

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RSAUtils.java

package security;import java.io.ByteArrayOutputStream; import java.security.Key; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.Signature; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.HashMap; import java.util.Map;import javax.crypto.Cipher;/** *//*** <p>* RSA公鑰/私鑰/簽名工具包* </p>* <p>* 羅納德·李維斯特（Ron [R]ivest）、阿迪·薩莫爾（Adi [S]hamir）和倫納德·阿德曼（Leonard [A]dleman）* </p>* <p>* 字符串格式的密鑰在未在特殊說明情況下都為BASE64編碼格式<br/>* 由于非對稱加密速度極其緩慢，一般文件不使用它來加密而是使用對稱加密，<br/>* 非對稱加密算法可以用來對對稱加密的密鑰加密，這樣保證密鑰的安全也就保證了數據的安全* </p>* * @author IceWee* @date 2012-4-26* @version 1.0*/ public class RSAUtils {/** *//*** 加密算法RSA*/public static final String KEY_ALGORITHM = "RSA";/** *//*** 簽名算法*/public static final String SIGNATURE_ALGORITHM = "MD5withRSA";/** *//*** 獲取公鑰的key*/private static final String PUBLIC_KEY = "RSAPublicKey";/** *//*** 獲取私鑰的key*/private static final String PRIVATE_KEY = "RSAPrivateKey";/** *//*** RSA最大加密明文大小*/private static final int MAX_ENCRYPT_BLOCK = 117;/** *//*** RSA最大解密密文大小*/private static final int MAX_DECRYPT_BLOCK = 128;/** *//*** <p>* 生成密鑰對(公鑰和私鑰)* </p>* * @return* @throws Exception*/public static Map<String, Object> genKeyPair() throws Exception {KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);keyPairGen.initialize(1024);KeyPair keyPair = keyPairGen.generateKeyPair();RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();Map<String, Object> keyMap = new HashMap<String, Object>(2);keyMap.put(PUBLIC_KEY, publicKey);keyMap.put(PRIVATE_KEY, privateKey);return keyMap;}/** *//*** <p>* 用私鑰對信息生成數字簽名* </p>* * @param data 已加密數據* @param privateKey 私鑰(BASE64編碼)* * @return* @throws Exception*/public static String sign(byte[] data, String privateKey) throws Exception {byte[] keyBytes = Base64Utils.decode(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initSign(privateK);signature.update(data);return Base64Utils.encode(signature.sign());}/** *//*** <p>* 校驗數字簽名* </p>* * @param data 已加密數據* @param publicKey 公鑰(BASE64編碼)* @param sign 數字簽名* * @return* @throws Exception* */public static boolean verify(byte[] data, String publicKey, String sign)throws Exception {byte[] keyBytes = Base64Utils.decode(publicKey);X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);PublicKey publicK = keyFactory.generatePublic(keySpec);Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initVerify(publicK);signature.update(data);return signature.verify(Base64Utils.decode(sign));}/** *//*** <P>* 私鑰解密* </p>* * @param encryptedData 已加密數據* @param privateKey 私鑰(BASE64編碼)* @return* @throws Exception*/public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)throws Exception {byte[] keyBytes = Base64Utils.decode(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, privateK);int inputLen = encryptedData.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 對數據分段解密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_DECRYPT_BLOCK) {cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);} else {cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_DECRYPT_BLOCK;}byte[] decryptedData = out.toByteArray();out.close();return decryptedData;}/** *//*** <p>* 公鑰解密* </p>* * @param encryptedData 已加密數據* @param publicKey 公鑰(BASE64編碼)* @return* @throws Exception*/public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)throws Exception {byte[] keyBytes = Base64Utils.decode(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicK = keyFactory.generatePublic(x509KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, publicK);int inputLen = encryptedData.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 對數據分段解密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_DECRYPT_BLOCK) {cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);} else {cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_DECRYPT_BLOCK;}byte[] decryptedData = out.toByteArray();out.close();return decryptedData;}/** *//*** <p>* 公鑰加密* </p>* * @param data 源數據* @param publicKey 公鑰(BASE64編碼)* @return* @throws Exception*/public static byte[] encryptByPublicKey(byte[] data, String publicKey)throws Exception {byte[] keyBytes = Base64Utils.decode(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicK = keyFactory.generatePublic(x509KeySpec);// 對數據加密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, publicK);int inputLen = data.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 對數據分段加密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);} else {cache = cipher.doFinal(data, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_ENCRYPT_BLOCK;}byte[] encryptedData = out.toByteArray();out.close();return encryptedData;}/** *//*** <p>* 私鑰加密* </p>* * @param data 源數據* @param privateKey 私鑰(BASE64編碼)* @return* @throws Exception*/public static byte[] encryptByPrivateKey(byte[] data, String privateKey)throws Exception {byte[] keyBytes = Base64Utils.decode(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, privateK);int inputLen = data.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 對數據分段加密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);} else {cache = cipher.doFinal(data, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_ENCRYPT_BLOCK;}byte[] encryptedData = out.toByteArray();out.close();return encryptedData;}/** *//*** <p>* 獲取私鑰* </p>* * @param keyMap 密鑰對* @return* @throws Exception*/public static String getPrivateKey(Map<String, Object> keyMap)throws Exception {Key key = (Key) keyMap.get(PRIVATE_KEY);return Base64Utils.encode(key.getEncoded());}/** *//*** <p>* 獲取公鑰* </p>* * @param keyMap 密鑰對* @return* @throws Exception*/public static String getPublicKey(Map<String, Object> keyMap)throws Exception {Key key = (Key) keyMap.get(PUBLIC_KEY);return Base64Utils.encode(key.getEncoded());}}

Base64Utils.java

package security;import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream;import it.sauronsoftware.base64.Base64;/** *//*** <p>* BASE64編碼解碼工具包* </p>* <p>* 依賴javabase64-1.3.1.jar* </p>* * @author IceWee* @date 2012-5-19* @version 1.0*/ public class Base64Utils {/** *//*** 文件讀取緩沖區大小*/private static final int CACHE_SIZE = 1024;/** *//*** <p>* BASE64字符串解碼為二進制數據* </p>* * @param base64* @return* @throws Exception*/public static byte[] decode(String base64) throws Exception {return Base64.decode(base64.getBytes());}/** *//*** <p>* 二進制數據編碼為BASE64字符串* </p>* * @param bytes* @return* @throws Exception*/public static String encode(byte[] bytes) throws Exception {return new String(Base64.encode(bytes));}/** *//*** <p>* 將文件編碼為BASE64字符串* </p>* <p>* 大文件慎用，可能會導致內存溢出* </p>* * @param filePath 文件絕對路徑* @return* @throws Exception*/public static String encodeFile(String filePath) throws Exception {byte[] bytes = fileToByte(filePath);return encode(bytes);}/** *//*** <p>* BASE64字符串轉回文件* </p>* * @param filePath 文件絕對路徑* @param base64 編碼字符串* @throws Exception*/public static void decodeToFile(String filePath, String base64) throws Exception {byte[] bytes = decode(base64);byteArrayToFile(bytes, filePath);}/** *//*** <p>* 文件轉換為二進制數組* </p>* * @param filePath 文件路徑* @return* @throws Exception*/public static byte[] fileToByte(String filePath) throws Exception {byte[] data = new byte[0];File file = new File(filePath);if (file.exists()) {FileInputStream in = new FileInputStream(file);ByteArrayOutputStream out = new ByteArrayOutputStream(2048);byte[] cache = new byte[CACHE_SIZE];int nRead = 0;while ((nRead = in.read(cache)) != -1) {out.write(cache, 0, nRead);out.flush();}out.close();in.close();data = out.toByteArray();}return data;}/** *//*** <p>* 二進制數據寫文件* </p>* * @param bytes 二進制數據* @param filePath 文件生成目錄*/public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {InputStream in = new ByteArrayInputStream(bytes); File destFile = new File(filePath);if (!destFile.getParentFile().exists()) {destFile.getParentFile().mkdirs();}destFile.createNewFile();OutputStream out = new FileOutputStream(destFile);byte[] cache = new byte[CACHE_SIZE];int nRead = 0;while ((nRead = in.read(cache)) != -1) { out.write(cache, 0, nRead);out.flush();}out.close();in.close();}}

RSATester.java

package security;import java.util.Map;public class RSATester {static String publicKey;static String privateKey;static {try {Map<String, Object> keyMap = RSAUtils.genKeyPair();publicKey = RSAUtils.getPublicKey(keyMap);privateKey = RSAUtils.getPrivateKey(keyMap);System.err.println("公鑰: \n\r" + publicKey);System.err.println("私鑰： \n\r" + privateKey);} catch (Exception e) {e.printStackTrace();}}public static void main(String[] args) throws Exception {test();testSign();}static void test() throws Exception {System.err.println("公鑰加密——私鑰解密");String source = "這是一行沒有任何意義的文字，你看完了等于沒看，不是嗎？";System.out.println("\r加密前文字：\r\n" + source);byte[] data = source.getBytes();byte[] encodedData = RSAUtils.encryptByPublicKey(data, publicKey);System.out.println("加密后文字：\r\n" + new String(encodedData));byte[] decodedData = RSAUtils.decryptByPrivateKey(encodedData, privateKey);String target = new String(decodedData);System.out.println("解密后文字: \r\n" + target);}static void testSign() throws Exception {System.err.println("私鑰加密——公鑰解密");String source = "這是一行測試RSA數字簽名的無意義文字";System.out.println("原文字：\r\n" + source);byte[] data = source.getBytes();byte[] encodedData = RSAUtils.encryptByPrivateKey(data, privateKey);System.out.println("加密后：\r\n" + new String(encodedData));byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, publicKey);String target = new String(decodedData);System.out.println("解密后: \r\n" + target);System.err.println("私鑰簽名——公鑰驗證簽名");String sign = RSAUtils.sign(encodedData, privateKey);System.err.println("簽名:\r" + sign);boolean status = RSAUtils.verify(encodedData, publicKey, sign);System.err.println("驗證結果:\r" + status);}}

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自己改進的：

package com.gd.rps.rb.service.util;import org.apache.geronimo.mail.util.Base64;import net.sf.json.JSONObject;import java.io.ByteArrayOutputStream; import java.security.Key; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.spec.InvalidKeySpecException; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import javax.crypto.Cipher;/*** RSA加解密* @author jiafuwei* created at 2017/6/8*/ public class UseRSAUtil {/** *//** * RSA最大加密明文大小 */ private static final int MAX_ENCRYPT_BLOCK = 117; /** *//** * RSA最大解密密文大小 */ private static final int MAX_DECRYPT_BLOCK = 128; public static final String KEY_ALGORITHM = "RSA";private static KeyFactory keyFactory = null;public static String PrivateKey = "私鑰。。。";public static String publicKey="公鑰。。。";static {try {keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);} catch (NoSuchAlgorithmException e) {// TODO Auto-generated catch block e.printStackTrace();}}/*** 解密方法* @param dataStr 要解密的數據* @return 解密后的原數據* @throws Exception*/public static String decrypt(String dataStr) throws Exception{//要加密的數據System.out.println("要解密的數據:"+dataStr);//對私鑰解密Key decodePrivateKey = getPrivateKeyFromBase64KeyEncodeStr(PrivateKey);//Log.i("機密",""+decodePrivateKey);Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);cipher.init(Cipher.DECRYPT_MODE, decodePrivateKey);byte[] encodedData = Base64.decode(dataStr);byte[] decodedData = cipher.doFinal(encodedData);String decodedDataStr = new String(decodedData,"utf-8");System.out.println("私鑰解密后的數據:"+decodedDataStr);return decodedDataStr;}public static Key getPrivateKeyFromBase64KeyEncodeStr(String keyStr) {byte[] keyBytes = Base64.decode(keyStr);// 取得私鑰PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);Key privateKey=null;try {privateKey = keyFactory.generatePrivate(pkcs8KeySpec);} catch (InvalidKeySpecException e) {// TODO Auto-generated catch block e.printStackTrace();}return privateKey;}/*** 獲取base64加密后的字符串的原始公鑰* @param keyStr* @return*/public static Key getPublicKeyFromBase64KeyEncodeStr(String keyStr) {byte[] keyBytes = Base64.decode(keyStr);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);Key publicKey = null;try {publicKey = keyFactory.generatePublic(x509KeySpec);} catch (Exception e) {// TODO Auto-generated catch block e.printStackTrace();}return publicKey;}/*** 公鑰加密方法* @param dataStr 要加密的數據* @param dataStr 公鑰base64字符串* @return 加密后的base64字符串* @throws Exception*/public static String encryptPublicKey(String dataStr) throws Exception{//要加密的數據System.out.println("要加密的數據:"+dataStr);byte[] data = dataStr.getBytes();// 對公鑰解密Key decodePublicKey = getPublicKeyFromBase64KeyEncodeStr(publicKey);// 對數據加密Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);cipher.init(Cipher.ENCRYPT_MODE, decodePublicKey);byte[] encodedData = cipher.doFinal(data);String encodedDataStr = new String(Base64.encode(encodedData));System.out.println("公鑰加密后的數據:"+encodedDataStr);return encodedDataStr;}/*** 使用公鑰進行分段加密* @param dataStr 要加密的數據* @return 公鑰base64字符串* @throws Exception*/public static String encryptByPublicKey(String dataStr) throws Exception { //要加密的數據System.out.println("要加密的數據:"+dataStr);byte[] data = dataStr.getBytes();// 對公鑰解密Key decodePublicKey = getPublicKeyFromBase64KeyEncodeStr(publicKey);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); // 對數據加密 Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, decodePublicKey); int inputLen = data.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段加密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_ENCRYPT_BLOCK) { cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_ENCRYPT_BLOCK; } byte[] encryptedData = out.toByteArray(); out.close(); String encodedDataStr = new String(Base64.encode(encryptedData));System.out.println("公鑰加密后的數據:"+encodedDataStr);return encodedDataStr; } /*** 使用私鑰進行分段解密* @param dataStr 使用base64處理過的密文* @return 解密后的數據* @throws Exception*/public static String decryptByPrivateKey(String dataStr) throws Exception { byte[] encryptedData = Base64.decode(dataStr);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); Key decodePrivateKey = getPrivateKeyFromBase64KeyEncodeStr(PrivateKey);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, decodePrivateKey); int inputLen = encryptedData.length; ByteArrayOutputStream out = new ByteArrayOutputStream(); int offSet = 0; byte[] cache; int i = 0; // 對數據分段解密 while (inputLen - offSet > 0) { if (inputLen - offSet > MAX_DECRYPT_BLOCK) { cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK); } else { cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * MAX_DECRYPT_BLOCK; } byte[] decryptedData = out.toByteArray(); out.close(); String decodedDataStr = new String(decryptedData,"utf-8");System.out.println("私鑰解密后的數據:"+decodedDataStr);return decodedDataStr; } public static void main(String[] args) throws Exception {} }

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轉載于:https://www.cnblogs.com/jiafuwei/p/7054500.html

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