Java使用RSA加密解密及签名校验

该工具类中用到了BASE64，需要借助第三方类库：javabase64-1.3.1.jar

注意：

RSA加密明文最大长度117字节，解密要求密文最大长度为128字节，所以在加密和解密的过程中需要分块进行。

RSA加密对明文的长度是有限制的，如果加密数据过大会抛出如下异常：

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

RSAUtils.java--RSA公钥/私钥/签名工具包

package com.ljq.test;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公钥/私钥/签名工具包* </p>* <p>* 罗纳德·李维斯特（Ron [R]ivest）、阿迪·萨莫尔（Adi [S]hamir）和伦纳德·阿德曼（Leonard [A]dleman）* </p>* <p>* 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/>* 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，<br/>* 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全* </p>* * @author IceWee* @date -4-26* @version 1.0*/public class RSAUtils {/*** 加密算法RSA*/public static final String KEY_ALGORITHM = "RSA";/*** 签名算法*/public static final String SIGNATURE_ALGORITHM = "MD5withRSA";/*** 获取公钥的key*/private static final String PUBLIC_KEY = "RSAPublicKey";/*** 获取私钥的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>* 生成密钥对(公钥和私钥)* </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>* 用私钥对信息生成数字签名* </p>* * @param data 已加密数据* @param privateKey 私钥(BASE64编码)* * @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>* 校验数字签名* </p>* * @param data 已加密数据* @param publicKey 公钥(BASE64编码)* @param sign 数字签名* * @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>* 私钥解密* </p>* * @param encryptedData 已加密数据* @param privateKey 私钥(BASE64编码)* @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;// 对数据分段解密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>* 公钥解密* </p>* * @param encryptedData 已加密数据* @param publicKey 公钥(BASE64编码)* @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;// 对数据分段解密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>* 公钥加密* </p>* * @param data 源数据* @param publicKey 公钥(BASE64编码)* @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);// 对数据加密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;// 对数据分段加密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>* 私钥加密* </p>* * @param data 源数据* @param privateKey 私钥(BASE64编码)* @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;// 对数据分段加密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>* 获取私钥* </p>* * @param keyMap 密钥对* @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>* 获取公钥* </p>* * @param keyMap 密钥对* @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--BASE64编码解码工具包

package com.ljq.test;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编码解码工具包* </p>* <p>* 依赖javabase64-1.3.1.jar* </p>* * @author IceWee* @date -5-19* @version 1.0*/public class Base64Utils {/*** 文件读取缓冲区大小*/private static final int CACHE_SIZE = 1024;/*** <p>* BASE64字符串解码为二进制数据* </p>* * @param base64* @return* @throws Exception*/public static byte[] decode(String base64) throws Exception {return Base64.decode(base64.getBytes());}/*** <p>* 二进制数据编码为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>* 将文件编码为BASE64字符串* </p>* <p>* 大文件慎用，可能会导致内存溢出* </p>* * @param filePath* 文件绝对路径* @return* @throws Exception*/public static String encodeFile(String filePath) throws Exception {byte[] bytes = fileToByte(filePath);return encode(bytes);}/*** <p>* BASE64字符串转回文件* </p>* * @param filePath* 文件绝对路径* @param base64* 编码字符串* @throws Exception*/public static void decodeToFile(String filePath, String base64) throws Exception {byte[] bytes = decode(base64);byteArrayToFile(bytes, filePath);}/*** <p>* 文件转换为二进制数组* </p>* * @param filePath* 文件路径* @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>* 二进制数据写文件* </p>* * @param bytes* 二进制数据* @param filePath* 文件生成目录*/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--测试类

package com.ljq.test;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("公钥: \n\r" + publicKey);System.err.println("私钥： \n\r" + privateKey);} catch (Exception e) {e.printStackTrace();}}public static void main(String[] args) throws Exception {test();testSign();testHttpSign();}static void test() throws Exception {System.err.println("公钥加密——私钥解密");String source = "这是一行没有任何意义的文字，你看完了等于没看，不是吗？";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("私钥加密——公钥解密");String source = "这是一行测试RSA数字签名的无意义文字";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("私钥签名——公钥验证签名");String sign = RSAUtils.sign(encodedData, privateKey);System.err.println("签名:\r" + sign);boolean status = RSAUtils.verify(encodedData, publicKey, sign);System.err.println("验证结果:\r" + status);}static void testHttpSign() throws Exception {String param = "id=1&name=张三";byte[] encodedData = RSAUtils.encryptByPrivateKey(param.getBytes(), privateKey);System.out.println("加密后：" + encodedData);byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, publicKey);System.out.println("解密后：" + new String(decodedData));String sign = RSAUtils.sign(encodedData, privateKey);System.err.println("签名：" + sign);boolean status = RSAUtils.verify(encodedData, publicKey, sign);System.err.println("签名验证结果：" + status);}}