RSA加解密VS加签与验签
原则：
1） 公钥加密数据
2）私钥进行签名
3）公私钥互加解密密钥。
其实也可以互换，私钥加密，公解解密 。 需要注意的是，我们只是将公钥公开， ps：私钥是可以推出公钥的。如果将私钥公开，那么全套就是明文 。
参考：co63oc.blog.51cto.com/904636/6254…
公钥加密，私钥解密时，因为加入随机数，每次得到的加密信息不固定。
私钥加密，公钥解密时，得到的加密信息固定。
下面引入几个常见的工具类
RSAUtils
/**
* <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 2012-4-26
* @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";
public static final String SIGNATURE_ALGORITHM = "SHA1withRSA";
/**
* 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;
}
/**
* 从文件中输入流中加载公钥
*
* @param in
* 公钥输入流
* @throws Exception
* 加载公钥时产生的异常
*/
public static RSAPublicKey loadPublicKey(InputStream in) throws Exception {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
if (readLine.charAt(0) == '-') {
continue;
} else {
sb.append(readLine);
sb.append('\r');
}
}
return loadPublicKey(sb.toString());
} catch (IOException e) {
throw new Exception("公钥数据流读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥输入流为空");
}
}
/**
* 从字符串中加载公钥
*
* @param publicKeyStr
* 公钥数据字符串
* @throws Exception
* 加载公钥时产生的异常
*/
public static RSAPublicKey loadPublicKey(String publicKeyStr) throws Exception {
try {
byte[] buffer = Base64Utils.decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公钥非法");
} catch (IOException e) {
throw new Exception("公钥数据内容读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥数据为空");
}
}
/**
* 从文件中加载私钥
*
* @param keyFileName
* 私钥文件名
* @return 是否成功
* @throws Exception
*/
public static RSAPrivateKey loadPrivateKey(InputStream in) throws Exception {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
if (readLine.charAt(0) == '-') {
continue;
} else {
sb.append(readLine);
sb.append('\r');
}
}
return loadPrivateKey(sb.toString());
} catch (IOException e) {
throw new Exception("私钥数据读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥输入流为空");
}
}
public static RSAPrivateKey loadPrivateKey(String privateKeyStr) throws Exception {
try {
byte[] buffer = Base64Utils.decode(privateKeyStr);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("私钥非法");
} catch (IOException e) {
throw new Exception("私钥数据内容读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥数据为空");
}
}
/**
* <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());
}
}
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();
}
}
测试demo
public class RSATester {
static String publicKey="MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC5wonDXZhItfDmRUlWQCFwjYL/SSb5PYU7x4mtKPzopnUamlDXTVcSbUdFGRr4K6ANNPs3UsviraN/QWmI3vguzd/xWlpIbGnkyAOzS4hErf+cQDHSW2/TAf1MqI0I6p6tjfLpp4jXJj0OcEeeVR1oVXkY3I8vuOW1v0wwByAkpwIDAQAB";
static String privateKey="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";
static {
try {
// Map<String, Object> keyMap = RSAUtils.genKeyPair();
// publicKey = RSAUtils.getPublicKey(keyMap);
// privateKey = RSAUtils.getPrivateKey(keyMap);
// System.out.println("公钥: \n\r" + publicKey);
// System.out.println("私钥： \n\r" + privateKey);
//
// publicKey= RSAUtils.loadPublicKey("");
// privateKey=RSAUtils.loadPrivateKey("");
//
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
//test();
testSign();
}
static void test() throws Exception {
System.out.println("公钥加密——私钥解密");
String source = "123456";
System.out.println("\r加密前文字：" + source);
byte[] data = source.getBytes();
byte[] encodedData = RSAUtils.encryptByPublicKey(data, publicKey);
System.out.println("加密后文字：" + Base64Utils.encode(encodedData));
byte[] decodedData = RSAUtils.decryptByPrivateKey(encodedData, privateKey);
String target = new String(decodedData);
System.out.println("解密后文字: " + target);
}
static void testSign() throws Exception {
System.out.println("私钥加密——公钥解密");
String source = "9876543";
System.out.println("原文字：" + source);
byte[] data = source.getBytes();
byte[] encodedData = RSAUtils.encryptByPrivateKey(data, privateKey);
System.out.println("加密后：" + Base64Utils.encode(encodedData));
byte[] decodedData = RSAUtils.decryptByPublicKey(encodedData, publicKey);
String target = new String(decodedData);
System.out.println("解密后: " + target);
System.out.println("私钥签名——公钥验证签名");
String sign = RSAUtils.sign(data, privateKey);
System.out.println("签名:" + sign);
boolean status = RSAUtils.verify(data, publicKey, sign);
System.out.println("验证结果:" + status);
}
}
结果
私钥加密——公钥解密
原文字：9876543
加密后：BuC21nX9C1QaW0M16b+Hxn54lnekLQHD1fNcaQgK7MvHNuQKNiwUQilYsi2vALm/yBEnIsR0SreXWYFFogq75SsbI/4fxF2tFz16JIR5+z5Wdm/uE0AFfQDqVMX2I0aJSKzTRhRmCJgE7+n0ALon/b2WLQfHguxGF8X9WjnqnXM=
解密后: 9876543
私钥签名——公钥验证签名
签名:aO9kIu3T4Q/irSxloqlSw+5Mm7TgNooqqkGFEuIyiFZ+KC2P8RFXnzhr2laggRpWVEEQ4cNysqoSE8uDnc3+Me/Ef4YHjK0F30sas1U8VsLuuBghptB406PZc0aStI7ZMp63AokNN+8FoVQ87ObYzRhkXOoKEy+W4gFjcT/usEg=
验证结果:true
