一、加密的原因
1.加密：是为了防止信息泄露；
2.签名：签名为了防止信息被篡改，保证数据完整性和发送方角色的可靠性和不可依赖性。
二、RSA加密简介
RSA加密是一种非对称加密。可在不直接传递密钥的情况下，完成解密；是由一对密钥来进行加密的过程，分别称为公钥和私钥。两者之间有数学相关，该加密算法的原理就是一对极大整数做因数分解的困难性来保证安全性。通常个人保存私钥，公钥是公开的（可能同时多人持有）。
三、RSA加密、签名区别
-
加解密过程简述
A和B进行通信加密,B要先生成一对RSA密钥,B自己持有私钥,给A公钥 --->A使用B的公钥加密要发送的内容,然后B接收到密文后通过自己的私钥解密内容
-
签名验签过程简述
A给B发送消息,A先计算出消息的消息摘要,然后使用自己的私钥加密消息摘要,被加密的消息摘要就是签名.(A用自己的私钥给消息摘要加密成为签名)
B收到消息后,也会使用和A相同的方法提取消息摘要,然后用A的公钥解密签名,并与自己计算出来的消息摘要进行比较-->如果相同则说明消息是A发送给B的,同时,A也无法否认自己发送消息给B的事实.(B使用A的公钥解密签名文件的过程,叫做"验签").
四、RSA原理
RSA算法常用于非对称加密，非对称加密流程如下：
（1）乙方生成两把密钥(公钥和私钥)。公钥是公开的，任何人都可以获得，私钥则是保密的。
（2）甲方获取乙方的公钥，然后用它对信息加密。
（3）乙方得到加密后的信息，用私钥解密。
五、代码实现
java
public class RSAUtil {
public static final String SIGN_ALGORITHMS = "SHA256WithRSA";
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
/** */
/**
* RSA最大加密明文大小
*/
private static final int MAX_ENCRYPT_BLOCK = 64;
/** */
/**
* RSA最大解密密文大小
*/
private static final int MAX_DECRYPT_BLOCK = 512;
public static KeyPair getKeyPair() throws Exception {
KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
generator.initialize(1024);
return generator.generateKeyPair();
}
/**
* 签名
*
* @param content
* @param privateKey
* @return
*/
public static String sign(String content, String privateKey) {
try {
PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(privateKey));
KeyFactory keyf = KeyFactory.getInstance("RSA");
PrivateKey priKey = keyf.generatePrivate(priPKCS8);
Signature signature = Signature.getInstance(SIGN_ALGORITHMS);
signature.initSign(priKey);
signature.update(content.getBytes(DEFAULT_CHARSET));
byte[] signed = signature.sign();
return Base64.getEncoder().encodeToString(signed);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**
* 验签
*
* @param content
* @param sign
* @param publicKey
* @return
*/
public static boolean verify(String content, String sign, String publicKey) {
try {
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
byte[] encodedKey = Base64.getDecoder().decode(publicKey);
PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
Signature signature = Signature.getInstance(SIGN_ALGORITHMS);
signature.initVerify(pubKey);
signature.update(content.getBytes(DEFAULT_CHARSET));
return signature.verify(Base64.getDecoder().decode(sign));
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
public static PublicKey getPublicKey(String key) throws Exception {
byte[] keyBytes = Base64.getDecoder().decode(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}
public static PrivateKey getPrivateKey(String key) throws Exception {
byte[] keyBytes = Base64.getDecoder().decode(key);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}
/**
* 公钥分段加密
*
* @param content
* @param publicKeyStr
* @return
* @throws Exception
*/
public static String publicEncrpyt(String content, String publicKeyStr) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(1, getPublicKey(publicKeyStr));
byte[] bytes = content.getBytes(DEFAULT_CHARSET);
int inputLen = bytes.length;
int offSet = 0;
byte[] cache;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int i = 0;
// 对数据分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(bytes, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(bytes, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptedData = out.toByteArray();
out.close();
return Base64.getEncoder().encodeToString(encryptedData);
}
/**
* 私钥分段加密
*
* @param content
* @param privateKeyStr
* @return
* @throws Exception
*/
public static String privateEncrpyt(String content, String privateKeyStr) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(1, getPrivateKey(privateKeyStr));
byte[] bytes = content.getBytes(DEFAULT_CHARSET);
int inputLen = bytes.length;
int offSet = 0;
byte[] cache;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int i = 0;
// 对数据分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(bytes, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(bytes, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptedData = out.toByteArray();
out.close();
return Base64.getEncoder().encodeToString(encryptedData);
}
/**
* 私钥分段解密
*
* @param content
* @param privateKeyStr
* @return
* @throws Exception
*/
public static String privateDecrypt(String content, String privateKeyStr) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(2, getPrivateKey(privateKeyStr));
byte[] bytes = Base64.getDecoder().decode(content);
int inputLen = bytes.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(bytes, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(bytes, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
byte[] decryptedData = out.toByteArray();
out.close();
return new String(decryptedData);
}
/**
* 公钥分段解密
*
* @param content
* @param publicKeyStr
* @return
* @throws Exception
*/
public static String publicDecrypt(String content, String publicKeyStr) throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(2, getPublicKey(publicKeyStr));
byte[] bytes = Base64.getDecoder().decode(content);
int inputLen = bytes.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(bytes, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(bytes, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
byte[] decryptedData = out.toByteArray();
out.close();
return new String(decryptedData);
}
public static void main(String[] args) throws Exception {
String content = "asdhaoddddddaosdjosadosaudosaudaosdusadadsadsadsadasdasdasdasdsadsadsadasdasdasdsadasdsadasdsadsadadsadsadadiugtiutujjjkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkka";
// 公钥216
String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCCaGn5+Yq9o7kxmDS2zwIREIEkcpKbx44uPT/PX22XOjgzkMvbCEamu7KyatNhkrrSH6E14l1F739WztXffJ/OCXUmgF4egMedyGCA8ymZWbzyhwnZcywa8me8S2rjb3gkCD6VFq8BSPJx9vaMvlR7eZxe1O5lllaV6tE6SlNY7QIDAQAB";
//私钥844
String privateKey =
"MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAIJoafn5ir2juTGYNLbPAhEQgSRy" +
"kpvHji49P89fbZc6ODOQy9sIRqa7srJq02GSutIfoTXiXUXvf1bO1d98n84JdSaAXh6Ax53IYIDz" +
"KZlZvPKHCdlzLBryZ7xLauNveCQIPpUWrwFI8nH29oy+VHt5nF7U7mWWVpXq0TpKU1jtAgMBAAEC" +
"gYBOzKsk+s4EM5dnSXKo+ENmblOq43SFnzrh4+7X7vD4zZxCRH96NfEDNS4Qs45RSmmLKMOwHL2B" +
"0etfWBJSPisNZomhOBgTSfvHDSIFNbvVFqQBH5zEtxIB3bPrkW5X6EDF2BYCatC70Al21kmzHr2d" +
"BaL/c2p/4ueTdna/zKSKwQJBAMZLvFeyLi9jiIXXUzv7AkxF4SICtOOL56mKMkVlAXOWQgQe9FVs" +
"O8lTTK6GqqLrYe5cqgTiQqcLCP8/5n33oF0CQQCoW0ospTg8JEqStTmwemF8HfgxLU6YGj5kegD2" +
"Fq6HfCTq/z59THohbq6l+yoSxO3mjZb+7Zv1zu6oDR7YXFHRAkB66dEaDtFAAJNMWxc107Yt7xbI" +
"zSKw9TSoy4ezqhNHQXk0MrfDB27bsS2T9NdqWzr91CRzGIi2IEn4ZfSKWmblAkB2S1bOEfV2hMWF" +
"WiND9mnDDUfUPhKIW4BVl0hPodZWSouiN2DQJ8l07lF3PQjuEUNcCUb8rzYzvIgCut1eh1fRAkEA" +
"qBOEqBuRq9W7vrBlHbqEk1EXu2MfeRLZWljZn6uoyedJCdSh+6neUUvqHDGi3DNdss/ByWHI9e+9" +
"zOXTURmMaQ==";
String s = publicEncrpyt(content, publicKey);
System.out.println("公钥加密后" + s);
String s1 = privateDecrypt(s, privateKey);
System.out.println("解密后" + s1);
//公钥加密-->私钥签名-->公钥验签-->私钥解密
/* String s = publicEncrpyt(content, publicKey);
System.out.println("公钥加密后"+s);
//签名 Authorization
String sign = sign(s, privateKey);
System.out.println("私钥签名后："+sign);
//验签
boolean verify = verify(s, sign, publicKey);
System.out.println("用公钥验签后"+verify);
String s1 = privateDecrypt(s, privateKey);
System.out.println("解密后"+s1 );*/
/*String s = privateEncrpyt(content, privateKey);
System.out.println("公钥加密后" + s);
String sign = sign(s, privateKey);
System.out.println("私钥签名后：" + sign);
boolean verify = verify(s, sign, publicKey);
System.out.println("用公钥验签后" + verify);
String s1 = publicDecrypt(s, publicKey);
System.out.println("解密后" + s1);*/
}
}六、如果上面代码还不满足你的需求也可以试试这个
java
/**
* @params str 要加密的字符串
*/
public static String rsaEncode(String str) {
String publicKey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANL378k3RiZHWx5AfJqdH9xRNBmD9wGD2iRe41HdTNF8RUhNnHit5NpMNtGL0NPTSSpPjjI1kJfVorRvaQerUgkCAwEAAQ==";
String outStr = "";
try {
// base64编码的公钥
byte[] decoded = Base64.decode(publicKey, Base64.DEFAULT);
RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
// RSA加密
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
outStr = Base64.encodeToString(cipher.doFinal(str.getBytes("UTF-8")), Base64.DEFAULT);
} catch (Exception e) {
e.printStackTrace();
}
return outStr;
}