概念
RSA是由罗纳德·李维斯特（Ron Rivest）、阿迪·萨莫尔（Adi Shamir）和伦纳德·阿德曼（Leonard Adleman）在1977年一起提出的。当时他们三人都在麻省理工学院工作。RSA 就是他们三人姓氏开头字母拼在一起组成的。
RSA算法（可用于加密和数字签名）的安全性基于这样的事实：大整数的因式分解 被认为是‘难以破解’的。
原理
-
公钥与私钥的产生
-
加密消息
-
解密消息
java jdk实现
package crypto.rsa;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
/**
* 非对称加密 RSA
*/
public class RsaUtils {
private static final String ALGORITHM = "RSA";
private static final String SIGNATURE_ALGORITHM = "MD5withRSA";
public static InnerKey generateKey() throws NoSuchAlgorithmException {
return generateKey(1024);
}
/**
* 初始化密钥
* <p>
* 工作模式 ECB
* 填充方式 NoPadding PKCS1Padding ...
*
* @param keysize 默认1024；范围在 [512~65536] ,且需要为 64 的倍数
* @return
* @throws NoSuchAlgorithmException
*/
public static InnerKey generateKey(int keysize) throws NoSuchAlgorithmException {
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);
keyPairGenerator.initialize(keysize);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
//RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
//RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
return InnerKey.builder()
.publicKey(keyPair.getPublic().getEncoded())
.privateKey(keyPair.getPrivate().getEncoded())
.build();
}
private static PublicKey getPublicKey(byte[] key) throws NoSuchAlgorithmException, InvalidKeySpecException {
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(key);
PublicKey publicKey = KeyFactory.getInstance(ALGORITHM).generatePublic(x509EncodedKeySpec);
return publicKey;
}
private static PrivateKey getPrivateKey(byte[] key) throws NoSuchAlgorithmException, InvalidKeySpecException {
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(key);
PrivateKey privateKey = KeyFactory.getInstance(ALGORITHM).generatePrivate(pkcs8EncodedKeySpec);
return privateKey;
}
/**
* 私钥加密 公钥解密---加密
*
* @param privateKey
* @param data
* @return
* @throws Exception
*/
public static byte[] encryptByPrivateKey(byte[] privateKey, byte[] data) throws Exception {
return encrypt(true, privateKey, data);
}
/**
* 私钥加密 公钥解密---解密
*
* @param publicKey
* @param data
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] publicKey, byte[] data) throws Exception {
return decrypt(false, publicKey, data);
}
/**
* 公钥加密 私钥解密---加密
*
* @param publicKey
* @param data
* @return
* @throws Exception
*/
public static byte[] encryptByPublicKey(byte[] publicKey, byte[] data) throws Exception {
return encrypt(false, publicKey, data);
}
/**
* 公钥加密 私钥解密---解密
*
* @param privateKey
* @param data
* @return
* @throws Exception
*/
public static byte[] decryptByPrivateKey(byte[] privateKey, byte[] data) throws Exception {
return decrypt(true, privateKey, data);
}
private static byte[] encrypt(boolean isPrivate, byte[] key, byte[] data) throws Exception {
Key thisKey = isPrivate ? getPrivateKey(key) : getPublicKey(key);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, thisKey);
return cipher.doFinal(data);
}
private static byte[] decrypt(boolean isPrivate, byte[] key, byte[] data) throws Exception {
Key thisKey = isPrivate ? getPrivateKey(key) : getPublicKey(key);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, thisKey);
return cipher.doFinal(data);
}
/**
* 用私钥对信息生成数字签名
*
* @param privateKey
* @param data
* @return
* @throws Exception
*/
public static byte[] sign(byte[] privateKey, byte[] data) throws Exception {
//
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(getPrivateKey(privateKey));
signature.update(data);
return signature.sign();
}
/**
* 验证签名
*
* @param publicKey
* @param data
* @param sign
* @return
* @throws Exception
*/
public static boolean verifySign(byte[] publicKey, byte[] data, byte[] sign) throws Exception {
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(getPublicKey(publicKey));
signature.update(data);
return signature.verify(sign);
}
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public static class InnerKey {
private byte[] publicKey;
private byte[] privateKey;
}
}
测试代码
package crypto.rsa;
import org.apache.commons.codec.binary.Base64;
public class RsaUtilsTest {
public static void main(String[] args) throws Exception {
RsaUtils.InnerKey innerKey = RsaUtils.generateKey();
System.out.println("公钥：" + Base64.encodeBase64String(innerKey.getPublicKey()));
System.out.println("私钥：" + Base64.encodeBase64String(innerKey.getPrivateKey()));
byte[] data = "你好，世界".getBytes();
testEncrypt1(innerKey.getPublicKey(), innerKey.getPrivateKey(), data);
testEncrypt2(innerKey.getPublicKey(), innerKey.getPrivateKey(), data);
testSign(innerKey.getPublicKey(), innerKey.getPrivateKey(), data);
}
private static void testEncrypt1(byte[] publicKey, byte[] privateKey, byte[] data) throws Exception {
// 私钥加密 公钥解密---加密
byte[] encryptBytes = RsaUtils.encryptByPrivateKey(privateKey, data);
System.out.println("私钥加密公钥解密-密文：" + Base64.encodeBase64String(encryptBytes));
// 私钥加密 公钥解密---解密
byte[] result = RsaUtils.decryptByPublicKey(publicKey, encryptBytes);
System.out.println("解密后：" + new String(result));
}
private static void testEncrypt2(byte[] publicKey, byte[] privateKey, byte[] data) throws Exception {
// 公钥加密 私钥解密---加密
byte[] encryptBytes = RsaUtils.encryptByPublicKey(publicKey, data);
System.out.println("公钥加密私钥解密-密文：" + Base64.encodeBase64String(encryptBytes));
// 公钥加密 私钥解密---解密
byte[] result = RsaUtils.decryptByPrivateKey(privateKey, encryptBytes);
System.out.println("解密后：" + new String(result));
}
private static void testSign(byte[] publicKey, byte[] privateKey, byte[] data) throws Exception {
byte[] sign = RsaUtils.sign(privateKey, data);
System.out.println("签名：" + Base64.encodeBase64String(sign));
boolean result = RsaUtils.verifySign(publicKey, data, sign);
System.out.println("验签结果：" + result);
}
}
