RSA后端加密，解密，加签及验签

1.说明

2.加密和加签的区别

3.示例

4.注意事项

1.说明

RSA算法是一种非对称加密算法，与对称加密算法不同的是,RSA算法有两个不同的密钥,一个是公钥,一个是私钥。

公钥是公开的，可以多人持有；私钥是保密的，只有自己持有。

加密常用的密钥长度有1024,2048，3072，4096。密钥长度越长，加密的强度也就越强，性能也会越低。可以使用1024或2048位的密码。

2.加密和加签的区别

①加密是防止信息泄露，确保数据传输的安全，如前端输入的一些账号，密码，卡号等敏感信息，必须加密后传输。

加签是防止信息被篡改，确保是发送方传递的数据。

②通过公钥进行加密传输，然后接收方使用私钥进行解密。

通过私钥进行加签，然后接收方使用公钥进行验签。

③加密是可逆的，也就是说加密后的密文可以进行解密。

加签是不可逆的，只能通过验签来验明真伪。

④加密是明文长度是有限制的，明文的最大长度=密文长度-11（单位是字节），当设置密钥为1024位时，1024/8-11=117字节，所以明文的最大长度为117个字节，解密的最大长度为127个字节，相差11个字节是因为加密时使用了填充模式。

加签是没有长度限制的。

3.示例

①引入依赖

        <dependency><groupId>commons-codec</groupId><artifactId>commons-codec</artifactId><version>1.14</version></dependency>

②工具类

package com.example.utils;import java.io.ByteArrayOutputStream;
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.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;import org.apache.commons.codec.binary.Base64;/*** @Author linaibo* @Date 2024/2/17 16:26* @Version 1.0*/
public class RsaTool {/*** 16      * RSA最大加密明文大小* 17*/private static final int MAX_ENCRYPT_BLOCK = 117;/*** 21      * RSA最大解密密文大小* 22*/private static final int MAX_DECRYPT_BLOCK = 128;/*** 26      * 获取密钥对* 27      ** 28      * @return 密钥对* 29*/public static KeyPair getKeyPair() throws Exception {KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");generator.initialize(1024);return generator.generateKeyPair();}/*** 37      * 获取私钥* 38      ** 39      * @param privateKey 私钥字符串* 40      * @return* 41*/public static PrivateKey getPrivateKey(String privateKey) throws Exception {KeyFactory keyFactory = KeyFactory.getInstance("RSA");byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);return keyFactory.generatePrivate(keySpec);}/*** 50      * 获取公钥* 51      ** 52      * @param publicKey 公钥字符串* 53      * @return* 54*/public static PublicKey getPublicKey(String publicKey) throws Exception {KeyFactory keyFactory = KeyFactory.getInstance("RSA");byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);return keyFactory.generatePublic(keySpec);}/*** 63      * RSA加密* 64      ** 65      * @param data 待加密数据* 66      * @param publicKey 公钥* 67      * @return* 68*/public static String encrypt(String data, PublicKey publicKey) throws Exception {Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE, publicKey);int inputLen = data.getBytes().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.getBytes(), offset, MAX_ENCRYPT_BLOCK);} else {cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);}out.write(cache, 0, cache.length);i++;offset = i * MAX_ENCRYPT_BLOCK;}byte[] encryptedData = out.toByteArray();out.close();// 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串// 加密后的字符串return new String(Base64.encodeBase64String(encryptedData));}/*** 96      * RSA解密* 97      ** 98      * @param data 待解密数据* 99      * @param privateKey 私钥* 100      * @return* 101*/public static String decrypt(String data, PrivateKey privateKey) throws Exception {Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE, privateKey);byte[] dataBytes = Base64.decodeBase64(data);int inputLen = dataBytes.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(dataBytes, offset, MAX_DECRYPT_BLOCK);} else {cache = cipher.doFinal(dataBytes, offset, inputLen - offset);}out.write(cache, 0, cache.length);i++;offset = i * MAX_DECRYPT_BLOCK;}byte[] decryptedData = out.toByteArray();out.close();// 解密后的内容return new String(decryptedData, "UTF-8");}/*** 129      * 签名* 130      ** 131      * @param data 待签名数据* 132      * @param privateKey 私钥* 133      * @return 签名* 134*/public static String sign(String data, PrivateKey privateKey) throws Exception {byte[] keyBytes = privateKey.getEncoded();PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance("RSA");PrivateKey key = keyFactory.generatePrivate(keySpec);// 不同的签名算法// Signature signature = Signature.getInstance("MD5withRSA");// Signature signature = Signature.getInstance("MD2withRSA");// Signature signature = Signature.getInstance("SHA1withRSA");// Signature signature = Signature.getInstance("SHA224withRSA");// Signature signature = Signature.getInstance("SHA256withRSA");// Signature signature = Signature.getInstance("SHA384withRSA");Signature signature = Signature.getInstance("SHA512withRSA");signature.initSign(key);signature.update(data.getBytes());return new String(Base64.encodeBase64(signature.sign()));}/*** 147      * 验签* 148      ** 149      * @param srcData 原始字符串* 150      * @param publicKey 公钥* 151      * @param sign 签名* 152      * @return 是否验签通过* 153*/public static boolean verify(String srcData, PublicKey publicKey, String sign) throws Exception {byte[] keyBytes = publicKey.getEncoded();X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance("RSA");PublicKey key = keyFactory.generatePublic(keySpec);// 不同的签名算法// Signature signature = Signature.getInstance("MD5withRSA");// Signature signature = Signature.getInstance("MD2withRSA");// Signature signature = Signature.getInstance("SHA1withRSA");// Signature signature = Signature.getInstance("SHA224withRSA");// Signature signature = Signature.getInstance("SHA256withRSA");// Signature signature = Signature.getInstance("SHA384withRSA");Signature signature = Signature.getInstance("SHA512withRSA");signature.initVerify(key);signature.update(srcData.getBytes());return signature.verify(Base64.decodeBase64(sign.getBytes()));}
}

③使用

package com.example.utils;import java.security.KeyPair;
import org.apache.commons.codec.binary.Base64;/*** @Author linaibo* @Date 2024/2/17 16:30* @Version 1.0*/
public class TestRsa {public static void main(String[] args) throws Exception {KeyPair keyPair = RsaTool.getKeyPair();String privateKey = new String(Base64.encodeBase64(keyPair.getPrivate().getEncoded()));String publicKey = new String(Base64.encodeBase64(keyPair.getPublic().getEncoded()));System.out.println("公钥：" + publicKey);System.out.println("私钥：" + privateKey);String data = "需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字";String encrypt = RsaTool.encrypt(data, RsaTool.getPublicKey(publicKey));System.out.println("加密后：" + encrypt);String decrypt = RsaTool.decrypt(encrypt, RsaTool.getPrivateKey(privateKey));System.out.println("解密后：" + decrypt);String sign = RsaTool.sign(data, RsaTool.getPrivateKey(privateKey));System.out.println("签名后：" + sign);boolean verify = RsaTool.verify(data, RsaTool.getPublicKey(publicKey), sign);System.out.println("验签结果" + verify);}
}

结果：

公钥：MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQD5Wa+wf44UliJLXLQ0UUTZXaH1EZv1bHM4nNSV2xVQY2RN8dKLgQ1J71y+90vJjusi0rOqfFdni2UU3VtnMdtYOYXbhsV14oFtU+3+gWYK28KlqOd5rtjjNR2Vv0sPDaZ+Lfdsq6+p5BpNjtWApPM9ghXj0S6BM3GWjsftNPM/IwIDAQAB
私钥：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
加密后：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
解密后：需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字需要加密的文字
签名后：FgpCHgRZg0AoR747wvDDBbPhYeVUCEJfRaJ3tGVJY3QplddTxprtMHYFQalLK3vVP5Dpo/6bMAzQyu8Y4oaArqtYpoURhPnvr4QXTH+fR8MG8PGYc1S11ysAuDPbsb6geAvHRFsspjGJ9oLH2nHBnZzMQ62HGZ+RzAKING219SY=
验签结果true