前言

• 簡介
  RSA公開密鑰密碼體制是一種使用不同的加密密鑰與解密密鑰，“由已知加密密鑰推導(dǎo)出解密密鑰在計算上是不可行的”密碼體制。

• 原理
  根據(jù)數(shù)論，尋求兩個大素數(shù)比較簡單，而將它們的乘積進行因式分解卻極其困難，因此可以將乘積公開作為加密密鑰，即公鑰，而兩個大素數(shù)組合成私鑰。公鑰是可發(fā)布的供任何人使用，私鑰則為自己所有，供解密之用。

• 運算速度
  由于進行的都是大數(shù)計算，使得RSA最快的情況也比DES慢上好幾倍，無論是軟件還是硬件實現(xiàn)。速度一直是RSA的缺陷。一般來說只用于少量數(shù)據(jù)加密。RSA的速度比對應(yīng)同樣安全級別的對稱密碼算法要慢1000倍左右。

• 其它鏈接
  RSA加密 - Vue
  RSA分段加密 - Java
  RSA分段解密 - Vue

具體實現(xiàn)

• 實現(xiàn)類

import javax.crypto.Cipher; import java.security.*; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Base64;/*** @Description RSA加密算法* @author coisini* @date Jul 5, 2021* @Version 1.0*/ public class RSAUtil {private static final String ALGO = "RSA";private static final String CHARSET = "UTF-8";/*** 公鑰 由generateKeyPair()生成*/private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCaaI4MBywkCjIppZnraqN3pbrcZTq/t0+aMBo8K3pK9BDD6XkM6N2Yfcva7BSFbUWuAcI7piXak0UKn9CElDuhNzUSgQn4IXKxIt3Iva5cV83qYumj+0yRjjLT8Muu1Y1rgBZjY9oBwhVoV+Twg25+UJ+6Q6HM4xTwQQJDoyy4jwIDAQAB";/*** 私鑰 由generateKeyPair()生成*/private static final String PRIVATE_KEY = "MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAJpojgwHLCQKMimlmetqo3elutxlOr+3T5owGjwrekr0EMPpeQzo3Zh9y9rsFIVtRa4BwjumJdqTRQqf0ISUO6E3NRKBCfghcrEi3ci9rlxXzepi6aP7TJGOMtPwy67VjWuAFmNj2gHCFWhX5PCDbn5Qn7pDoczjFPBBAkOjLLiPAgMBAAECgYBnBBKhG7frY5IMDxwd4Euna767hB4qAlbte+JE+ozgrOzyiDXm0wXk0yjKqm8WhczTRwEbYsImjdKmP/GSQoN1AU7yEzM8j0Jgq46m9ZVrHhu2NpuZpr+XueWnA6FNz6tybBgcCwA4t8dvfbOrvjqhrCu01O1xWIpjronyFBN4IQJBAPGuF58xjXyANnp5YU8NhUQ73tTIveRlOpMXDSYkf9lWG26XIGUIsTe0f5jssiNmYtxG+lUm9LLfZgOLcrVkDZ0CQQCjjrBNMXub49efVTCg+nCGT2QXW2BHg/qs5vu8Y34LUHoD/hoEJ+AOWOdnhpRoYOpBwJAm3Gu4a1VmZGGafp0bAkAdfY3aWhSWtZpwNXF/UPoLCnc1Zc1uGkAchLqRBfEn1w7/3qcQTRA66OaNBYzzLuIvWOXhECDZ1tK+6fw0UCItAkAOLibW6n1fDKf7JnWq30u2OVfiNofoa2bmarhUowOgk3+grP0wcwyX8dlOPnrLeeuVe86DsASe3p9u2zEjJesVAkEAhkLiv4TXrC1QlJl7ghksUfFmdT7M4Zxlzj10ConMgq68HkLdmn2nNLsjhUHGwJe3EqM6aozn4zw/Z7uPIT9Fsw==";/*** 生成密鑰對* @throws NoSuchAlgorithmException*/private static void generateKeyPair() throws NoSuchAlgorithmException {// KeyPairGenerator 類用于生成公鑰和私鑰對，基于RSA算法生成對象KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(ALGO);// 初始化密鑰對生成器，密鑰大小為 96-1024 位keyPairGen.initialize(1024, new SecureRandom());// 生成一個密鑰對，保存在 keyPair 中KeyPair keyPair = keyPairGen.generateKeyPair();// 得到私鑰RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();// 得到公鑰RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();String publicKeyString = new String(Base64.getEncoder().encode(publicKey.getEncoded()));// 得到私鑰字符串String privateKeyString = new String(Base64.getEncoder().encode((privateKey.getEncoded())));System.out.println(publicKeyString);System.out.println(privateKeyString);}/*** RSA公鑰加密* @param data 加密字符串* @return 密文* @throws Exception 加密過程中的異常信息*/private static String encryptByPublicKey(String data) throws Exception {// base64 編碼的公鑰byte[] decoded = Base64.getDecoder().decode(PUBLIC_KEY);RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance(ALGO).generatePublic(new X509EncodedKeySpec(decoded));// RSA加密Cipher cipher = Cipher.getInstance(ALGO);// 公鑰加密cipher.init(Cipher.ENCRYPT_MODE, pubKey);return Base64.getEncoder().encodeToString(cipher.doFinal(data.getBytes(CHARSET)));}/*** RSA私鑰解密* @param data 加密字符串* @return 明文* @throws Exception 解密過程中的異常信息*/private static String decryptByPrivateKey(String data) throws Exception {byte[] inputByte = Base64.getDecoder().decode(data.getBytes(CHARSET));// base64 編碼的私鑰byte[] decoded = Base64.getDecoder().decode(PRIVATE_KEY);RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance(ALGO).generatePrivate(new PKCS8EncodedKeySpec(decoded));// RSA 解密Cipher cipher = Cipher.getInstance(ALGO);// 私鑰解密cipher.init(Cipher.DECRYPT_MODE, priKey);return new String(cipher.doFinal(inputByte));}/*** 私鑰加密* 前端公鑰解密* @param data 加密字符串* @return 密文* @throws Exception 加密過程中的異常信息*/public static String encryptByPrivateKey(String data) throws Exception {// 獲取私鑰PrivateKey privateKey = getPrivateKey(PRIVATE_KEY);Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE, privateKey);byte[] cipherText = cipher.doFinal(data.getBytes());String cipherStr = Base64.getEncoder().encodeToString(cipherText);return cipherStr;}/*** 公鑰解密* @param data 解密字符串* @return 明文* @throws Exception 解密過程中的異常信息*/public static String decryptByPublicKey(String data) throws Exception {// 獲取公鑰PublicKey publicKey = getPublicKey(PUBLIC_KEY);Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE, publicKey);byte[] cipherText = Base64.getDecoder().decode(data);byte[] decryptText = cipher.doFinal(cipherText);return new String(decryptText);}/*** 將base64編碼后的私鑰字符串轉(zhuǎn)成PrivateKey實例* @param privateKey 私鑰* @return PrivateKey實例* @throws Exception 異常信息*/private static PrivateKey getPrivateKey(String privateKey) throws Exception {byte[] keyBytes = Base64.getDecoder().decode(privateKey);PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGO);return keyFactory.generatePrivate(keySpec);}/*** 將base64編碼后的公鑰字符串轉(zhuǎn)成PublicKey實例* @param publicKey 公鑰* @return PublicKey實例* @throws Exception 異常信息*/private static PublicKey getPublicKey(String publicKey) throws Exception {byte[] keyBytes = Base64.getDecoder().decode(publicKey);X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(ALGO);return keyFactory.generatePublic(keySpec);}public static void main(String[] args) {String data = "RSA encrypt!";try {// generateKeyPair();String encryDataByPublicKey = encryptByPublicKey(data);System.out.println("encryDataByPublicKey: " + encryDataByPublicKey);String decryDataByPrivateKey = decryptByPrivateKey(encryDataByPublicKey);System.out.println("decryDataByPrivateKey: " + decryDataByPrivateKey);String encryDataByPrivateKey = encryptByPrivateKey(data);System.out.println("encryDataByPrivateKey: " + encryDataByPrivateKey);String decryDataByPublicKey = decryptByPublicKey(encryDataByPrivateKey);System.out.println("decryDataByPublicKey: " + decryDataByPublicKey);} catch (Exception e) {e.printStackTrace();}}}

• 結(jié)果如下所示：
  
  
  

源碼

• GitHub： https://github.com/Maggieq8324/coisini-rsa
• Gitee：https://gitee.com/maggieq8324/coisini-rsa

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