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Java实现RSA加密算法

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生成密钥对

首先创建 KeyPairGenerator 类的对象,用于生成公钥和私钥对

// 生成公钥和私钥对,基于RSA算法生成对象 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

然后初始化密钥对的长度,最低长度512位,并且长度不能低于明文的长度

// 初始化密钥大小为1024位 keyPairGen.initialize(1024);

利用 keyPairGen 对象生成密钥对,保存在 KeyPair 类中

KeyPair keyPair = keyPairGen.generateKeyPair();

从 keyPair 类中获取公钥和私钥

RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); 加密(encrypt) protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) { if (publicKey != null) { try { // Cipher负责完成加密或解密工作,基于RSA Cipher cipher = Cipher.getInstance(ALGORITHM); // 根据公钥,对Cipher对象进行初始化 cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 加密,结果保存进resultBytes,并返回 byte[] resultBytes = cipher.doFinal(srcBytes); return resultBytes; } catch (Exception e) { e.printStackTrace(); } } return null; } 解密(decrypt) protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) { if (publicKey != null) { try { // Cipher负责完成加密或解密工作,基于RSA Cipher cipher = Cipher.getInstance("RSA"); // 根据公钥,对Cipher对象进行初始化 cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 加密,结果保存进resultBytes,并返回 byte[] resultBytes = cipher.doFinal(srcBytes); return resultBytes; } catch (Exception e) { e.printStackTrace(); } } return null; } 完整代码 import java.security.*; import java.security.interfaces.*; import javax.crypto.*; public class RSA { private RSAPublicKey publicKey; private RSAPrivateKey privateKey; private byte[] resultBytes; private final static String ALGORITHM = "RSA"; public RSA() { try { String message = "你好,我很喜欢加密算法"; System.out.println("明文是:" + message); // 生成公钥和私钥对,基于RSA算法生成对象 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(ALGORITHM); // 初始化密钥对生成器,密钥大小为1024位 keyPairGen.initialize(1024); // 生成一个密钥对,保存在keyPair中 KeyPair keyPair = keyPairGen.generateKeyPair(); // 得到公钥和私钥 publicKey = (RSAPublicKey) keyPair.getPublic(); privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 用公钥加密 byte[] srcBytes = message.getBytes(); resultBytes = RSA.encrypt(publicKey, srcBytes); String result = new String(resultBytes); System.out.println("用公钥加密后密文是:" + result); } catch (Exception e) { e.printStackTrace(); } } protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) { if (publicKey != null) { try { // Cipher负责完成加密或解密工作,基于RSA Cipher cipher = Cipher.getInstance(ALGORITHM); // 根据公钥,对Cipher对象进行初始化 cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 加密,结果保存进resultBytes,并返回 byte[] resultBytes = cipher.doFinal(srcBytes); return resultBytes; } catch (Exception e) { e.printStackTrace(); } } return null; } protected byte[] decrypt(RSAPrivateKey privateKey, byte[] encBytes) { if (privateKey != null) { try { Cipher cipher = Cipher.getInstance(ALGORITHM); // 根据私钥对Cipher对象进行初始化 cipher.init(Cipher.DECRYPT_MODE, privateKey); // 解密并将结果保存进resultBytes byte[] decBytes = cipher.doFinal(encBytes); return decBytes; } catch (Exception e) { e.printStackTrace(); } } return null; } public static void main(String[] args) { long rsaStart = System.currentTimeMillis(); RSA rsa = new RSA(); byte[] decBytes = rsa.decrypt(rsa.privateKey, rsa.resultBytes); String dec = new String(decBytes); long rsaEnd = System.currentTimeMillis(); System.out.println("用私钥解密后的结果是:" + dec); System.out.println("共计用时:" + (rsaEnd - rsaStart)); } }

运行结果见下面的GIF:


Java实现RSA加密算法

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