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private static final String KEY_ALGORITHM = "RSA"; 

private static final String PUBLIC_KEY ="publicKey"; 

private static final String PRIVATE_KEY ="privateKey"; 

public static void main(String[] args) throws Exception{ 

    Map<String,String> keyMap = genKey(); 

    RSAPublicKey publicKey = getPublicKey(keyMap.get(PUBLIC_KEY)); 

    RSAPrivateKey privateKey = getPrivateKey(keyMap.get(PRIVATE_KEY)); 

    String info ="明文123456"; 

    //加密 

    byte[] bytes = encrypt(info.getBytes("utf-8"),publicKey); 

    //解密 

    bytes = decrypt(bytes, privateKey); 

    System.out.println(new String(bytes,"utf-8")); 
  
} 

public static Map<String,String> genKey() throws NoSuchAlgorithmException{ 

    Map<String,String> keyMap = new HashMap<String,String>(); 

    KeyPairGenerator keygen = KeyPairGenerator.getInstance(KEY_ALGORITHM); 

    SecureRandom random = new SecureRandom(); 

    // random.setSeed(keyInfo.getBytes()); 

    // 初始加密，512位已被破解，用1024位,最好用2048位 

    keygen.initialize(1024, random); 

    // 取得密钥对 

    KeyPair kp = keygen.generateKeyPair(); 

    RSAPrivateKey privateKey = (RSAPrivateKey)kp.getPrivate(); 

    String privateKeyString = Base64.encode(privateKey.getEncoded()); 

    RSAPublicKey publicKey = (RSAPublicKey)kp.getPublic(); 

    String publicKeyString = Base64.encode(publicKey.getEncoded()); 

    keyMap.put(PUBLIC_KEY, publicKeyString); 

    keyMap.put(PRIVATE_KEY, privateKeyString); 

    return keyMap; 

} 

public static RSAPublicKey getPublicKey(String publicKey) throws Exception{ 

    byte[] keyBytes = LBase64.decode(publicKey); 

    X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes); 

    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); 

    return (RSAPublicKey) keyFactory.generatePublic(spec); 

} 

public static RSAPrivateKey getPrivateKey(String privateKey) throws Exception{ 

    byte[] keyBytes = LBase64.decode(privateKey); 

    PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes); 

    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM); 

    return (RSAPrivateKey) keyFactory.generatePrivate(spec); 

}

转载自

https://blog.csdn.net/mafei852213034/article/details/53319908?locationNum=10&fps=1