如何使用Java创建X509证书？

java public-key certificate x509certificate

2022-09-03 04:40:03

我想使用Java语言创建一个X509证书，然后从中提取公钥。

我搜索了互联网并找到了许多代码示例，但它们都有错误（未知变量或未知类型）或有许多警告，上面写着：“方法......从类型 ...已弃用“等。

例如，为什么以下代码不起作用：

PublicKey pk;
CertificateFactory cf = CertificateFactory.getInstance("X.509");
String PKstr = pk.toString();
InputStream PKstream = new ByteArrayInputStream(PKstr.getBytes());
X509Certificate pkcert = (X509Certificate)cf.generateCertificate(PKstream);

任何人都可以向我展示如何使用纯Java或Bouncy Castle创建证书，然后从中获取公钥？

谢谢大家。

答案 1

您还可以仅使用 JDK 类生成证书。缺点是必须使用 sun.security.x509 包中的两个类。代码为：

KeyStore keyStore = ... // your keystore

// generate the certificate
// first parameter  = Algorithm
// second parameter = signrature algorithm
// third parameter  = the provider to use to generate the keys (may be null or
//                    use the constructor without provider)
CertAndKeyGen certGen = new CertAndKeyGen("RSA", "SHA256WithRSA", null);
// generate it with 2048 bits
certGen.generate(2048);

// prepare the validity of the certificate
long validSecs = (long) 365 * 24 * 60 * 60; // valid for one year
// add the certificate information, currently only valid for one year.
X509Certificate cert = certGen.getSelfCertificate(
   // enter your details according to your application
   new X500Name("CN=My Application,O=My Organisation,L=My City,C=DE"), validSecs);

// set the certificate and the key in the keystore
keyStore.setKeyEntry(certAlias, certGen.getPrivateKey(), null, 
                        new X509Certificate[] { cert });