Java读取OpenSSL生成的PEM公钥文件操作

JDK8的JCE是不支持读取PEM文件的。需要使用bouncycastle。

项目需求，使用SHA1WithRSA算法，对接口数据做签名。

代码如下：

@Service
class SignService {
 private static Logger LOG = LoggerFactory.getLogger(SignService.class);

 @Autowired
 private Config config;

 private Signature signature;

 @PostConstruct
 private void init() {
  try {
   PKCS8EncodedKeySpec priKeySpec = new PKCS8EncodedKeySpec(
     getDecoder().decode(config.getPrivateKey().getBytes(ISO_8859_1)));

   KeyFactory factory = KeyFactory.getInstance("RSA");
   PrivateKey privateKey = factory.generatePrivate(priKeySpec);

   signature = Signature.getInstance("SHA1WithRSA");
   signature.initSign(privateKey);

  } catch (NoSuchAlgorithmException |
    /*InvalidAlgorithmParameterException |*/
    InvalidKeySpecException |
    InvalidKeyException ex) {
   LOG.warn("RSA init error: {}.", ex);
  }
 }

 String signAndEncode(String source) {
  if (Objects.isNull(source)) {
   return null;
  } else {
   return sign(source)
     .map(this::encode)
     .orElse("");
  }
 }

 private String encode(byte[] source) {
  return getEncoder()
    .encodeToString(source);
 }

 private synchronized Optional<byte[]> sign(String source) {
  try {
   signature.update(source.getBytes(ISO_8859_1));
   return Optional.of(signature.sign());
  } catch (SignatureException e) {
   LOG.warn("SHA1WithRSA {} error: {}.", source, e);
   return Optional.empty();
  }
 }
}

单元测试，验证签名是否正确。先初始化Signature：

 private Signature signature;

 @Before
 public void init() {
  try {
   byte[] key = Files.readAllBytes(Paths.get("/home/ls", "ras_public_key.pem"));

   Security.addProvider(new BouncyCastleProvider());

   final PemObject pemObject;

   try (PemReader pemReader = new PemReader(new InputStreamReader(
     new ByteArrayInputStream(key)))) {
    pemObject = pemReader.readPemObject();
   }

   X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(pemObject.getContent());

   KeyFactory factory = KeyFactory.getInstance("RSA");
   PublicKey publicKey = factory.generatePublic(pubKeySpec);

   signature = Signature.getInstance("SHA1WithRSA");
   signature.initVerify(publicKey);
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

验证方法

 private boolean verify(String source, String sign) {
  byte[] data = getDecoder().decode(sign);
  try {
   signature.update(source.getBytes());
   return signature.verify(data);
  } catch (SignatureException e) {
   e.printStackTrace();
   return false;
  }
 }

测试

  String source = service.signature(request);
  String sign = signService.signAndEncode(source);
  System.out.println(sign);
  assertTrue(verify(source, sign));

证明，内容没有被篡改。

其中，ras_public_key.pem文件由openSSL生成。

ls@LS-8500:~$ openssl genrsa -out rsa_private_key.pem 1024
Generating RSA private key, 1024 bit long modulus (2 primes)
...+++++
...............+++++
e is 65537 (0x010001)
ls@LS-8500:~$ openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----
ls@LS-8500:~$ openssl rsa -in rsa_private_key.pem -pubout -out ras_public_key.pem
writing RSA key

补充知识：Java导入OpenSSL生成的公私钥文件

1. 生成2048-bit RSA私钥

$ openssl genrsa -out private_key.pem 2048

2. 导出RSA公钥

$ openssl rsa -in private_key.pem -pubout -out public_key.pem

3. 将公私钥文件private_key.pem和public_key.pem的头尾注释去掉

即：

-----BEGIN PUBLIC KEY-----

-----END PUBLIC KEY-----

-----BEGIN RSA PRIVATE KEY-----

-----END RSA PRIVATE KEY-----

4. 读取公私钥文件内容

// filePath即为private_key.pem和public_key.pem
public static String getKeyFromFile(String filePath) throws Exception {
 File file = new File(filePath);
 InputStream ins = new FileInputStream(file);
 BufferedReader br = new BufferedReader(new InputStreamReader(ins));
 String readLine = null;
 StringBuffer sb = new StringBuffer();
 while ((readLine = br.readLine()) != null) {
  sb.append(readLine);
 }
 br.close();
 ins.close();
 return new String(sb);
}

5. 读取私钥

public static PrivateKey getPrivateKey(String privateKey) throws Exception {
 // 解码由base64编码的私钥
 byte[] keyBytes = decryptBASE64(privateKey);
 PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
 KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
 // 取得私钥
 PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
 return priKey;
}

6. 读取公钥

public static PublicKey getPublicKey(String publicKeyStr) throws Exception {
 // 解码由base64编码的公钥
 byte[] keyBytes = decryptBASE64(publicKeyStr);
 // 取得公钥
 X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
 KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
 PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);
 return publicKey;
}

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