从 RSA .pem 文件中获取私钥

Question

鉴于此 .pem 文件（使用 openssl 生成并使用密码加密）：

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,AC009672952033EB

2wegzxf3MtncXS1CY3c.....
....
....
-----END RSA PRIVATE KEY-----

如何在 Java 中获取 PrivateKey 对象？我写了下面的代码，但我找不到正确的方法来获得 KeySpec:

PrivateKey readFromPem(File keyFile, String password){
    PemReader r = new PemReader(new InputStreamReader(new FileInputStream(keyFile)));
    PemObject pemObject = r.readPemObject();
    byte[] encodedKey = pemObject.getContent();

    KeySpec keySpec = ???? // how to get this?

    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    PrivateKey key = keyFactory.generatePrivate(keySpec);
    return key;
}

我想我应该构建一个 RSAPrivateKeySpec，但我不知道如何构建。我尝试了 this answer and this other answer 中的方法，但它们在解析字节数组时都会导致错误。

Answer 1

使用 Bouncy Castle 的 bcpkix 依赖项，它知道如何处理 OpenSSL 密钥。

<dependency>
  <groupId>org.bouncycastle</groupId>
  <artifactId>bcpkix-jdk14</artifactId>
  <version>1.57</version>
</dependency>

然后像这样尝试：

private PrivateKey readFromPem(File keyFile, String password) throws IOException {
    Security.addProvider(new BouncyCastleProvider());

    PEMParser pemParser = new PEMParser(new InputStreamReader(new FileInputStream(keyFile)));
    PEMEncryptedKeyPair encryptedKeyPair = (PEMEncryptedKeyPair) pemParser.readObject();
    PEMDecryptorProvider decryptorProvider = new JcePEMDecryptorProviderBuilder().build(password.toCharArray());
    PEMKeyPair pemKeyPair = encryptedKeyPair.decryptKeyPair(decryptorProvider);

    JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider("BC");
    return converter.getPrivateKey(pemKeyPair.getPrivateKeyInfo());
}

Answer 2

我正在使用 BouncyCastle 1.57（bcprov-jdk15on、bcmail-jdk15on 和 bcpkix-jdk15on）和 Java 7.

您可以使用JcaPEMKeyConverter class读取私钥。下面的代码适用于有密码和没有密码的密钥：

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMDecryptorProvider;
import org.bouncycastle.openssl.PEMEncryptedKeyPair;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.bouncycastle.openssl.jcajce.JcePEMDecryptorProviderBuilder;

// don't forget to add the provider
Security.addProvider(new BouncyCastleProvider());
String password = "your password";

// reads your key file
PEMParser pemParser = new PEMParser(new FileReader(keyFile));
Object object = pemParser.readObject();
JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider("BC");

KeyPair kp;
if (object instanceof PEMEncryptedKeyPair) {
    // Encrypted key - we will use provided password
    PEMEncryptedKeyPair ckp = (PEMEncryptedKeyPair) object;
    // uses the password to decrypt the key
    PEMDecryptorProvider decProv = new JcePEMDecryptorProviderBuilder().build(password.toCharArray());
    kp = converter.getKeyPair(ckp.decryptKeyPair(decProv));
} else {
    // Unencrypted key - no password needed
    PEMKeyPair ukp = (PEMKeyPair) object;
    kp = converter.getKeyPair(ukp);
}

// RSA
KeyFactory keyFac = KeyFactory.getInstance("RSA");
RSAPrivateCrtKeySpec privateKey = keyFac.getKeySpec(kp.getPrivate(), RSAPrivateCrtKeySpec.class);

System.out.println(privateKey.getClass());

privateKey 的 class 将是 java.security.spec.RSAPrivateCrtKeySpec（扩展 RSAPrivateKeySpec）。

从 RSA .pem 文件中获取私钥

Get a PrivateKey from a RSA .pem file

java

rsa

bouncycastle

private-key