Can org.bouncycastle.openssl.PEMReader read java.security.PrivateKey?

Question

I have following code:

PrivateKey key = null;
X509Certificate cert = null;
KeyPair keyPair = null;

final Reader reader = new StringReader(pem);
try {
    final PEMReader pemReader = new PEMReader(reader, new PasswordFinder() {
        @Override
        public char[] getPassword() {
            return password == null ? null : password.toCharArray();
        }
    });

    Object obj;
    while ((obj = pemReader.readObject()) != null) {
        if (obj instanceof X509Certificate) {
            cert = (X509Certificate) obj;
        } else if (obj instanceof PrivateKey) {
            key = (PrivateKey) obj;
        } else if (obj instanceof KeyPair) {
            keyPair = (KeyPair) obj;
        }
    }
} finally {
    reader.close();
}

Will it ever read PrivateKey? In other words, can any PEM file contain pure private key only? If yes, could you provide me a sample PEM file?

Thanks in advace.

Answer 1

A file can contain only a private key, and it can be encrypted or clear text. OpenSSL does this all the time.

I reviewed the code for PEMReader, however, and it looks like it will return a KeyPair from an RSA private key (the private key file contains all the necessary information for the corresponding public key). It looks like it will never return simply a PrivateKey from readObject().

Here's an unencrypted 1024 RSA private key from OpenSSL.

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

Here's the corresponding public key:

-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC/oBTZGo0cgHHdZD8LgDpUVOPj
sI58PrTJPtrlVT7kyznmzFEtTW9cqxlw6EOo09tTTrjikLDA2M5xzejbLGPb8sa7
AzVhuHkChgGh9eZmphsnvq1WLjuXCk5yWOR9ziaBKKFeNXOsdvDp3eMDM+wz3vzn
1wrGrg00jMvKP5kcpwIDAQAB
-----END PUBLIC KEY-----

A KeyStore is meant to be used to carry public, private, and symmetric keys in a Java application. Most Java applications store private keys in a PKCS #8 encoding (which is not the same as the OpenSSL format), and public keys are represented with a SubjectPublicKeyInfo structure (which is the same as OpenSSL).