private static PrivateKey readPrivateKeyPEM()

in jsign-core/src/main/java/net/jsign/PrivateKeyUtils.java [74:110]

• 26 lines of code
• 6 McCabe index (conditional complexity)

    private static PrivateKey readPrivateKeyPEM(File file, String password) throws IOException, OperatorCreationException, PKCSException {
        try (FileReader reader = new FileReader(file)) {
            PEMParser parser = new PEMParser(reader);
            Object object = parser.readObject();
            
            if (object == null) {
                throw new IllegalArgumentException("No key found in " + file);
            }
            
            BouncyCastleProvider provider = new BouncyCastleProvider();
            JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider(provider);

            if (object instanceof PEMEncryptedKeyPair) {
                // PKCS1 encrypted key
                PEMDecryptorProvider decryptionProvider = new JcePEMDecryptorProviderBuilder().setProvider(provider).build(password.toCharArray());
                PEMKeyPair keypair = ((PEMEncryptedKeyPair) object).decryptKeyPair(decryptionProvider);
                return converter.getPrivateKey(keypair.getPrivateKeyInfo());

            } else if (object instanceof PKCS8EncryptedPrivateKeyInfo) {
                // PKCS8 encrypted key
                InputDecryptorProvider decryptionProvider = new JceOpenSSLPKCS8DecryptorProviderBuilder().setProvider(provider).build(password.toCharArray());
                PrivateKeyInfo info = ((PKCS8EncryptedPrivateKeyInfo) object).decryptPrivateKeyInfo(decryptionProvider);
                return converter.getPrivateKey(info);
                
            } else if (object instanceof PEMKeyPair) {
                // PKCS1 unencrypted key
                return converter.getKeyPair((PEMKeyPair) object).getPrivate();
                
            } else if (object instanceof PrivateKeyInfo) {
                // PKCS8 unencrypted key
                return converter.getPrivateKey((PrivateKeyInfo) object);
                
            } else {
                throw new UnsupportedOperationException("Unsupported PEM object: " + object.getClass().getSimpleName());
            }
        }
    }