PGPSignatureGenerator generator = new PGPSignatureGenerator(new BcPGPContentSignerBuilder(secretKey.getPublicKey().getAlgorithm(), PGPUtil.SHA512))
        generator.init(PGPSignature.BINARY_DOCUMENT, getPrivateKey(secretKey, password))
        generator
    }

    private static PGPPrivateKey getPrivateKey(PGPSecretKey secretKey, String password) {

        def armored = new ArmoredSignatureType()
        return armored.sign(validSignatory, toSign)
    }

    static PGPSecretKey readSecretKey(File keyringsDir) {
        def keyring = new File(keyringsDir, "secring.gpg")
        PGPSecretKey secretKey = null
        keyring.withInputStream {
            new PGPSecretKeyRingCollection(it, new BcKeyFingerprintCalculator()).each {

        }
        return readSecretKey(keyRingCollection, normalizeKeyId(keyId), sourceDescription);
    }

    protected PGPSecretKey readSecretKey(PGPSecretKeyRingCollection keyRings, final PgpKeyId keyId, String sourceDescription) {
        PGPSecretKey key = findSecretKey(keyRings, keyId);
        if (key == null) {

            if (keyId == null) {
                PGPSecretKey key = new JcaPGPSecretKeyRing(in).getSecretKey();
                return factory.createSignatory(name, key, password);
            } else {
                PgpKeyId expectedKeyId = new PgpKeyId(keyId);
                for (PGPSecretKeyRing keyring : new JcaPGPSecretKeyRingCollection(in)) {
                    for (PGPSecretKey key : keyring) {

    static {
        SecuritySupport.assertInitialized();
    }

    private final String name;
    private final PGPSecretKey secretKey;
    private final PGPPrivateKey privateKey;

    public PgpSignatory(String name, PGPSecretKey secretKey, String password) {
        this.name = name;
        this.secretKey = secretKey;
        this.privateKey = createPrivateKey(secretKey, password);
    }

Method <org.gradle.plugins.signing.signatory.pgp.PgpSignatoryFactory.readSecretKey(java.lang.String, java.io.File)> has arguments/return type org.bouncycastle.openpgp.PGPSecretKey that is not Gradle public API or primitive or built-in...