Example usage for org.bouncycastle.bcpg SignatureSubpacketTags EMBEDDED_SIGNATURE

Introduction

In this page you can find the example usage for org.bouncycastle.bcpg SignatureSubpacketTags EMBEDDED_SIGNATURE.

Prototype

int EMBEDDED_SIGNATURE

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Usage

From source file:com.google.e2e.bcdriver.KeyChecker.java

License:Apache License

private static final boolean isGoodBackSignature(PGPSignature sig, PGPPublicKey signer, PGPPublicKey target,
        StringBuilder errors) throws PGPException, SignatureException, IOException {

    SignatureSubpacket esigpack = null;/*from w w w  .j a va2s  .  c  o  m*/

    // Prefer to get it from the hashed subpacket.
    PGPSignatureSubpacketVector svec = sig.getHashedSubPackets();
    if (svec != null) {
        esigpack = svec.getSubpacket(SignatureSubpacketTags.EMBEDDED_SIGNATURE);
    }

    if (esigpack == null) {
        svec = sig.getUnhashedSubPackets();
        if (svec != null) {
            esigpack = svec.getSubpacket(SignatureSubpacketTags.EMBEDDED_SIGNATURE);
        }
    }

    if (esigpack == null) {
        errors.append("Rejecting " + niceSig(sig) + " for subkey " + nicePk(target)
                + " because it doesn't have a cross-certification.\n"
                + "See https://www.gnupg.org/faq/subkey-cross-certify.html\n");
        return false;
    }

    // Unfortunately, since PGPSignature(byte[]) is not public, we
    // have to go through this ugly contortion to get a signature.

    ByteArrayOutputStream baout = new ByteArrayOutputStream();
    // dump out an old-style header.
    int hdr = 0x80 | (PacketTags.SIGNATURE << 2);
    int len = esigpack.getData().length;
    if (len <= 0xff) {
        baout.write(hdr);
        baout.write(len);
    } else if (len <= 0xffff) {
        baout.write(hdr | 0x01);
        baout.write((len >> 8) & 0xff);
        baout.write(len & 0xff);
    } else {
        baout.write(hdr | 0x02);
        baout.write((len >> 24) & 0xff);
        baout.write((len >> 16) & 0xff);
        baout.write((len >> 8) & 0xff);
        baout.write(len & 0xff);
    }

    baout.write(esigpack.getData());
    baout.close();

    PGPObjectFactory fact = new PGPObjectFactory(new ByteArrayInputStream(baout.toByteArray()),
            new BcKeyFingerprintCalculator());

    Object obj = fact.nextObject();

    if (!(obj instanceof PGPSignatureList)) {
        errors.append("Rejecting " + niceSig(sig) + " for subkey " + nicePk(target)
                + " because no usable embedded signature is available.\n");
        return false;
    }
    PGPSignatureList esiglist = (PGPSignatureList) obj;
    if (esiglist.size() != 1) {
        errors.append("Rejecting " + niceSig(sig) + " for subkey " + nicePk(target)
                + " because no usable embedded signature is available.\n");
        return false;
    }

    PGPSignature esig = esiglist.get(0);
    if (esig.getSignatureType() != PGPSignature.PRIMARYKEY_BINDING) {
        errors.append("Rejecting " + niceSig(sig) + " for subkey " + nicePk(target) + " because the embedded "
                + niceSig(esig) + " is not a proper backsignature.\n");
        return false;
    }

    esig.init(new BcPGPContentVerifierBuilderProvider(), target);

    return esig.verifyCertification(signer, target) && isSignatureCurrent(esig, errors);
}

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