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Experimental implementation of signing of existing hash contexts (MessageDigest instances)

This commit is contained in:
Paul Schaub 2022-04-16 00:23:20 +02:00
parent b64d6e8e55
commit c3dfb254b1
Signed by: vanitasvitae
GPG Key ID: 62BEE9264BF17311
3 changed files with 400 additions and 0 deletions
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237
pgpainless-core/src/main/java/org/pgpainless/signature/builder/HashContextPGPContentSignerBuilder.java Normal file
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// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.signature.builder;
import java.io.IOException;
import java.io.OutputStream;
import java.security.MessageDigest;
import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
import org.bouncycastle.crypto.signers.DSADigestSigner;
import org.bouncycastle.crypto.signers.DSASigner;
import org.bouncycastle.crypto.signers.ECDSASigner;
import org.bouncycastle.crypto.signers.Ed25519Signer;
import org.bouncycastle.crypto.signers.Ed448Signer;
import org.bouncycastle.crypto.signers.RSADigestSigner;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.operator.PGPContentSigner;
import org.bouncycastle.openpgp.operator.PGPContentSignerBuilder;
import org.bouncycastle.openpgp.operator.bc.BcPGPKeyConverter;
import org.bouncycastle.util.Arrays;
import org.pgpainless.algorithm.HashAlgorithm;
import org.pgpainless.algorithm.PublicKeyAlgorithm;
/**
* Implementation of {@link PGPContentSignerBuilder} using the BC API, which can be used to sign hash contexts.
* This can come in handy to sign data, which was already processed to calculate the hash context, without the
* need to process it again to calculate the OpenPGP signature.
*/
public class HashContextPGPContentSignerBuilder implements PGPContentSignerBuilder {
private final BcPGPKeyConverter keyConverter = new BcPGPKeyConverter();
private final MessageDigest messageDigest;
private final HashAlgorithm hashAlgorithm;
public HashContextPGPContentSignerBuilder(MessageDigest messageDigest) {
this.messageDigest = messageDigest;
this.hashAlgorithm = HashAlgorithm.fromName(messageDigest.getAlgorithm());
if (hashAlgorithm == null) {
throw new IllegalArgumentException("Cannot recognize OpenPGP Hash Algorithm: " + messageDigest.getAlgorithm());
}
}
@Override
public PGPContentSigner build(int signatureType, PGPPrivateKey privateKey) throws PGPException {
PublicKeyAlgorithm keyAlgorithm = PublicKeyAlgorithm.requireFromId(privateKey.getPublicKeyPacket().getAlgorithm());
AsymmetricKeyParameter privKeyParam = keyConverter.getPrivateKey(privateKey);
final Signer signer = createSigner(keyAlgorithm, messageDigest, privKeyParam);
signer.init(true, privKeyParam);
return new PGPContentSigner() {
public int getType() {
return signatureType;
}
public int getHashAlgorithm() {
return hashAlgorithm.getAlgorithmId();
}
public int getKeyAlgorithm() {
return keyAlgorithm.getAlgorithmId();
}
public long getKeyID() {
return privateKey.getKeyID();
}
public OutputStream getOutputStream() {
return new SignerOutputStream(signer);
}
public byte[] getSignature() {
try {
return signer.generateSignature();
} catch (CryptoException e) {
throw new IllegalStateException("unable to create signature");
}
}
public byte[] getDigest() {
return messageDigest.digest();
}
};
}
static Signer createSigner(
PublicKeyAlgorithm keyAlgorithm,
MessageDigest messageDigest,
CipherParameters keyParam)
throws PGPException {
ExistingMessageDigest staticDigest = new ExistingMessageDigest(messageDigest);
switch (keyAlgorithm.getAlgorithmId()) {
case PublicKeyAlgorithmTags.RSA_GENERAL:
case PublicKeyAlgorithmTags.RSA_SIGN:
return new RSADigestSigner(staticDigest);
case PublicKeyAlgorithmTags.DSA:
return new DSADigestSigner(new DSASigner(), staticDigest);
case PublicKeyAlgorithmTags.ECDSA:
return new DSADigestSigner(new ECDSASigner(), staticDigest);
case PublicKeyAlgorithmTags.EDDSA:
if (keyParam instanceof Ed25519PrivateKeyParameters || keyParam instanceof Ed25519PublicKeyParameters) {
return new EdDsaSigner(new Ed25519Signer(), staticDigest);
}
return new EdDsaSigner(new Ed448Signer(new byte[0]), staticDigest);
default:
throw new PGPException("cannot recognise keyAlgorithm: " + keyAlgorithm);
}
}
static class ExistingMessageDigest implements Digest {
private final MessageDigest digest;
ExistingMessageDigest(MessageDigest messageDigest) {
this.digest = messageDigest;
}
@Override
public void update(byte in) {
digest.update(in);
}
@Override
public void update(byte[] in, int inOff, int len) {
digest.update(in, inOff, len);
}
@Override
public int doFinal(byte[] out, int outOff) {
byte[] hash = digest.digest();
System.arraycopy(hash, 0, out, outOff, hash.length);
return getDigestSize();
}
@Override
public void reset() {
// Nope!
// We cannot reset, since BCs signer classes are resetting in their init() methods, which would also reset
// the messageDigest, losing its state. This would shatter our intention.
}
@Override
public String getAlgorithmName() {
return digest.getAlgorithm();
}
@Override
public int getDigestSize() {
return digest.getDigestLength();
}
}
// Copied from BCs BcImplProvider - required since BCs class is package visible only :/
private static class EdDsaSigner
implements Signer {
private final Signer signer;
private final Digest digest;
private final byte[] digBuf;
EdDsaSigner(Signer signer, Digest digest) {
this.signer = signer;
this.digest = digest;
this.digBuf = new byte[digest.getDigestSize()];
}
public void init(boolean forSigning, CipherParameters param) {
this.signer.init(forSigning, param);
this.digest.reset();
}
public void update(byte b) {
this.digest.update(b);
}
public void update(byte[] in, int off, int len) {
this.digest.update(in, off, len);
}
public byte[] generateSignature()
throws CryptoException, DataLengthException {
digest.doFinal(digBuf, 0);
signer.update(digBuf, 0, digBuf.length);
return signer.generateSignature();
}
public boolean verifySignature(byte[] signature) {
digest.doFinal(digBuf, 0);
signer.update(digBuf, 0, digBuf.length);
return signer.verifySignature(signature);
}
public void reset() {
Arrays.clear(digBuf);
signer.reset();
digest.reset();
}
}
// Copied from BC, required since BCs class is package visible only
static class SignerOutputStream
extends OutputStream {
private Signer sig;
SignerOutputStream(Signer sig) {
this.sig = sig;
}
public void write(byte[] bytes, int off, int len)
throws IOException {
sig.update(bytes, off, len);
}
public void write(byte[] bytes)
throws IOException {
sig.update(bytes, 0, bytes.length);
}
public void write(int b)
throws IOException {
sig.update((byte) b);
}
}
}

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pgpainless-core/src/main/java/org/pgpainless/signature/builder/HashContextSigner.java Normal file
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// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.signature.builder;
import java.security.MessageDigest;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.openpgp.PGPSignatureGenerator;
import org.pgpainless.algorithm.SignatureType;
public class HashContextSigner {
/**
* Create an OpenPGP Signature over the given {@link MessageDigest} hash context.
*
* WARNING: This method does not yet validate the signing key.
* TODO: Change API to receive and evaluate PGPSecretKeyRing + SecretKeyRingProtector instead.
*
* @param hashContext hash context
* @param privateKey signing-capable key
* @return signature
* @throws PGPException in case of an OpenPGP error
*/
public static PGPSignature signHashContext(MessageDigest hashContext, SignatureType signatureType, PGPPrivateKey privateKey)
throws PGPException {
// TODO: Validate signing key
PGPSignatureGenerator sigGen = new PGPSignatureGenerator(
new HashContextPGPContentSignerBuilder(hashContext)
);
sigGen.init(signatureType.getCode(), privateKey);
return sigGen.generate();
}
}

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pgpainless-core/src/test/java/org/pgpainless/signature/HashContextSignerTest.java Normal file
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// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.signature;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKeyRing;
import org.bouncycastle.openpgp.PGPSecretKeyRing;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.util.io.Streams;
import org.junit.jupiter.api.Test;
import org.pgpainless.PGPainless;
import org.pgpainless.algorithm.HashAlgorithm;
import org.pgpainless.algorithm.SignatureType;
import org.pgpainless.decryption_verification.ConsumerOptions;
import org.pgpainless.decryption_verification.DecryptionStream;
import org.pgpainless.decryption_verification.OpenPgpMetadata;
import org.pgpainless.key.generation.type.rsa.RsaLength;
import org.pgpainless.key.protection.UnlockSecretKey;
import org.pgpainless.signature.builder.HashContextSigner;
import org.pgpainless.util.Passphrase;
public class HashContextSignerTest {
private static final String message = "Hello, World!\n";
private static final String KEY = "-----BEGIN PGP PRIVATE KEY BLOCK-----\n" +
"Version: PGPainless\n" +
"Comment: 62D5 CBED 8BD0 7D3F D167 240D 4364 E4C1 C4ED 8F59\n" +
"Comment: Sigfried <sig@fri.ed>\n" +
"\n" +
"lFgEYlnOkRYJKwYBBAHaRw8BAQdA7Kxn/sPIXo44xnxLBL81G5ghGzMikFc5ib9/\n" +
"qgJpZSUAAQCZnJN2l/cfWWh4DijBAwFWoVJOCphKhsJEjKxOzWdqMA2DtBVTaWdm\n" +
"cmllZCA8c2lnQGZyaS5lZD6IjwQTFgoAQQUCYlnOkQkQQ2TkwcTtj1kWIQRi1cvt\n" +
"i9B9P9FnJA1DZOTBxO2PWQKeAQKbAQUWAgMBAAQLCQgHBRUKCQgLApkBAAAd/gEA\n" +
"kiPFDdMGjZV/7Do/3ox46iCH3N1I3BGmA2Jt8PsYwe0BAKe5ahLzCNAXjBQU4iSD\n" +
"A4FGipNaG2ZWgAMkdwVjMLEAnF0EYlnOkRIKKwYBBAGXVQEFAQEHQI3n0cWbBh+7\n" +
"zeuBjMWevsyxLUCExKSj5fxCh/0GuJgAAwEIBwAA/16V22vjZfAvtnUrVtUZQoYZ\n" +
"E8h87Jzj/XxXFy63I6qoER2IdQQYFgoAHQUCYlnOkQKeAQKbDAUWAgMBAAQLCQgH\n" +
"BRUKCQgLAAoJEENk5MHE7Y9ZzhsA+gPb2FNutetjrYUSY7BEsk+PPkCXF9W6JZmb\n" +
"W/zyRxgpAP9zNzpWrO7kKQ0PwMMd3R1F4Rg6GH+vjXsIbd6jT25UBJxYBGJZzpEW\n" +
"CSsGAQQB2kcPAQEHQPOZhITstSj3cPfsTiBEPhtCrc184fkAjl4s+gSB9ttRAAD/\n" +
"RVpdc9BhJ/ZXtqQaCBL65h7Uym7i+HExQphHOiuB3iwQOIjVBBgWCgB9BQJiWc6R\n" +
"Ap4BApsCBRYCAwEABAsJCAcFFQoJCAtfIAQZFgoABgUCYlnOkQAKCRDXXcvYX8Ym\n" +
"crh9AP99WWietGWYs2//FYi0bEAWp6D0HmHP42rvC3qsqyMa8wD8D1Pi2atKwQTP\n" +
"JAxQFa06cUIw2POE3llaB0MKQXdTVgQACgkQQ2TkwcTtj1mF+gD+OHo68KeGFUi0\n" +
"VcVV/dx/6ES9GAIf1TI6jEsaU8TPBcMBAOHG+5MMVvyNiVKLA0JgJPF3JXOOEU+5\n" +
"qiHwlVoGncUM\n" +
"=431t\n" +
"-----END PGP PRIVATE KEY BLOCK-----";
@Test
public void signContextWithEdDSAKeys() throws PGPException, NoSuchAlgorithmException, IOException {
PGPSecretKeyRing secretKeys = PGPainless.readKeyRing().secretKeyRing(KEY);
signWithKeys(secretKeys);
}
@Test
public void signContextWithRSAKeys() throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, IOException {
PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleRsaKeyRing("Sigfried", RsaLength._3072);
signWithKeys(secretKeys);
}
@Test
public void signContextWithEcKeys() throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, IOException {
PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing("Sigfried");
signWithKeys(secretKeys);
}
private void signWithKeys(PGPSecretKeyRing secretKeys) throws PGPException, NoSuchAlgorithmException, IOException {
for (HashAlgorithm hashAlgorithm : new HashAlgorithm[] {
HashAlgorithm.SHA256, HashAlgorithm.SHA384, HashAlgorithm.SHA512
}) {
signFromContext(secretKeys, hashAlgorithm);
}
}
private void signFromContext(PGPSecretKeyRing secretKeys, HashAlgorithm hashAlgorithm) throws PGPException, NoSuchAlgorithmException, IOException {
PGPPublicKeyRing certificate = PGPainless.extractCertificate(secretKeys);
long signingKeyId = PGPainless.inspectKeyRing(certificate).getSigningSubkeys().get(0).getKeyID();
PGPPrivateKey signingKey = UnlockSecretKey.unlockSecretKey(secretKeys.getSecretKey(signingKeyId), Passphrase.emptyPassphrase());
byte[] messageBytes = message.getBytes(StandardCharsets.UTF_8);
ByteArrayInputStream messageIn = new ByteArrayInputStream(messageBytes);
PGPSignature signature = signMessage(messageBytes, hashAlgorithm, signingKey);
assertEquals(hashAlgorithm.getAlgorithmId(), signature.getHashAlgorithm());
DecryptionStream decryptionStream = PGPainless.decryptAndOrVerify()
.onInputStream(messageIn)
.withOptions(new ConsumerOptions()
.addVerificationCert(certificate)
.addVerificationOfDetachedSignature(signature));
ByteArrayOutputStream out = new ByteArrayOutputStream();
Streams.pipeAll(decryptionStream, out);
decryptionStream.close();
OpenPgpMetadata metadata = decryptionStream.getResult();
assertTrue(metadata.isVerified());
}
private PGPSignature signMessage(byte[] message, HashAlgorithm hashAlgorithm, PGPPrivateKey signingKey)
throws NoSuchAlgorithmException, PGPException {
// Prepare the hash context
// This would be done by the caller application
MessageDigest messageDigest = MessageDigest.getInstance(hashAlgorithm.getAlgorithmName(), new BouncyCastleProvider());
messageDigest.update(message);
return HashContextSigner.signHashContext(messageDigest, SignatureType.BINARY_DOCUMENT, signingKey);
}
}