SignatureVerifier.java
// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.signature.consumer;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.openpgp.PGPUserAttributeSubpacketVector;
import org.pgpainless.algorithm.SignatureType;
import org.pgpainless.exception.SignatureValidationException;
import org.pgpainless.implementation.ImplementationFactory;
import org.pgpainless.policy.Policy;
/**
* Collection of static methods for signature verification.
* Signature verification entails validation of certain criteria (see {@link SignatureValidator}), as well as
* cryptographic verification of signature correctness.
*/
public final class SignatureVerifier {
private SignatureVerifier() {
}
/**
* Verify a signature (certification or revocation) over a user-id.
*
* @param userId user-id
* @param signature certification signature
* @param signingKey key that created the certification
* @param keyWithUserId key carrying the user-id
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if signature verification is successful
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifySignatureOverUserId(String userId, PGPSignature signature, PGPPublicKey signingKey, PGPPublicKey keyWithUserId, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureType type = SignatureType.valueOf(signature.getSignatureType());
switch (type) {
case GENERIC_CERTIFICATION:
case NO_CERTIFICATION:
case CASUAL_CERTIFICATION:
case POSITIVE_CERTIFICATION:
return verifyUserIdCertification(userId, signature, signingKey, keyWithUserId, policy, validationDate);
case CERTIFICATION_REVOCATION:
return verifyUserIdRevocation(userId, signature, signingKey, keyWithUserId, policy, validationDate);
default:
throw new SignatureValidationException("Signature is not a valid user-id certification/revocation signature: " + type);
}
}
/**
* Verify a certification self-signature over a user-id.
*
* @param userId user-id
* @param signature certification signature
* @param primaryKey primary key
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the self-signature is verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserIdCertification(String userId, PGPSignature signature, PGPPublicKey primaryKey, Policy policy, Date validationDate)
throws SignatureValidationException {
return verifyUserIdCertification(userId, signature, primaryKey, primaryKey, policy, validationDate);
}
/**
* Verify a user-id certification.
*
* @param userId user-id
* @param signature certification signature
* @param signingKey key that created the certification
* @param keyWithUserId primary key that carries the user-id
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if signature verification is successful
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserIdCertification(String userId, PGPSignature signature, PGPPublicKey signingKey, PGPPublicKey keyWithUserId, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsCertification().verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverUserId(userId, keyWithUserId, signingKey).verify(signature);
return true;
}
/**
* Verify a user-id revocation self-signature.
*
* @param userId user-id
* @param signature user-id revocation signature
* @param primaryKey primary key
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the user-id revocation signature is successfully verified
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserIdRevocation(String userId, PGPSignature signature, PGPPublicKey primaryKey, Policy policy, Date validationDate)
throws SignatureValidationException {
return verifyUserIdRevocation(userId, signature, primaryKey, primaryKey, policy, validationDate);
}
/**
* Verify a user-id revocation signature.
*
* @param userId user-id
* @param signature revocation signature
* @param signingKey key that created the revocation signature
* @param keyWithUserId primary key carrying the user-id
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the user-id revocation signature is successfully verified
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserIdRevocation(String userId, PGPSignature signature, PGPPublicKey signingKey, PGPPublicKey keyWithUserId, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.CERTIFICATION_REVOCATION).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverUserId(userId, keyWithUserId, signingKey).verify(signature);
return true;
}
/**
* Verify a certification self-signature over a user-attributes packet.
*
* @param userAttributes user attributes
* @param signature certification self-signature
* @param primaryKey primary key that carries the user-attributes
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserAttributesCertification(PGPUserAttributeSubpacketVector userAttributes,
PGPSignature signature, PGPPublicKey primaryKey,
Policy policy, Date validationDate)
throws SignatureValidationException {
return verifyUserAttributesCertification(userAttributes, signature, primaryKey, primaryKey, policy, validationDate);
}
/**
* Verify a certification signature over a user-attributes packet.
*
* @param userAttributes user attributes
* @param signature certification signature
* @param signingKey key that created the user-attributes certification
* @param keyWithUserAttributes key that carries the user-attributes certification
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserAttributesCertification(PGPUserAttributeSubpacketVector userAttributes,
PGPSignature signature, PGPPublicKey signingKey,
PGPPublicKey keyWithUserAttributes, Policy policy,
Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsCertification().verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverUserAttributes(userAttributes, keyWithUserAttributes, signingKey).verify(signature);
return true;
}
/**
* Verify a user-attributes revocation self-signature.
*
* @param userAttributes user-attributes
* @param signature user-attributes revocation signature
* @param primaryKey primary key that carries the user-attributes
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the revocation signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserAttributesRevocation(PGPUserAttributeSubpacketVector userAttributes,
PGPSignature signature, PGPPublicKey primaryKey,
Policy policy, Date validationDate)
throws SignatureValidationException {
return verifyUserAttributesRevocation(userAttributes, signature, primaryKey, primaryKey, policy, validationDate);
}
/**
* Verify a user-attributes revocation signature.
*
* @param userAttributes user-attributes
* @param signature revocation signature
* @param signingKey revocation key
* @param keyWithUserAttributes key that carries the user-attributes
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the revocation signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyUserAttributesRevocation(PGPUserAttributeSubpacketVector userAttributes,
PGPSignature signature, PGPPublicKey signingKey,
PGPPublicKey keyWithUserAttributes, Policy policy,
Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.CERTIFICATION_REVOCATION).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverUserAttributes(userAttributes, keyWithUserAttributes, signingKey).verify(signature);
return true;
}
/**
* Verify a subkey binding signature.
*
* @param signature binding signature
* @param primaryKey primary key
* @param subkey subkey
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the binding signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifySubkeyBindingSignature(PGPSignature signature, PGPPublicKey primaryKey, PGPPublicKey subkey, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.SUBKEY_BINDING).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(primaryKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.hasValidPrimaryKeyBindingSignatureIfRequired(primaryKey, subkey, policy, validationDate).verify(signature);
SignatureValidator.correctSubkeyBindingSignature(primaryKey, subkey).verify(signature);
return true;
}
/**
* Verify a subkey revocation signature.
*
* @param signature subkey revocation signature
* @param primaryKey primary key
* @param subkey subkey
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the subkey revocation signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifySubkeyBindingRevocation(PGPSignature signature, PGPPublicKey primaryKey, PGPPublicKey subkey, Policy policy, Date validationDate) throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.SUBKEY_REVOCATION).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(primaryKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverKey(primaryKey, subkey).verify(signature);
return true;
}
/**
* Verify a direct-key self-signature.
*
* @param signature signature
* @param primaryKey primary key
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the signature can be verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyDirectKeySignature(PGPSignature signature, PGPPublicKey primaryKey, Policy policy, Date validationDate)
throws SignatureValidationException {
return verifyDirectKeySignature(signature, primaryKey, primaryKey, policy, validationDate);
}
/**
* Verify a direct-key signature.
*
* @param signature signature
* @param signingKey signing key
* @param signedKey signed key
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if signature verification is successful
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyDirectKeySignature(PGPSignature signature, PGPPublicKey signingKey, PGPPublicKey signedKey, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.DIRECT_KEY).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverKey(signingKey, signedKey).verify(signature);
return true;
}
/**
* Verify a key revocation signature.
*
* @param signature signature
* @param primaryKey primary key
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if signature verification is successful
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyKeyRevocationSignature(PGPSignature signature, PGPPublicKey primaryKey, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.signatureIsOfType(SignatureType.KEY_REVOCATION).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(primaryKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
SignatureValidator.correctSignatureOverKey(primaryKey, primaryKey).verify(signature);
return true;
}
/**
* Initialize a signature and verify it afterwards by updating it with the signed data.
*
* @param signature OpenPGP signature
* @param signedData input stream containing the signed data
* @param signingKey the key that created the signature
* @param policy policy
* @param validationDate reference date of signature verification
* @return true if the signature is successfully verified
*
* @throws SignatureValidationException if the signature verification fails for some reason
*/
public static boolean verifyUninitializedSignature(PGPSignature signature, InputStream signedData, PGPPublicKey signingKey, Policy policy, Date validationDate) throws SignatureValidationException {
initializeSignatureAndUpdateWithSignedData(signature, signedData, signingKey);
return verifyInitializedSignature(signature, signingKey, policy, validationDate);
}
/**
* Initialize a signature and then update it with the signed data from the given {@link InputStream}.
*
* @param signature OpenPGP signature
* @param signedData input stream containing signed data
* @param signingKey key that created the signature
*
* @throws SignatureValidationException in case the signature cannot be verified for some reason
*/
public static void initializeSignatureAndUpdateWithSignedData(PGPSignature signature, InputStream signedData, PGPPublicKey signingKey)
throws SignatureValidationException {
try {
signature.init(ImplementationFactory.getInstance().getPGPContentVerifierBuilderProvider(), signingKey);
int read;
byte[] buf = new byte[8192];
byte lastByte = -1;
while ((read = signedData.read(buf)) != -1) {
// If we previously omitted a newline, but the stream is not yet empty, add it now
if (lastByte == (byte) '\n') {
signature.update(lastByte);
}
lastByte = buf[read - 1];
if (lastByte == (byte) '\n') {
// if last byte in buffer is newline, omit it for now
signature.update(buf, 0, read - 1);
} else {
// otherwise, write buffer as usual
signature.update(buf, 0, read);
}
}
} catch (PGPException e) {
throw new SignatureValidationException("Cannot init signature.", e);
} catch (IOException e) {
throw new SignatureValidationException("Cannot update signature.", e);
}
}
/**
* Verify an initialized signature.
* An initialized signature was already updated with the signed data.
*
* @param signature OpenPGP signature
* @param signingKey key that created the signature
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if signature is verified successfully
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifyInitializedSignature(PGPSignature signature, PGPPublicKey signingKey, Policy policy, Date validationDate)
throws SignatureValidationException {
SignatureValidator.wasPossiblyMadeByKey(signingKey).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective(validationDate).verify(signature);
try {
if (!signature.verify()) {
throw new SignatureValidationException("Signature is not correct.");
}
return true;
} catch (PGPException e) {
throw new SignatureValidationException("Could not verify signature correctness.", e);
}
}
public static boolean verifyOnePassSignature(PGPSignature signature, PGPPublicKey signingKey, OnePassSignatureCheck onePassSignature, Policy policy)
throws SignatureValidationException {
try {
SignatureValidator.wasPossiblyMadeByKey(signingKey).verify(signature);
SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
SignatureValidator.signatureIsEffective().verify(signature);
} catch (SignatureValidationException e) {
throw new SignatureValidationException("Signature is not valid: " + e.getMessage(), e);
}
try {
if (onePassSignature.getSignature() == null) {
throw new IllegalStateException("No comparison signature provided.");
}
if (!onePassSignature.getOnePassSignature().verify(signature)) {
throw new SignatureValidationException("Bad signature of key " + Long.toHexString(signingKey.getKeyID()));
}
} catch (PGPException e) {
throw new SignatureValidationException("Could not verify correctness of One-Pass-Signature: " + e.getMessage(), e);
}
return true;
}
/**
* Verify a signature (certification or revocation) over a user-id.
*
* @param userId user-id
* @param signature self-signature
* @param primaryKey primary key that created the signature
* @param policy policy
* @param validationDate reference date for signature verification
* @return true if the signature is successfully verified
*
* @throws SignatureValidationException if signature verification fails for some reason
*/
public static boolean verifySignatureOverUserId(String userId, PGPSignature signature, PGPPublicKey primaryKey, Policy policy, Date validationDate)
throws SignatureValidationException {
return verifySignatureOverUserId(userId, signature, primaryKey, primaryKey, policy, validationDate);
}
}