396 lines
17 KiB
Java
396 lines
17 KiB
Java
// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
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//
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// SPDX-License-Identifier: Apache-2.0
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package org.pgpainless.signature.consumer;
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import java.util.Collections;
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import java.util.Date;
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import java.util.Iterator;
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import java.util.List;
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import org.bouncycastle.openpgp.PGPKeyRing;
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import org.bouncycastle.openpgp.PGPPublicKey;
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import org.bouncycastle.openpgp.PGPSignature;
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import org.pgpainless.algorithm.SignatureType;
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import org.pgpainless.exception.SignatureValidationException;
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import org.pgpainless.policy.Policy;
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import org.pgpainless.signature.SignatureUtils;
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import org.pgpainless.util.CollectionUtils;
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/**
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* Pick signatures from keys.
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*
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* The format of a V4 OpenPGP key is:
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*
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* Primary-Key
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* [Revocation Self Signature]
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* [Direct Key Signature...]
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* User ID [Signature ...]
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* [User ID [Signature ...] ...]
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* [User Attribute [Signature ...] ...]
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* [[Subkey [Binding-Signature-Revocation] Primary-Key-Binding-Signature] ...]
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*/
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public final class SignaturePicker {
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private SignaturePicker() {
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}
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/**
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* Pick the at validation date most recent valid key revocation signature.
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* If there are hard revocation signatures, the latest hard revocation sig is picked, even if it was created after
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* validationDate or if it is already expired.
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*
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* @param keyRing key ring
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* @param policy policy
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* @param validationDate date of signature validation
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* @return most recent, valid key revocation signature
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*/
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public static PGPSignature pickCurrentRevocationSelfSignature(PGPKeyRing keyRing, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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List<PGPSignature> signatures = getSortedSignaturesOfType(primaryKey, SignatureType.KEY_REVOCATION);
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PGPSignature mostCurrentValidSig = null;
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for (PGPSignature signature : signatures) {
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try {
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SignatureVerifier.verifyKeyRevocationSignature(signature, primaryKey, policy, validationDate);
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} catch (SignatureValidationException e) {
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// Signature is not valid
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continue;
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}
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mostCurrentValidSig = signature;
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}
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return mostCurrentValidSig;
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}
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/**
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* Pick the at validationDate most recent, valid direct key signature.
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* This method might return null, if there is no direct key self-signature which is valid at validationDate.
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*
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* @param keyRing key ring
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* @param policy policy
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* @param validationDate validation date
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* @return direct-key self-signature
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*/
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public static PGPSignature pickCurrentDirectKeySelfSignature(PGPKeyRing keyRing, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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return pickCurrentDirectKeySignature(primaryKey, primaryKey, policy, validationDate);
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}
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/**
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* Pick the at validationDate, latest, valid direct key signature made by signingKey on signedKey.
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* This method might return null, if there is no direct key self signature which is valid at validationDate.
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*
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* @param signingKey key that created the signature
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* @param signedKey key that carries the signature
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* @param policy policy
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* @param validationDate validation date
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* @return direct key sig
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*/
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public static PGPSignature pickCurrentDirectKeySignature(PGPPublicKey signingKey, PGPPublicKey signedKey, Policy policy, Date validationDate) {
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List<PGPSignature> directKeySignatures = getSortedSignaturesOfType(signedKey, SignatureType.DIRECT_KEY);
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PGPSignature mostRecentDirectKeySigBySigningKey = null;
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for (PGPSignature signature : directKeySignatures) {
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try {
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SignatureVerifier.verifyDirectKeySignature(signature, signingKey, signedKey, policy, validationDate);
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} catch (SignatureValidationException e) {
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// Direct key sig is not valid
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continue;
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}
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mostRecentDirectKeySigBySigningKey = signature;
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}
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return mostRecentDirectKeySigBySigningKey;
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}
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/**
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* Pick the at validationDate latest direct key signature.
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* This method might return an expired signature.
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* If there are more than one direct-key signature, and some of those are not expired, the latest non-expired
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* yet already effective direct-key signature will be returned.
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*
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* @param keyRing key ring
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* @param policy policy
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* @param validationDate validation date
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* @return latest direct key signature
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*/
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public static PGPSignature pickLatestDirectKeySignature(PGPKeyRing keyRing, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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return pickLatestDirectKeySignature(primaryKey, primaryKey, policy, validationDate);
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}
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/**
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* Pick the at validationDate latest direct key signature made by signingKey on signedKey.
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* This method might return an expired signature.
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* If a non-expired direct-key signature exists, the latest non-expired yet already effective direct-key
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* signature will be returned.
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*
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* @param signingKey signing key (key that made the sig)
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* @param signedKey signed key (key that carries the sig)
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* @param policy policy
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* @param validationDate date of validation
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* @return latest direct key sig
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*/
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public static PGPSignature pickLatestDirectKeySignature(PGPPublicKey signingKey, PGPPublicKey signedKey, Policy policy, Date validationDate) {
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List<PGPSignature> signatures = getSortedSignaturesOfType(signedKey, SignatureType.DIRECT_KEY);
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PGPSignature latestDirectKeySignature = null;
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for (PGPSignature signature : signatures) {
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try {
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SignatureValidator.signatureIsOfType(SignatureType.DIRECT_KEY).verify(signature);
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SignatureValidator.signatureStructureIsAcceptable(signingKey, policy).verify(signature);
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SignatureValidator.signatureIsAlreadyEffective(validationDate).verify(signature);
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// if the currently latest signature is not yet expired, check if the next candidate is not yet expired
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if (latestDirectKeySignature != null && !SignatureUtils.isSignatureExpired(latestDirectKeySignature, validationDate)) {
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SignatureValidator.signatureIsNotYetExpired(validationDate).verify(signature);
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}
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SignatureValidator.correctSignatureOverKey(signingKey, signedKey).verify(signature);
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} catch (SignatureValidationException e) {
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// Direct key signature is not valid
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continue;
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}
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latestDirectKeySignature = signature;
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}
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return latestDirectKeySignature;
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}
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/**
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* Pick the at validationDate most recent, valid user-id revocation signature.
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* If there are hard revocation signatures, the latest hard revocation sig is picked, even if it was created after
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* validationDate or if it is already expired.
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*
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* @param keyRing key ring
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* @param userId user-Id that gets revoked
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* @param policy policy
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* @param validationDate validation date
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* @return revocation signature
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*/
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public static PGPSignature pickCurrentUserIdRevocationSignature(PGPKeyRing keyRing, String userId, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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List<PGPSignature> signatures = getSortedSignaturesOfType(primaryKey, SignatureType.CERTIFICATION_REVOCATION);
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PGPSignature latestUserIdRevocation = null;
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for (PGPSignature signature : signatures) {
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PGPPublicKey signer = keyRing.getPublicKey(signature.getKeyID());
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if (signer == null) {
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// Signature made by external key. Skip.
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continue;
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}
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try {
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SignatureVerifier.verifyUserIdRevocation(userId, signature, primaryKey, policy, validationDate);
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} catch (SignatureValidationException e) {
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// User-id revocation is not valid
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continue;
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}
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latestUserIdRevocation = signature;
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}
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return latestUserIdRevocation;
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}
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/**
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* Pick the at validationDate latest, valid certification self-signature for the given user-id.
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* This method might return null, if there is no certification self signature for that user-id which is valid
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* at validationDate.
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*
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* @param keyRing keyring
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* @param userId userid
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* @param policy policy
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* @param validationDate validation date
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* @return user-id certification
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*/
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public static PGPSignature pickCurrentUserIdCertificationSignature(PGPKeyRing keyRing, String userId, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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Iterator<PGPSignature> userIdSigIterator = primaryKey.getSignaturesForID(userId);
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List<PGPSignature> signatures = CollectionUtils.iteratorToList(userIdSigIterator);
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Collections.sort(signatures, new SignatureCreationDateComparator());
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PGPSignature mostRecentUserIdCertification = null;
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for (PGPSignature signature : signatures) {
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if (primaryKey.getKeyID() != signature.getKeyID()) {
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// Signature not made by primary key
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continue;
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}
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try {
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SignatureVerifier.verifyUserIdCertification(userId, signature, primaryKey, policy, validationDate);
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} catch (SignatureValidationException e) {
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// User-id certification is not valid
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continue;
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}
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mostRecentUserIdCertification = signature;
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}
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return mostRecentUserIdCertification;
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}
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/**
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* Pick the at validationDate latest certification self-signature for the given user-id.
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* This method might return an expired signature.
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* If a non-expired user-id certification signature exists, the latest non-expired yet already effective
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* user-id certification signature for the given user-id will be returned.
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*
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* @param keyRing keyring
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* @param userId userid
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* @param policy policy
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* @param validationDate validation date
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* @return user-id certification
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*/
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public static PGPSignature pickLatestUserIdCertificationSignature(PGPKeyRing keyRing, String userId, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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Iterator<PGPSignature> userIdSigIterator = primaryKey.getSignaturesForID(userId);
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List<PGPSignature> signatures = CollectionUtils.iteratorToList(userIdSigIterator);
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Collections.sort(signatures, new SignatureCreationDateComparator());
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PGPSignature latestUserIdCert = null;
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for (PGPSignature signature : signatures) {
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try {
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SignatureValidator.wasPossiblyMadeByKey(primaryKey).verify(signature);
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SignatureValidator.signatureIsCertification().verify(signature);
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SignatureValidator.signatureStructureIsAcceptable(primaryKey, policy).verify(signature);
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SignatureValidator.signatureIsAlreadyEffective(validationDate).verify(signature);
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SignatureValidator.correctSignatureOverUserId(userId, primaryKey, primaryKey).verify(signature);
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} catch (SignatureValidationException e) {
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// User-id certification is not valid
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continue;
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}
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latestUserIdCert = signature;
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}
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return latestUserIdCert;
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}
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/**
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* Pick the at validationDate most recent, valid subkey revocation signature.
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* If there are hard revocation signatures, the latest hard revocation sig is picked, even if it was created after
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* validationDate or if it is already expired.
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*
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* @param keyRing keyring
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* @param subkey subkey
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* @param policy policy
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* @param validationDate validation date
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* @return subkey revocation signature
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*/
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public static PGPSignature pickCurrentSubkeyBindingRevocationSignature(PGPKeyRing keyRing, PGPPublicKey subkey, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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if (primaryKey.getKeyID() == subkey.getKeyID()) {
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throw new IllegalArgumentException("Primary key cannot have subkey binding revocations.");
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}
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List<PGPSignature> signatures = getSortedSignaturesOfType(subkey, SignatureType.SUBKEY_REVOCATION);
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PGPSignature latestSubkeyRevocation = null;
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for (PGPSignature signature : signatures) {
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try {
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SignatureVerifier.verifySubkeyBindingRevocation(signature, primaryKey, subkey, policy, validationDate);
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} catch (SignatureValidationException e) {
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// subkey binding revocation is not valid
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continue;
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}
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latestSubkeyRevocation = signature;
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}
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return latestSubkeyRevocation;
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}
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/**
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* Pick the at validationDate latest, valid subkey binding signature for the given subkey.
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* This method might return null, if there is no subkey binding signature which is valid
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* at validationDate.
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*
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* @param keyRing key ring
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* @param subkey subkey
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* @param policy policy
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* @param validationDate date of validation
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* @return most recent valid subkey binding signature
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*/
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public static PGPSignature pickCurrentSubkeyBindingSignature(PGPKeyRing keyRing, PGPPublicKey subkey, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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if (primaryKey.getKeyID() == subkey.getKeyID()) {
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throw new IllegalArgumentException("Primary key cannot have subkey binding signature.");
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}
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List<PGPSignature> subkeyBindingSigs = getSortedSignaturesOfType(subkey, SignatureType.SUBKEY_BINDING);
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PGPSignature mostCurrentValidSig = null;
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for (PGPSignature signature : subkeyBindingSigs) {
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try {
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SignatureVerifier.verifySubkeyBindingSignature(signature, primaryKey, subkey, policy, validationDate);
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} catch (SignatureValidationException validationException) {
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// Subkey binding sig is not valid
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continue;
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}
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mostCurrentValidSig = signature;
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}
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return mostCurrentValidSig;
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}
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/**
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* Pick the at validationDate latest subkey binding signature for the given subkey.
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* This method might return an expired signature.
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* If a non-expired subkey binding signature exists, the latest non-expired yet already effective
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* subkey binding signature for the given subkey will be returned.
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*
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* @param keyRing key ring
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* @param subkey subkey
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* @param policy policy
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* @param validationDate validationDate
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* @return subkey binding signature
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*/
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public static PGPSignature pickLatestSubkeyBindingSignature(PGPKeyRing keyRing, PGPPublicKey subkey, Policy policy, Date validationDate) {
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PGPPublicKey primaryKey = keyRing.getPublicKey();
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if (primaryKey.getKeyID() == subkey.getKeyID()) {
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throw new IllegalArgumentException("Primary key cannot have subkey binding signature.");
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}
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List<PGPSignature> signatures = getSortedSignaturesOfType(subkey, SignatureType.SUBKEY_BINDING);
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PGPSignature latestSubkeyBinding = null;
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for (PGPSignature signature : signatures) {
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try {
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SignatureValidator.signatureIsOfType(SignatureType.SUBKEY_BINDING).verify(signature);
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SignatureValidator.signatureStructureIsAcceptable(primaryKey, policy).verify(signature);
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SignatureValidator.signatureDoesNotPredateSignee(subkey).verify(signature);
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SignatureValidator.signatureIsAlreadyEffective(validationDate).verify(signature);
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// if the currently latest signature is not yet expired, check if the next candidate is not yet expired
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if (latestSubkeyBinding != null && !SignatureUtils.isSignatureExpired(latestSubkeyBinding, validationDate)) {
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SignatureValidator.signatureIsNotYetExpired(validationDate).verify(signature);
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}
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SignatureValidator.correctSubkeyBindingSignature(primaryKey, subkey).verify(signature);
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} catch (SignatureValidationException e) {
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// Subkey binding sig is not valid
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continue;
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}
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latestSubkeyBinding = signature;
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}
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return latestSubkeyBinding;
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}
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/**
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* Return a list of all signatures of the given {@link SignatureType} on the given key, sorted using a
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* {@link SignatureCreationDateComparator}.
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*
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* The returned list will be sorted first by ascending signature creation time.
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*
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* @param key key
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* @param type type of signatures which shall be collected and sorted
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* @return sorted list of signatures
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*/
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private static List<PGPSignature> getSortedSignaturesOfType(PGPPublicKey key, SignatureType type) {
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Iterator<PGPSignature> signaturesOfType = key.getSignaturesOfType(type.getCode());
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List<PGPSignature> signatureList = CollectionUtils.iteratorToList(signaturesOfType);
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Collections.sort(signatureList, new SignatureCreationDateComparator());
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return signatureList;
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}
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}
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