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Code Issues Releases Wiki Activity

Cleanup signature verification

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This commit is contained in:
Paul Schaub 2023-07-09 13:43:44 +02:00
parent 8db8b76a26
commit 09fabd4608
Signed by: vanitasvitae
GPG key ID: 62BEE9264BF17311
2 changed files with 81 additions and 8 deletions
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4
pgpainless-core/src/main/java/org/pgpainless/signature/consumer/SignatureValidator.java
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@ -182,7 +182,7 @@ public abstract class SignatureValidator {
* @param signingKey signing key
* @return validator
*/
private static SignatureValidator signatureUsesAcceptablePublicKeyAlgorithm(Policy policy,
public static SignatureValidator signatureUsesAcceptablePublicKeyAlgorithm(Policy policy,
PGPPublicKey signingKey) {
return new SignatureValidator() {
@Override
@ -207,7 +207,7 @@ public abstract class SignatureValidator {
* @param policy policy
* @return validator
*/
private static SignatureValidator signatureUsesAcceptableHashAlgorithm(Policy policy) {
public static SignatureValidator signatureUsesAcceptableHashAlgorithm(Policy policy) {
return new SignatureValidator() {
@Override
public void verify(PGPSignature signature) throws SignatureValidationException {

83
pgpainless-wot/src/main/kotlin/org/pgpainless/wot/WebOfTrust.kt
View file

@ -8,6 +8,7 @@ import org.bouncycastle.openpgp.PGPPublicKey
import org.bouncycastle.openpgp.PGPSignature
import org.pgpainless.PGPainless
import org.pgpainless.algorithm.KeyFlag
import org.pgpainless.algorithm.SignatureType
import org.pgpainless.exception.SignatureValidationException
import org.pgpainless.key.OpenPgpFingerprint
import org.pgpainless.key.info.KeyRingInfo
@ -15,7 +16,7 @@ import org.pgpainless.key.util.KeyRingUtils
import org.pgpainless.key.util.RevocationAttributes
import org.pgpainless.policy.Policy
import org.pgpainless.signature.SignatureUtils
import org.pgpainless.signature.consumer.SignatureVerifier
import org.pgpainless.signature.consumer.SignatureValidator
import org.pgpainless.signature.subpackets.SignatureSubpacketsUtil
import org.pgpainless.wot.network.*
import org.pgpainless.wot.network.ReferenceTime.Companion.now
@ -114,6 +115,8 @@ class WebOfTrust(private val certificateStore: PGPCertificateStore) {
val expirationDate: Date? = try {
cert.getExpirationDateForUse(KeyFlag.CERTIFY_OTHER)
} catch (e: NoSuchElementException) {
LOGGER.warn("Could not deduce expiration time of ${cert.fingerprint}. " +
"Possibly hard revoked cert or illegal algorithms? Skip certificate.");
// Some keys are malformed and have no KeyFlags
// TODO: We also end up here for expired keys unfortunately
return
@ -193,8 +196,7 @@ class WebOfTrust(private val certificateStore: PGPCertificateStore) {
val issuer = nodeMap[issuerFingerprint]!!
try {
val valid = SignatureVerifier.verifyDirectKeySignature(delegation, issuerSigningKey,
targetPrimaryKey, policy, referenceTime.timestamp)
val valid = verifyDelegation(candidate, delegation, issuerSigningKey, targetPrimaryKey, policy)
if (valid) {
networkBuilder.addEdge(fromDelegation(issuer, target, delegation))
return // we're done
@ -207,6 +209,23 @@ class WebOfTrust(private val certificateStore: PGPCertificateStore) {
}
}
/**
* Verify a delegation signature over a primary key.
* This method returns true, if the signature is correct and well-formed.
* It does not reject expired or revoked signatures.
*/
fun verifyDelegation(issuer: KeyRingInfo, signature: PGPSignature, signingKey: PGPPublicKey, signedKey: PGPPublicKey, policy: Policy): Boolean {
// Check signature type
SignatureValidator.signatureIsOfType(SignatureType.KEY_REVOCATION, SignatureType.DIRECT_KEY).verify(signature)
// common verification steps that are shared by delegations and certifications
verifyCommonSignatureCriteria(issuer, signature, signingKey, signedKey, policy)
// check signature correctness
SignatureValidator.correctSignatureOverKey(signingKey, signedKey).verify(signature)
return true
}
/**
* Process a certification (third-party-issued certification over the given [userId])
* and add it upon successful verification as an edge to the [Network.Builder].
@ -231,8 +250,7 @@ class WebOfTrust(private val certificateStore: PGPCertificateStore) {
val issuer = nodeMap[issuerFingerprint]!!
try {
val valid = SignatureVerifier.verifySignatureOverUserId(userId, certification,
issuerSigningKey, targetPrimaryKey, policy, referenceTime.timestamp)
val valid = verifyCertification(candidate, certification, issuerSigningKey, targetPrimaryKey, userId, policy)
if (valid) {
networkBuilder.addEdge(fromCertification(issuer, target, userId, certification))
return // we're done
@ -244,6 +262,61 @@ class WebOfTrust(private val certificateStore: PGPCertificateStore) {
}
}
/**
* Verify a certification over a user-ID.
* This method returns true, if the signature is correct and well-formed.
* It does not reject expired or revoked signatures.
*/
fun verifyCertification(issuer: KeyRingInfo, signature: PGPSignature, signingKey: PGPPublicKey, signedKey: PGPPublicKey, userId: String, policy: Policy): Boolean {
// check signature type
SignatureValidator.signatureIsOfType(SignatureType.CERTIFICATION_REVOCATION, SignatureType.GENERIC_CERTIFICATION, SignatureType.NO_CERTIFICATION, SignatureType.CASUAL_CERTIFICATION, SignatureType.POSITIVE_CERTIFICATION).verify(signature)
// perform shared verification steps
verifyCommonSignatureCriteria(issuer, signature, signingKey, signedKey, policy)
// check correct signature
SignatureValidator.correctSignatureOverUserId(userId, signedKey, signingKey).verify(signature)
return true
}
fun verifyCommonSignatureCriteria(issuer: KeyRingInfo,
signature: PGPSignature,
signingKey: PGPPublicKey,
signedKey: PGPPublicKey,
policy: Policy): Boolean {
// Check for general "well-formed-ness" (has legal creation time)
SignatureValidator.signatureIsNotMalformed(signingKey).verify(signature)
// Check for unknown critical notations or subpackets
if (signature.version >= 4) {
SignatureValidator.signatureDoesNotHaveCriticalUnknownNotations(policy.notationRegistry).verify(signature)
SignatureValidator.signatureDoesNotHaveCriticalUnknownSubpackets().verify(signature)
}
// check for signature effectiveness at reference time (was created before reference time, is not expired)
SignatureValidator.signatureIsEffective(referenceTime.timestamp).verify(signature)
// check if signature is not invalidated by hard-revoked cert
if (issuer.revocationState == org.pgpainless.algorithm.RevocationState.hardRevoked()) {
// cert is hard revoked
throw SignatureValidationException("Signature is invalid because certificate ${issuer.fingerprint} is hard revoked.")
}
// check if signature is not invalidated by soft-revoked cert
if (issuer.revocationState.isSoftRevocation) {
SignatureValidator.signatureWasCreatedInBounds(issuer.creationDate, issuer.revocationDate).verify(signature)
}
// check if signature is not invalidated by expired primary key
val exp = issuer.primaryKeyExpirationDate
if (exp != null) {
SignatureValidator.signatureWasCreatedInBounds(issuer.creationDate, exp).verify(signature)
}
// check signature algorithms against our algorithm policy
SignatureValidator.signatureUsesAcceptableHashAlgorithm(policy).verify(signature)
SignatureValidator.signatureUsesAcceptablePublicKeyAlgorithm(policy, signingKey).verify(signature)
// check if signature is not created before the target key
SignatureValidator.signatureDoesNotPredateSignee(signedKey).verify(signature)
return true
}
/**
* Map an [OpenPgpFingerprint] to a [Fingerprint].
*