diff --git a/pgpainless-core/src/main/kotlin/org/bouncycastle/extensions/PGPSignatureExtensions.kt b/pgpainless-core/src/main/kotlin/org/bouncycastle/extensions/PGPSignatureExtensions.kt
index 657abba9..ccbb8f45 100644
--- a/pgpainless-core/src/main/kotlin/org/bouncycastle/extensions/PGPSignatureExtensions.kt
+++ b/pgpainless-core/src/main/kotlin/org/bouncycastle/extensions/PGPSignatureExtensions.kt
@@ -9,15 +9,38 @@ import org.pgpainless.key.OpenPgpFingerprint
 import org.pgpainless.signature.SignatureUtils
 import java.util.*
 
+/**
+ * Return the value of the KeyExpirationDate subpacket, or null, if the signature does not carry
+ * such a subpacket.
+ */
 fun PGPSignature.getKeyExpirationDate(keyCreationDate: Date): Date? =
         SignatureUtils.getKeyExpirationDate(keyCreationDate, this)
 
+/**
+ * Return the value of the signature ExpirationTime subpacket, or null, if the signature
+ * does not carry such a subpacket.
+ */
 fun PGPSignature.getSignatureExpirationDate(): Date? =
         SignatureUtils.getSignatureExpirationDate(this)
 
+/**
+ * Return true, if the signature is expired at the given reference time.
+ */
 fun PGPSignature.isExpired(referenceTime: Date = Date()) =
         SignatureUtils.isSignatureExpired(this, referenceTime)
 
+/**
+ * Return the key-ID of the issuer, determined by examining the IssuerKeyId and IssuerFingerprint
+ * subpackets of the signature.
+ */
 fun PGPSignature.getIssuerKeyId() = SignatureUtils.determineIssuerKeyId(this)
 
+/**
+ * Return true, if the signature was likely issued by the key with the given fingerprint.
+ */
 fun PGPSignature.wasIssuedBy(fingerprint: OpenPgpFingerprint) = SignatureUtils.wasIssuedBy(fingerprint, this)
+
+/**
+ * Return true, if this signature is a hard revocation.
+ */
+fun PGPSignature.isHardRevocation() = SignatureUtils.isHardRevocation(this)