diff --git a/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/SelectUserId.java b/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/SelectUserId.java
deleted file mode 100644
index 5c1611af..00000000
--- a/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/SelectUserId.java
+++ /dev/null
@@ -1,231 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.util.selection.userid;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.bouncycastle.openpgp.PGPKeyRing;
-import org.pgpainless.PGPainless;
-import org.pgpainless.key.info.KeyRingInfo;
-
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-
-/**
- * Filter for selecting user-ids from keys and from lists.
- */
-public abstract class SelectUserId {
-
-    /**
-     * Return true, if the given user-id is accepted by this particular filter, false otherwise.
-     *
-     * @param userId user-id
-     * @return acceptance of the filter
-     */
-    protected abstract boolean accept(String userId);
-
-    /**
-     * Select all currently valid user-ids of the given key ring.
-     *
-     * @param keyRing public or secret key ring
-     * @return valid user-ids
-     */
-    @Nonnull
-    public List<String> selectUserIds(@Nonnull PGPKeyRing keyRing) {
-        List<String> userIds = PGPainless.inspectKeyRing(keyRing).getValidUserIds();
-        return selectUserIds(userIds);
-    }
-
-    /**
-     * Select all acceptable (see {@link #accept(String)}) from the given list of user-ids.
-     *
-     * @param userIds list of user-ids
-     * @return sub-list of acceptable user-ids
-     */
-    @Nonnull
-    public List<String> selectUserIds(@Nonnull List<String> userIds) {
-        List<String> selected = new ArrayList<>();
-        for (String userId : userIds) {
-            if (accept(userId)) {
-                selected.add(userId);
-            }
-        }
-        return selected;
-    }
-
-    /**
-     * Return the first valid, acceptable user-id from the given public or secret key ring.
-     *
-     * @param keyRing public or secret key ring
-     * @return first matching valid user-id or null
-     */
-    @Nullable
-    public String firstMatch(PGPKeyRing keyRing) {
-        return firstMatch(selectUserIds(keyRing));
-    }
-
-    /**
-     * Return the first valid, acceptable user-id from the list of user-ids.
-     *
-     * @param userIds list of user-ids
-     * @return first matching valid user-id or null
-     */
-    @Nullable
-    public String firstMatch(@Nonnull List<String> userIds) {
-        for (String userId : userIds) {
-            if (accept(userId)) {
-                return userId;
-            }
-        }
-        return null;
-    }
-
-    /**
-     * Filter that filters for user-ids which contain the given <pre>query</pre> as a substring.
-     *
-     * @param query query
-     * @return filter
-     */
-    public static SelectUserId containsSubstring(@Nonnull CharSequence query) {
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                return userId.contains(query.toString());
-            }
-        };
-    }
-
-    /**
-     * Filter that filters for user-ids which match the given <pre>query</pre> exactly.
-     *
-     * @param query query
-     * @return filter
-     */
-    public static SelectUserId exactMatch(@Nonnull CharSequence query) {
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                return userId.equals(query.toString());
-            }
-        };
-    }
-
-    /**
-     * Filter that filters for user-ids which start with the given <pre>substring</pre>.
-     *
-     * @param substring substring
-     * @return filter
-     */
-    public static SelectUserId startsWith(@Nonnull CharSequence substring) {
-        String string = substring.toString();
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                return userId.startsWith(string);
-            }
-        };
-    }
-
-    /**
-     * Filter that filters for user-ids which contain the given <pre>email</pre> address.
-     * Note: This only accepts user-ids which properly have the email address surrounded by angle brackets.
-     *
-     * The argument <pre>email</pre> can both be a plain email address (<pre>"foo@bar.baz"</pre>),
-     * or surrounded by angle brackets ({@code <pre>"<foo@bar.baz>"</pre>}), the result of the filter will be the same.
-     *
-     * @param email email address
-     * @return filter
-     */
-    public static SelectUserId containsEmailAddress(@Nonnull CharSequence email) {
-        String string = email.toString();
-        return containsSubstring(string.matches("^<.+>$") ? string : '<' + string + '>');
-    }
-
-    /**
-     * Filter that filters for valid user-ids on the given <pre>keyRing</pre> only.
-     *
-     * @param keyRing public / secret keys
-     * @return filter
-     */
-    public static SelectUserId validUserId(PGPKeyRing keyRing) {
-        final KeyRingInfo info = PGPainless.inspectKeyRing(keyRing);
-
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                return info.isUserIdValid(userId);
-            }
-        };
-    }
-
-    /**
-     * Filter that filters for user-ids which pass all the given <pre>filters</pre>.
-     *
-     * @param filters filters
-     * @return filter
-     */
-    public static SelectUserId and(SelectUserId... filters) {
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                boolean accept = true;
-                for (SelectUserId filter : filters) {
-                    accept &= filter.accept(userId);
-                }
-                return accept;
-            }
-        };
-    }
-
-    /**
-     * Filter that filters for user-ids which pass at least one of the given <pre>filters</pre>.
-     *
-     * @param filters filters
-     * @return filter
-     */
-    public static SelectUserId or(SelectUserId... filters) {
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                boolean accept = false;
-                for (SelectUserId filter : filters) {
-                    accept |= filter.accept(userId);
-                }
-                return accept;
-            }
-        };
-    }
-
-    /**
-     * Filter that inverts the result of the given <pre>filter</pre>.
-     *
-     * @param filter filter
-     * @return inverting filter
-     */
-    public static SelectUserId not(SelectUserId filter) {
-        return new SelectUserId() {
-            @Override
-            protected boolean accept(String userId) {
-                return !filter.accept(userId);
-            }
-        };
-    }
-
-    /**
-     * Filter that selects user-ids by the given <pre>email</pre> address.
-     * It returns user-ids which either contain the given <pre>email</pre> address as angle-bracketed string,
-     * or which equal the given <pre>email</pre> string exactly.
-     *
-     * @param email email
-     * @return filter
-     */
-    public static SelectUserId byEmail(CharSequence email) {
-        return SelectUserId.or(
-                SelectUserId.exactMatch(email),
-                SelectUserId.containsEmailAddress(email)
-        );
-    }
-}
diff --git a/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/package-info.java b/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/package-info.java
deleted file mode 100644
index 5b70f412..00000000
--- a/pgpainless-core/src/main/java/org/pgpainless/util/selection/userid/package-info.java
+++ /dev/null
@@ -1,8 +0,0 @@
-// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-/**
- * UserID selection strategies.
- */
-package org.pgpainless.util.selection.userid;
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.kt
index 2fde469c..b219a739 100644
--- a/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.kt
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.kt
@@ -31,7 +31,9 @@ import org.pgpainless.signature.subpackets.*
 import org.pgpainless.util.Passphrase
 import org.pgpainless.util.selection.userid.SelectUserId
 import java.util.*
+import java.util.function.Predicate
 import javax.annotation.Nonnull
+import kotlin.NoSuchElementException
 
 class SecretKeyRingEditor(
         var secretKeyRing: PGPSecretKeyRing,
@@ -109,14 +111,22 @@ class SecretKeyRingEditor(
         return this
     }
 
+    @Deprecated("Use of SelectUserId class is deprecated.", replaceWith = ReplaceWith("removeUserId(protector, predicate)"))
     override fun removeUserId(selector: SelectUserId, protector: SecretKeyRingProtector): SecretKeyRingEditorInterface {
         return revokeUserIds(selector, protector, RevocationAttributes.createCertificateRevocation()
                 .withReason(RevocationAttributes.Reason.USER_ID_NO_LONGER_VALID)
                 .withoutDescription())
     }
 
+    override fun removeUserId(protector: SecretKeyRingProtector, predicate: (String) -> Boolean): SecretKeyRingEditorInterface {
+        return revokeUserIds(protector, RevocationAttributes.createCertificateRevocation()
+                .withReason(RevocationAttributes.Reason.USER_ID_NO_LONGER_VALID)
+                .withoutDescription(),
+                predicate)
+    }
+
     override fun removeUserId(userId: CharSequence, protector: SecretKeyRingProtector): SecretKeyRingEditorInterface {
-        return removeUserId(SelectUserId.exactMatch(userId), protector)
+        return removeUserId(protector) { uid -> userId == uid }
     }
 
     override fun replaceUserId(oldUserId: CharSequence, newUserId: CharSequence, protector: SecretKeyRingProtector): SecretKeyRingEditorInterface {
@@ -246,21 +256,23 @@ class SecretKeyRingEditor(
     }
 
     override fun revokeUserId(userId: CharSequence, protector: SecretKeyRingProtector, callback: RevocationSignatureSubpackets.Callback?): SecretKeyRingEditorInterface {
-        return revokeUserIds(SelectUserId.exactMatch(sanitizeUserId(userId)), protector, callback)
+        return revokeUserIds(protector, callback, SelectUserId.exactMatch(sanitizeUserId(userId)))
     }
 
-    override fun revokeUserIds(selector: SelectUserId, protector: SecretKeyRingProtector, revocationAttributes: RevocationAttributes?): SecretKeyRingEditorInterface {
-        return revokeUserIds(selector, protector, object : RevocationSignatureSubpackets.Callback {
+    override fun revokeUserIds(protector: SecretKeyRingProtector,
+                               revocationAttributes: RevocationAttributes?,
+                               predicate: (String) -> Boolean): SecretKeyRingEditorInterface {
+        return revokeUserIds(protector, object : RevocationSignatureSubpackets.Callback {
             override fun modifyHashedSubpackets(hashedSubpackets: RevocationSignatureSubpackets) {
-                if (revocationAttributes != null) {
-                    hashedSubpackets.setRevocationReason(revocationAttributes)
-                }
+                if (revocationAttributes != null) hashedSubpackets.setRevocationReason(revocationAttributes)
             }
-        })
+        }, predicate)
     }
 
-    override fun revokeUserIds(selector: SelectUserId, protector: SecretKeyRingProtector, callback: RevocationSignatureSubpackets.Callback?): SecretKeyRingEditorInterface {
-        selector.selectUserIds(secretKeyRing).also {
+    override fun revokeUserIds(protector: SecretKeyRingProtector,
+                               callback: RevocationSignatureSubpackets.Callback?,
+                               predicate: (String) -> Boolean): SecretKeyRingEditorInterface {
+        selectUserIds(predicate).also {
             if (it.isEmpty()) throw NoSuchElementException("No matching user-ids found on the key.")
         }.forEach { userId -> doRevokeUserId(userId, protector, callback) }
         return this
@@ -348,7 +360,7 @@ class SecretKeyRingEditor(
 
     private fun sanitizeUserId(userId: CharSequence): CharSequence =
     // TODO: Further research how to sanitize user IDs.
-            //  eg. what about newlines?
+            //  e.g. what about newlines?
             userId.toString().trim()
 
     private fun callbackFromRevocationAttributes(attributes: RevocationAttributes?) =
@@ -454,6 +466,9 @@ class SecretKeyRingEditor(
                 }.build(secretKeyRing.publicKey)
     }
 
+    private fun selectUserIds(predicate: Predicate<String>): List<String> =
+            inspectKeyRing(secretKeyRing).validUserIds.filter { predicate.test(it) }
+
     private class WithKeyRingEncryptionSettingsImpl(
             private val editor: SecretKeyRingEditor,
             private val keyId: Long?,
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.kt
index 45a09fb2..8a26161b 100644
--- a/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.kt
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.kt
@@ -4,11 +4,7 @@
 
 package org.pgpainless.key.modification.secretkeyring
 
-import org.bouncycastle.openpgp.PGPException
-import org.bouncycastle.openpgp.PGPKeyPair
-import org.bouncycastle.openpgp.PGPPublicKeyRing
-import org.bouncycastle.openpgp.PGPSecretKeyRing
-import org.bouncycastle.openpgp.PGPSignature
+import org.bouncycastle.openpgp.*
 import org.pgpainless.algorithm.KeyFlag
 import org.pgpainless.key.OpenPgpFingerprint
 import org.pgpainless.key.generation.KeySpec
@@ -23,6 +19,7 @@ import java.io.IOException
 import java.security.InvalidAlgorithmParameterException
 import java.security.NoSuchAlgorithmException
 import java.util.*
+import java.util.function.Predicate
 
 interface SecretKeyRingEditorInterface {
 
@@ -82,8 +79,25 @@ interface SecretKeyRingEditorInterface {
      *
      * @throws PGPException in case we cannot generate a revocation signature for the user-id
      */
+    @Deprecated("Use of SelectUserId class is deprecated.",
+            ReplaceWith("removeUserId(protector, predicate)"))
     @Throws(PGPException::class)
-    fun removeUserId(selector: SelectUserId, protector: SecretKeyRingProtector): SecretKeyRingEditorInterface
+    fun removeUserId(selector: SelectUserId, protector: SecretKeyRingProtector) =
+            removeUserId(protector, selector)
+
+    /**
+     * Convenience method to revoke selected user-ids using soft revocation signatures.
+     * The revocation will use [RevocationAttributes.Reason.USER_ID_NO_LONGER_VALID], so that the user-id
+     * can be re-certified at a later point.
+     *
+     * @param protector protector to unlock the primary key
+     * @param predicate predicate to select user-ids for revocation
+     * @return the builder
+     *
+     * @throws PGPException in case we cannot generate a revocation signature for the user-id
+     */
+    @Throws(PGPException::class)
+    fun removeUserId(protector: SecretKeyRingProtector, predicate: (String) -> Boolean): SecretKeyRingEditorInterface
 
     /**
      * Convenience method to revoke a single user-id using a soft revocation signature.
@@ -342,9 +356,32 @@ interface SecretKeyRingEditorInterface {
      * @throws PGPException in case we cannot generate a revocation signature for the user-id
      */
     @Throws(PGPException::class)
+    @Deprecated("Use of SelectUserId class is deprecated.",
+            ReplaceWith("revokeUserIds(protector, revocationAttributes, predicate)"))
     fun revokeUserIds(selector: SelectUserId,
                       protector: SecretKeyRingProtector,
-                      revocationAttributes: RevocationAttributes?): SecretKeyRingEditorInterface
+                      revocationAttributes: RevocationAttributes?) =
+            revokeUserIds(protector, revocationAttributes, selector)
+
+    /**
+     * Revoke all user-ids that match the provided [SelectUserId] filter.
+     * The provided [RevocationAttributes] will be set as reason for revocation in each
+     * revocation signature.
+     *
+     * Note: If you intend to re-certify these user-ids at a later point, make sure to choose
+     * a soft revocation reason. See [RevocationAttributes.Reason] for more information.
+     *
+     * @param protector protector to unlock the primary secret key
+     * @param revocationAttributes revocation attributes
+     * @param predicate to select user-ids for revocation
+     * @return builder
+     *
+     * @throws PGPException in case we cannot generate a revocation signature for the user-id
+     */
+    @Throws(PGPException::class)
+    fun revokeUserIds(protector: SecretKeyRingProtector,
+                      revocationAttributes: RevocationAttributes?,
+                      predicate: (String) -> Boolean): SecretKeyRingEditorInterface
 
     /**
      * Revoke all user-ids that match the provided [SelectUserId] filter.
@@ -364,9 +401,34 @@ interface SecretKeyRingEditorInterface {
      * @throws PGPException in case we cannot generate a revocation signature for the user-id
      */
     @Throws(PGPException::class)
+    @Deprecated("Use of SelectUserId class is deprecated.",
+            ReplaceWith("revokeUserIds(protector, callback, predicate)"))
     fun revokeUserIds(selector: SelectUserId,
                       protector: SecretKeyRingProtector,
-                      callback: RevocationSignatureSubpackets.Callback?): SecretKeyRingEditorInterface
+                      callback: RevocationSignatureSubpackets.Callback?) =
+            revokeUserIds(protector, callback, selector)
+
+    /**
+     * Revoke all user-ids that match the provided [SelectUserId] filter.
+     * The provided [RevocationSignatureSubpackets.Callback] will be used to modify the
+     * revocation signatures subpackets.
+     *
+     * Note: If you intend to re-certify these user-ids at a later point, make sure to set
+     * a soft revocation reason in the revocation signatures hashed subpacket area using the callback.
+     *
+     * See [RevocationAttributes.Reason] for more information.
+     *
+     * @param protector protector to unlock the primary secret key
+     * @param callback callback to modify the revocations subpackets
+     * @param predicate to select user-ids for revocation
+     * @return builder
+     *
+     * @throws PGPException in case we cannot generate a revocation signature for the user-id
+     */
+    @Throws(PGPException::class)
+    fun revokeUserIds(protector: SecretKeyRingProtector,
+                      callback: RevocationSignatureSubpackets.Callback?,
+                      predicate: (String) -> Boolean): SecretKeyRingEditorInterface
 
     /**
      * Set the expiration date for the primary key of the key ring.
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/util/selection/userid/SelectUserId.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/util/selection/userid/SelectUserId.kt
new file mode 100644
index 00000000..3c215d80
--- /dev/null
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/util/selection/userid/SelectUserId.kt
@@ -0,0 +1,104 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.util.selection.userid
+
+import org.bouncycastle.openpgp.PGPKeyRing
+import org.pgpainless.PGPainless
+import java.util.function.Predicate
+
+abstract class SelectUserId : Predicate<String>, (String) -> Boolean {
+
+    /**
+     * Legacy glue code to forward accept() calls to invoke() instead.
+     */
+    @Deprecated("Use invoke() instead.", ReplaceWith("invoke(userId)"))
+    protected fun accept(userId: String): Boolean = invoke(userId)
+
+    override fun test(userId: String): Boolean = invoke(userId)
+
+    companion object {
+
+        /**
+         * Filter for user-ids which match the given [query] exactly.
+         *
+         * @param query query
+         * @return filter
+         */
+        @JvmStatic
+        fun exactMatch(query: CharSequence) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    userId == query
+        }
+
+        /**
+         * Filter for user-ids which start with the given [substring].
+         *
+         * @param substring substring
+         * @return filter
+         */
+        @JvmStatic
+        fun startsWith(substring: CharSequence) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    userId.startsWith(substring)
+        }
+
+        /**
+         * Filter for user-ids which contain the given [substring].
+         *
+         * @param substring query
+         * @return filter
+         */
+        @JvmStatic
+        fun containsSubstring(substring: CharSequence) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    userId.contains(substring)
+        }
+
+        /**
+         * Filter for user-ids which contain the given [email] address.
+         * Note: This only accepts user-ids which properly have the email address surrounded by angle brackets.
+         *
+         * The argument [email] can both be a plain email address (`foo@bar.baz`),
+         * or surrounded by angle brackets (`<foo@bar.baz>`), the result of the filter will be the same.
+         *
+         * @param email email address
+         * @return filter
+         */
+        @JvmStatic
+        fun containsEmailAddress(email: CharSequence) =
+                if (email.startsWith('<') && email.endsWith('>'))
+                    containsSubstring(email)
+                else
+                    containsSubstring("<$email>")
+
+        @JvmStatic
+        fun byEmail(email: CharSequence) = or(exactMatch(email), containsEmailAddress(email))
+
+        @JvmStatic
+        fun validUserId(keyRing: PGPKeyRing) = object : SelectUserId() {
+            private val info = PGPainless.inspectKeyRing(keyRing)
+            override fun invoke(userId: String): Boolean =
+                    info.isUserIdValid(userId)
+        }
+
+        @JvmStatic
+        fun and(vararg filters: SelectUserId) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    filters.all { it.invoke(userId) }
+        }
+
+        @JvmStatic
+        fun or(vararg filters: SelectUserId) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    filters.any { it.invoke(userId) }
+        }
+
+        @JvmStatic
+        fun not(filter: SelectUserId) = object : SelectUserId() {
+            override fun invoke(userId: String): Boolean =
+                    !filter.invoke(userId)
+        }
+    }
+}
\ No newline at end of file
diff --git a/pgpainless-core/src/test/java/org/pgpainless/util/selection/userid/SelectUserIdTest.java b/pgpainless-core/src/test/java/org/pgpainless/util/selection/userid/SelectUserIdTest.java
index 3a49247c..99a0c87c 100644
--- a/pgpainless-core/src/test/java/org/pgpainless/util/selection/userid/SelectUserIdTest.java
+++ b/pgpainless-core/src/test/java/org/pgpainless/util/selection/userid/SelectUserIdTest.java
@@ -4,6 +4,15 @@
 
 package org.pgpainless.util.selection.userid;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.junit.jupiter.api.Test;
@@ -11,20 +20,10 @@ import org.pgpainless.PGPainless;
 import org.pgpainless.key.protection.SecretKeyRingProtector;
 import org.pgpainless.key.util.UserId;
 
-import java.security.InvalidAlgorithmParameterException;
-import java.security.NoSuchAlgorithmException;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 public class SelectUserIdTest {
 
     @Test
-    public void testSelectUserIds() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+    public void testSelectUserIds() throws PGPException {
         PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing()
                 .simpleEcKeyRing("<alice@wonderland.lit>");
         secretKeys = PGPainless.modifyKeyRing(secretKeys)
@@ -34,48 +33,53 @@ public class SelectUserIdTest {
                         SecretKeyRingProtector.unprotectedKeys())
                 .done();
 
-        List<String> validEmail = SelectUserId.and(
+        List<String> userIds = PGPainless.inspectKeyRing(secretKeys).getValidUserIds();
+        List<String> validEmail = userIds.stream().filter(SelectUserId.and(
                 SelectUserId.validUserId(secretKeys),
                 SelectUserId.containsEmailAddress("alice@wonderland.lit")
-        ).selectUserIds(secretKeys);
+        )).collect(Collectors.toList());
 
         assertEquals(Collections.singletonList("<alice@wonderland.lit>"), validEmail);
 
-        List<String> startsWithAlice = SelectUserId.startsWith("Alice").selectUserIds(secretKeys);
+        List<String> startsWithAlice = userIds.stream().filter(SelectUserId.startsWith("Alice")).collect(Collectors.toList());
         assertEquals(Collections.singletonList("Alice Liddell <crazy@the-rabbit.hole>"), startsWithAlice);
 
-        List<String> exactMatch = SelectUserId.or(
+        List<String> exactMatch = userIds.stream().filter(SelectUserId.or(
                 SelectUserId.exactMatch("<alice@wonderland.lit>"),
                 SelectUserId.startsWith("Not Found")
-        ).selectUserIds(secretKeys);
+        )).collect(Collectors.toList());
         assertEquals(Collections.singletonList("<alice@wonderland.lit>"), exactMatch);
     }
 
     @Test
-    public void testContainsSubstring() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+    public void testContainsSubstring() throws PGPException {
         PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing("wine drinker");
         secretKeys = PGPainless.modifyKeyRing(secretKeys)
                 .addUserId("this is not a quine", SecretKeyRingProtector.unprotectedKeys())
                 .addUserId("this is not a crime", SecretKeyRingProtector.unprotectedKeys())
                 .done();
 
-        List<String> containSubstring = SelectUserId.containsSubstring("ine")
-                .selectUserIds(secretKeys);
+        List<String> userIds = PGPainless.inspectKeyRing(secretKeys).getValidUserIds();
+
+        List<String> containSubstring = userIds.stream().filter(SelectUserId.containsSubstring("ine")).collect(Collectors.toList());
         assertEquals(Arrays.asList("wine drinker", "this is not a quine"), containSubstring);
     }
 
     @Test
-    public void testContainsEmailAddress() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+    public void testContainsEmailAddress() {
         PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing("Alice <alice@wonderland.lit>");
+        List<String> userIds = PGPainless.inspectKeyRing(secretKeys).getValidUserIds();
 
-        assertEquals("Alice <alice@wonderland.lit>", SelectUserId.containsEmailAddress("alice@wonderland.lit").firstMatch(secretKeys));
-        assertEquals("Alice <alice@wonderland.lit>", SelectUserId.containsEmailAddress("<alice@wonderland.lit>").firstMatch(secretKeys));
+        assertEquals("Alice <alice@wonderland.lit>", userIds.stream().filter(
+                SelectUserId.containsEmailAddress("alice@wonderland.lit")).findFirst().get());
+        assertEquals("Alice <alice@wonderland.lit>", userIds.stream().filter(
+                SelectUserId.containsEmailAddress("<alice@wonderland.lit>")).findFirst().get());
 
-        assertNull(SelectUserId.containsEmailAddress("mad@hatter.lit").firstMatch(secretKeys));
+        assertFalse(userIds.stream().anyMatch(SelectUserId.containsEmailAddress("mad@hatter.lit")));
     }
 
     @Test
-    public void testAndOrNot() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+    public void testAndOrNot() throws PGPException {
         PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing("Alice <alice@wonderland.lit>");
         secretKeys = PGPainless.modifyKeyRing(secretKeys)
                 .addUserId("Alice <another@email.address>", SecretKeyRingProtector.unprotectedKeys())
@@ -83,34 +87,32 @@ public class SelectUserIdTest {
                 .addUserId("Crazy Girl <alice@wonderland.lit>", SecretKeyRingProtector.unprotectedKeys())
                 .done();
 
-        List<String> or = SelectUserId.or(
+        List<String> userIds = PGPainless.inspectKeyRing(secretKeys).getValidUserIds();
+
+        List<String> or = userIds.stream().filter(SelectUserId.or(
                 SelectUserId.containsEmailAddress("alice@wonderland.lit"),
-                SelectUserId.startsWith("Alice"))
-                .selectUserIds(secretKeys);
+                SelectUserId.startsWith("Alice"))).collect(Collectors.toList());
         assertEquals(Arrays.asList("Alice <alice@wonderland.lit>", "Alice <another@email.address>", "Crazy Girl <alice@wonderland.lit>"), or);
 
-        List<String> and = SelectUserId.and(
+        List<String> and = userIds.stream().filter(SelectUserId.and(
                 SelectUserId.containsEmailAddress("alice@wonderland.lit"),
-                SelectUserId.startsWith("Alice"))
-                .selectUserIds(secretKeys);
+                SelectUserId.startsWith("Alice"))).collect(Collectors.toList());
         assertEquals(Collections.singletonList("Alice <alice@wonderland.lit>"), and);
 
-        List<String> not = SelectUserId.not(
-                SelectUserId.startsWith("Alice"))
-                .selectUserIds(secretKeys);
+        List<String> not = userIds.stream().filter(SelectUserId.not(
+                SelectUserId.startsWith("Alice"))).collect(Collectors.toList());
         assertEquals(Arrays.asList("<crazy@the-rabbit.hole>", "Crazy Girl <alice@wonderland.lit>"), not);
     }
 
     @Test
-    public void testFirstMatch() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException {
+    public void testFirstMatch() throws PGPException {
         PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing("First UserID");
         secretKeys = PGPainless.modifyKeyRing(secretKeys)
                 .addUserId("Second UserID", SecretKeyRingProtector.unprotectedKeys())
                 .done();
-        assertEquals("First UserID", SelectUserId.validUserId(secretKeys).firstMatch(secretKeys));
-        assertEquals("Second UserID", SelectUserId.containsSubstring("Second").firstMatch(
-                PGPainless.inspectKeyRing(secretKeys).getUserIds()
-        ));
+        List<String> userIds = PGPainless.inspectKeyRing(secretKeys).getValidUserIds();
+        assertEquals("First UserID", userIds.stream().filter(SelectUserId.validUserId(secretKeys)).findFirst().get());
+        assertEquals("Second UserID", userIds.stream().filter(SelectUserId.containsSubstring("Second")).findFirst().get());
     }
 
     @Test