diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/BaseSignatureSubpackets.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/BaseSignatureSubpackets.kt
index 4b4c40d5..87e8d57e 100644
--- a/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/BaseSignatureSubpackets.kt
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/BaseSignatureSubpackets.kt
@@ -175,52 +175,4 @@ interface BaseSignatureSubpackets {
     fun addEmbeddedSignature(embeddedSignature: EmbeddedSignature): BaseSignatureSubpackets
 
     fun clearEmbeddedSignatures(): BaseSignatureSubpackets
-
-    companion object {
-
-        /** Factory method for a [Callback] that does nothing. */
-        @JvmStatic fun nop() = object : Callback {}
-
-        /**
-         * Factory function with receiver, which returns a [Callback] that modifies the hashed
-         * subpacket area of a [BaseSignatureSubpackets] object.
-         *
-         * Can be called like this:
-         * ```
-         * val callback = BaseSignatureSubpackets.applyHashed {
-         *     setCreationTime(date)
-         *     ...
-         * }
-         * ```
-         */
-        @JvmStatic
-        fun applyHashed(function: BaseSignatureSubpackets.() -> Unit): Callback {
-            return object : Callback {
-                override fun modifyHashedSubpackets(hashedSubpackets: BaseSignatureSubpackets) {
-                    function(hashedSubpackets)
-                }
-            }
-        }
-
-        /**
-         * Factory function with receiver, which returns a [Callback] that modifies the unhashed
-         * subpacket area of a [BaseSignatureSubpackets] object.
-         *
-         * Can be called like this:
-         * ```
-         * val callback = BaseSignatureSubpackets.applyUnhashed {
-         *     setCreationTime(date)
-         *     ...
-         * }
-         * ```
-         */
-        @JvmStatic
-        fun applyUnhashed(function: BaseSignatureSubpackets.() -> Unit): Callback {
-            return object : Callback {
-                override fun modifyUnhashedSubpackets(unhashedSubpackets: BaseSignatureSubpackets) {
-                    function(unhashedSubpackets)
-                }
-            }
-        }
-    }
 }
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/SignatureSubpackets.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/SignatureSubpackets.kt
index e30c6100..8b831969 100644
--- a/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/SignatureSubpackets.kt
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/signature/subpackets/SignatureSubpackets.kt
@@ -70,51 +70,6 @@ class SignatureSubpackets(
         fun createEmptySubpackets(): SignatureSubpackets {
             return SignatureSubpackets(PGPSignatureSubpacketGenerator())
         }
-
-        /** Factory method for a [Callback] that does nothing. */
-        @JvmStatic fun nop() = object : Callback {}
-
-        /**
-         * Factory function with receiver, which returns a [Callback] that modifies the hashed
-         * subpacket area of a [SignatureSubpackets] object.
-         *
-         * Can be called like this:
-         * ```
-         * val callback = SignatureSubpackets.applyHashed {
-         *     setCreationTime(date)
-         *     ...
-         * }
-         * ```
-         */
-        @JvmStatic
-        fun applyHashed(function: SignatureSubpackets.() -> Unit): Callback {
-            return object : Callback {
-                override fun modifyHashedSubpackets(hashedSubpackets: SignatureSubpackets) {
-                    function(hashedSubpackets)
-                }
-            }
-        }
-
-        /**
-         * Factory function with receiver, which returns a [Callback] that modifies the unhashed
-         * subpacket area of a [SignatureSubpackets] object.
-         *
-         * Can be called like this:
-         * ```
-         * val callback = SignatureSubpackets.applyUnhashed {
-         *     setCreationTime(date)
-         *     ...
-         * }
-         * ```
-         */
-        @JvmStatic
-        fun applyUnhashed(function: SignatureSubpackets.() -> Unit): Callback {
-            return object : Callback {
-                override fun modifyUnhashedSubpackets(unhashedSubpackets: SignatureSubpackets) {
-                    function(unhashedSubpackets)
-                }
-            }
-        }
     }
 
     override fun setRevocationReason(