diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpKeyBuilder.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpKeyBuilder.kt
new file mode 100644
index 00000000..2d46322a
--- /dev/null
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpKeyBuilder.kt
@@ -0,0 +1,99 @@
+package org.pgpainless.key.generation
+
+import org.bouncycastle.openpgp.PGPKeyPair
+import org.bouncycastle.openpgp.PGPSecretKeyRing
+import org.pgpainless.implementation.ImplementationFactory
+import org.pgpainless.key.generation.type.KeyType
+import org.pgpainless.key.generation.type.eddsa.EdDSACurve
+import org.pgpainless.key.generation.type.rsa.RsaLength
+import org.pgpainless.key.generation.type.xdh.XDHSpec
+import org.pgpainless.provider.ProviderFactory
+import java.security.KeyPairGenerator
+import java.util.Date
+
+class OpenPgpKeyBuilder {
+
+    fun buildV4Key(
+        type: KeyType,
+        creationTime: Date = Date()
+    ): V4PrimaryKeyBuilder = V4PrimaryKeyBuilder(type, creationTime)
+
+    abstract class V4KeyBuilder<T: V4KeyBuilder<T>>(
+        protected val type: KeyType,
+        protected val creationTime: Date,
+        val certificateCreationTime: Date = Date()
+    ) {
+
+        internal val keyPair = generateKeyPair()
+
+        fun subkey(
+            type: KeyType,
+            creationTime: Date = certificateCreationTime
+        ): V4SubkeyBuilder = V4SubkeyBuilder(type, creationTime, this)
+
+        fun generate(): PGPSecretKeyRing {
+            val keys = collectKeysForGeneration()
+
+            assert(keys.first() is V4PrimaryKeyBuilder)
+            assert(keys.drop(1).all { it is V4SubkeyBuilder })
+
+            val primaryKey: V4PrimaryKeyBuilder = keys.first() as V4PrimaryKeyBuilder
+
+        }
+
+        private fun collectKeysForGeneration(): List<V4KeyBuilder<*>> =
+            if (this is V4SubkeyBuilder) {
+                predecessor.collectKeysForGeneration().plus(this)
+            } else {
+                listOf(this)
+            }
+
+        private fun generateKeyPair(): PGPKeyPair {
+            // Create raw Key Pair
+            val keyPair = KeyPairGenerator.getInstance(type.name, ProviderFactory.provider)
+                .also { it.initialize(type.algorithmSpec) }
+                .generateKeyPair()
+
+            // Form PGP Key Pair
+            return ImplementationFactory.getInstance()
+                .getPGPV4KeyPair(type.algorithm, keyPair, creationTime)
+        }
+    }
+
+    class V4PrimaryKeyBuilder(
+        type: KeyType,
+        creationTime: Date
+    ): V4KeyBuilder<V4PrimaryKeyBuilder>(type, creationTime) {
+
+        fun userId(userId: CharSequence) = userId(userId, OpenPgpV4KeyGenerator.Preferences())
+
+        fun userId(userId: CharSequence, preferences: OpenPgpV4KeyGenerator.Preferences) = apply {
+            keyPair.publicKey.
+        }
+
+        fun selfSignature(preferences: OpenPgpV4KeyGenerator.Preferences) = apply {
+
+        }
+    }
+
+    class V4SubkeyBuilder(
+        type: KeyType,
+        creationTime: Date,
+        internal val predecessor: V4KeyBuilder<*>,
+    ): V4KeyBuilder<V4SubkeyBuilder>(type, creationTime, predecessor.certificateCreationTime) {
+        fun bindingSignature(preferences: OpenPgpV4KeyGenerator.Preferences) = apply {
+
+        }
+    }
+}
+
+fun test() {
+    OpenPgpKeyBuilder()
+        .buildV4Key(KeyType.RSA(RsaLength._4096))
+        .selfSignature(OpenPgpV4KeyGenerator.Preferences())
+        .userId("Alice", OpenPgpV4KeyGenerator.Preferences())
+        .subkey(KeyType.EDDSA(EdDSACurve._Ed25519))
+        .bindingSignature(OpenPgpV4KeyGenerator.Preferences())
+        .subkey(KeyType.XDH(XDHSpec._X25519))
+        .bindingSignature(OpenPgpV4KeyGenerator.Preferences())
+}
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGenerator.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGenerator.kt
new file mode 100644
index 00000000..9b0ff6f4
--- /dev/null
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGenerator.kt
@@ -0,0 +1,117 @@
+package org.pgpainless.key.generation
+
+import org.bouncycastle.openpgp.PGPSecretKeyRing
+import org.pgpainless.algorithm.KeyFlag
+import org.pgpainless.key.generation.type.KeyType
+import org.pgpainless.policy.Policy
+import java.util.*
+
+class OpenPgpV4KeyGenerator(
+    private val policy: Policy,
+    private val referenceTime: Date = Date()
+) {
+
+    fun primaryKey(
+        type: KeyType,
+        vararg flag: KeyFlag = arrayOf(KeyFlag.CERTIFY_OTHER, KeyFlag.SIGN_DATA)
+    ) = primaryKey(type, referenceTime, *flag)
+
+    fun primaryKey(
+        type: KeyType,
+        creationTime: Date,
+        vararg flag: KeyFlag = arrayOf(KeyFlag.CERTIFY_OTHER, KeyFlag.SIGN_DATA)
+    ) = WithSubkeys(
+        KeyDescription(type, creationTime, flag.toList()),
+        policy,
+        referenceTime
+    )
+
+    class WithSubkeys(
+        private val primaryKey: KeyDescription,
+        private val policy: Policy,
+        private val referenceTime: Date
+    ) {
+
+        val builder = OpenPgpKeyBuilder()
+            .buildV4Key(primaryKey.type)
+            .
+
+        init {
+
+        }
+
+        fun encryptionSubkey(
+            type: KeyType,
+            vararg flag: KeyFlag = arrayOf(KeyFlag.ENCRYPT_COMMS, KeyFlag.ENCRYPT_STORAGE)
+        ) = encryptionSubkey(type, referenceTime, *flag)
+
+        fun encryptionSubkey(
+            type: KeyType,
+            creationTime: Date,
+            vararg flag: KeyFlag = arrayOf(KeyFlag.ENCRYPT_COMMS, KeyFlag.ENCRYPT_STORAGE)
+        ) = subkey(type, creationTime, *flag)
+
+        fun signingSubkey(
+            type: KeyType
+        ) = signingSubkey(type, referenceTime)
+
+        fun signingSubkey(
+            type: KeyType,
+            creationTime: Date
+        ) = subkey(type, creationTime, KeyFlag.SIGN_DATA)
+
+        fun subkey(
+            type: KeyType,
+            vararg flag: KeyFlag
+        ) = subkey(type, referenceTime, *flag)
+
+        fun subkey(
+            type: KeyType,
+            creationTime: Date = referenceTime,
+            vararg flag: KeyFlag
+        ) = apply {
+
+        }
+
+        fun noUserId(
+            preferences: Preferences
+        ): PGPSecretKeyRing {
+
+        }
+
+        fun userId(
+            userId: CharSequence,
+            preferences: Preferences
+        ): WithUserIds = WithUserIds().apply {
+            userId(userId, preferences)
+        }
+    }
+
+    class WithUserIds {
+        fun userId(
+            userId: CharSequence,
+            preferences: Preferences
+        ): WithUserIds {
+
+        }
+
+        fun done(): PGPSecretKeyRing {
+
+        }
+
+        fun directKeySignature(
+            preferences: Preferences
+        ): PGPSecretKeyRing {
+
+        }
+    }
+
+    data class KeyDescription(
+        val type: KeyType,
+        val creationTime: Date,
+        val flags: List<KeyFlag>
+    )
+
+    data class Preferences()
+
+}
diff --git a/pgpainless-core/src/test/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGeneratorTest.kt b/pgpainless-core/src/test/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGeneratorTest.kt
new file mode 100644
index 00000000..b201d54e
--- /dev/null
+++ b/pgpainless-core/src/test/kotlin/org/pgpainless/key/generation/OpenPgpV4KeyGeneratorTest.kt
@@ -0,0 +1,26 @@
+package org.pgpainless.key.generation
+
+import org.junit.jupiter.api.Test
+import org.pgpainless.algorithm.KeyFlag
+import org.pgpainless.key.generation.type.KeyType
+import org.pgpainless.key.generation.type.rsa.RsaLength
+import org.pgpainless.policy.Policy
+
+class OpenPgpV4KeyGeneratorTest {
+
+    @Test
+    fun test() {
+
+        OpenPgpV4KeyGenerator(Policy.getInstance())
+
+        OpenPgpV4KeyGenerator(Policy.getInstance())
+            .primaryKey(
+                KeyType.RSA(RsaLength._4096),
+                KeyFlag.CERTIFY_OTHER
+            ).signingSubkey(
+                KeyType.RSA(RsaLength._4096)
+            ).encryptionSubkey(
+                KeyType.RSA(RsaLength._4096)
+            )
+    }
+}