diff --git a/src/main/kotlin/dev/usbharu/hideout/plugins/ActivityPub.kt b/src/main/kotlin/dev/usbharu/hideout/plugins/ActivityPub.kt
index a01ef3ff..17a9530e 100644
--- a/src/main/kotlin/dev/usbharu/hideout/plugins/ActivityPub.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/plugins/ActivityPub.kt
@@ -22,6 +22,7 @@ import java.net.URI
 import java.security.KeyFactory
 import java.security.PrivateKey
 import java.security.PublicKey
+import java.security.spec.PKCS8EncodedKeySpec
 import java.security.spec.X509EncodedKeySpec
 import java.text.SimpleDateFormat
 import java.util.*
@@ -160,10 +161,10 @@ class KtorKeyMap(private val userAuthRepository: IUserAuthService) : KeyMap {
         val publicBytes = Base64.getDecoder().decode(
             userAuthRepository.findByUsername(
                 username
-            ).privateKey?.replace("-----BEGIN PUBLIC KEY-----", "-----END PUBLIC KEY-----")?.replace("", "")
+            ).privateKey?.replace("-----BEGIN RSA PRIVATE KEY-----", "")?.replace("-----END RSA PRIVATE KEY-----", "")
                 ?.replace("\\n", "")
         )
-        val x509EncodedKeySpec = X509EncodedKeySpec(publicBytes)
+        val x509EncodedKeySpec = PKCS8EncodedKeySpec(publicBytes)
         return@runBlocking KeyFactory.getInstance("RSA").generatePrivate(x509EncodedKeySpec)
     }
 
diff --git a/src/test/kotlin/dev/usbharu/hideout/plugins/KtorKeyMapTest.kt b/src/test/kotlin/dev/usbharu/hideout/plugins/KtorKeyMapTest.kt
new file mode 100644
index 00000000..b89418e0
--- /dev/null
+++ b/src/test/kotlin/dev/usbharu/hideout/plugins/KtorKeyMapTest.kt
@@ -0,0 +1,103 @@
+package dev.usbharu.hideout.plugins
+
+import dev.usbharu.hideout.domain.model.User
+import dev.usbharu.hideout.domain.model.UserAuthentication
+import dev.usbharu.hideout.domain.model.UserAuthenticationEntity
+import dev.usbharu.hideout.domain.model.UserEntity
+import dev.usbharu.hideout.repository.IUserAuthRepository
+import dev.usbharu.hideout.repository.IUserRepository
+import dev.usbharu.hideout.service.UserAuthService
+import org.junit.jupiter.api.Test
+import java.security.KeyPairGenerator
+import java.security.interfaces.RSAPrivateKey
+import java.security.interfaces.RSAPublicKey
+import java.util.*
+
+class KtorKeyMapTest {
+
+    @Test
+    fun getPrivateKey() {
+        val ktorKeyMap = KtorKeyMap(UserAuthService(object : IUserRepository {
+            override suspend fun create(user: User): UserEntity {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findById(id: Long): UserEntity? {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findByName(name: String): UserEntity? {
+                return UserEntity(1, "test", "localhost", "test", "")
+            }
+
+            override suspend fun update(userEntity: UserEntity) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun delete(id: Long) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findAll(): List<User> {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findAllByLimitAndByOffset(limit: Int, offset: Long): List<UserEntity> {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun createFollower(id: Long, follower: Long) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun deleteFollower(id: Long, follower: Long) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findFollowersById(id: Long): List<UserEntity> {
+                TODO("Not yet implemented")
+            }
+
+        }, object : IUserAuthRepository {
+            override suspend fun create(userAuthentication: UserAuthentication): UserAuthenticationEntity {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findById(id: Long): UserAuthenticationEntity? {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun update(userAuthenticationEntity: UserAuthenticationEntity) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun delete(id: Long) {
+                TODO("Not yet implemented")
+            }
+
+            override suspend fun findByUserId(id: Long): UserAuthenticationEntity? {
+                val keyPairGenerator = KeyPairGenerator.getInstance("RSA")
+                keyPairGenerator.initialize(1024)
+                val generateKeyPair = keyPairGenerator.generateKeyPair()
+                return UserAuthenticationEntity(
+                    1, 1, "test", (generateKeyPair.public as RSAPublicKey).toPem(),
+                    (generateKeyPair.private as RSAPrivateKey).toPem()
+                )
+            }
+        }))
+
+        ktorKeyMap.getPrivateKey("test")
+    }
+
+    private fun RSAPublicKey.toPem(): String {
+        return "-----BEGIN RSA PUBLIC KEY-----" +
+                Base64.getEncoder().encodeToString(encoded) +
+                "-----END RSA PUBLIC KEY-----"
+    }
+
+    private fun RSAPrivateKey.toPem(): String {
+        return "-----BEGIN RSA PRIVATE KEY-----" +
+                Base64.getEncoder().encodeToString(encoded) +
+                "-----END RSA PRIVATE KEY-----"
+    }
+}