diff --git a/.idea/dictionaries/tateisu.xml b/.idea/dictionaries/tateisu.xml
index 87c760aa..9bf393b1 100644
--- a/.idea/dictionaries/tateisu.xml
+++ b/.idea/dictionaries/tateisu.xml
@@ -32,6 +32,7 @@
       <w>foregrounder</w>
       <w>gifv</w>
       <w>github</w>
+      <w>hansshake</w>
       <w>hashtag</w>
       <w>hashtags</w>
       <w>hhmm</w>
diff --git a/app/build.gradle b/app/build.gradle
index a604d80d..1350235e 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -116,6 +116,7 @@ dependencies {
     kapt 'com.github.bumptech.glide:compiler:4.7.1'
     // kotlin では annotationProcessor の代わりに kapt を使う
 
+    implementation "org.conscrypt:conscrypt-android:1.3.0"
 
     implementation 'uk.co.chrisjenx:calligraphy:2.3.0'
 
diff --git a/app/src/main/java/jp/juggler/subwaytooter/ActMediaViewer.kt b/app/src/main/java/jp/juggler/subwaytooter/ActMediaViewer.kt
index d5050ba0..ef80bf24 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/ActMediaViewer.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/ActMediaViewer.kt
@@ -46,6 +46,7 @@ import org.json.JSONObject
 import java.io.ByteArrayInputStream
 import java.io.IOException
 import java.util.*
+import javax.net.ssl.HttpsURLConnection
 
 class ActMediaViewer : AppCompatActivity(), View.OnClickListener {
 	
@@ -330,6 +331,9 @@ class ActMediaViewer : AppCompatActivity(), View.OnClickListener {
 			return
 		}
 		
+		// https://github.com/google/ExoPlayer/issues/1819
+		HttpsURLConnection.setDefaultSSLSocketFactory(MySslSocketFactory)
+		
 		exoView.visibility = View.VISIBLE
 		
 		val defaultBandwidthMeter = DefaultBandwidthMeter()
diff --git a/app/src/main/java/jp/juggler/subwaytooter/App1.kt b/app/src/main/java/jp/juggler/subwaytooter/App1.kt
index 3c8ccea0..3ddb6839 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/App1.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/App1.kt
@@ -29,8 +29,10 @@ import jp.juggler.subwaytooter.util.CustomEmojiLister
 import jp.juggler.subwaytooter.util.ProgressResponseBody
 import jp.juggler.util.*
 import okhttp3.*
+import org.conscrypt.Conscrypt
 import java.io.File
 import java.io.InputStream
+import java.security.Security
 import java.util.*
 import java.util.concurrent.LinkedBlockingQueue
 import java.util.concurrent.ThreadFactory
@@ -219,20 +221,20 @@ class App1 : Application() {
 			timeoutSecondsConnect : Int,
 			timeoutSecondsRead : Int
 		) : OkHttpClient.Builder {
+
 			val spec = ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
-				.cipherSuites(*APPROVED_CIPHER_SUITES)
+				.allEnabledCipherSuites()
+				.allEnabledTlsVersions()
+				.supportsTlsExtensions(true)
 				.build()
 			
-			val spec_list = ArrayList<ConnectionSpec>()
-			spec_list.add(spec)
-			spec_list.add(ConnectionSpec.CLEARTEXT)
-			
 			return OkHttpClient.Builder()
 				.connectTimeout(timeoutSecondsConnect.toLong(), TimeUnit.SECONDS)
 				.readTimeout(timeoutSecondsRead.toLong(), TimeUnit.SECONDS)
 				.writeTimeout(timeoutSecondsRead.toLong(), TimeUnit.SECONDS)
 				.pingInterval(10, TimeUnit.SECONDS)
-				.connectionSpecs(spec_list)
+				.connectionSpecs(Collections.singletonList(spec))
+				.sslSocketFactory(MySslSocketFactory,MySslSocketFactory.trustManager)
 				.addInterceptor(ProgressResponseBody.makeInterceptor())
 				.addInterceptor(user_agent_interceptor)
 		}
@@ -257,6 +259,12 @@ class App1 : Application() {
 			var state = appStateX
 			if(state != null) return state
 			
+			// initialize Conscrypt
+			Security.insertProviderAt(
+				Conscrypt.newProvider(),
+				1 /* 1 means first position */
+			)
+			
 			initializeFont()
 			
 			pref = Pref.pref(app_context)
diff --git a/app/src/main/java/jp/juggler/subwaytooter/api/TootApiClient.kt b/app/src/main/java/jp/juggler/subwaytooter/api/TootApiClient.kt
index 1822c086..86530d04 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/api/TootApiClient.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/api/TootApiClient.kt
@@ -50,6 +50,7 @@ class TootApiClient(
 	companion object {
 		private val log = LogCategory("TootApiClient")
 		
+		val debugHandshake = true
 		
 		private const val DEFAULT_CLIENT_NAME = "SubwayTooter"
 		internal const val KEY_CLIENT_CREDENTIAL = "SubwayTooterClientCredential"
@@ -266,6 +267,8 @@ class TootApiClient(
 	//////////////////////////////////////////////////////////////////////
 	// ユーティリティ
 	
+	
+	
 	// リクエストをokHttpに渡してレスポンスを取得する
 	internal inline fun sendRequest(
 		result : TootApiResult,
@@ -288,7 +291,15 @@ class TootApiClient(
 				)
 			)
 			
-			result.response = httpClient.getResponse(request, tmpOkhttpClient = tmpOkhttpClient)
+			val response = httpClient.getResponse(request, tmpOkhttpClient = tmpOkhttpClient)
+			result.response = response
+			
+			if(debugHandshake) {
+				val handshake = response.handshake()
+				if(handshake != null) {
+					log.d("handshake ${handshake.tlsVersion()},${handshake.cipherSuite()} ${request.url()}")
+				}
+			}
 			
 			null == result.error
 			
diff --git a/app/src/main/java/jp/juggler/util/MySslSocketFactory.kt b/app/src/main/java/jp/juggler/util/MySslSocketFactory.kt
new file mode 100644
index 00000000..8bbf7fd3
--- /dev/null
+++ b/app/src/main/java/jp/juggler/util/MySslSocketFactory.kt
@@ -0,0 +1,119 @@
+package jp.juggler.util
+
+import java.io.IOException
+import java.net.InetAddress
+import java.net.Socket
+import java.net.UnknownHostException
+import java.security.KeyStore
+import javax.net.ssl.*
+
+object MySslSocketFactory : SSLSocketFactory() {
+	
+	var debugCipherSuites = false
+	
+	private val log = LogCategory("MySslSocketFactory")
+	
+	private val originalFactory: SSLSocketFactory =
+		SSLContext.getInstance("TLS").apply {
+			init(null, null, null)
+		}.socketFactory
+	
+	private fun check(socket: Socket?): Socket? {
+		
+		// 端末のデフォルトでは1.3が含まれないので追加する
+		(socket as? SSLSocket)?.enabledProtocols = arrayOf("TLSv1.1", "TLSv1.2", "TLSv1.3")
+		
+		// デバッグフラグが変更された後に１回だけ、ソケットの暗号化スイートを列挙する
+		if (debugCipherSuites) {
+			debugCipherSuites = false
+			(socket as? SSLSocket)?.enabledCipherSuites?.forEach { cs ->
+				log.d("getEnabledCipherSuites : $cs")
+			}
+		}
+		
+		return socket
+	}
+	
+	override fun getDefaultCipherSuites(): Array<String> {
+		return originalFactory.defaultCipherSuites
+	}
+	
+	override fun getSupportedCipherSuites(): Array<String> {
+		return originalFactory.supportedCipherSuites
+	}
+	
+	@Throws(IOException::class)
+	override fun createSocket(): Socket? {
+		return check(originalFactory.createSocket())
+	}
+	
+	@Throws(IOException::class)
+	override fun createSocket(s: Socket, host: String, port: Int, autoClose: Boolean): Socket? {
+		return check(
+			originalFactory.createSocket(
+				s,
+				host,
+				port,
+				autoClose
+			)
+		)
+	}
+	
+	@Throws(IOException::class, UnknownHostException::class)
+	override fun createSocket(host: String, port: Int): Socket? {
+		return check(
+			originalFactory.createSocket(
+				host,
+				port
+			)
+		)
+	}
+	
+	@Throws(IOException::class, UnknownHostException::class)
+	override fun createSocket(host: String, port: Int, localHost: InetAddress, localPort: Int): Socket? {
+		return check(
+			originalFactory.createSocket(
+				host,
+				port,
+				localHost,
+				localPort
+			)
+		)
+	}
+	
+	@Throws(IOException::class)
+	override fun createSocket(host: InetAddress, port: Int): Socket? {
+		return check(
+			originalFactory.createSocket(
+				host,
+				port
+			)
+		)
+	}
+	
+	@Throws(IOException::class)
+	override fun createSocket(address: InetAddress, port: Int, localAddress: InetAddress, localPort: Int): Socket? {
+		return check(
+			originalFactory.createSocket(
+				address,
+				port,
+				localAddress,
+				localPort
+			)
+		)
+	}
+	
+	//
+	val trustManager: X509TrustManager by lazy {
+		val trustManagers = TrustManagerFactory
+			.getInstance(TrustManagerFactory.getDefaultAlgorithm())
+			.apply { init(null as KeyStore?) }
+			.trustManagers
+		
+		trustManagers
+			.find { it is X509TrustManager }
+			as? X509TrustManager
+			?: error("missing X509TrustManager in $trustManagers")
+	}
+	
+}
\ No newline at end of file