Simple snippet that demonstrates how to make https request with SSL pinning by using ktor on Android

ssl_pinning_android_ktor.kt

class AndroidRemote(private val context: Context) : Remote {

    companion object {
        private const val SSL_PROTOCOL = "TLSv1.2"
        private const val KEYSTORE_PROTOCOL = "BKS"
        private const val KEY_MANAGER_ALG = "X509"
        private const val KEYSTORE_PATH = "YOUR_ASSET_NAME.bks"
        private val KEYSTORE_PASSWORD = "YOUR_PASS".toCharArray() // Find better place to store this please hahaha

        private const val API_ENDPOINT = "API_ENDPOINT"
    }

    private val sslContext by lazy {
        SSLContext.getInstance(SSL_PROTOCOL)
            .apply {
                val fis = context.assets.open(KEYSTORE_PATH)
                val keystore = KeyStore.getInstance(KEYSTORE_PROTOCOL)
                keystore.load(fis, KEYSTORE_PASSWORD)

                val manager = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm())
                manager.init(keystore)

                val kmf: KeyManagerFactory = KeyManagerFactory.getInstance(KEY_MANAGER_ALG)
                kmf.init(keystore, KEYSTORE_PASSWORD)

                val random = SecureRandom()

                init(kmf.keyManagers, manager.trustManagers, random)
            }
    }

    private fun buildClient() = HttpClient(Android.config {
        sslManager = { conn -> conn.sslSocketFactory = sslContext.socketFactory }
    }) {
        defaultRequest {
            val urlBuilder = URLBuilder(API_ENDPOINT)
            url {
                protocol = urlBuilder.protocol
                host = urlBuilder.host
            }
        }
    }

    // Just an example, obviously we should get the response and handle it
    override suspend fun testSslPinning(phone: String): Either<Error, Success> {
      try {
            buildClient().use { it.get<String> { url { encodedPath = "path" } } }
            return Either.Right(Success)
        } catch (e: Exception) {
            return Either.Left(Error.Default)
        }    
    }
}

If you want to generate a bks file from jks one, please, execute the following command:

keytool -importkeystore -srckeystore YOUR_KEYSTORE.jks -destkeystore YOUR_KEYSTORE.bks -srcstoretype JKS -deststoretype BKS -srcstorepass KEYSTORE_PASS -deststorepass KEYSTORE_PASS -provider org.bouncycastle.jce.provider.BouncyCastleProvider --providerpath "bcprov-jdk16-1.46.jar"

You will need the bcprov library (https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk16/1.46) and move the JAR to the jks-located folder