Retrieve android app's signature programmatically

AppSignature.kt

import android.content.Context
import android.content.pm.PackageManager
import android.util.Log
import java.security.MessageDigest
import java.security.NoSuchAlgorithmException

object AppSignature {

    @Suppress("unused")
    enum class Hash {
        SHA1, SHA256, MD5
    }

    fun get(context: Context, hash: Hash): String? {
        try {
            val signatures = with(context.packageManager) {
                getPackageInfo(
                    context.packageName,
                    PackageManager.GET_SIGNING_CERTIFICATES
                ).signingInfo.apkContentsSigners
            }
            
            for (signature in signatures) {
                val md = MessageDigest.getInstance(hash.name)
                md.update(signature.toByteArray())

                val digest = md.digest()
                val toRet = StringBuilder()

                digest.indices.forEach {
                    if (it != 0) toRet.append(":")
                    val b = digest[it].toInt() and 0xff
                    val hex = Integer.toHexString(b)
                    if (hex.length == 1) toRet.append("0")
                    toRet.append(hex.uppercase())
                }
                Log.d("AppSignature", "$hash.name $toRet")

                return toRet.toString()
            }
        } catch (e1: PackageManager.NameNotFoundException) {
            Log.d("AppSignature", e1.toString())
        } catch (e: NoSuchAlgorithmException) {
            Log.d("AppSignature", e.toString())
        } catch (e: Exception) {
            Log.d("AppSignature", e.toString())
        }
        return null
    }
}

Thank you. I have started using it in app and it works great