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July 7, 2020 17:24
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Android Sms AutoRetrieval hash-generator in Kotlin
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| package sms | |
| import android.annotation.SuppressLint | |
| import android.content.Context | |
| import android.content.pm.PackageManager | |
| import android.os.Build | |
| import android.util.Base64 | |
| import android.util.Log | |
| import java.nio.charset.StandardCharsets | |
| import java.security.MessageDigest | |
| import java.security.NoSuchAlgorithmException | |
| import java.util.ArrayList | |
| import java.util.Arrays | |
| /** | |
| * This is a helper class to generate your message hash to be included in your SMS message. | |
| * | |
| * Without the correct hash, your app won't receive the message callback. This only needs to be | |
| * generated once per app and stored. Then you can remove this helper class from your code. | |
| * | |
| * See https://stackoverflow.com/questions/53849023/android-sms-retriever-api-computing-apps-hash-string-problem | |
| * See https://developers.google.com/identity/sms-retriever/verify#generating_a_one-time_code | |
| */ | |
| class AppSignatureSmsVerificationHelper(context: Context) { | |
| /** | |
| * Get all the app signatures for the current package | |
| */ | |
| val appSignatures: ArrayList<String> | |
| val appSignature: String? | |
| get() = appSignatures.firstOrNull() | |
| init { | |
| val appCodes = ArrayList<String>() | |
| try { | |
| val packageName = context.packageName | |
| val packageManager = context.packageManager | |
| val signatures = | |
| if (Build.VERSION.SDK_INT >= 28) { | |
| packageManager.getPackageInfo(packageName, PackageManager.GET_SIGNING_CERTIFICATES).signingInfo.apkContentsSigners | |
| } else { | |
| @Suppress("DEPRECATION") | |
| packageManager.getPackageInfo(packageName, PackageManager.GET_SIGNATURES).signatures | |
| } | |
| // For each signature create a compatible hash | |
| for (signature in signatures) { | |
| val hash = hash(packageName, signature.toCharsString()) | |
| if (hash != null) { | |
| appCodes.add(String.format("%s", hash)) | |
| } | |
| Log.v(TAG, "Hash $hash") | |
| } | |
| } catch (e: PackageManager.NameNotFoundException) { | |
| Log.w(TAG, "PackageManager error", e) | |
| } | |
| appSignatures = appCodes | |
| } | |
| /** | |
| * Generates the hash by running sha on the string 'package hash'. | |
| */ | |
| @SuppressLint("ObsoleteSdkInt") | |
| private fun hash(packageName: String, signature: String): String? { | |
| val appInfo = "$packageName $signature" | |
| try { | |
| val messageDigest = MessageDigest.getInstance(HASH_TYPE) | |
| if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { | |
| messageDigest.update(appInfo.toByteArray(StandardCharsets.UTF_8)) | |
| } | |
| var hashSignature = messageDigest.digest() | |
| // truncated into NUM_HASHED_BYTES | |
| hashSignature = Arrays.copyOfRange(hashSignature, 0, NUM_HASHED_BYTES) | |
| // encode into Base64 | |
| var base64Hash = Base64.encodeToString(hashSignature, Base64.NO_PADDING or Base64.NO_WRAP) | |
| base64Hash = base64Hash.substring(0, NUM_BASE64_CHAR) | |
| // Log.d(TAG, String.format("pkg: %s -- hash: %s", packageName, base64Hash)) | |
| return base64Hash | |
| } catch (e: NoSuchAlgorithmException) { | |
| Log.w(TAG, "hash:NoSuchAlgorithm", e) | |
| } | |
| return null | |
| } | |
| companion object { | |
| val TAG = AppSignatureSmsVerificationHelper::class.java.simpleName | |
| private const val HASH_TYPE = "SHA-256" | |
| const val NUM_HASHED_BYTES = 9 | |
| const val NUM_BASE64_CHAR = 11 | |
| } | |
| } |
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