Getting SHA1 through programming

Question

This is a something like signinig report's my app:

Variant: release
Config: config
Store: C:\Users\Superman\Desktop\web.jks
Alias: web
MD5: 8C:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
SHA1: D3:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
SHA-256: A0:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
Valid until: Sunday, December 4, 2044

Is there a way to get this code(MD5, SHA1, SHA-256) through Android programming? I want to save one of them on the server. When using the app, these values should be checked with the values stored in the server, if it is not equal exit and kill the process (I do this to prevent my app from cracking)

Answer 1

This answer it taken from another answer Check out this function

// key like: SHA1, SHA256, MD5.
private fun get(key: String, info: PackageInfo) {
    try {
        for (signature in info.signatures) {
            val md: MessageDigest = MessageDigest.getInstance(key)
            md.update(signature.toByteArray())
            val digest: ByteArray = md.digest()
            val toRet = StringBuilder()
            for (i in digest.indices) {
                if (i != 0) toRet.append(":")
                val b: Byte = digest[i] and 0xff.toByte()
                val hex = Integer.toHexString(b.toInt())
                if (hex.length == 1) toRet.append("0")
                toRet.append(hex)
            }
            Log.d(TAG, "key: $key $toRet")
        }
    } catch (e1: PackageManager.NameNotFoundException) {
        Log.e(TAG, e1.toString())
    } catch (e: NoSuchAlgorithmException) {
        Log.e(TAG, e.toString())
    } catch (e: Exception) {
        Log.e(TAG, e.toString())
    }
}

To use it call it like this

get("SHA1", packageManager.getPackageInfo(packageName, PackageManager.GET_SIGNATURES))

Answer 2

It seems that you are looking for a version check. If so, you are misunderstanding the purpose of hashing. Hashing is for checking data integrity and not for verifying. It makes no security difference using hash or not, if you are just uploading the value and check it in the server.