Compute SHA256 Hash in Android/Java and C#

Question

I am trying to generate a SHA256 hash in android, that I then pass to an ASP.NET Web API web service and compare the hash there. As such, I need to construct a hash in Andro

Answer 1

Your Java code is wrong: you are adding the input bytes twice. If you are calculating this in one go, you need to either call only digest(bytes) or call digest() after update(bytes);

Answer 2

I was looking for a Kotlin version for my Android app.

I could not find one; here is what I came up with:

fun String.getSha256(): String {
    val digest = MessageDigest.getInstance("SHA-256").apply { reset() }
    val byteData: ByteArray = digest.digest(this.toByteArray())
    return StringBuffer().apply {
        byteData.forEach {
            append(((it.toInt() and 0xff) + 0x100).toString(16).substring(1))
        }
    }.toString()
}