MD5 Extension Function

md5_extension.kt

fun main(argv: Array<String>) {
    val md5Result = "Hello World".saltMD5(null)
    println("The Salted MD5 Hash is = $md5Result")
}

private fun String.saltMD5(salt: String?): String {
    val saltedString = salt?.let { this + it } ?: this
    val md5MessageDigest = MessageDigest.getInstance("MD5")
    val digest = md5MessageDigest.digest(saltedString.toByteArray())
    val stringBuilder = StringBuilder()
    for (byte in digest) {
        val value = byte.toInt() and 0xff
        var hexString = Integer.toHexString(value)
        if (hexString.length < 2) {
            hexString = "0" + hexString
        }

        stringBuilder.append(hexString)
    }
    return stringBuilder.toString()
}