yaotp/app/src/main/java/com/chameth/yaotp/algos/Hmac.kt

package com.chameth.yaotp.algos

import javax.crypto.Mac
import javax.crypto.spec.SecretKeySpec

typealias HmacFunc = (ByteArray, ByteArray) -> ByteArray

fun getHmacFunc(name: String?): HmacFunc {
    return when (name?.toLowerCase()) {
        "sha1" -> ::hmacSha1
        "sha256" -> ::hmacSha256
        "sha512" -> ::hmacSha512
        else -> ::hmacSha1
    }
}

fun hmacSha1(keyMaterial: ByteArray, input: ByteArray) = hmac(keyMaterial, input, "HmacSHA1")
fun hmacSha256(keyMaterial: ByteArray, input: ByteArray) = hmac(keyMaterial, input, "HmacSHA256")
fun hmacSha512(keyMaterial: ByteArray, input: ByteArray) = hmac(keyMaterial, input, "HmacSHA512")

private fun hmac(keyMaterial: ByteArray, input: ByteArray, algorithm: String): ByteArray {
    return with(Mac.getInstance(algorithm)) {
        init(SecretKeySpec(keyMaterial, algorithm))
        doFinal(input)
    }
}