in src/main/scala/com/gu/googleamp/AmpFlusher.scala [39:47]
private def computeSignature(
data: Array[Byte],
privateKey: PrivateKey
): Array[Byte] = {
val signer = Signature.getInstance("SHA256withRSA")
signer.initSign(privateKey)
signer.update(data)
signer.sign()
}