let decryptor = aes.CreateDecryptor (key, iv)
new CryptoStream (inputStream, decryptor, CryptoStreamMode.Read)
// Create a stream to compute the HMAC-SHA256 against all data being written.
let HMACStream (key: byte[]) (outputStream: Stream) : Stream * HMACSHA256 =
let decryptor = aes.CreateDecryptor (key, iv)
new CryptoStream (inputStream, decryptor, CryptoStreamMode.Read)
// Create a stream to compute the HMAC-SHA256 against all data being written.
let HMACStream (key: byte[]) (outputStream: Stream) : Stream * HMACSHA256 =