title: How can I compute two hashes without reading the same file twice?
body: <p>I have a program which is going to be used on very large files (current test data is 250GB). I need to be able to calculate both MD5 and SHA1 hashes for these files. Currently my code drops the stream into MD5.Create().ComputeHash(Stream stream), and then the same for SHA1. These, as far as I can tell, read the file in 4096-byte blocks to a buffer internal to the hashing function, until the end of the stream.</p>
  
  <p>The problem is, doing this one after the other takes a VERY long time! Is there any way I can take data into a buffer and provide the buffer to BOTH algorithms before reading a new block into the buffer?</p>
  
  <p>Please explain thoroughly as I'm not an experienced coder.</p>