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I am currently creating an encrypted file format that needs to be signed. For this I need to calculate the hash code of the content I have written to a stream. In the .net framework there is numerous hash algorithms that can be used, and it works fine, but it requires me to process the stream three times. byte[] content = new byte[] { 0, 1, 2, 3, 4, 5, 6 }; using (Stream fileStream = File.Open("myfile.bin", FileMode.Create)) { //Write content fileStream.Write(content, 0, content.Length); } byte[] hashValue = null; using (Stream fileStream = File.Open("myfile.bin", FileMode.Open)) { HashAlgorithm hash = SHA256.Create(); hashValue = hash.ComputeHash(fileStream); } using (Stream fileStream = File.Open("myfile.bin", FileMode.Append)) { fileStream.Write(hashValue, 0, hashValue.Length); } This is okay if it is encrypted to a file, but if it is encrypted to a network destination, the bytes are no longer available. So basically I need to only process the data once. On CodeProject there is an article that has implemented CRC32 as a Stream that calculates the CRC32 code every time there is written data to it. Something like: byte[] content = new byte[] { 0, 1, 2, 3, 4, 5, 6 }; using (FileStream fileStream = File.Create("myfile.bin")) using (Stream crcStream = new CRCStream(fileStream)) //Takes a base stream { //Write content crcStream.Write(content, 0, content.Length); //Write checksum fileStream.Write(crcStream.WriteCRC, 0, 4); } Obviously CRC32 is not a hash alogorithm, but it would be nice to have something like a HashStream that takes a HashAlgorithm. The HashStream would update the hash value every time write/read is called. Something like: byte[] content = new byte[] { 0, 1, 2, 3, 4, 5, 6 }; HashAlgorithm hashAlgo = SHA256.Create(); using (File

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