This chapter illustrates how to create SHA-256 hashing in C# and VB.NET using the NCiphers.Crypto library.
The output of this hash function is 256 bit long (32 bytes) and it is very commonly used for transforming string passwords into byte array keys for symmetric cipher algorithms that require 32 bytes long keys.
Table of contents
1. Digest output
2. digest from a byte array
3. digest from a String
4. digest from a file
5. digest from a Stream
1. Digest output
The raw digest output from a hash function is a byte array constructed by computing the hash algorithm over the input data:
C# example
byte[] hash = NCiphers.Hashing.HashTools.Sha256(data);
VB.NET example
Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256(data)
There may be cases when we need the digest to be received as a String from the hexadecimal representation of the hash bytes. In that case we shall use:
C# example
byte[] hash = NCiphers.Hashing.HashTools.Sha256Hex(data);
VB.NET example
Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256Hex(data)
2. Sha256 from a byte array
Here is how to compute the Sha256 message digest of a byte array:
C# example
byte[] data = new byte[] {1,2,3,4,5,6,7,8,9,100,200,300,400,500}; byte[] hash = NCiphers.Hashing.HashTools.Sha256(data); string hashAsString = NCiphers.Hashing.HashTools.Sha256Hex(data);
VB.NET example
Dim data As New Byte() {1,2,3,4,5,6,7,8,9,100,200,300,400,500} Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256(data) Dim hashAsString As String = NCiphers.Hashing.HashTools.Sha256Hex(data)
3. Sha256 from a String
Getting the Sha256 hash of a String is similar to the above example:
C# example
string data = "Hello World"; byte[] hash = NCiphers.Hashing.HashTools.Sha256(data); string hashAsString = NCiphers.Hashing.HashTools.Sha256Hex(data);
VB.NET example
Dim data As String = "Hello World" Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256(data) Dim hashAsString As String = NCiphers.Hashing.HashTools.Sha256Hex(data)
4. Sha256 from a file
To get the Sha256 hash of a file, we simply supply a System.IO.FileInfo object as parameter:
C# example
System.IO.FileInfo data = new System.IO.FileInfo(@"c:\myfile.txt"); byte[] hash = NCiphers.Hashing.HashTools.Sha256(data); string hashAsString = NCiphers.Hashing.HashTools.Sha256Hex(data);
VB.NET example
Dim data As New System.IO.FileInfo("c:\myfile.txt") Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256(data) Dim hashAsString As String = NCiphers.Hashing.HashTools.Sha256Hex(data)
5. Sha256 from a Stream
The overloaded methods that accept System.IO.Stream parameter, are reading the input byte by byte and compute the Sha256 digest over this data. Of course the caller must ensure that the Stream is positioned at the start of the data and after the method call its position will be at the end of the Stream. It is also the obligation of the caller to close the Stream.
C# example
byte[] bytes = new byte[] {1,2,3,4,5,6,7,8,9,100,200,300,400,500}; System.IO.Stream data = new MemoryStream(bytes); byte[] hash = NCiphers.Hashing.HashTools.Sha256(data); string hashAsString = NCiphers.Hashing.HashTools.Sha256Hex(data);
VB.NET example
Dim bytes As New Byte() {1,2,3,4,5,6,7,8,9,100,200,300,400,500} Dim data As New System.IO.MemoryStream(bytes) Dim hash As Byte() = NCiphers.Hashing.HashTools.Sha256(data) Dim hashAsString As String = NCiphers.Hashing.HashTools.Sha256Hex(data)
6. Summary
This article demonstrated how to compute Sha256 message digest hashes with the NCiphers.Crypto library. Probably you may be interested to see also the other hash functions offered by the library.
List of methods used:
- NCiphers.Hashing.HashTools.Sha256 – returns the Sha256 hash as byte array
- NCiphers.Hashing.HashTools.Sha256Hex – returns the Sha256 hash as hexadecimal String