Start with this or similar articles about general knowledge: [ur=https://www.agus*********/*********/what-is-a-virus-signature-are-they-still-used-3.htm]What is a virus signature? Are they still used?[/url]
Internet searches and Wiki searches is also recommended.
About code you should start with FileStream class to read bytes from files.
Here is a very basic algorithm that searches for a virus signature in a file:
Code:
Function detect() As Boolean
Dim file() As Byte = {1, 2, 3, 4, 5, 6, 7, 8, 9} 'sample file
Dim virus() As Byte = {4, 5, 6} 'sample signature
For ix As Integer = 0 To file.Length - virus.Length
If file(ix) = virus(0) Then 'found first byte in signature, check rest
For vx As Integer = 1 To virus.Length - 1
If file(ix + vx) <> virus(vx) Then
Exit For
ElseIf vx = virus.Length - 1 Then
Return True 'virus found
End If
Next
End If
Next
Return False 'virus not found
End Function