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+---- Thread: [.NET] Small collection of checksum algorithms [Xor8,Adler,Fletcher,SysV32,Bsd32] (/showthread.php?tid=5541895)
Small collection of checksum algorithms [Xor8,Adler,Fletcher,SysV32,Bsd32] - Barret - Feb 3, 2017
These algorithms have been ported to vb.net and come from all over the net, mainly wiki, if you are looking for quick dirty checksum functions on a byte array.
XOR8
Code
''' <summary>
''' The longitudinal redundancy check (LRC) or horizontal redundancy check that is applied independently to each of a parallel group of bit streams
''' </summary>
''' <returns>UInt16</returns>
Public Shared Function Xor8(buffer() As Byte) As UInt16
Dim lrc As UInt16 = 0
For i As Integer = 0 To buffer.Length - 1
lrc = Convert.ToUInt16((lrc + buffer(i)) And &HFF)
Next
Return Convert.ToUInt16((((lrc Xor &HFF) + 1) And &HFF))
End FunctionADLER (16/32/64)
Code
''' <summary>
''' The Adler checksum algorithm was invented by Mark Adler in 1995 and is a modification of the Fletcher checksum.
''' </summary>
''' <returns>UInt16</returns>
Public Shared Function Adler16(buffer() As Byte) As UInt16
Dim a As UInt16 = 0, b As UInt16 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt16((a + buffer(i)) Mod &HFFF1)
b = Convert.ToUInt16((b + a) Mod &HFFF1)
Next
Return (b << 8) Or a
End Function
''' <summary>
''' The Adler checksum algorithm was invented by Mark Adler in 1995 and is a modification of the Fletcher checksum.
''' </summary>
''' <returns>UInt32</returns>
Public Shared Function Adler32(buffer() As Byte) As UInt32
Dim a As UInt32 = 0, b As UInt32 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt32((a + buffer(i)) Mod &HFFF1)
b = Convert.ToUInt32((b + a) Mod &HFFF1)
Next
Return (b << 16) Or a
End Function
''' <summary>
''' The Adler checksum algorithm was invented by Mark Adler in 1995 and is a modification of the Fletcher checksum.
''' </summary>
''' <returns>UInt64</returns>
Public Shared Function Adler64(buffer() As Byte) As UInt64
Dim a As UInt64 = 0, b As UInt64 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt64((a + buffer(i)) Mod &HFFF1)
b = Convert.ToUInt64((b + a) Mod &HFFF1)
Next
Return (b << 32) Or a
End FunctionFLETCHER (16/32/64)
Code
''' <summary>
''' The Fletcher checksum is an algorithm for computing a position-dependent checksum devised by John G. Fletcher
''' </summary>
''' <returns>UInt16</returns>
Public Shared Function Fletcher16(buffer() As Byte) As UInt16
Dim a As UInt16 = 0, b As UInt16 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt16((a + buffer(i)) Mod &HFF)
b = Convert.ToUInt16((b + a) Mod &HFF)
Next
Return (b << 8) Or a
End Function
''' <summary>
''' The Fletcher checksum is an algorithm for computing a position-dependent checksum devised by John G. Fletcher
''' </summary>
''' <returns>UInt23</returns>
Public Shared Function Fletcher32(buffer() As Byte) As UInt32
Dim a As UInt32 = 0, b As UInt32 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt32((a + buffer(i)) Mod &HFF)
b = Convert.ToUInt32((b + a) Mod &HFF)
Next
Return (b << 16) Or a
End Function
''' <summary>
''' The Fletcher checksum is an algorithm for computing a position-dependent checksum devised by John G. Fletcher
''' </summary>
''' <returns>UInt64</returns>
Public Shared Function Fletcher64(buffer() As Byte) As UInt64
Dim a As UInt64 = 0, b As UInt64 = 0
For i As Integer = 0 To buffer.Length - 1
a = Convert.ToUInt64((a + buffer(i)) Mod &HFF)
b = Convert.ToUInt64((b + a) Mod &HFF)
Next
Return (b << 32) Or a
End FunctionSYSV32
Code
''' <summary>
''' The SYSV checksum algorithm is a commonly used, legacy checksum algorithm.
''' </summary>
''' <returns>UInt32</returns>
Public Shared Function SysV32(buffer() As Byte) As UInt32
Dim a As UInt32 = 0, b As UInt32 = 0
Do While b <= buffer.Length - 1
a = Convert.ToUInt32((a + buffer(Convert.ToInt32(b))) Mod &HFFFF)
b = Convert.ToUInt32(b + 1)
Loop
Return (a << 32) Or a
End FunctionBSD32
Code
''' <summary>
''' The BSD checksum algorithm is a commonly used, legacy checksum algorithm
''' </summary>
''' <returns>UInt32</returns>
Public Shared Function Bsd32(buffer() As Byte) As UInt32
Dim sum As UInt32 = 0, count As UInt32 = 0
Do While count <= buffer.Length - 1
sum = Convert.ToUInt32((sum >> 1) + &H8000 * (sum And 1))
sum = Convert.ToUInt32((sum + buffer(Convert.ToInt32(count))) And &HFFFF)
count = Convert.ToUInt32(count + 1)
Loop
Return sum
End FunctionReason: After hours of f*%#$ around with Mono.Cecil i was so fed up with not accomplishing anything, i had to make something that did work to feel better about myself. lol
RE: Small collection of checksum algorithms [Xor8,Adler,Fletcher,SysV32,Bsd32] - fec-ri.muhayyel - Mar 8, 2019
good subject but how i encrypt/decrypt words? how to use? give me a example please
thanks
RE: Small collection of checksum algorithms [Xor8,Adler,Fletcher,SysV32,Bsd32] - gigajew - Mar 8, 2019
You don't encrypt/decrypt with these checksum calculators, it just gives you a unique number basically.
RE: Small collection of checksum algorithms [Xor8,Adler,Fletcher,SysV32,Bsd32] - 0xDEAD10CC - Mar 10, 2019
(Mar 8, 2019 10:32 AM)fec-ri.muhayyel Wrote: good subject but how i encrypt/decrypt words? how to use? give me a example please
thanks
Quite a few of these, including pretty much all other checksums are only intended for integrity checks.