Rexor Wiki Rss Feed

Updated Wiki: Documentation

Todd434 — Wed, 27 Jan 2010 19:08:33 GMT

Rexor Documentation

Rexor is an encryption algorithm developed with cryptography beginners in mind. It's designed to be simple and easy to use and a good starting point for beginners. The algorithm is written in VB.NET but I hope to expand on that soon. Rexor stands for RE REverse XOR Exclusive OR. I am actively working on the project and I hope to get some more people soon.

Here is a step-by-step analysis of the code.
How it works:

Starting from the very top, this four line snippet imports the necessary namespaces needed to execute the code. Without these we wouldn't be able to use most of the commands below.

Imports Microsoft.VisualBasic
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO

This line says what the block of text is called, Rexor.

Module Rexor

This block of code is the main function. It is called when a programmer wants to encrypt a string.

Public Function Rexorcrypt(ByVal Input As String, ByVal Key As String) As String
Return xorstring(Reverse(xorstring(Input, Key)), Key)
End Function

This line declares the encrypt function's name and the variables it needs to execute.

Private Function xorstring(ByVal input As String, ByVal key As String) As String

In this block we declare the variables needed in order to store the necessary information required to carry out the algorithm successfully.

Dim Result1 As String
key = Hashkey(key)
Dim a As Array = input.ToCharArray
Dim k As Array = key.ToCharArray
Dim q As Integer = 0

Where it says ‘Key = Hashkey(Key)’ we turn the Password (Key) into a SHA1 Hash so if the key is bob, then the hash is "SBgazSKz7a68ikR4aKfffOYpkgo="

But that was just calling the function, here is the code:

Private Function Hashkey(ByVal key As String)
'Hash the key
Dim sha1CryptoService As New SHA1CryptoServiceProvider()
Dim byteValue = Encoding.UTF8.GetBytes(key)
Dim hashValue = sha1CryptoService.ComputeHash(byteValue)
Return Convert.ToBase64String(hashValue)
End Function

After that these lines turn the hashed key and the input string into character arrays.

Dim a As Array = input.ToCharArray
Dim k As Array = key.ToCharArray

Here the function finds the character codes of each letter in the ket and input strings and then xor’s them together.

For i = 0 To a.Length - 1
If q = 27 Then
q = 0
End If
'Dim k As String = Mid((key), q, 1)
Result1 = Result1 + Chr((Asc(k(q))) Xor Asc(a(i)))
q = q + 1
Next

The result is returned and the function ended.

Return Result1
End Function

But up to here, we have only xor’d the input string with the key once, now the algorithm moves onto reversing the output string and then xoring the old output with the key again.

Public Function Rexorcrypt(ByVal Input As String, ByVal Key As String) As String
Return xorstring(Reverse(xorstring(Input, Key)), Key)
End Function

(The reverse function is:

Private Function Reverse(ByVal input As String)
'Reverse the string
'Turn the string into an array
Dim rev() As Char = input.ToCharArray
'Reverse the array
Array.Reverse(rev)
'Convert the array to a string again.
Return CStr(rev)
End Function

)

So we:
- Xored a string with a hashed key
- Reversed the result
- Xored the result with the hashed key again
- Returned the result.

Email me: tyopdfdf@live.co.uk

Updated Wiki: Documentation

Todd434 — Sun, 10 Jan 2010 21:23:54 GMT

Rexor Documentation

Rexor is an encryption algorithm developed with cryptography begginers in mind. It's designed to be simple and easy to use, but also to have security and advanced features available if you choose to use them. The algorithm is written in VB.NET but I hope to expand on that soon. If you read the home page, then you will know rexor stands for RE REverse XOR Exclusive OR. I am activly working on the project and I hope to get some more people soon.

Here is a step by step analysis of the code.
How it works:

Starting from the very top, this four line snippet imports the nessesery namespaces needed to excecute the code. Without these we wouldn't be able to use most of the commands below.

Imports Microsoft.VisualBasic
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO

This line says what the block of text is called, Rexor.
Module Rexor

This line declares the encrypt function's name and the variables it needs to excecute.
Public Function RexorEncrypt(ByVal Input As String, ByVal Key As String)

In this block we declare the variables needed in order to store the nessecery information required to carry out the algorithm sucessfully.

        Dim Result1 As String = ""
        Dim KeyChar As Integer
        Dim Result2 As String = ""

Here we turn the Password (Key) into a SHA1 Hash so if the key is bob, then the hash is "SBgazSKz7a68ikR4aKfffOYpkgo="
Key = Hashkey(Key)
But that was just calling the function, here is the code:

    Private Function Hashkey(ByVal key As String)
        'Hash the key
        Dim sha1CryptoService As New SHA1CryptoServiceProvider()
        Dim byteValue = Encoding.UTF8.GetBytes(key)
        Dim hashValue = sha1CryptoService.ComputeHash(byteValue)
        Return Convert.ToBase64String(hashValue)
    End Function

For each letter of the Input string, we combine (XOR) it with a letter of the Key

 KeyChar = Asc(Key)
        Dim q As Integer = 0
        For i = 1 To Len(Input)
            q = q + 1
            If q = Len(Key) Then
                q = 1
            End If
            Dim k As String = Mid((Key), q, 1)
            Result1 = Result1 + Chr((Asc(k)) Xor Asc(Mid((Input), i, 1)))
        Next

Reset the variable for next time.
q = 0

Now we reverse the combined (XOR'd) string

Input = Reverse(Result1)

But again that was just calling a function. Here is the code.

    Private Function Reverse(ByVal input As String)
        Dim rev() As Char = input.ToCharArray
        Array.Reverse(rev)
        Return CStr(rev)
    End Function

Now we XOR the reversed result with the key again.

 For i = 1 To Len(Input)
            q = q + 1
            If q = Len(Key) Then
                q = 1
            End If
            Dim k As String = Mid((Key), q, 1)
            Result2 = Result2 + Chr(Asc(k) Xor Asc(Mid(Input, i, 1)))
        Next

Reset the variable q
q = 0

And return the result
Return Result2

Because the cipher has only one (main) function it is called symmetrical.
Todd.

Updated Wiki: Documentation

Todd434 — Sat, 09 Jan 2010 13:06:03 GMT

Rexor Documentation

Imports Microsoft.VisualBasic
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO

This line says what the block of text is called, Rexor.
Module Rexor

This line declares the encrypt function's name and the variables it needs to excecute.
// single line
Public Function RexorEncrypt(ByVal Input As String, ByVal Key As String)

In this block we declare the variables needed in order to store the nessecery information required to carry out the algorithm sucessfully.

        Dim Result1 As String = ""
        Dim KeyChar As Integer
        Dim Result2 As String = ""

Here we turn the Password (Key) into a SHA1 Hash so if the key is bob, then the hash is "SBgazSKz7a68ikR4aKfffOYpkgo="
// multi-line

        Key = Hashkey(Key)

But that was just calling the function, here is the code:

    Private Function Hashkey(ByVal key As String)
        'Hash the key
        Dim sha1CryptoService As New SHA1CryptoServiceProvider()
        Dim byteValue = Encoding.UTF8.GetBytes(key)
        Dim hashValue = sha1CryptoService.ComputeHash(byteValue)
        Return Convert.ToBase64String(hashValue)
    End Function

For each letter of the Input string, we combine (XOR) it with a letter of the Key

 KeyChar = Asc(Key)
        Dim q As Integer = 0
        For i = 1 To Len(Input)
            q = q + 1
            If q = Len(Key) Then
                q = 1
            End If
            Dim k As String = Mid((Key), q, 1)
            Result1 = Result1 + Chr((Asc(k)) Xor Asc(Mid((Input), i, 1)))
        Next

Reset the variable for next time.

q = 0

Now we reverse the combined (XOR'd) string

Input = Reverse(Result1)

But again that was just calling a function. Here is the code.

    Private Function Reverse(ByVal input As String)
        Dim rev() As Char = input.ToCharArray
        Array.Reverse(rev)
        Return CStr(rev)
    End Function

Now we XOR the reversed result with the key again.

 For i = 1 To Len(Input)
            q = q + 1
            If q = Len(Key) Then
                q = 1
            End If
            Dim k As String = Mid((Key), q, 1)
            Result2 = Result2 + Chr(Asc(k) Xor Asc(Mid(Input, i, 1)))
        Next

Reset the variable q
q = 0

And return the result
Return Result2

Because the cipher has only one (main) function it is called symmetrical.
Todd.

Updated Wiki: Documentation

Todd434 — Sat, 09 Jan 2010 12:08:31 GMT

Rexor Documentation

Imports Microsoft.VisualBasic
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO

        Dim Result1 As String = ""
        Dim KeyChar As Integer
        Dim Result2 As String = ""

Here we turn the Password (Key) into a SHA1 Hash so if the key is bob, then the hash is "SBgazSKz7a68ikR4aKfffOYpkgo="
// multi-line

        Key = Hashkey(Key)

But that was just calling the function, here is the code:

    Private Function Hashkey(ByVal key As String)
        'Hash the key
        Dim sha1CryptoService As New SHA1CryptoServiceProvider()
        Dim byteValue = Encoding.UTF8.GetBytes(key)
        Dim hashValue = sha1CryptoService.ComputeHash(byteValue)
        Return Convert.ToBase64String(hashValue)
    End Function

For each letter of the Input string, we combine (XOR) it with a letter of the Key

 KeyChar = Asc(Key)
        Dim q As Integer = 0
        For i = 1 To Len(Input)
            q = q + 1
            If q = Len(Key) Then
                q = 1
            End If
            Dim k As String = Mid((Key), q, 1)
            Result1 = Result1 + Chr((Asc(k)) Xor Asc(Mid((Input), i, 1)))
        Next

Reset the variable for next time.

q = 0

Now we reverse the combined (XOR'd) string

Input = Reverse(Result1)

But again that was just calling a function. Here is the code.

    Private Function Reverse(ByVal input As String)
        Dim rev() As Char = input.ToCharArray
        Array.Reverse(rev)
        Return CStr(rev)
    End Function

---

Updated Wiki: Documentation

Todd434 — Fri, 08 Jan 2010 21:51:23 GMT

Rexor Documentation

Imports Microsoft.VisualBasic
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO

This line says what the block of text is called, Rexor.
// single line
Module Rexor

This line declares the encrypt function's name and the variables it needs to excecute.
// single line
Public Function RexorEncrypt(ByVal Input As String, ByVal Key As String)

In this block we declare the variables needed in order to store the nessecery information required to carry out the algorithm sucessfully.
// multi-line

 Dim i As Short
        Dim Result1 As String
        Dim KeyChar As Integer
        Dim Result2 As String
        Dim Result3 As String
        Dim Rand As String

Here we turn the Password (Key) into a SHA1 Hash so if the key is bob, then the hash is "SBgazSKz7a68ikR4aKfffOYpkgo="
// multi-line

Dim sha1CryptoService As New SHA1CryptoServiceProvider()
        Dim byteValue = Encoding.UTF8.GetBytes(key)
        Dim hashValue = sha1CryptoService.ComputeHash(byteValue)
        Key = Convert.ToBase64String(hashValue)

So, for each letter of the input string we generate some random characters here it was "CDyFlSLKI1q/CwLjjuPtkZBjKdFr"
A random character is placed after every character in the input string. This helps make it harder to decipher.
// multi-line

    For i = 1 To Len(Input)
            Dim randomNumGen As RandomNumberGenerator = RNGCryptoServiceProvider.Create()
            Dim randomBytes(Len(input)) As Byte
            randomNumGen.GetBytes(randomBytes)
            Rand = Convert.ToBase64String(randomBytes)
            Dim s As Integer
            s = s + 1
            If s = Len(Rand) Then
                s = 1
            End If
            Result3 = Result3 + (Mid(Input, i, 1) + (Mid(Rand, s, 1)))
        Next

Now we get the ASCII values for the key, if the key is "bob" then the values are 83, 66 etc... (Remember Bob was converted to a hash)
Now we XOR the input file (with the random data added) with the (hashed Key + the length of the key).
//multi-line

         For i = 1 To Len(Result3)
            'Get the ASCII values for the Key
            Dim keylength As Integer
            KeyChar = Asc(Mid((Key), keylength, 1))
            keylength = keylength + 1
            If keylength = Len(Key) Then
                keylength = 1
            End If
            'XOR the input with the key whilst adding the length of
            'the Key to the ASCII value of the key
            Result1 = Result1 + Chr((KeyChar + Len(Key)) Xor Asc(Mid((Result3), i, 1)))
        Next

INCOMPLETE I WILL FINISH LATER!

Updated Wiki: Home

Todd434 — Fri, 08 Jan 2010 17:28:11 GMT

Project Description
A small encryption algorithm written in VB.NET.
Please contribute and develop with me!

The name stands for REverse eXclusive OR. Find out why in the source or documentation.

Updated Wiki: Documentation

Todd434 — Wed, 06 Jan 2010 21:50:08 GMT

Rexor Documentation

Updated Wiki: Home

Todd434 — Wed, 06 Jan 2010 21:30:09 GMT

Project Description
A small encryption algorithm written in VB.NET.
Please contribute and develop with me!

The name stands for RE REverse XOR Exclusive OR. You will see why in the source.