التشفير بـ RC4 Encryption - Decryption - نسخة قابلة للطباعة

كاتب الموضوع : tibo

هذا* شرح كيف نشفر ونفك التشفير بطريقه RC4 والطريقه سهله جدا بتكون عن طريق داله واحده فقط سواء للتشفير او فك التشفير وبنحطها فى الكود متاعنا كالتالى

كود :

Public Function rc4(ByVal message As String, ByVal password As String) As String

Dim i As Integer = 0

Dim j As Integer = 0

Dim cipher As New StringBuilder

Dim returnCipher As String = String.Empty

Dim sbox As Integer() = New Integer(256) {}

Dim key As Integer() = New Integer(256) {}

Dim intLength As Integer = password.Length

Dim a As Integer = 0

While a <= 255

Dim ctmp As Char = (password.Substring((a Mod intLength), 1).ToCharArray()(0))

key(a) = Microsoft.VisualBasic.Strings.Asc(ctmp)

sbox(a) = a

System.Math.Max(System.Threading.Interlocked.Increment(a), a - 1)

End While

Dim x As Integer = 0

Dim b As Integer = 0

While b <= 255

x = (x + sbox(b) + key(b)) Mod 256

Dim tempSwap As Integer = sbox(b)

sbox(b) = sbox(x)

sbox(x) = tempSwap

System.Math.Max(System.Threading.Interlocked.Increment(b), b - 1)

End While

a = 1

While a <= message.Length

Dim itmp As Integer = 0

i = (i + 1) Mod 256

j = (j + sbox(i)) Mod 256

itmp = sbox(i)

sbox(i) = sbox(j)

sbox(j) = itmp

Dim k As Integer = sbox((sbox(i) + sbox(j)) Mod 256)

Dim ctmp As Char = message.Substring(a - 1, 1).ToCharArray()(0)

itmp = Asc(ctmp)

Dim cipherby As Integer = itmp Xor k

cipher.Append(Chr(cipherby))

System.Math.Max(System.Threading.Interlocked.Increment(a), a - 1)

End While

returnCipher = cipher.ToString

cipher.Length = 0

Return returnCipher

End Function