RSA Encyption example with large numbers using System.Numerics.BigInteger, Visual Basic

RSA Encyption example with large numbers using System.Numerics.BigInteger

' RSA Encyption example with large numbers using System.Numerics.BigInteger

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text.RegularExpressions
Imports System.Numerics
Imports Microsoft.VisualBasic

Namespace Rextester
    Public Module Program
        Dim n as biginteger = biginteger.parse("145906768007583323230186939349070635292401872375357164399581871019873438799005358938369571402670149802121818086292467422828157022922076746906543401224889672472407926969987100581290103199317858753663710862357656510507883714297115637342788911463535102712032765166518411726859837988672111837205085526346618740053")
        Dim e as biginteger = biginteger.parse("65537")
        Dim d as biginteger = biginteger.parse("89489425009274444368228545921773093919669586065884257445497854456487674839629818390934941973262879616797970608917283679875499331574161113854088813275488110588247193077582527278437906504015680623423550067240042466665654232383502922215493623289472138866445818789127946123407807725702626644091036502372545139713")
    
        Public Sub Main(args() As string)
            ' Public key is (e,n)
            ' Private key = (d,n))
            Dim plainText1before as biginteger = biginteger.parse("1976620216402300889624482718775150")
            Dim plainText2before as biginteger = biginteger.parse("7268237837345551102925775245561192465854311")
            
            Dim cipherText1 as biginteger = Encrypt(plainText1before)
            Dim cipherText2 as biginteger = Encrypt(plainText2before)
            
            Dim plainText1after as biginteger = Decrypt(cipherText1)
            Dim plainText2after as biginteger = Decrypt(cipherText2)
            
            Console.WriteLine("plainText1 before encryption = " & plainText1before.ToString() & vbcrlf)
            Console.WriteLine("plainText2 before encryption = " & plainText2before.ToString() & vbcrlf)
            
            Console.WriteLine("cipherText1 = " & vbcrlf & cipherText1.ToString() & vbcrlf)
            Console.WriteLine("cipherText2 = " & vbcrlf & cipherText2.ToString() & vbcrlf)
            
            Console.WriteLine("plainText1 after decryption = "  & plainText1after.ToString() & vbcrlf)
            Console.WriteLine("plainText2 after decryption = "  & plainText2after.ToString() & vbcrlf)
            
            if plainText1before = plainText1after then
                Console.WriteLine("plainText1 -- OK" & vbcrlf)
            else
                Console.WriteLine("plainText1 -- NOT OK" & vbcrlf)
            end if
            
            if plainText2before = plainText2after then
                Console.WriteLine("plainText2 -- OK")
            else
                Console.WriteLine("plainText2 -- NOT OK")
            end if 
        End Sub
        
        Private Function Encrypt(value as biginteger) as biginteger
            return biginteger.modpow(value,e,n)
        End Function
        
        Private Function Decrypt(value as biginteger) as biginteger
            return biginteger.modpow(value,d,n)
        End Function
        
        
    End Module
End Namespace


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