How to verify signature using RSA 256 algorithm in ASP.NET with C#?

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C#

ASP.NET

signature

I want to verify signature using RSA 256 Algorithm in asp.net with c#. On verifying the signed Original Message as bytes following issue comes (invalid characters).

Signed original message as below:

1:F01BNZWOMRXAXXX0001000001}{2:I102CBOMOMRUXACHN}{3:{113:0100}}{4:
:20:BNZW0M00017DW
:23:CREDIT
:50K:/00410039933001
SUBAIH NASSER SALIM AL SIYABI
POBOX 644 MUSCAT
MANOOMA - SEEB
,OMAN
:52A:BNZWOMRX
BANK NIZWA
:26T:001
:77B:/DNUM/492282
/DDATE/170423
:71A:SHA
:21:TRF000492282/1
:32B:OMR75,000
:57A:BMUSOMRX
:59:/0301011157980014
FAREEQ AL RAHMA
:70:SO
:32A:170427OMR75,000
:72:/PRT/10
/CODTYPTR/001
-}

What I have tried:

public static bool VerifyData(string originalMessage, string signedMessage, RSAParameters publicKey)
   {
       bool success = false;

       using (var rsa = new RSACryptoServiceProvider())
       {


           byte[] bytesToVerify = Convert.FromBase64String(originalMessage);

           byte[] signedBytes = Convert.FromBase64String(signedMessage);
           try
           {
               rsa.ImportParameters(publicKey);

               SHA512Managed Hash = new SHA512Managed();

               byte[] hashedData = Hash.ComputeHash(signedBytes);

               success = rsa.VerifyData(bytesToVerify, CryptoConfig.MapNameToOID("SHA256"), signedBytes);
           }
           catch (CryptographicException e)
           {
               Console.WriteLine(e.Message);
           }
           finally
           {
               rsa.PersistKeyInCsp = false;
           }
       }
       return success;
   }