.NET-äquivalent dieser native code mit crypto-api

Habe ich folgende native code (Powerbuilder) mit verwendet die Crypto-API zum verschlüsseln einer Zeichenfolge. Ich brauche C# - code zum entschlüsseln der verschlüsselten Daten. Kann jemand mir einen Tipp geben oder ein Beispiel?

Dank, Jaap

private function blob of_encryptdecrypt (blob ablob_data, string as_password, boolean ab_encrypt)
//-----------------------------------------------------------------------------
//SCRIPT:     n_cryptoapi.of_EncryptDecrypt
//
//PURPOSE:    This function will encrypt/decrypt the blob passed to it. Both
//                 encrypt/decrypt have the same api calls except one so they
//                 are combined to save coding.
//
//ARGUMENTS:  ablob_data   - The blob to be decrypted
//                 as_password - The secret password
//
//RETURN:      Blob containing the decrypted data.
//
//DATE        PROG/ID      DESCRIPTION OF CHANGE /REASON
//----------  --------     -----------------------------------------------------
//12/26/2006   RolandS     Initial Coding
//-----------------------------------------------------------------------------

ULong hCryptProv, hHash, hKey
ULong lul_datalen, lul_buflen, lul_error
Blob lblob_buffer, lblob_value
String ls_msgtext
string ls_password

//Get handle to CSP
If Not CryptAcquireContext(hCryptProv, KEY_CONTAINER, is_cryptoservice, PROV_RSA_FULL, 0) Then
    If Not CryptAcquireContext(hCryptProv, KEY_CONTAINER, is_cryptoservice, PROV_RSA_FULL, CRYPT_NEWKEYSET) Then
        of_GetLastError(lul_error, ls_msgtext)
        SignalError(lul_error, "CryptAcquireContext:~r~n~r~n" + ls_msgtext)
    End If
End If

//Create a hash object
If Not CryptCreateHash(hCryptProv, CALG_MD5, 0, 0, hHash) Then
    of_GetLastError(lul_error, ls_msgtext)
    SignalError(lul_error, "CryptCreateHash:~r~n~r~n" + ls_msgtext)
End If

//Hash the password
If Not CryptHashData(hHash,as_password, Len(as_password), 0) Then
    of_GetLastError(lul_error, ls_msgtext)
    SignalError(lul_error, "CryptHashData:~r~n~r~n" + ls_msgtext)
End If

//Derive a session key from the hash object
If Not CryptDeriveKey(hCryptProv, ENCRYPT_ALGORITHM, hHash, 0, hKey) Then
    of_GetLastError(lul_error, ls_msgtext)
    SignalError(lul_error, "CryptDeriveKey:~r~n~r~n" + ls_msgtext)
End If

//allocate buffer space
lul_datalen = Len(ablob_data)
lblob_buffer = ablob_data + Blob(Space(8))
lul_buflen = Len(lblob_buffer)

If ab_encrypt Then
    //Encrypt data
    If CryptEncrypt(hKey, 0, True, 0, lblob_buffer, lul_datalen, lul_buflen) Then
        lblob_value = BlobMid(lblob_buffer, 1, lul_datalen)
    Else
        of_GetLastError(lul_error, ls_msgtext)
        SignalError(lul_error, "CryptEncrypt:~r~n~r~n" + ls_msgtext)
    End If
Else
    //Decrypt data
    If CryptDecrypt(hKey, 0, True, 0, lblob_buffer, lul_datalen) Then
        lblob_value = BlobMid(lblob_buffer, 1, lul_datalen)
    Else
        of_GetLastError(lul_error, ls_msgtext)
        SignalError(lul_error, "CryptDecrypt:~r~n~r~n" + ls_msgtext)
    End If
End If

//Destroy session key
If hKey > 0 Then
    CryptDestroyKey(hKey)
End If

//Destroy hash object
If hHash > 0 Then
    CryptDestroyHash(hHash)
End If

//Release CSP handle
If hCryptProv > 0 Then
    CryptReleaseContext(hCryptProv, 0)
End If

Return lblob_value
end function