C# to vb.net

Question

Can anyone convert this code to vb.net for me or at least explain the syntax?
public class SecureQueryString : NameValueCollection
{
public SecureQueryString() : base() {}
public SecureQueryString(string encryptedString)
{
deserialize(decrypt(encryptedString));
// Compare the Expiration Time with the current Time to ensure
// that the queryString has not expired.
if (DateTime.Compare(ExpireTime, DateTime.Now)
/// Returns the encrypted query string.
///
public string EncryptedString
{
get
{
return HttpUtility.UrlEncode(encrypt(serialize()));
}
}
private DateTime _expireTime = DateTime.MaxValue;
///
/// The timestamp in which the EncryptedString should expire
///
public DateTime ExpireTime
{
get
{
return _expireTime;
}
set
{
_expireTime = value;
}
}
///
/// Returns the EncryptedString property.
///
public override string ToString()
{
return EncryptedString;
}
///
/// Encrypts a serialized query string
///
private string encrypt(string serializedQueryString)
{
byte[] buffer = Encoding.ASCII.GetBytes(serializedQueryString);
TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
des.Key = MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(cryptoKey));
des.IV = IV;
return Convert.ToBase64String(
des.CreateEncryptor().TransformFinalBlock(
buffer,
0,
buffer.Length
)
);
}
///
/// Decrypts a serialized query string
///
private string decrypt(string encryptedQueryString)
{
try
{
byte[] buffer = Convert.FromBase64String(encryptedQueryString);
TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
des.Key = MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(cryptoKey));
des.IV = IV;
return Encoding.ASCII.GetString(
des.CreateDecryptor().TransformFinalBlock(
buffer,
0,
buffer.Length
)
);
}
catch (CryptographicException)
{
throw new InvalidQueryStringException();
}
catch (FormatException)
{
throw new InvalidQueryStringException();
}
}
///
/// Deserializes a decrypted query string and stores it
/// as name/value pairs.
///
private void deserialize(string decryptedQueryString)
{
string[] nameValuePairs = decryptedQueryString.Split('&');
for (int i=0; i
/// Serializes the underlying NameValueCollection as a QueryString
///
private string serialize()
{
StringBuilder sb = new StringBuilder();
foreach (string key in base.AllKeys)
{
sb.Append(key);
sb.Append('=');
sb.Append(base[key]);
sb.Append('&');
}
// Append timestamp
sb.Append(timeStampKey);
sb.Append('=');
sb.Append(_expireTime);
return sb.ToString();
}
private const string timeStampKey = "__TimeStamp__";
// The key used for generating the encrypted string
private const string cryptoKey = "ChangeThis!";
// The Initialization Vector for the DES encryption routine
private readonly byte[] IV = new byte[8] {240, 3, 45, 29, 0, 76, 173, 59};
}

spgilmore · Answer

I'm not going to convert the whole thing for you, but I'll summarize things for you. First, if you want to use this unit, just compile it as an assembly and use it from your vb.net code, or just include the class in your project. If you want to make changes to it or convert it so that you understand it, here's how to read it:
//this line is commented because it's preceeded by "//".
The curly braces { } define a block. Every block. In Basic, the blocks would be if .. end if, while .. end while, etc. In C#, you define the if, the for, the while, the function, etc in one line, then the curly braces define where it starts and ends.
The classes should be about the same as vb.net. The outer block is the class declaration. All the other blocks directly inside it are methods of the class.
In C#, for any declaration, the type preceeds the symbol name. In Basic, it would be like this:
as
Example:
public myvariable as string
public function dostuff() as uint32
In C#, it would be like this:
Example:
public string myvariable
public uint32 dostuff()
The constructor is any function with the same name as the class (there are 2 in this class).
This is a property. It defines the property get and the property set. In the SET, the value keyword is special. It provides the rvalue that is being assigned to the property.
public DateTime ExpireTime
{
get
{
return _expireTime;
}
set
{
_expireTime = value;
}
}
This should be obvious:
return sb.ToString();
Instead of assigning the return value to the function name, you use the return keyword. This will exit the function.
These are just variables and constants:
private const string timeStampKey = "__TimeStamp__";
// The key used for generating the encrypted string
private const string cryptoKey = "ChangeThis!";
// The Initialization Vector for the DES encryption routine
private readonly byte[] IV = new byte[8] {240, 3, 45, 29, 0, 76, 173, 59};
To translate a FOR loop:
(C#) Here, i goes out of scope after the for block.
for (int i=0; i<nameValuePairs.Length; i++)
{
}
(VB) I'm not sure how to make the variable i bound to the scope of the for loop in VB.
dim i as int;
for i = 0 to nameValuePairs.Length-1 step 1
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