RC4 Stream Cipher ActiveX Library

RC4 Stream Cipher ActiveX Library 1.0

This library will encrypt information using the RC4 stream cipher by RSA. It also has a built-in system to export the encrypted information to a more appropiate format to travel through network or modem connections, including e-mail.

LEGAL STATUS OF THE RC4 ALGORITHM: RC4 is a symmetric stream cipher designed by RSADSI. This cipher used to be trade secret of RSADSI, but some anonymous person distributed the source code on the internet last year. It is not known whether the code was "leaked" by a source license holder or whether someone reverse engineered one of the libraries which used RC4. In either case now that it is no longer a trade secret you can use it legally without paying RSA. Using RC4 in a commercial product without buying a license from RSADSI, whilst technically legal, would be impolite, and it is possible that RSADSI may take it upon themselves to reward you with a court case. If they do this it may turn out to be cheaper to buy a license than fight a protracted legal battle. (Taken from 'RC4 in 3 lines of perl', by Adam Back).

IMPORTANT NOTICE ABOUT RESTRICTIONS ON IMPORTING STRONG ENCRYPTION ALGORITHMS IN SOME COUNTRIES: This encryption algorithm is a stream cipher that uses a length-variable key, with no limited length. Due to this, some people might not be allowed by the goverments of their countries to download this library and make use of it. Check your local restrictions. Spanish citizens don't have restrictions of any kind over encryption algorythms, so please enjoy and make use of this library. Anyways, no information is saved about where this library goes to when people download it, neither on who comes to this web. This doesn't mean, at all, that I'm inviting you not to follow the law in your country, if it is the case.

Methods:

Encrypt (Text As String, Key As String) As String. Encrypts the information in Text using Key as the key, and returns the encrypted text.
Decrypt (Text As String, Key As String) As String. Decrypts the ciphertext in Text using Key as the key, and returns the plain text.
AscEncrypt (Text As String, Key As String) As String. The same as 'Encrypt', but the returned text is composed by standard ASCII characters. The result is like 1/3 longer than in the 'Encrypt' function.
AscDecrypt (Text As String, Key As String) As String. The same as 'Decrypt', but in 'Text' you have to put the result of the 'AscEncrypt' function.

The 'Encrypt' and 'Decrypt' functions do the very same process. This means that you can decrypt a text using the 'Encrypt' function and it will work. The RC4 algorythm works like that. It doesn't happen the same way with the Asc??? functions.

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