Determine Encryption Algorithm used Delphi .DCU

I have a Delphi DCU from a company which is no longer in operation. Unfortunately we don't have the source code. The DCU is a simple encryption/decryption component. I need to reverse engineer it and/or determine the algorithm that is used so that a compatible replacement can be rebuilt. I need Delphi source code that is compatible. D4,D5,D7 versions of the DCU attached. The DCU can easily be decompiled to assembly (I already have an INT file showing function definitions and assembly code). The challenge to whoever wishes to accept it is to analyse the algorithm and recreate it in Delphi source code. Each procedure/function within the DCU needs to be rebuilt using the same algorithm, so that the new source is compatible with the DCU (can decrypt data encrypted with the DCU component). Attached is a zip file containing D4,D5 and D7 versions of the DCU and some sample encrypted files. The encryption key used for the encrypted files is "rentacoder" (without the quotes). Challenge: Decrypt the files and tell me what they say. As stated before, the company that originally built and supplied the DCU is no longer in operation and cannot be contacted, else I would not need it recreated. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). * * *This broadcast message was sent to all bidders on Friday Nov 17, 2006 7:32:31 AM: Sending this to all bidders to clarify a few questions that have been asked. 1. I have decompiled the DCU to assembly language and have the function definitions. There are free tools to do this. 2. This project is therefore suitable for someone with good assembly skills. If you do not know assembly language it probably isn't for you. The assembly is available. Someone with good assembly skills will be able to analyse the algorithms and recreate in source. 3. Why can't we use another encryption component? Well, we could, but that would mean backward compatible issues and existing customers would need to decrypt all their data before upgrading. This is a worst case scenario - not an ideal situation. We would rather have source code that is compatible with the DCU's encryption method to avoid backward compatibility problems. 4. Why don't we have the souce of t his component? The developers have gone out of business. We tried to contact them to obtain the source some time ago but we could not find them. ## Platform Delphi Source