how to add "security key" functionality in the software.

hi, i want to implement "security key" functionality in the java software so that only one system (clienta0 can use that software. this is to prevent multiple usage of my software. what i have to do? how to generate the keys and implement them. please help. thanks

there are many encryptions available.. MD5 being a popular one.

Aniruddh Joshi wrote:there are many encryptions available.. MD5 being a popular one.

1) How does 'encryptions' solve the OP's problem?
2) MD5 is a digest and not an encryption.

James Sabre wrote:
1) How does 'encryptions' solve the OP's problem?

It normally works like this... There is some kind of functionality that the application wants to limit, or a condition that needs to be satisfied. The application uses a file that defines everything. For example, the application must be on a particular subnet, or can talk to a limited number of machines, or expires after a certain number of days, etc. All of this information are defined in some sort of file will lines that define all of this.

To detect that the file won't get changed, a checksum is added to the file. It could be MD5, but it is more likely something else is done in addition to that -- to make it more complicated or maybe make the checksum shorter or maybe only certain fields can't be changed.

Henry