The Six-Step Sequence
8 RSA BSAFE Crypto-C Developer’s Guide
The Six-Step Sequence
The Crypto-C model generally follows a six-step sequence:
1. Create
2. Set
3. Init
4. Update
5. Final
6. Destroy
In addition, for every application, you must include the necessary header files; we
will call this Step 0.
The six-step sequence makes it easier to maintain your code. For example, if you have
implemented a message digest routine using MD2 and wish to use SHA1 instead, you
simply need to make changes in Steps 2 and 3, Set and Init. The rest of your code can
be reused. Similarly, if you originally programmed a routine under the assumption
that it would get all the data from a single buffer, and you want to modify it to take
data from multiple buffers, you can simply change Step 4, Update.
Note: In some cases, an algorithm may not require an Update step.
The sections in this chapter show the following:
• A six-step encryption example
• A six-step decryption example
• An example using multiple Updates
• A summary of the six-step process
