trfcrypt is an add-on package to the tcl-extension trf. It provides the encryption functionality which was removed from the base package to allow its inclusion on the Tcl/Tk CDROM without violating US export control laws on cryptography.
The C API is layered on top of the trf C API and provides a set of commands for the management, implementation and usage of blockciphers and stream.
Although it is possible to implement ciphers using only the trf C API the code in this package makes it much easier, as general things like the handling of blockcipher modes are done here, thus obviating the need to reimplement them every time. A new cipher just has to provide some information about itself (key sizes) and functions to:
· generate the internal keyschedule from the specified key
· encrypt/decrypt a character or a block of data