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First a small note: This manual deals with the tcl-level commands only. For a description of the C-level API please read the provided manpages or the C API chapter.
The behaviour of all transformations with respect to seeking is described on its own page.
All commands are available in 2 modes of operation, ``immediate'' and ``attached''. The generic syntactical forms of these modes are:
immediate |
command -option <value> ... <sourcevalue> In this mode the command processes the given <sourcevalue> and returns the transformed information as interpreter result. With tcl 7.6 this may yield incorrect results due to embedded \0 characters, either in source or result. To allow for correct operation with this version too 2 additional options are provided: -in and -out. If option -in is present, its argument is interpreted as channelhandle and the data to transform is read from it. A <sourcevalue> must not be specified in that case. If option -out is present, its argument is interpreted as channelhandle and the transformation result will be written into it. Please note that it is not necessary to specify both options, each of them can be used alone. |
attached |
This mode is the one which required the patches to the older cores. Not so since version 8.2 of tcl. Without them we would be unable to stack our transforming channel onto the named one. command -attach <channel> -option <value> ... This creates a channel filter, configured as defined by the options and then attached to the <channel>. All data read from or written into the <channel> will be transformed accordingly from now on. Neither -in nor -out nor a <sourcevalue> must be specified here. |
Now a quick reference describing the available commands, their type of algorithm and location of implementation of the underlying algorithm.
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Transformers doing encryption are not available as part of this package, to avoid problems with the US export regulation. Please don't ask me to explain them.
Having said this I would like to mention the TrfCrypt package, which is an add-on to this extension providing the desired functionality.
Last update at Mon Aug 20 22:52:27 PDT 2001