Fabric key is a secure key for users to generate bitstream for a specific FPGA fabric.
With this key, OpenFPGA can generate correct bitstreams for the FPGA.
Using a wrong key, OpenFPGA may error out or generate wrong bitstreams.
The fabric key support allows users to build secured/classified FPGA chips even with an open-source tool.
..note:: Users are the only owner of the key. OpenFPGA will not store or replicate the key.
Key Generation
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A fabric key can be achieved in the following ways:
- OpenFPGA can auto-generate a fabric key using random algorithms (see detail in :ref:`cmd_build_fabric`)
- Users can craft a fabric key based on auto-generated file by following the file format description.
File Format
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A fabric key follows an XML format. As shown in the following XML code, the key file includes the organization of configurable memory blocks in the top-level FPGA fabric:
-``id`` indicates the sequence of the configurable memory block in the top-level FPGA fabric.
-``value`` indicates the instance id of the configurable memory block in the top-level FPGA fabric. This property becomes optional when ``alias`` is defined.
-``alias`` indicates the instance name of the configurable memory block in the top-level FPGA fabric. If a valid alias is specified, the ``name`` and ``value`` are not required.
..note:: For fast loading of fabric key, strongly recommend to use pairs ``name`` and ``alias`` or ``name`` and ``value`` in the fabric key file. Using only ``alias`` may cause long parsing time for fabric key.
