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Secure-T – Deframing and Decryption Tests
Using the test_SecureT.vhd test bench, the deframing and decryption processes were
tested in parallel. Files produced by the test_SecureT module running in encrypt/frame
mode were input into the test_SecureT module running in decrypt/deframe mode. These
values were then compared to the original plain text files to see if they match after the
frame bit has been stripped. The following pages are sampled here:
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Page 1 – this pages shows the data is the same with a latency of 4. The frame bits
will add an extra latency of 1 for every 193 bits.
Page 2 – this page shows that deframe successfully identifies the framing bit.
However, the latency here is too great (36) to view the correlation between the
expected dig_data_out and the actual dig_data_out.
Page 3 – this is the same data as page 2, however, the dig_data_out (expected)
column has been shifted (arificially with Excel) 36 bits down. It can now be seen that
the frame pulse adds a latency of 1 between expected and output values. Thus, the
frame pulse must be identifying the correct framing bit (which was added by the
framer and should not be in the comparison data).
Ian Kuon
Mark Calder
Secure-T
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