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Message
From: Jonathan Valamehr<jkv@u...>
Date: Wed Jan 17 03:04:04 CET 2007
Subject: [oc] AES128 Question
Ah I see....Thanks a lot Hemanth, sorry for the late response.----- Original Message -----
From: Hemanth<hemanths@d...>
To:
Date: Fri Oct 27 10:31:22 CEST 2006
Subject: [oc] AES128 Question
> Jonathan,
> The signal spy option is provided by many simulators and in
> Modelsim it
> goes like this:
> signal_spy:process
> begin
> init_signal_spy("/aes_tester/aes_i/expand_key/new_key0",
> "/aes_tester/key_op0", 0);
> init_signal_spy("/aes_tester/aes_i/expand_key/new_key1",
> "/aes_tester/key_op1", 0);
> init_signal_spy("/aes_tester/aes_i/expand_key/new_key2",
> "/aes_tester/key_op2", 0);
> init_signal_spy("/aes_tester/aes_i/expand_key/new_key3",
> "/aes_tester/key_op3", 0);
> wait;
> end process signal_spy;
> In the above code new_key0,new_key1,new_key2,new_key3 are the
> signals
> declared in the TB module aes_tester. The syntax being
> init_signal_spy(src,dest,0). You should refer to Modelsim user
> guide for
> further explanation. Now with the key values available on new_key*
> you can
> use them depending on your requirement.
> Best wishes,
> Hemanth
> >
> > Thanks Hemanth. What is the easiest way to "spy" on
> the key during
> > the key's transformation? Much of the AES code is rather
> complicated
> > for me.
> >
> > ----- Original Message -----
> > From: Hemanth<hemanths at d...>
> > To:
> > Date: Mon Oct 23 08:15:29 CEST 2006
> > Subject: [oc] AES128 Question
> >
> >> Hmm..,
> >> I got where you are pointing at, I think I missed
> answering this in
> >> my
> >> previous post. You are right the RTL does'nt ouput the
> inverse key.
> >> I
> >> think my assumption was that the RTL need'nt take the
> burden of it.
> >> So
> >> looks like you have to record the inverse key by looking
> at the
> >> waveform
> >> or better still adding a piece of code to the TB to spy on
> the
> >> interior
> >> signals of the key expander module at the end of its
> >> encryption/decryption
> >> phase or even better you could have an excel spread sheet
> or some
> >> program
> >> do that.
> >> Hope this answers your doubts,
> >> Hemanth
> >> > Yes I understand Hemanth but the inverse key is not
> an output
> >> of the
> >> > AES core, I dont know where to access it. Everything
> you said
> >> makes
> >> > perfect sense so if I could figure out how to access
> the
> >> inverse key I'll
> >> > be fine. Thanks!
> >> >
> >> > ----- Original Message -----
> >> > From: Hemanth<hemanths at d...>
> >> > To:
> >> > Date: Wed Oct 18 13:37:36 CEST 2006
> >> > Subject: [oc] AES128 Question
> >> >
> >> >> Hi Jonathan,
> >> >> I am sorry for not being able to reply earlier, I
> have
> >> been
> >> >> travelling a
> >> >> lot and hardly have checked my mails in between.
> Hmm..
> >> that was a
> >> >> long
> >> >> time back and dont remember exactly but if my
> memory is
> >> correct the
> >> >> inverse key is the key that is output after an
> encryption
> >> is
> >> >> completed. If
> >> >> you observe, both data and key undergo a series
> of
> >> transformation
> >> >> and at
> >> >> the end there is both a garbled key and encrypted
> data
> >> coming out.
> >> >> This
> >> >> key is taken as the inverse key for decryption.
> Infact I
> >> have used
> >> >> one set
> >> >> of key pairs as default in my test bench. This
> information
> >> is also
> >> >> explained in the FIPS document.
> >> >> Hope this helps,
> >> >> Hemanth
> >> >> > While using the AES128 core
> (aes_crypto_core) I have
> >> come
> >> >> across a
> >> >> > problem; after encrypting data with a key
> and
> >> receiving an
> >> >> output, how
> >> >> > do I know what the inverse key is in order
> to decrypt >> the >> >> output? I had >>
> >> > an example from the fips document about AES so I was
> >> able to >> >> test >> >> >
> given their key and output key, and was successful in >>
> doing >> >> so. >> >> > However, making
> up a key wont work for me as I have >> no idea >>
> >> what the >> >> > inverse key is. Clearing
> this issue up would really >> help me >> >> out.
> Thanks. >> >> >
> _______________________________________________ >> >>
> > http://www.opencores.org/mailman/listinfo/cores >>
> >> > >> >>
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