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Date: Thu, 14 Apr 2011 08:44:18 +0400
From: Solar Designer <>
Subject: Re: Answering and asking some of the first questions

On Wed, Apr 13, 2011 at 09:49:35AM -0300, Yuri Gonzaga wrote:
> 1. I have started to implement the bcrypt using SystemVerilog language and
> Altera's Quartus II design software. The ExpandKey of EksBlowFish is almost
> done, including SBoxes initialization, F function and the 18 rounds. Then, I
> will get into the setup stage and, later, finish the bcrypt.

Note that some parts of bcrypt are not actually performance critical -
you may leave those for the host system's CPU.  In JtR's BF_std.c, only
this loop:

		count = salt[4];
		do {
		} while (--count);

is performance-critical, or you may look at crypt_blowfish for simpler
code (lacking some optimizations not relevant to you):

> 2. I am thinking of use the JTAG port avaiable in the development boards to
> receive the input parameters and send back the result. This a serial port
> that connects to a USB port on the Computer. Maybe, David has any suggestion
> to this part.

I assume it connects via an adapter.  Sounds fine unless you've got a
more suitable port.

> 3. I have downloaded the JtR source code. In the "c3_fmt.c" file, there is a
> function named "crypt_all()", which looks like to be the right point where I
> will change the code to communicate to the hardware implementation. Input
> parameters are the strings "saved_key[index]" and "saved_salt", and output
> result is the string "crypt_out[index]".

You might also want to look at this sample:

You'll need to define a new "format" and register it in john.c like it's
done for existing ones.

> Based in the article, where is the third input parameter, "cost"?

It's encoded in the salt string.

In BF_fmt.c and BF_std.c in JtR, the "cost" is decoded into salt[4]:

 * Binary salt type, also keeps the number of rounds.
typedef BF_word BF_salt[4 + 1];

> There is an API to access the JTAG communication port inside the C code. So,
> I will pass the parameters through the JTAG port, the FPGA will calculate
> the hash and send it back to the computer. Finally, I will receive that in
> the JtR using the API I mentioned.

Sounds fine.  These hashes are slow enough that the communication method
does not matter much.

> How do I can present the working code to you?

Since this initial task is closely related to JtR, you may create this
wiki page:

and upload your files to there.  To upload a file to the wiki, click on
the picture icon while editing the page.



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