How to customize input and output length?

Embedded Security ChipWhisperer Software
1

Hi.

I need to implement a symmetric crypto which has 64-bit input and output and 128-bit key.
So, I change ‘simpleserial-aes.c’ like below:

uint8_t get_pt(uint8_t* pt)
{
	ENC(pt); /* encrypting the data block */

	simpleserial_put('r', 8, pt);
	return 0x00;
}

int main(void)
{
	uint8_t tmp[KEY_LENGTH] = {DEFAULT_KEY};

    platform_init();
    init_uart();
    trigger_setup();

	ROUND_KEY_GEN(tmp);

	simpleserial_init();
    simpleserial_addcmd('k', 16, get_key);
    simpleserial_addcmd('p', 8, get_pt);
    while(1)
        simpleserial_get();
}

Moreover, I changed jupyter notebook.

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How can I solve this problem?

2

Try changing target.setOutuptLen = 8 to target.output_len = 8. As far as I can tell, setOutputLen and setTextLen are not properties, values, or methods of SimpleSerial.

Alex

3

I changed as you told me.

target.textlength = 8
target.output_len = 8

However, the problem does not solved.
Isn’t there any example to change text length?

4

I’d recommend just bypassing capture trace and doing the steps (sending key, arming, sending plaintext, capturing, creating trace) of capture_trace instead.

Alex

5

Hi，
I have a question on this section.It is that how can I receive or send data whose length is larger than 256 like 1024, is there a method to complete this operation directly ?

Thanks a lot!

6

You’ll need to break it into multiple packets. We do something similar in the Fault201 RSA lab in SimpleSerial v1, except we do it on the target->PC end:

if SS_VER!='SS_VER_2_0':
    target.simpleserial_write("1", bytearray())
    time.sleep(0.2)
    output = target.simpleserial_read_witherrors('r', 48, timeout=10)
    if output['valid']:
        sig.extend(output['payload'])

    target.simpleserial_write("2", bytearray())
    time.sleep(0.2)
    output = target.simpleserial_read_witherrors('r', 32, timeout=10)
    if output['valid']:
        sig.extend(output['payload'])

    print(sig)
7

Hi,

Thanks for your answer!
I have known how to do that, but I saw that the len is set to 48, and when I took a try , 128 is wrong for it.What’s the reason?
The parameter type is uint8_t, it means that it allows value from 0-255, isn’t it?

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Thanks a lot!
luffy

8

IIRC we ran into consistency issues with longer packets. There’s a limited serial buffer on the capture board as well and if you overrun that data will be lost. We did increase the size of that buffer between when I wrote the code I posted, so longer data strings will probably work better now.

For SimpleSerialV1, the absolute max for data commands will be 192 data bytes - this is in the target code. SimpleSerialV2 will let you transmit more data, since it’s sent in binary instead of being ASCII encoded.