CW Lite Received fewer points than expected

Embedded Security ChipWhisperer Software
1

Hi,

I’m using a ChipWhisperer Lite to capture power traces from the CW308T-STM32F3 target.
The target is running a Masked AES implementation.

However, I’ve noticed that whenever I set an offset value by changing scope.adc.offset, one of the following errors appears:

  • (ChipWhisperer Scope ERROR|File OpenADC.py:787) Received fewer points than expected
  • (ChipWhisperer Scope WARNING|File _OpenADCInterface.py:955) Trigger not found in ADC data. No data reported!

My scope settings are as follows:

 fw_version = 
      major = 0
      minor = 65
      debug = 0
gain = 
    mode = high
    gain = 30
    db   = 24.8359375
adc = 
    state          = False
    basic_mode     = rising_edge
    timeout        = 12
    offset         = 17000
    presamples     = 0
    samples        = 5000
    decimate       = 1
    trig_count     = 309844672
    fifo_fill_mode = normal
clock = 
    adc_src       = clkgen_x1
    adc_phase     = 0
    adc_freq      = 23140571
    adc_rate      = 23140571.0
    adc_locked    = True
    freq_ctr      = 0
    freq_ctr_src  = extclk
    clkgen_src    = system
    extclk_freq   = 10000000
    clkgen_mul    = 2
    clkgen_div    = 26
    clkgen_freq   = 7384615.384615385
    clkgen_locked = True
trigger = 
    triggers = tio4
    module   = basic
io = 
    tio1         = serial_rx
    tio2         = serial_tx
    tio3         = high_z
    tio4         = high_z
    pdid         = high_z
    pdic         = high_z
    nrst         = high_z
    glitch_hp    = False
    glitch_lp    = False
    extclk_src   = hs1
    hs2          = clkgen
    target_pwr   = True
    tio_states   = (1, 1, 0, 0)
    cdc_settings = bytearray(b'\x00\x00\x00\x00')
glitch = 
    clk_src     = target
    width       = 10.15625
    width_fine  = 0
    offset      = 10.15625
    offset_fine = 0
    trigger_src = manual
    arm_timing  = after_scope
    ext_offset  = 0
    repeat      = 1
    output      = clock_xor

My capturing code is as follows:

trace_array = []
plaintext_array = []

for i in trange(N, desc='Capturing traces'):
    _, text = ktp.next()
    scope.arm()

    target.simpleserial_write('p', text)

    ret = scope.capture()
    if ret:
        print("Target timed out!")
        continue

    response = target.simpleserial_read('r', 16)

    print("plaintext: {},  ciphertext:{}".format(binascii.hexlify(text), binascii.hexlify(response)))
    trace_array.append(scope.get_last_trace())
    plaintext_array.append(text)
    splot.update(scope.get_last_trace())

The program output showing the errors/warnings during capture is as below:

image
image1131×410 27.7 KB

I’m not sure why this is happening. The encryption/decryption seems to be working fine. However, this issue makes it impossible to capture long traces.

Thanks in advance for replying!

2

Hi,

There might be something wrong in your setup code as you’re trying to clock the ADC and target at the same speed (~7.37MHz), but your ADC is running at a strange clock frequency. Can you post this code as well?

Also, can you verify that your trigger is working properly?

Alex

3

My setup code looks as follows:

PLATFORM="CW308_STM32F3"  # F071: CW308_STM32F0 , F303: CW308_STM32F3
SCOPETYPE = "OPENADC"
scope = cw.scope(cw.scopes.OpenADC)
target = cw.target(scope, cw.targets.SimpleSerial)

scope.default_setup()
while scope.clock.clkgen_locked == False:
    print(".", end='')


def reset_target(scope):  #source: https://rtfm.newae.com/tutorials/CWLITEARM/SOLN_Fault%202_3%20-%20Voltage%20Glitching%20to%20Memory%20Dump/
    scope.io.nrst = 'low'
    time.sleep(0.05)
    scope.io.nrst = 'high_z'
    time.sleep(0.05)


def reboot_flush():  
    reset_target(scope)
    #Flush garbage too
    target.flush()



cw.program_target(scope, cw.programmers.STM32FProgrammer, "program. Hex")


scope.clock.adc_src = "clkgen_x1"  
reboot_flush()

scope.adc.samples = 5000
scope.adc.offset = 17000
scope.adc.timeout = 12

And for verifying the trigger, do I have to use something like an oscilloscope?