Changes

The code is currently held in a separate repository at [https://github.com/newaetech/cw-apiexample1/tree/master/matlabrepository]. You'll have to clone that repository (or use the download link inside of GITHub) to copy the files into your own local working directory.

To run Since the examplesnew CW 4, you will need 0 API exposes the internals of chipwhisperer the easiest way to get access to ensure you set the chipwhisperer module in MATLAB working directory is to use this API. Run this command in MATLAB.<syntaxhighlight lang=matlab> >> [cw, scope, target] = cwconnect()</syntaxhighlight>or <pre> >> [cw, scope, target] = cwconnect(int64(1250), int64(3000))</pre>where the location first argument is the default offset, and the second argument is default number of samples. This command should return the 4.m script files0 API, scope object, and target object, each having their own interface. The following shows my example setup:

[[FileIf this works it should print the information about the 'cw', 'scope' and 'target' object:api_matlab_path.png]]<syntaxhighlight> cw =

The matlab files internally will reference a .py file in that same directory. You should be able to simply connect to the ChipWhisperer-Lite Python module with the followingproperties:

If this works it should print the information about the <module 'cwchipwhisperer' objectfrom 'c:\chipwhisperer\software\chipwhisperer\__init__.pyc'>

If this FAILS, you may need to simply unplug key_len = 16 input_len = 16 output_len = 16 mask_len = 18 init_cmd = key_cmd = k$KEY$\n input_cmd = go_cmd = p$TEXT$\n output_cmd = r$RESPONSE$\n mask_cmd = m$MASK$\n mask_enabled = False mask_type = fixed fixed_mask = baud = 38400 protver = </replug the ChipWhisperer-Lite. You may have not closed the connection from the previous test. Note you can actually interact directly with the 'cw' object as in Python. For example we can get information about the current scope module:syntaxhighlight>

>> cwIf this FAILS, you may need to simply unplug/replug the ChipWhisperer-Lite. You may not have closed the connection from the previous test.getScope()

But == Interfacing with AES ==What you probably just want to run an do is capture a trace during AES encryption, to testyour side channel skills in MATLAB. To You can do thisby running<syntaxhighlight lang=matlab> >> [textout, simply perform trace] = measure_AES(scope, target, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15],[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15])</syntaxhighlight>This will return the following:cipher-text and the power trace.

[cipher, trace] = measure_AES(cw, [0 1 2 3 = 4 5 6 7 8 9 10 11 12 13 14 15],[.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]);API Notes ==Once the <code>cwconnect.m</code> function is executed you have access to the scope and target options, which are part of the new exposed API in <code>chipwhisperer</code>. To list the properties that are available type this inside your MATLAB interpreter:<pre> >> scope</pre>This should print the MATLAb output for the scope object but python also prints the attributes you can change and customize. The output should look like this:<pre>scope =

You can plot this power trace with connectStatus:[1×1 py.chipwhisperer.common.utils.util.Observable] scopetype: [1×1 py.chipwhisperer.capture.scopes.openadc_interface.naeusbchip.OpenADCInterface_NAEUSBChip] digitalPattern: [1×1 py.NoneType] adc: [1×1 py.chipwhisperer.capture.scopes._OpenADCInterface.TriggerSettings] params: [1×1 py.chipwhisperer.common.utils.parameter.Parameter] qtadc: [1×1 py.chipwhisperer.capture.scopes._qt.OpenADCQt] advancedSettings: [1×1 py.chipwhisperer.capture.scopes.cwhardware.ChipWhispererExtra.ChipWhispererExtra] trigger: [1×1 py.chipwhisperer.capture.scopes.cwhardware.ChipWhispererExtra.TriggerSettings] refreshTimer: [1×1 py.chipwhisperer.common.utils.timer.FakeQTimer] glitch: [1×1 py.chipwhisperer.capture.scopes.cwhardware.ChipWhispererGlitch.GlitchSettings] advancedSAD: [1×1 py.NoneType] clock: [1×1 py.chipwhisperer.capture.scopes._OpenADCInterface.ClockSettings] gain: [1×1 py.chipwhisperer.capture.scopes._OpenADCInterface.GainSettings] channels: [1×1 py.list] io: [1×1 py.chipwhisperer.capture.scopes.cwhardware.ChipWhispererExtra.GPIOSettings]

cwlite Device gain = mode = low gain = 45 db plot= 22.50390625 adc = state = False basic_mode = rising_edge timeout = 2 offset = 1250 presamples = 0 samples = 3000 decimate = 1 trig_count = 173067711 clock = adc_src = clkgen_x4 adc_phase = 0 adc_freq = 29538471 adc_rate = 29538471 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 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 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</pre>So to change the offset we set earlier with the matlab function we could do this:<pre> >> scope.adc.offset = int64(trace1500);</pre>The <code>int64()</code> function is needed so matlab does not pass a string through to the python function. We can see that the value has now changed by running:<pre> >> scope.adc.offset</pre>with this result:<pre>ans =

You can run a number 1500</pre><b>Note: it is good practice to check what type the attribute of measure_AES() calls with the same cw object without running cwconnectscope and target objects is, so you can assign the correct type using MATALB's int64() again. Note if you want to reconnect, you will first need to run cw.disconnect() to close the USB connection.etc functions.</b>

If you receive === Manual 4.0 API Usage ===To import the chipwhisperer python module into MATLAB run<pre> >> cw = py.importlib.import_module('device in usechipwhisperer' error messages, this is likely )</pre>This will work as long as you have the problem<code>chipwhisperer</code> module on your python path or system path. You can also simply unplug/replug actually interact directly with the USB connection 'cw' as in Python, just as you would after running <code> import chipwhisperer as cw </code> in Python. So you can initialize a scope and a target:<syntaxhighlight lang=matlab> >> scope = cw.scope() >> target = cw.target(scope)</syntaxhighlight>Do some fun things with your chipwhisperer tool, like follow a wiki tutorial (you will just have to force-implement the examples with MATLAB instead), and close any existing connectionsthe connection when you are done:<syntaxhighlight lang=matlab> >> scope.dis() >> target.dis()</syntaxhighlight>

Most of the capture parameters are set inside of the 'cwapi.py' Python file. For example sample rate is fixed at 4x the clock frequency, and the clock frequency is fixed at 7.37 MHz. However the sample offset from trigger & length of capture can be set on the call to 'cwconnect'. By default the CW-Lite starts recording at 1250 samples after the trigger (1250 / 4 = 312.5 target device clock cyles), and records for 3000 samples (3000 / 4 = 750 target device clock cycles). These are suitable for the example AES in C, but you may need to reduce the offset if running AES in assembly for example.