Speck Masking Notebook

The following block initializes the chipwhisperer, as always

import chipwhisperer as cw
import time

WARNING:ChipWhisperer Other:ChipWhisperer update available! See https://chipwhisperer.readthedocs.io/en/latest/installing.html for updating instructions

# Path to the Speck .hex file for reflashing
PATH="/home/msc/documents/obsidian_notes/master-aits/subjects/implementation_attacks_and_countermeasures/praktikum/speck_cpa_cw/cw_firmware/simple-speck-CWLITEARM.hex"
PATH="/home/juan/documents/master-aits/subjects/implementation_attacks_and_countermeasures/praktikum/speck_cpa_cw/cw_firmware/simple-speck-CWLITEARM.hex"
PATH="/home/juan/documents/master-aits/subjects/implementation_attacks_and_countermeasures/praktikum/speck_cpa_cw/cw_firmware_masked/simple-speck-CWLITEARM.hex"
PATH="/home/msc/documents/obsidian_notes/master-aits/subjects/implementation_attacks_and_countermeasures/praktikum/speck_cpa_cw/cw_firmware_hiding/simple-speck-CWLITEARM.hex"

scope.dis()

def flash(scope, prog):
    cw.program_target(scope, prog, PATH)

def reset_target(scope):
    scope.io.nrst = 'low'
    time.sleep(0.05)
    scope.io.nrst = 'high_z'
    time.sleep(0.05)

try:
    if not scope.connectStatus:
        scope.con()
except NameError:
    scope = cw.scope()

try:
    target = cw.target(scope)
except IOError:
    print("INFO: Caught exception on reconnecting to target - attempting to reconnect to scope first.")
    print("INFO: This is a work-around when USB has died without Python knowing. Ignore errors above this line.")
    scope = cw.scope()
    target = cw.target(scope)

print("INFO: Found ChipWhispererðŸ˜")

prog = cw.programmers.STM32FProgrammer
time.sleep(0.05)
scope.default_setup()

INFO: Found ChipWhispererðŸ˜

Reset the target if required:

reset_target(scope)

Reflash the target if required:

flash(scope, prog)

Detected known STMF32: STM32F302xB(C)/303xB(C)
Extended erase (0x44), this can take ten seconds or more
Attempting to program 10563 bytes at 0x8000000
STM32F Programming flash...
STM32F Reading flash...
Verified flash OK, 10563 bytes

Set an encryption key:

# 32 bytes of encryption key
#encryption_key = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"

# 8 byte encryption key
encryption_key = b"\x11\x22\x33\x44\x55\x66\x77\x88"
if len(encryption_key) == 8:
    target.simpleserial_write("s", encryption_key)

Get the encryption key:

target.simpleserial_write("k", b'\x00'*4)
print(target.simpleserial_read("o", 8))

CWbytearray(b'11 22 33 44 55 66 77 88')

Encrypt a 4-byte block:

#pt = b"\x70\x6f\x6f\x6e\x65\x72\x2e\x20\x49\x6e\x20\x74\x68\x6f\x73\x65"
pt = b"\x4c\x69\x74\x65"
target.simpleserial_write("e", pt)
print(target.simpleserial_read("c", 4))

CWbytearray(b'5d 7c 46 6d')

Output is supposed to be: CWbytearray(b'5d 7c 46 6d')

Capturing the Data

The following code snippet traces the encryption process with random plaintetext 2000 times

from tqdm.notebook import trange
import random
import numpy as np

ktp = cw.ktp.Basic()
trace_array = []
trace_array_mean = []
textin_array = []

pt = b"\x4c\x69\x74\x65"
reference_pt = pt
N = 800
random.seed(0x5222223) 


# Capturing the traces for the random plaintexts
for i in trange(N, desc='Capturing traces with random plaintextsd'):
    pt = bytes([random.randint(0, 255) for i in range(4)])
    scope.arm()
    
    
    target.simpleserial_write('e', pt)
    
    ret = scope.capture()
    if ret:
        print("Target timed out!")
        continue
    
    response = target.simpleserial_read('c', 4)
    
    trace_array.append(scope.get_last_trace())
    textin_array.append(pt)

for i in trange(N, desc='Capturing reference traces'):
   
    scope.arm()
    target.simpleserial_write('e', reference_pt)
    ret = scope.capture()
    if ret:
        print("Target timed out!")
        continue
    response = target.simpleserial_read('c', 4)
    
    trace_array_mean.append(scope.get_last_trace())

    
    
    
trace_array = np.array(trace_array)
trace_array_mean = np.array(trace_array_mean)

Capturing traces with random plaintextsd:   0%|          | 0/800 [00:00<?, ?it/s]

Capturing reference traces:   0%|          | 0/800 [00:00<?, ?it/s]

Saving the traces

np.save("sample_traces/800_encryption_traces_hiding.npy", trace_array)
np.save("sample_traces/800_plaintext_traces_hiding.npy", textin_array)

Offline Mode

If no CW is available, load the trace array from a file

import numpy as np
trace_array = np.load("sample_traces/2200_encryption_traces.npy")
textin_array = np.load("sample_traces/2200_plaintext_traces.npy")

[0;31m---------------------------------------------------------------------------[0m
[0;31mFileNotFoundError[0m                         Traceback (most recent call last)
[0;32m/tmp/ipykernel_3602764/924883979.py[0m in [0;36m<module>[0;34m[0m
[1;32m      1[0m [0;32mimport[0m [0mnumpy[0m [0;32mas[0m [0mnp[0m[0;34m[0m[0;34m[0m[0m
[0;32m----> 2[0;31m [0mtrace_array[0m [0;34m=[0m [0mnp[0m[0;34m.[0m[0mload[0m[0;34m([0m[0;34m"sample_traces/2200_encryption_traces.npy"[0m[0;34m)[0m[0;34m[0m[0;34m[0m[0m
[0m[1;32m      3[0m [0mtextin_array[0m [0;34m=[0m [0mnp[0m[0;34m.[0m[0mload[0m[0;34m([0m[0;34m"sample_traces/2200_plaintext_traces.npy"[0m[0;34m)[0m[0;34m[0m[0;34m[0m[0m

[0;32m/usr/lib/python3.10/site-packages/numpy/lib/npyio.py[0m in [0;36mload[0;34m(file, mmap_mode, allow_pickle, fix_imports, encoding)[0m
[1;32m    415[0m             [0mown_fid[0m [0;34m=[0m [0;32mFalse[0m[0;34m[0m[0;34m[0m[0m
[1;32m    416[0m         [0;32melse[0m[0;34m:[0m[0;34m[0m[0;34m[0m[0m
[0;32m--> 417[0;31m             [0mfid[0m [0;34m=[0m [0mstack[0m[0;34m.[0m[0menter_context[0m[0;34m([0m[0mopen[0m[0;34m([0m[0mos_fspath[0m[0;34m([0m[0mfile[0m[0;34m)[0m[0;34m,[0m [0;34m"rb"[0m[0;34m)[0m[0;34m)[0m[0;34m[0m[0;34m[0m[0m
[0m[1;32m    418[0m             [0mown_fid[0m [0;34m=[0m [0;32mTrue[0m[0;34m[0m[0;34m[0m[0m
[1;32m    419[0m [0;34m[0m[0m

[0;31mFileNotFoundError[0m: [Errno 2] No such file or directory: 'sample_traces/2200_encryption_traces.npy'

Plotting the Data

%matplotlib notebook
import matplotlib.pylab as plt
plt.figure()
plt.plot(trace_array[2], 'orange')
#plt.plot(trace_array[4], 'g')
plt.show()

T-Test

Helper Functions

def mean(n):
    n[np.isnan(n)]  = 0
    return n.mean(0)

def var(n):
    n[np.isnan(n)] = 0
    return n.var(0)

def ttest(a,b,c,d,e,f):
    t = (a-b)/((c/e + d/f)**0.5)
    return t

Tracing

%matplotlib notebook
import matplotlib.pylab as plt
f1 = trace_array.shape[0]

a1 = mean(trace_array)
c1 = var(trace_array)

b1 = mean(trace_array_mean)
d1 = var(trace_array_mean)

t = ttest(a1, b1, c1, d1, f1, f1)

plt.plot(t)
plt.plot([4.5] * scope.adc.samples, color="red")
plt.plot([-4.5] * scope.adc.samples, color="red")
plt.show()

Speck-Masked.ipynb 126 KB History Raw