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1#!/usr/bin/env python
2"""Memory Readback Tool
3The number of bytes you read must be a multiple of 16!
4"""
5
6import serial
7import struct
8import sys
9import argparse
10import random
11import argparse
12import shutil
13import struct
14import json
15import zlib
16import os
17import random
18from Crypto.Cipher import AES 
19from Crypto.Random.random import StrongRandom
20
21   
22from intelhex import IntelHex
23def CMACHash(key,inBytes):
24    encryptor = AES.new(key,AES.MODE_CBC,b'\x00'*16,segment_size=128)
25    if len(inBytes) % 16 != 0:
26        block = inBytes + b'\x00'*(len(inBytes)%16)
27    else:
28        block = inBytes
29    output = (encryptor.encrypt(block))
30    return output[-16:]
31
32def encryptCBC(key, iv, inBytes,outfile):
33    """ Takes in a key, initialization vector, and a file location of the     input, and location of the output"""
34    encryptor = AES.new(key, AES.MODE_CBC, iv,segment_size=128)
35    if len(inBytes) % 16 != 0:
36        block = inBytes + b'\x00'*(len(inBytes)%16)
37    else:
38        block = inBytes
39    outfile.write(encryptor.encrypt(block))
40
41def encryptAES(key, iv, inBytes):
42    """ Takes in a key, initialization vector, and a file location of the     input, and location of the output"""
43    encryptor = AES.new(key, AES.MODE_CFB, iv,segment_size=128)
44    if len(inBytes) % 16 != 0:
45        block = inBytes + b'\x00'*(len(inBytes)%16)
46    else:
47        block = inBytes
48    return encryptor.encrypt(block)
49
50def decryptAES(key, iv, inBytes):
51    """ Takes in a key, initialization vector, and a file location of the     input, and location of the output"""
52    encryptor = AES.new(key, AES.MODE_CFB, iv,segment_size=128)
53#    if len(inBytes) % 16 != 0:
54#        block = inBytes + b'\x00'*(len(inBytes)%16)
55#    else:
56#        block = inBytes
57    block = inBytes
58    return encryptor.decrypt(block)
59
60
61def readSecrets():
62    with open("secret_configure_output.txt",'r') as keyFile:
63        y = keyFile.readline()
64        keyValues = {}
65        while len(y) > 5:
66            y = y.split(" ")
67            z = y[2]
68            z=z[1:-2]
69            key = []
70            for i in range(len(z)//4):
71                    key.append(struct.pack(">B",int(z[4*i+2:4*i+4],16)))
72            key = b''.join(key)
73            keyValues[y[1]] = key
74            y = keyFile.readline()
75        return keyValues
76     
77def construct_request(start_addr, num_bytes,PASSWORD):
78    """Construct a request frame to send the the AVR.
79    The frame consists of a 24 byte password followed by the start address (4
80    bytes) and then the number of bytes to read (4 bytes).
81    """
82    # yeah, this function depends on variables defined outside of it. Sorry. 
83    formatstring = '>' + str(len(PASSWORD)) + 'sII'
84    return struct.pack(formatstring, PASSWORD, start_addr, num_bytes)
85
86if __name__ == '__main__':
87    parser = argparse.ArgumentParser(description='Memory Readback Tool')
88
89    parser.add_argument("--port", help="Serial port to send update over.",
90                        required=True)
91    parser.add_argument("--address", help="First address to read from.",
92                        required=True)
93    parser.add_argument("--num-bytes", help="Number of bytes to read.",
94                        required=True)
95    parser.add_argument("--datafile", help="File to write data to (optional).")
96    args = parser.parse_args()
97
98    secrets = readSecrets()
99    request = construct_request(int(args.address), int(args.num_bytes),secrets["PC_RB_PW"])
100    # Read in secret key from file.
101    SECRET_KEY = secrets['PC_RB_KEY']
102    IV = secrets['RB_IV']
103    HASH_KEY =  secrets['PC_RBH_KEY']
104
105    request = encryptAES(SECRET_KEY, IV, request)
106    request_hash = CMACHash(HASH_KEY, request)
107    request = struct.pack('>' + str(len(request)) + 's' +
108        str(len(request_hash)) + 's', request, request_hash)
109    # Open serial port. Set baudrate to 115200. Set timeout to 3.7 seconds.
110    ser = serial.Serial(args.port, baudrate=115200,timeout=3.7)
111
112    # Wait for bootloader to reset/enter readback mode.
113    while ser.read(1) != 'R':
114        pass
115
116    # Send the request.
117    ser.write(request)
118
119    addr = int(args.address)
120    sz = int(args.num_bytes)
121    
122    # Read in apropriate amount of data.
123    # Reading is done by the page.
124    # sz - 1 is used because address is 0 indexed
125    # while sz is implicitly 1 indexed 
126    for i in range(addr//256,(addr+sz-1)//256+1):
127        data += ser.read(256)
128    
129    data = decryptAES(SECRET_KEY, IV, data)
130    #Slice off excess data
131    data = data[addr%256:][:sz]
132    printable = ["{:02x}".format(ord(x)) for x in data]
133    print(":".join(printable))