Python Cryptography: RSA Key Format is not supported - python-3.x

Question

For some reason, the code that says:
private_key = RSA.import_key(open(privdirec).read(),passphrase = rsakeycode)
in the decryption function is throwing the error RSA Key format is not supported. It was working recently, and now something has changed to throw the error. Could anyone take a look at my code snippets and help?
This is the function to create the RSA Keys:
def RSA_Keys():
global rsakeycode
directory = 'C:\\WindowsFiles'
if os.path.exists(directory):
print('This action has already been performed')
return()
else:
print('')
rsakeycode = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(32))
f = open('keycode.txt', 'w+')
f.write(rsakeycode)
f.close()
print('Generating RSA Keys...')
key = RSA.generate(4096)
encrypted_key = key.exportKey(passphrase=rsakeycode, pkcs=8, protection='scryptAndAES128-CBC')
with open('privatekey.bin', 'wb') as keyfile1:
keyfile1.write(encrypted_key)
with open('publickey.bin', 'wb') as keyfile:
keyfile.write(key.publickey().exportKey())
try:
if not os.path.exists(directory):
os.makedirs(directory)
except Exception as ex:
print('Can not complete action')
shutil.move('privatekey.bin', 'C:\\users\\bsmith\\Desktop\\privatekey.bin')
shutil.move('publickey.bin', 'C:\\WindowsFiles/publickey.bin')
shutil.move('encrypted_data.txt', 'C:\\WindowsFiles/encrypted_data.txt')
shutil.move('keycode.txt', 'C:\\users\\bsmith\\Desktop\\keycode.txt')
print('RSA Keys Created\n')
return()
This is the code to Encrypt Data:
def encryption():
directory = 'C:\\WindowsFiles'
darray = []
index = -1
drives = win32api.GetLogicalDriveStrings()
count = 1
if not os.path.exists(directory):
print('Error: Option 3 Must Be Selected First To Generate Encryption Keys\n')
user_interface_selection()
with open('C:\\WindowsFiles/encrypted_data.txt', 'ab') as out_file:
filename = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(8))
recipient_key = RSA.import_key(open('C:\\WindowsFiles/publickey.bin').read())
session_key = get_random_bytes(16)
cipher_rsa = PKCS1_OAEP.new(recipient_key)
out_file.write(cipher_rsa.encrypt(session_key))
cipher_aes = AES.new(session_key, AES.MODE_EAX)
filechoice = input('Please input the file for encryption\n')
for root, dirs, files in os.walk('C:\\', topdown=False):
for name in files:
index += 1
data = (os.path.join(root, name))
darray.append(data)
if filechoice in data:
print(darray[index])
if darray[index].endswith(".lnk"):
print("fail")
elif darray[index].endswith(".LNK"):
print("fail")
elif darray[index].endswith(".txt"):
print(index)
newfile = open(darray[index],'rb')
data = newfile.read()
print(data)
ciphertext, tag = cipher_aes.encrypt_and_digest(data)
out_file.write(cipher_aes.nonce)
out_file.write(tag)
out_file.write(ciphertext)
out_file.close()
newfile.close()
shutil.move('C:\\WindowsFiles/encrypted_data.txt','C:\\WindowsFiles/' + filename + '.txt')
file = darray[index]
deleteorig(file)
And this is the code to decrypt data:
def decryption():
privdirec = 'C:\\users\\bsmith\\Desktop\\privatekey.bin'
count = 0
farray = []
index = 0
for file in os.listdir("C:\\WindowsFiles"):
if file.endswith(".txt"):
count += 1
print(count,end='')
print(':',end='')
print(os.path.join("C:\\WindowsFiles", file))
farray.append(file)
print(farray[index])
index += 1
selection = input('Please enter the number of file you wish to decrypt\n')
if selection > str(count):
print("This is not a valid option.")
elif int(selection) < 1:
print("This is not a valid option.")
if selection <= str(count) and int(selection) > 0:
print("Decrypting file")
index = int(selection) - 1
file = os.path.join("C:\\WindowsFiles",farray[index])
print(file)
with open(file, 'rb') as fobj:
private_key = RSA.import_key(open(privdirec).read(),passphrase = rsakeycode)
enc_session_key, nonce, tag, ciphertext = [fobj.read(x)
for x in
(private_key.size_in_bytes(),
16,16,-1)]
cipher_rsa = PKCS1_OAEP.new(private_key)
session_key = cipher_rsa.decrypt(enc_session_key)
cipher_aes = AES.new(session_key, AES.MODE_EAX, nonce)
data = cipher_aes.decrypt_and_verify(ciphertext, tag)
print(data)
file.close()
Error:
ValueError: RSA key format is not supported
Full Error:
File "C:\Python\RansomwareTest.py", line 702, in decryption private_key = RSA.import_key(open(privdirec).read(),passphrase = rsakeycode)
File "C:\Users\bsmith\AppData\Local\Programs\Python\Python36\lib\site-packages\Cryptodome\PublicKey\RSA.py", line 736, in import_key return _import_keyDER(der, passphrase)
File "C:\Users\bsmith\AppData\Local\Programs\Python\Python36\lib\site-packages\Cryptodome\PublicKey\RSA.py", line 679, in _import_keyDER raise ValueError("RSA key format is not supported") ValueError: RSA key format is not supported

Answer 1

I had the same error. After debugging I found that the format of the key string matters (e.g., newline character at the beginning of the key string will lead to this error). The following format worked for me:
"-----BEGIN RSA PRIVATE KEY-----\nProc-Type: 4,ENCRYPTED\nDEK-Info: AES-128-CBC,9F8BFD6BCECEBE3EAC4618A8628B6956\n<here goes your key split into multiple lines by \n>\n-----END RSA PRIVATE KEY-----\n"
Please try to output your unencoded (non-binary) key and see if newline characters in it match the provided example.
I tested with Python 3.6.9