在《<a href="https://www.361way.com/securecrt-decrypt/6335.html" target="_blank" rel="noopener noreferrer">python3解密SecureCRT的密码</a>》篇中提到了利用python进行SecureCRT加密后的密文进行解密的方法。但在不同版本的SecureCRT中%APPDATA%\VanDyke\Config\Sessions\example.com.ini配置中对应的password可能是不一样的，有些密码存储在password项，有些存储的是Password V2项，具体类似如下：
<br />
S:"Password"=u17cf50e394ecc2a06fa8919e1bd67cf0f37da34c78e7eb87a3a9a787a9785e802dd0eae4e8039c3ce234d34bfe28bbdc
S:"Password V2"=02:7b9f594a1f39bb36bbaa0d9688ee38b3d233c67b338e20e2113f2ba4d328b6fc8c804e3c02324b1eaad57a5b96ac1fc5cc1ae0ee2930e6af2e5e644a28ebe3fc
这两者之间的加解密方法是有区别的。具体一般以SecureCRT 7.3.3版本进行分界。之前的版本一般会使用password加密算法，之后的一般使用password v2算法。
一、Password算法
这个也是开篇链接中我之前的博文中提到的，其使用的是2次Blowfish-CBC加密，这里记录为cipher1和cipher2。两者使用的初始公共因子是8位的16进制的0，具体表示如下：
<br />
uint8_t IV[8] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
}
cipher1 使用的key是：
<br />
uint8_t Key1[16] = {
0x24, 0xa6, 0x3d, 0xde, 0x5b, 0xd3, 0xb3, 0x82,
0x9c, 0x7e, 0x06, 0xf4, 0x08, 0x16, 0xaa, 0x07
}
<br />
cipher2 使用的key是：
<br />
uint8_t Key2[16] = {
0x5f, 0xb0, 0x45, 0xa2, 0x94, 0x17, 0xd9, 0x16,
0xc6, 0xc6, 0xa2, 0xff, 0x06, 0x41, 0x82, 0xb7
}
其加密过程如下：
<a href="https://www.361way.com/wp-content/uploads/2019/12/scrt-password-encrypt.png" target="_blank" rel="noopener noreferrer"><img src="https://www.361way.com/wp-content/uploads/2019/12/scrt-password-encrypt.png" width="886" height="696" title="scrt-password-encrypt" alt="scrt-password-encrypt" /></a>
同样对应的其解密过程如下：
<a href="https://www.361way.com/wp-content/uploads/2019/12/scrt-password-decry.png" target="_blank" rel="noopener noreferrer"><img src="https://www.361way.com/wp-content/uploads/2019/12/scrt-password-decry.png" width="888" height="594" title="scrt-password-decry" alt="scrt-password-decry" /></a>
二、password v2算法
password v2使用的是AES256-CBC 算法，其初始因子是16位16进制的0，具体如下：
<br />
uint8_t IV[16] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
}
其使用的32位key是：
<br />
uint8_t Key[32] = {
0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c,
0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55
}
对应的加密过程是：
<img src="https://www.361way.com/wp-content/uploads/2019/12/passwordv2-encryption.png" width="875" height="513" title="passwordv2-encryption" alt="passwordv2-encryption" />
对应的解密过程如下：
<img src="https://www.361way.com/wp-content/uploads/2019/12/passwordv2-decryption.png" width="877" height="423" title="passwordv2-decryption" alt="passwordv2-decryption" />
三、解密代码
这里还是以python为例，对应的即可以解密password也可以解密password v2的代码如下：
<br />
#!/usr/bin/env python3
import os
from Crypto.Hash import SHA256
from Crypto.Cipher import AES, Blowfish
class SecureCRTCrypto:
def __init__(self):
'''
Initialize SecureCRTCrypto object.
'''
self.IV = b'\x00' * Blowfish.block_size
self.Key1 = b'\x24\xA6\x3D\xDE\x5B\xD3\xB3\x82\x9C\x7E\x06\xF4\x08\x16\xAA\x07'
self.Key2 = b'\x5F\xB0\x45\xA2\x94\x17\xD9\x16\xC6\xC6\xA2\xFF\x06\x41\x82\xB7'
def Encrypt(self, Plaintext : str):
'''
Encrypt plaintext and return corresponding ciphertext.
Args:
Plaintext: A string that will be encrypted.
Returns:
Hexlified ciphertext string.
'''
plain_bytes = Plaintext.encode('utf-16-le')
plain_bytes += b'\x00\x00'
padded_plain_bytes = plain_bytes + os.urandom(Blowfish.block_size - len(plain_bytes) % Blowfish.block_size)
cipher1 = Blowfish.new(self.Key1, Blowfish.MODE_CBC, iv = self.IV)
cipher2 = Blowfish.new(self.Key2, Blowfish.MODE_CBC, iv = self.IV)
return cipher1.encrypt(os.urandom(4) + cipher2.encrypt(padded_plain_bytes) + os.urandom(4)).hex()
def Decrypt(self, Ciphertext : str):
'''
Decrypt ciphertext and return corresponding plaintext.
Args:
Ciphertext: A hex string that will be decrypted.
Returns:
Plaintext string.
'''
cipher1 = Blowfish.new(self.Key1, Blowfish.MODE_CBC, iv = self.IV)
cipher2 = Blowfish.new(self.Key2, Blowfish.MODE_CBC, iv = self.IV)
ciphered_bytes = bytes.fromhex(Ciphertext)
if len(ciphered_bytes) <= 8:
raise ValueError('Invalid Ciphertext.')
padded_plain_bytes = cipher2.decrypt(cipher1.decrypt(ciphered_bytes)[4:-4])
i = 0
for i in range(0, len(padded_plain_bytes), 2):
if padded_plain_bytes[i] == 0 and padded_plain_bytes[i + 1] == 0:
break
plain_bytes = padded_plain_bytes[0:i]
try:
return plain_bytes.decode('utf-16-le')
except UnicodeDecodeError:
raise(ValueError('Invalid Ciphertext.'))
class SecureCRTCryptoV2:
def __init__(self, ConfigPassphrase : str = ''):
'''
Initialize SecureCRTCryptoV2 object.
Args:
ConfigPassphrase: The config passphrase that SecureCRT uses. Leave it empty if config passphrase is not set.
'''
self.IV = b'\x00' * AES.block_size
self.Key = SHA256.new(ConfigPassphrase.encode('utf-8')).digest()
def Encrypt(self, Plaintext : str):
'''
Encrypt plaintext and return corresponding ciphertext.
Args:
Plaintext: A string that will be encrypted.
Returns:
Hexlified ciphertext string.
'''
plain_bytes = Plaintext.encode('utf-8')
if len(plain_bytes) > 0xffffffff:
raise OverflowError('Plaintext is too long.')
plain_bytes = \
len(plain_bytes).to_bytes(4, 'little') + \
plain_bytes + \
SHA256.new(plain_bytes).digest()
padded_plain_bytes = \
plain_bytes + \
os.urandom(AES.block_size - len(plain_bytes) % AES.block_size)
cipher = AES.new(self.Key, AES.MODE_CBC, iv = self.IV)
return cipher.encrypt(padded_plain_bytes).hex()
def Decrypt(self, Ciphertext : str):
'''
Decrypt ciphertext and return corresponding plaintext.
Args:
Ciphertext: A hex string that will be decrypted.
Returns:
Plaintext string.
'''
cipher = AES.new(self.Key, AES.MODE_CBC, iv = self.IV)
padded_plain_bytes = cipher.decrypt(bytes.fromhex(Ciphertext))
plain_bytes_length = int.from_bytes(padded_plain_bytes[0:4], 'little')
plain_bytes = padded_plain_bytes[4:4 + plain_bytes_length]
if len(plain_bytes) != plain_bytes_length:
raise ValueError('Invalid Ciphertext.')
plain_bytes_digest = padded_plain_bytes[4 + plain_bytes_length:4 + plain_bytes_length + SHA256.digest_size]
if len(plain_bytes_digest) != SHA256.digest_size:
raise ValueError('Invalid Ciphertext.')
if SHA256.new(plain_bytes).digest() != plain_bytes_digest:
raise ValueError('Invalid Ciphertext.')
return plain_bytes.decode('utf-8')
if __name__ == '__main__':
import sys
def Help():
print('Usage:')
print(' SecureCRTCipher.py [-v2] [-p ConfigPassphrase] ')
print('')
print(' "enc" for encryption, "dec" for decryption.')
print(' This parameter must be specified.')
print('')
print(' [-v2] Encrypt/Decrypt with "Password V2" algorithm.')
print(' This parameter is optional.')
print('')
print(' [-p ConfigPassphrase] The config passphrase that SecureCRT uses.')
print(' This parameter is optional.')
print('')
print(' Plaintext string or ciphertext string.')
print(' NOTICE: Ciphertext string must be a hex string.')
print(' This parameter must be specified.')
print('')
def EncryptionRoutine(UseV2 : bool, ConfigPassphrase : str, Plaintext : str):
try:
if UseV2:
print(SecureCRTCryptoV2(ConfigPassphrase).Encrypt(Plaintext))
else:
print(SecureCRTCrypto().Encrypt(Plaintext))
return True
except:
print('Error: Failed to encrypt.')
return False
def DecryptionRoutine(UseV2 : bool, ConfigPassphrase : str, Ciphertext : str):
try:
if UseV2:
print(SecureCRTCryptoV2(ConfigPassphrase).Decrypt(Ciphertext))
else:
print(SecureCRTCrypto().Decrypt(Ciphertext))
return True
except:
print('Error: Failed to decrypt.')
return False
def Main(argc : int, argv : list):
if 3 <= argc and argc <= 6:
bUseV2 = False
ConfigPassphrase = ''
if argv[1].lower() == 'enc':
bEncrypt = True
elif argv[1].lower() == 'dec':
bEncrypt = False
else:
Help()
return -1
i = 2
while i < argc - 1:
if argv[i].lower() == '-v2':
bUseV2 = True
i += 1
elif argv[i].lower() == '-p' and i + 1 < argc - 1:
ConfigPassphrase = argv[i + 1]
i += 2
else:
Help()
return -1
if bUseV2 == False and len(ConfigPassphrase) != 0:
print('Error: ConfigPassphrase is not supported if "-v2" is not specified')
return -1
if bEncrypt:
return 0 if EncryptionRoutine(bUseV2, ConfigPassphrase, argv[-1]) else -1
else:
return 0 if DecryptionRoutine(bUseV2, ConfigPassphrase, argv[-1]) else -1
else:
Help()
exit(Main(len(sys.argv), sys.argv))
该脚本需要依赖pycryptodome模块，该模块是一个加解密算法的模块包，该模块是pyCyrpto模块的延续。由于pyCyrpto在python3.4已停止更新。后面新的版本就变成了pycryptodome。