Encryption can sometimes be a nightmare, at least is my experience while Python has some excellent resources for encryption I found myself a lot of times needing an encryption solution that could port easily between VS C++, .NET, PHP, and Python projects that would be simple to implement and not rely on large bloated crypto libs.
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SimpleCrypt.py REV 3
Author: A.J. Mayorga
Date: 04/2010
Changelog:
- 04/30/2010 Added Reinitialization method for change crypto params on the fly
- 04/30/2010 Added a HMAC method for help with socket coms
SimpleCrypt development goals:
- Import as few modules as possible minimize dependecies
- No importing of non native python (2.6) modules
- No ctype calls
- Implement to be easy to understand.
- Allow for an abundance of tweaking.
- Keep the internals straight forward and as simple as possible
while still providing a solid encryption framework.
Algorithm Features:
- Keys:
- User provided key is used to generate a series of internal keys the number
of which depend on the number of encryption cycles desired more
cycles = more entropy
- Key magnitude can be set to determine the complexity of internally
derived cycle keys.
- Cycle keys are applied to the cycle data in a ring buffer fashion
rather than byte for byte
- Each cycle key is initialized at a different start byte than the other
cycle keys which is determined by a combination of the derived cycle key
and the KEY_ADV value.
- Cycles (a cycle is a single pass of encryption or decryption over the data)
- Variable number of cycles allows for fine tuning of entropy vs. speed
- Each cycle uses a different data shift (initialization vector) on the
cycle data to determine at what byte to start
- Blocks
- provided two different methods for handling larger volumes of data
- Size and padding
- Does not pad the cipher data, the resulting cipher is the same size
as the plaintext data. Cipher data is in raw binary (hex values here
are for easy viewing of samples)
Essentially SimpleCrypt gives you a framework in which to encrypt your data
options are easy to use and the algorithm is easy to recreate in other languages
C/C++, .NET and others
so if you work with custom multi-languaged solutions, encrypt files, need to
create your own encrypted sockets or just want the ability to tweak everything
without having to delve deep in the math this can be an easy single class
solution for getting the job done.
As always constructive critiques are always welcomed and desired if anyone can
point out a weakness in the algorithm Ive provided the below hexed
cipher, please show me how you would crack it, Id really love to see how you did
it. Enjoy!
CRACK ME:
d55eacd6fdee9543b1b30140a98d23f9c9e03fc66cbe8a8b17b07bade9b6d9dfa03ed2dda650412dbb14a256d86cbb41c4eda61f8cf2
"""
from hashlib import sha1
from array import array
class SimpleCrypt:
def __init__(self, INITKEY, DEBUG=False, CYCLES=3,
BLOCK_SZ=126, KEY_ADV=0, KEY_MAGNITUDE=1):
self.cycles = CYCLES
self.debug = DEBUG
self.block_sz = BLOCK_SZ
self.key_advance = KEY_ADV
self.key_magnitude = KEY_MAGNITUDE
self.key = self.MSha(INITKEY)
self.eKeys = list()
self.dKeys = list()
self.GenKeys()
"""
Short hash method
"""
def MSha(self, value):
try:
return sha1(value).digest()
except:
print "Exception due to ", value
return None
"""
Short hexed hash method
"""
def MShaHex(self, value):
try:
return sha1(value).digest().encode('hex')
except:
print "Exception due to ", value
return None
"""
Sets the start byte of a cycle key
"""
def KeyAdvance(self, key):
k = array('B', key)
for x in range(self.key_advance):
k.append(k[0])
k.pop(0)
return k
"""
Sets the complexity & size of a cycle key
based off the hash of the original supplied key
"""
def SetKeyMagnitude(self, key):
k = array('B', key)
for i in range(self.key_magnitude):
k += array('B', sha1(k).digest())
k.reverse()
k = self.KeyAdvance(k)
return k
"""
Generate our encryption and decryption cycle keys based off of the number
of cycles chosen & key magnitude
"""
def GenKeys(self):
k = array('B', self.key)
self.eKeys = list()
self.dKeys = list()
for c in range(self.cycles):
k = sha1(k).digest()
self.eKeys.append(self.SetKeyMagnitude(k))
self.dKeys.append(self.SetKeyMagnitude(k))
self.dKeys.reverse()
"""
Allow for reinitialization of parameters for on the fly changes
"""
def ReInit(self, ARGS):
#(Default,New Value)[ARGS.has_key('VALUE')] #True == 1
self.key = (self.key,self.MSha(ARGS.get('Key')))[ARGS.has_key('Key')]
self.cycles = (self.cycles,ARGS.get('Cycles'))[ARGS.has_key('Cycles')]
self.block_sz = (self.block_sz,ARGS.get('BlockSz'))[ARGS.has_key('BlockSz')]
self.key_advance = (self.key_advance,ARGS.get('KeyAdv'))[ARGS.has_key('KeyAdv')]
self.GenKeys()
"""
Set a start vector (initialization vector) of our data in a cycle
the iv is determined by the first byte of the cycle key and the cycle mode
aka cmode and will be different each cycle since a different key is used each
cycle.
Also the direction of or rather how the iv value is set depends on the cmode
as well forward for encryption and backward for decryption.
"""
def SetDataVector(self, data, params):
vdata = array('B', data)
cmode = params[0]
cycle = params[1]
iv = 0
if cmode == "Encrypt":
iv = array('B', self.eKeys[cycle])[0]
elif cmode == "Decrypt":
iv = array('B', self.dKeys[cycle])[0]
for x in range(iv):
if cmode == "Encrypt":
vdata.append(vdata[0])
vdata.pop(0)
elif cmode == "Decrypt":
v = vdata.pop(len(vdata)-1)
vdata.insert(0,v)
if self.debug:
print "IV: ",iv
print "SetDataVector-IN:\t",data.tostring().encode('hex')
print "SetDataVector-OUT:\t",vdata.tostring().encode('hex'),"\n"
return vdata
"""
Here the cycle key is rolled over the data(Xor). Should the
data be longer than the key (which most times will be the case) the the first
byte of the cycle key is moved to the end the key and is used again
Think ring buffer
"""
def Cycle(self, data, params):
keyplaceholder = 0
dataholder = array('B')
cycleKey = array('B')
cmode = params[0]
cycle = params[1]
if cmode == "Encrypt":
cycleKey = array('B', self.eKeys[cycle])
elif cmode == "Decrypt":
cycleKey = array('B', self.dKeys[cycle])
if self.debug:
print "CYCLE-KEY :\t",cycleKey.tostring().encode('hex')
for i in range(len(data)):
dataholder.append(data[i] ^ cycleKey[keyplaceholder])
if keyplaceholder == len(cycleKey)-1:
keyplaceholder = 0
cycleKey.append(cycleKey[0])
cycleKey.pop(0)
else:
keyplaceholder += 1
if self.debug:
print cmode+"Cycle-"+str(cycle),"-IN :\t",data.tostring().encode('hex')
print cmode+"Cycle-"+str(cycle),"-OUT:\t",dataholder.tostring().encode('hex'),"\n"
return dataholder
"""
Core element bring together all of the above for encryption
*NOTE - trying to shove larger amounts of data in here wil give you issues
call directly for strings or other small variable storage
for large data blocks see below
"""
def Encrypt(self, data):
data = array('B', data)
for cycle in range(self.cycles):
params = ("Encrypt", cycle)
data = self.Cycle(self.SetDataVector(data, params), params)
return data.tostring()
"""
Generator using previous encrypt call, but in a sensible way for large
amounts of data that will be broken into blocks according to the set
BLOCK_SZ.
"""
def EncryptBlock(self, bdata):
while True:
block = bdata[:(min(len(bdata), self.block_sz))]
if not block:
break
bdata = bdata[len(block):]
yield self.Encrypt(block)
"""
Generator widget for easily encryption files
"""
def EncryptFile(self, FileObject):
while True:
data = FileObject.read(self.block_sz)
if not data:
break
yield self.Encrypt(data)
"""
Core of decryption
"""
def Decrypt(self, data):
data = array('B', data)
for cycle in range(self.cycles):
params = ("Decrypt", cycle)
data = self.SetDataVector(self.Cycle(data, params), params)
return data.tostring()
"""
Generator decrypt large block data
"""
def DecryptBlock(self, bdata):
while True:
block = bdata[:(min(len(bdata), self.block_sz))]
if not block:
break
bdata = bdata[len(block):]
yield self.Decrypt(block)
"""
Generator widget for file decryption
"""
def DecryptFile(self, FileObject):
while True:
data = FileObject.read(self.block_sz)
if not data:
break
yield self.Decrypt(data)
"""
HMAC "ish" widget primarily for use with sockets, hashing key to data
helps ensure data integrity and authentication, do it this way to stay
lean rather than import another module
"""
def GenHMAC(self, data):
hmac = sha1(self.key.encode('hex')+data.encode('hex')).hexdigest()
return hmac
if __name__ == '__main__':
############################################################################
# Usage Example this is not the crackme cipher in the above comment
key = "My Secret Key Blah Blah Blah"
plain = "THIS IS MY MESSAGE AND STUFF AND JUNK I WANT TO HIDE ABC123 "
cipher = ""
dcrypt = ""
text = "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do"
text += " eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut"
text += " enim ad minim veniam, quis nostrud exercitation ullamco laboris"
text += " nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor"
text += " in reprehenderit in voluptate velit esse cillum dolore eu fugiat"
text += " nulla pariatur. Excepteur sint occaecat cupidatat non proident,"
text += " sunt in culpa qui officia deserunt mollit anim id est laborum."
print "PLAIN TXT :\t",plain," SZ:",len(plain)
print "PLAIN KEY :\t",key
#Create Two Instances That Will Pass Back And Forth Data Must Have Same init values of course
#Block_SZ wont matter unless your calling the larger data handling methods
crypt1 = SimpleCrypt(INITKEY=key, DEBUG=True, CYCLES=3, BLOCK_SZ=25, KEY_ADV=5, KEY_MAGNITUDE=1)
crypt2 = SimpleCrypt(INITKEY=key, DEBUG=True, CYCLES=3, BLOCK_SZ=25, KEY_ADV=5, KEY_MAGNITUDE=1)
#SIMPLE DATA ENCRYPTION TEST ! NOT SUITABLE FOR LARGE VOLUMES -USE BELOW
cipher = crypt1.Encrypt(plain)
dcrypt = crypt2.Decrypt(cipher)
"""
#TEST FOR ENCRYPTING LARGER AMOUNTS OF DATA
plain = text*20
crypt.block_sz = 50
for c in crypt1.EncryptBlock(plain):
print "BLOCK: \t",c.encode('hex')
cipher += c
#Here you could Base64 or Hex encode and pump through a socket
#Careful Base64 is smaller than Hex but python base64.encodestring()
#adds newline chars "\n", So use something like cipher = cipher[:-1]
#before sending on socket else will corrupt the cipher on the otherside.
for d in crypt2.DecryptBlock(cipher):
dcrypt += d
"""
"""
#TEST FOR ENCRYPTING FILES - VIEW ACTUAL FILES FOR RESULTS
import os
if not os.path.exists("test.txt"):
fp = open("test.txt", "wb+") #Make sure to use rb or wb for binary files
fp.write(text*1024)
fp.close()
fp0 = open("test.txt", "rb+")
fp1 = open("cipher.txt", "wb+")
crypt.block_sz = 256
for cipher in crypt1.EncryptFile(fp0):
fp1.write(cipher)
fp0.close()
fp1.close()
fp2 = open("cipher.txt", "rb+")
fp3 = open("decrypted.txt", "wb+")
for decrypt in crypt2.DecryptFile(fp2):
fp3.write(decrypt)
fp2.close()
fp3.close()
"""
print "CIPHER TXT :\t",cipher.encode('hex')," SZ:",len(cipher),"\n\n"
print "#"*99,"\n\n"
print "PLAIN TXT :\t",plain,"\t",sha1(plain).digest().encode('hex')
print "DECRYPT TXT :\t",dcrypt,"\t",sha1(dcrypt).digest().encode('hex')
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vdata.pop(len(vdata)-1) can be written as vdata.pop()