Monthly Archives: September 2014

MD5 algo in Python

I just came across the solution for an MD5 python implementation. There is ofcourse an easier way to do that…hashlib.md5(). you can read more about it here in the python documentation:

https://docs.python.org/3.1/library/hashlib.html

############CODE starts here######################################

# March 26, 2013
# Greenlaw and Snyder
# This is an implementation of the MD5 hashing algorithm.
# It is adopted from a C implementation found at
# http://en.wikipedia.org/wiki/MD5

import binascii

#The per-round shift amounts
S = (7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20,
4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21)

#for simplicity, I just do a for loop. to increase performance, constants are better.

#Use binary integer part of the sines of integers (Radians) as constants:
for i from 0 to 63
K[i] := floor(abs(sin(i + 1)) × (2 pow 32))
end for

#Leftrotate function
def leftRotate(x, c):
#If x has more than 32 bits, this selects just the last 32 bits
x &= 0xFFFFFFFF
return ((x<<c)|(x>>(32-c)) & 0xFFFFFFFF)

#MD5 function itself
def MD5(input):

#input.encode() converts the string to the byte level.  Message will be
#prefaced by a b.
message = (input.encode())

#This gives the number of bytes in the string.
length = len(message)

#Append padded bits
newLength = length + 1

#Here we are counting bytes
while(newLength%64 != 56):
newLength += 1
paddingLength = newLength – length
#The first byte is two hex numbers 8 and 0.  This gives us the bit string
#1000000 and this is the first part of the padding.
padding = b’\x80′ + bytes(paddingLength – 1)
message += padding

#Append a 64-bit representation of the length of the original message in bits
message += (length*8).to_bytes(8, byteorder=’little’)

#Initialize variables
A = 0x67452301
B = 0xefcdab89
C = 0x98badcfe
D = 0x10325476

#Process the message with 512-bit chucks
chunk_offset = 0
for chunk_offset in range(0, len(message), 64):

#Initialize buffer
RA = A
RB = B
RC = C
RD = D

chunk = message[chunk_offset:chunk_offset+64]
for i in range(64):
if i in range(16):
F = (RB&RC)|((~RB)&RD)
g = i
elif i in range(16, 32):
F = (RD&RB)|((~RD)&RC)
g = ((5*i)+1)%16
elif i in range(32, 48):
F = RB^RC^RD
g = ((3*i)+5)%16
elif i in range(48, 64):
F = RC^(RB|(~RD))
g = (7*i)%16
temp = RD
RD = RC
RC = RB
#Convert the revelant part of the message from bytes to an int
M = int.from_bytes(chunk[4*g:4*g+4], byteorder=’little’)
#And with the 32-bit string of 1s to elminate any carry bits
RB = RB + leftRotate(RA + F + K[i] + M, S[i]) & 0xFFFFFFFF
RA = temp

#Add the hash of the current chunk to the result so far
A += RA
B += RB
C += RC
D += RD

#And with the 32-bit string of 1s to elminate any carry bits
A &= 0xFFFFFFFF
B &= 0xFFFFFFFF
C &= 0xFFFFFFFF
D &= 0xFFFFFFFF

#Return output
ret = “”
for i in [A, B, C, D]:
ret += binascii.hexlify(i.to_bytes(4, byteorder=’little’)).decode()
return ret

string = input(‘Please enter string: ‘)
print(“MD5:”, MD5(string))

The Navy and Cyber…

Since 2011, the Navy has been offering a new Designator (job) that is quite interesting…here’s some info taken from their  information page…

Cyber Warfare Engineer (CWE)
Requirements
applicants must have a 4 year degree major in a cyber-related major, such as:

Computer Science
Computer Engineering
Computer Programming
Electrical Engineering
Electronics & Communications Engineering
Information Technology
or a related academic programs with different titles

Community Vision
CWE Officers use specific cyber warfare expertise to develop Computer Network Operations capabilities.

Mission Statement
Cyber Warfare Engineer (CWE) is a Restricted Line community within the Information Dominance Corps (IDC). CWE Officers have focused Computer Network Operations (CNO) knowledge, skills and abilities.

Guiding Principles
CNO Competency: CWE Officers employ a thorough understanding of the tenets of CNO, and know how to optimally use all CNO resources for “effects-based” cyber warfare. CWE Officers develop CNO capabilities that will deliver tactical, operational, and strategic advantages.

Leadership: Leadership is a core competency for all Naval Officers. CWE Officers must be engaged, seize the initiative, motivate people, effectively apply resources and execute the mission while taking care of Sailors.

Professional Expertise: CWE Officers require knowledge of computer science, engineering and technology as well as the human elements of adversaries’ use of cyberspace. CWE Officers will build this expertise through a combination of formal education and experience.

Career Path
CWE Officers serve in challenging billets that are designed to leverage their specific CNO expertise and develop capabilities and tools.

CWE Officers must serve at least six years on active duty from date of appointment.

Active duty service for CWE Officers terminates at the sixth anniversary of commissioning, upon which time they will be encouraged to compete for lateral transfer into another IDC community:

Information Warfare (1810)
Information Professional (1820),
Intelligence(1830)
or seek employment in a Department of Defense civilian capacity..