An Enhanced Message Digest Hash Algorithm for Information Security

ISSN 2349-7815
International Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE)
Vol. 2, Issue 1, pp: (54-62), Month: January - March 2015, Available at: www.paperpublications.org
Page | 54
Paper Publications
An Enhanced Message Digest Hash Algorithm
for Information Security
1
Akanksha Rawat, 2
Deepak Agrawal
1
Research Scholar, 2
Professor, TITECH Jabalpur, India
Abstract: Information is an important commodity in the world of Electronic communication. To achieve a secure
communication between communicating parties, the protection of authenticity and integrity of information is
necessary. Cryptographic hash functions play a central role in cryptology. A cryptographic hash function takes an
input of arbitrary large size and returns a small fixed size hash value. It satisfies three major cryptographic
properties: preimage resistance, second preimage resistance and collision resistance. Due to its cryptographic
properties hash function has become an important cryptographic tool which is used to protect information
authenticity and integrity. This thesis presents a review of cryptographic hash functions. The thesis includes
various applications of hash functions. It gives special emphasis on dedicated hash functions MD5. Recent
breakthroughs in cryptanalysis of standard hash functions like SHA-1 and MD5 raise the need for alternatives. In
the past few years, there have been significant research advances in the analysis of hash functions and it was shown
that none of the hash algorithm is secure enough for critical purposes whether it is MD5 or SHA-1. Nowadays
scientists have found weaknesses in a number of hash functions, including MD5, SHA and RIPEMD. So the
purpose of this thesis is combination of some function to reinforce these functions and also increasing hash code of
message digest of length up to 160 that makes stronger algorithm against collision and brute force attacks.
Keywords: Hash Algorithm, Information Security.
1. INTRODUCTION
MD stands for Message Digest‗and describes a mathematical function that can take place on a variable length string. The
number 5 simply depicts that MD5 was the successor to MD4. MD5 is essentially a checksum that is used to validate the
authenticity of a file or a string and this is one of its most common uses. Let‗s take a look at a working example. Let‗s say
you have released some software or a program that you want people to freely distribute, this is all good and well but what
if someone was to tamper with your application with malicious intent? For example what if they added malware onto your
program, how would people know? Well if you had taken an MD5 checksum of your original program and made this
information public, then when people downloaded your software could then check their downloaded file and check that
the MD5 checksum matches yours. If it does then great! If not then it means your program has been tampered with. MD5,
with the full name of the Message-digest Algorithm 5, is the fifth generation on behalf of the message digest algorithm.
The MD5 message digest algorithm was developed by Ron Rivest at MIT. Until the last few years when both burst force
and cryptanalytic concerns have arose , MD5 was most widely used secure hash algorithm. It is a widely-used 128-bit
hash function, used in various applications Including SSL/TLS, IPSec, and many other cryptographic protocols. The MD5
algorithm breaks a sleeve into 512 bit input blocks. Every block is run from side to side a series of functions to produce a
exceptional bit hash value for the sleeve [1].
2. HASH FUNCTION
A hash function H is a transformation that takes a variable-size input m and proceeds a fixed-size string, which is called
the hash value h .Hash functions with just this property have a variety of general computational uses, but when working in

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cryptography the hash functions are regular chosen to have some supplementary properties. This is a contract in lots of
programming languages that allocate the user to dominate equality and hash functions for an object, that if two objects are
the same their hash codes must be the same. Hash functions compress a n (arbitrarily) large number of bits into a small
number of bits.
The hash function properties are:-
ash).
3. MD5 ALGORITHM
MD5 stands for Message-Digest Algorithm 5. MD5 algorithm is co-invented by Rivets in MIT Computer Science
Laboratory and RSA Data Security Company. MD5 is a non-reversible encryption algorithm [3]. It is widely applied in
many aspects, including digital signature, encryption of information in a database and encryption of communication
information. It makes large amounts of information to be compressed into a confidential format before signing the private
key by digital signature soft (that is, any length byte string is transformed into a certain length of big integer). A brief
description of MD5 algorithm as follows: MD5 algorithm divides plaintext input into blocks each which has 512- bit, and
each block is again divided into sixteen 32-bit message words, after a series of processing, the outputs of the algorithm
consist of four 32-bit message words. After these four 32-bit message words are cascaded, the algorithm generates a 128-
bit hash value which is the required cipher text. Specific steps are as follows [3, 4, 5].
(1) Padding-bit: Without loss of generality, supposes that the original data at the source has k bits (mk-1, mk-2…
m0),where mi_ {0, 1}. For MD5 algorithm, its k bits data must be processed in 512-bit message block, so if the length of
source is less than that length, padding is always added until its length in bits is congruent to 448modulo 512 (length≡448
mod 512). The padding consists of a single 1-bit followed by the necessary number of 0-bits.
(2) Padding the length of data: a 64-bit representation of the length on bits of the original message is appended to the
result of above step. It is present by two 32-bitdigits. At this time, the length of message is filled to amultiple of 512.
Figure 1: Working principle of an iterated hash function

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(3) Initialize MD5 Parameters: four 32-bit integers A, B, C, D are called chaining variables, used to calculate themes
age digest, are initialized by hexadecimal number
A=0x01234567
B=0x89abcdef
C=0xfedcba98
D=0x76543210
(4) Bit operation functions: We define four bit operation functions, F, G, H and I respectively, in which x, y, z are three
32 -bit integers. The operation is as follows:
F(x, y, z) = (x ∧ y)∨ ((￢x) ∧ z) ………….…….1
G(x, y, z) = (x ∧ z) ∨(y∧ (￢z))……………..….2
H(x, y, z) = x⊕y⊕z..….…………….…...….3
I(x, y, z)=y⊕(x∨ (￢z))…. ………..……...4
(5) Main transformation process: The number of main loop in this algorithm is the number of 512-bit information
groups. The main loop have four rounds, each round carries out 16 operations, so the total of operations are64 steps. The
above four chaining variables are assigned to another four chaining values: a0=A, b0=B, c0=C, d0=D. One of the
chaining values is updated in each step and computation is continued in sequence. Here we have defined four rounds
composite functions of main loop FF, GG, HH, and II respectively, which change from F, G, H and I. the operation is as
follows:
FF →a = b + ((a + F (b c d) Mi+ ti)<< s)……..…5
GG →a = b + ((a + H (b c d) )Mi+ ti<<s)….…....6
HH →a = b + ((a + H (b c d) )Mi+ ti<<s)…..…...7
II →a = b + ((a + I (b c d) ) Mi+ ti<<s)……….…8
Where, + is addition module232, Mi (0_i_15) is a 32-bit message word and the 512- bit message block is divided into 16
32-bit message words. x _ s is the left shift rotation of x by s bits. The ti and s are step-dependent constants, ti has the
following options: in i-th step, ti is the integer part of 4294967296×abs (sin (i)),4294967296 = 232.
After all of these steps, A, B, C, D add a, b, c, d Respectively, then the algorithm is continued to run the next 512-bit
message block, the final output is A, B, C, D of cascading. Application of MD5 algorithm is to generate a message digest
of information in order to prevent tampering. We view the entire file as a large text message, and result in a unique MD5
message digest by the irreversible string transform method. In the future, if the contents of file are changed, we only
recalculate MD5 message digest of this file, and will find the difference from the original message digest. Thereby, we
can sure the checked file is incorrect.[2]
4. SECURITY ATTACKS
Security attack can be classified in two categories Active attack and Passive attack.
4.1 Active attack:
An intrusion into a computer network which attempts to delete or modify the data stored on the computers which form
part of the network. This is one of the most important forms of strike since many companies operations deprecatory
depend on data. This type of attack requires the assailant to be able to transmit data to one or both of the parties, or block

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the data stream in one or both directions. It is also feasible that the assailant is detected between the communicating
parties. In this condition the assailant can terminate all or parts of the data sent by the communicating parties. This
assailant can e.g. try to take the place of the client (or server) when the authentication method has been executed. Without
probity checks of the received data, the server will not find out that the origin of the data is not the validated person. A
wise programmer can, with not too much attempt, execute a system like this on a computer acting as a gateway (bridge)
between two subnets.
4.2 Passive Attack:
An intrusion into a computer network which reads the data passing along some of the transmission lines without
modifying it. A passive attack is an attack where an unauthorized assailant monitors or listens in on the communication
between two parties. A passive attack on a cryptosystem is one in which the cryptanalyst cannot interact with any of the
parties intricate, attempting to break the system solely based upon observed data. This can also include known plain text
attacks where [2] both the plain text and its comparable cheaper text are available.
A pounce is the procedure of trying to find out a way around security controls on a computer system. It can be active or
passive. An active attack is an attack in which the assailant manipulates data and adds unauthorized data. In a passive
attack, the assailant only monitors and/or records data.
4.3 Password Guessing Attack:
A different type of network attack is Password Guessing attack. Here a permissible users access rights to a computer and
network capitals are compromised by recognizing the user id/password combination of the permissible user. This attack
takes place when an unauthorized user frequently tries to log on to a computer or network by approximating usernames
and passwords. Many password-guessing programs that used to guess passwords are available on the Internet. Following
are the types of password guessing attacks.
4.4 Brute Force Attack:
In cryptography, a brute-force attack, or comprehensive key search, is a master plan that can, in theory, be employed
against any converted data. Such an attack might be deployed when it is not feasible to take favor of other weaknesses in
an encryption system that would convert it in easier task. The key length used in the encryption regulates the practical
employability of executing a brute-force attack, with longer keys exponentially more tough to crack than shorter ones.
Brute-force attacks can be made less successfully by confusing the data to be encoded, something that makes it tougher
for an attacker to identify when he/she has break the code.
4.5 Dictionary Attack:
A dictionary attack uses a specified technique of continuously trying all the words in a comprehensive list called a
dictionary. In difference with a brute force attack, where a large portion key space is searched specifically, a dictionary
attack strives only those probability which are most likely to triumph, typically derived from a list of words for example a
dictionary.
4.6 Denial-of-Service Attack:
A Denial-of-Service (DoS) attack sources a negative effect on the staging of a computer or network. This attack is
depicting to bring loss of network connectivity and services by absorbing the bandwidth of the user‘s network. It can also
define as network saturation attack or bandwidth consumption attack. Attacker makes Denial-of-Service attacks by
introducing a large number of protocol packets to a network. DoS (Denial-of-Service) attacks are possibly the nastiest,
and most difficult to find.
4.7 Replay Attack:
Replay attack is a type of attack in which assailants capture packets containing passwords or digital signatures whenever
packets pass between two hosts on a network. These assailants then filter the data and extract the passwords, encryption
keys, or digital signatures from the captured packets. In an attempt to obtain an authenticated connection, the assailants
then resend this information to the system.

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5. LITERATURE REVIEW/ WORK DONE
MD5 is one in a series of message digest algorithms designed by Professor Ronald Rives of MI (Rivest, 1994). When
analytic work indicated that MD5's predecessor MD was likely to be insecure, MD5 was designed in 1991 to be a secure
replacement. (Weaknesses were indeed later found in MD4 by Hans Dobbertin.)
In 1993, Den Boer and Bosselaers gave an early, although limited, result of finding a "pseudo-collision" of the MD5
compression function; that is, two different initialization vector which produce an identical digest. At Crypto ‗91 Ronald
L. Rivest introduced the MD5 MessageDigest Algorithm as a strengthened version of MD4, differing from it on six
points. Four changes are due to the two existing attacks on the two round versions of MD4. The other two changes should
additionally streng then MD5. However both these changes cannot be described as well-considered. One of them results
in an approximate relation between any four consecutive additive constants. The other allows creating collisions for the
compression function of MD5.
Bert den Boer and Antoon Bosselaers implemented a C program algorithm that establishes a work load offinding about
216 collisions for the first two rounds of the MD5 compression function to find a collision for the entire four round
functions. On a 33MHz 80386 based PC the mean run time of this program is about 4 minutes.[9]
In 1996, Dobbertin announced a collision of the compression function of MD5 (Dobbertin, 1996). While this was not an
attack on the full MD5 hash function, it was close enough for cryptographers to recommend switching to a replacement,
such as SHA- or RIPEMD-16Hans Dobbert in proposed an attack on the compress function of MD5, which is based on
similar methods as previous attacks on RIPEMD, MD4and the 256-bit extension of MD4 (see [18], [19]). Below we give
a collision1of the compress function of MD5. [10]
Since the first feasible collision differential was given for MD5 in 2004 by Wang et al, a lot of work has been
concentrated on how to improve it, but the researches on how to select weak input deference for MD5 collision attack are
only sporadically scattered in literature. Collision resistance of several hash functions was broken by Wang et al. The
strategy of determining message differential is the most important part of collision attacks against hash functions. So far,
there are only three other message differentials attack published, one of which is 6 bits difference and two are 1 bit
difference. [4]Wang et al. revealed the first MD5 collision with 6 bits message differences in two-block message. Later, a
great many of researches greatly improved the complexity of computations and the best result is 230 MD5 operations.
However, no other message. Differentials are found to generate collision before 2008.
In 2004, more serious flaws were discovered, making further use of the algorithm for security purposes questionable;
specifically, a group of researchers described how to create a pair of files that share the same MD5 checksum.[4][5]
Further advances were made in breaking MD5 in 2005, 2006, and 2007.[6] In an attack on MD5 published in December
2008, a group of researchers used this technique to fake SSL certificate validity.[7][8]
The size of the hash—128 bits—is small enough to contemplate a birthday attack. MD5CR was a distributed project
started in March 2004 with the aim of demonstrating that MD5 is practically insecure by finding a collision using a
birthday attack. In 2009, the United States Cyber Command used an MD5 hash of their mission statement as a part of
their official emblem.[15
On December 24, 2010, Tao Xie and Dengguo Feng announced the first published single-block MD5 collision (two 64-
byte messages with the same MD5 hash).[16 Previous collision discoveries relied on multi-block attacks. For "security
reasons", Xie and Feng did not disclose the new attack method. They have issued a challenge to the cryptographic
community, offering a US$ 10,000 reward to the first finder of a different 64-byte collision before January 1, 2013.
In 2011 an informational RF was approved to update the security considerations in RFC 132 (MD5) and RFC 210
(HMAC-MD5). HMAC-MD5 describes a keyed-MD5 mechanism (called HMAC-MD5) for use as a message
authentication code (or, integrity check value). It is mainly intended for integrity verification of information transmitted
over open networks (e.g., Internet) between parties that share a common secret key. The proposed mechanism combines
the (key-less) MD5 hash function [RFC-132] with a shared secret key. [17]
In, January 29, 2012, Cryptology Group, CWI, announced the collision attack on MD5.
Xie Tao, Fanbao Liu, and Dengguo Feng (2013). Found Fast Collision Attack on MD5.

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6. PROPOSED FRAMEWORK
In this dissertation work, we have proposed an advanced message digest hash algorithm, which is better to dealt with pre-
image attack in contrast to actual MD5 hash algorithm. Our advanced message digest hash algorithm enclosed following
features-
1. We have used 4 rounds each of 20 operations (actual MD5 hash algorithm also uses 4 rounds but each of 16
operations.
2. Because we have used 4 rounds each of 20 operations, so that we uses 5 word buffers A, B, C, D and E each of 32 bits
for computing message digest.
3. Fixed length 160-bit message digest is produced by the proposed algorithm as output, which is more robust and secure
as compared to 128-bit message digest produced by the actual MD5 hash algorithm.
6.1 Proposed Algorithm:
The proposed algorithm is depicted by the following steps:
6.2.1 Padding Bits:
The message is "padded" (extended) so that its length (in bits) is congruent to 448, modulo 512. That is, the message is
extended so that it is just 64 bits shy of being a multiple of 512 bits long. Padding is always performed, even if the length
of the message is already congruent to 448, modulo 512.Padding is performed as follows: a single "1" bit is appended to
the message, and then "0" bits are appended so that the length in bits of the padded message becomes congruent to 448,
modulo 512. In all, at least one bit and at most 512 bits are appended [11].
A 64-bit representation of b (the length of the message before the padding bits were added) is appended to the result of the
previous step. In the unlikely event that b is greater than 2^64, then only the low-order 64 bits of b are used [11].
6.2.3 Initialize MD Buffer:
A Five-word buffer (A, B, C, D, E) is used to compute the message digest. Here each of A, B, C, D, E is a 32-bit register.
These registers are initialized to the following values in hexadecimal, low-order bytes first.
Word A: 01 23 45 67
Word B: 89 ab cd ef
Word C: fe dc ba 98
Word D: 76 54 32 10
Word E: c3 d2 d1 f0
This step uses a 80-element table T [1 ... 80] constructed from the sine function.
6.2.4 Process Message in 16-Word Blocks:
We define eight bit operation functions F, G, H, I, J, K, L and M respectively in two group first F, G, H, I and other one J,
K, L, M in which x, y, z are three 32-bit integers. The operation is as follows:
Group 1:
F(x,y,z) =(x∧y)∨ ((￢x) ∧ z) ………….......1
G(x,y,z) = (x∧ z) ∨ (y∧ (￢z))……………...2
H(x,y,z) = x⊕y⊕z..….…………………...3
I(x, y, z) = y⊕(x ∨ (￢z))………………….4

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Group 2:
J(x,y,z) =(x∧ y)∨ ((￢x) ∧ z) ………....…....5
K(x,y,z) = x⊕y⊕z……………..…………6
L(x,y,z) =( x∧ y) ⊕( y∧ z) ∨ (z∧ x)...…........7
M(x, y, z) = x⊕y⊕z ……….…. …………8
In eight functions, if the corresponding bits of x, y and z are independent and uniform, then each bit of the results should
be independent and uniform as well.
7. COMPARISON OF COMPRESSION FUNCTION
The modified message algorithm has eight compression functions in two groups. Four function in each group. It is
compared with the existing message digest which generates 128 bits secure output and sha-1 which generates 160 bits
secure output. The existing message digest md5 and sha1 perform four compression functions whereas the modified
message algorithm has eight compression functions. The comparison of compression function of modified message
digest, existing message digest and sha-1 is shown here:
8. ADVANCED MESSAGE DIGEST COMPRESSION FUNCTION
Group 1:
J(x,y,z) =(x∧y)∨ ((￢x) ∧ z) …………............1
K(x,y,z) = (x∧ z) ∨(y∧ (￢z))…………….......2
L(x,y,z) = x ⊕ y ⊕ z..….…………………....3
M(x, y, z) = y ⊕ (x ∨ (￢z))…………………4
Group 2:
N(x,y,z) =(x∧y)∨ ((￢x) ∧ z) ………....…......5
O(x,y,z) = x ⊕ y⊕ z……………..………….6
P(x,y,z) =( x∧y) ⊕ ( y∧z) ∨ (z∧x)...…............7
Q(x, y, z) = x ⊕ y ⊕ z ……….…. …………8
Message Digest 5 Compression Function
J(x,y,z) =(x∧y)∨ ((￢x) ∧ z) …………...…….1
K(x,y,z) = (x∧ z) ∨(y∧ (￢z))………………...2
L(x,y,z) = x ⊕ y ⊕ z..….……………………3
M(x, y, z) = y⊕(x ∨ (￢z))……………….….4
SHA-1 Compression Function
N(x,y,z) =(x∧y)∨ ((￢x) ∧ z) ………....………1
O(x,y,z) = x ⊕ y ⊕ z……………..…………..2
P(x,y,z) =( x∧y) ⊕ ( y∧z) ∨ (z∧x)...………......3
Q(x, y, z) = y⊕(x ∨ (￢z))….….……………...4

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9. ALGORITHM COMPARISON [19, 20]
Table 1.1 Comparison of MD5, SHA-1 and Advanced Message Diegest
10. CONCLUSION AND FUTURE WORK
At present work, it is proposed an enhanced message digest algorithm, which is better to dealt with pre-image attack in
contrast to actual Message Digest hash algorithm.
Our enhanced Message Digest hash algorithm enclosed following features-
1. We have used 4 rounds each of 20 operations (actual MD5 hash algorithm also uses 4 rounds but each of 16
operations.
2. Because we have used 4 rounds each of 20 operations, so that we uses 5 word buffers A, B, C, D and E each of 32 bits
for computing message digest.
3. Fixed length 160-bit message digest is produced by the proposed algorithm as output, which is more robust and secure
as compared to 128-bit message digest produced by the actual MD5 hash algorithm.
We observed that the Message Digest algorithm with 128 bit message digest length is slightly cheaper to compute, but it
is currently very vulnerable to collision attacks, as compared to Message Digest algorithm with 160 bit message digest
length. Based on the above analyzed results we conclude that the enhanced Message Digest Algorithm is more strong,
secure and better to dealt with pre-image attack in contrast to actual MD5 hash algorithm. In future we have to analyze the
Message Digest algorithm with higher bit values then proposed algorithm and were compare the results. We can extend
the length of hash to 256 or 512 bits to be more resistible against birthday attack.
REFERENCES
[1] R. Rivest. The MD5 Message-Digest Algorithm [rfc1321]
[2] Tao Xie and Dengguo Feng (30 May 2009). How to Find Weak Input Differences for MD5 Collision Attack.
[3] Rivest R L. The MD5 message digest algorithm [EB/OL].
[4] Xiaoyun Wang, Dengguo, k., m., m, HAVAL-128 and RIPEMD], Cryptology ePrint Archive Report 2004/199, 16
August 2004,
[5] J. Black, M. Cochran, T. Highland: A Study of the MD5 Attacks: Insights and Improvement, March 3, 2006
Function MD5 SHA-1 Advanced Message Digest
Block length 512 bit 512 bit 512 bit
Algorithm length 128 bit 160 bit 160 bit
Rotation steps 64 steps 80 steps 160 steps
Initialization variables 4 5 5
Compression functions 4 4 8
Brute Force Attack Operations 264
264
2160
Brute Force Attack
Time(4.7*109)
Hash/Sec)
53*10-11
yrs 38 yrs 285
yrs
Security against cryptanalysis Vulnerable to
attacks
Vulnerable
to attacks
Not to be vulnerable yet

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[6] Marc Stevens, Arjen Lenstra, Benne de Weger: Vulnerability of software integrity and code signing applications to
chosen-prefix collisions for MD, Nov 30, 2007.
[7] Sotirov, Alexander; Marc Stevens, Jacob Appelbaum, Arjen Lenstra, David Molnar, Dag Arne Osvik, Benne de
Weger (2008-12-30). "MD5 considered harmful today. Announce at the 25th Chaos Communication Congress.
[8] Stray, Jonathan (2008-12-30). "Web browser flaw could put e-commerce security at risk.
[9] Bert den Boer, Antoon Bosselaers. Collisions for the compression function on Md5.
[10] Hans Dobbertin. Cryptanalysis of MD5 Compress
[11] Philip Hawkes and Michael Paddon and Gregory G. Rose: Musings on the Wang et al. MD5 Collision, 13 Oct
2004.
[12] Arjen Lenstra, Xiaoyun Wang, and Benne de Weger: Colliding X.509 Certificate, Cryptology ePrint Archive
Report 2005/067, 1 March 2005.
[13] Vlastimil Klima: Finding MD5 Collisions – a Toy for a Noteboo, Cryptology ePrint Archive Report 2005/075, 5
March 2005, revised 8 March 2005.
[14] Vlastimil Klima: Tunnels in Hash Functions: MD5 Collisions within a Minute, Cryptology ePrint Archive Report
2006/105, 18 March 2006, revised 17 April 2006.
[15] http://www.wired.com/dangerroom/2010/07/code-cracked-cyber-command-logos-mystery-solved Code Cracked!
Cyber Command Logo Mystery Solved
[16] http://eprint.iacr.org/2010/64
[17] RFC 615, Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms
[18] H. Tiwari and K. Asawa, 2010, ―A Secure Hash Function MD-192 with Modified Message Expansion‖, IJCSIS,
Vol. 7, No. 2, pp. 108-111.
[19] http://blog.codinghorror.com/speed-hashing/
[20] www.troyhunt.com201206our-password-hashing-has-no-clothes.html.

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