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Design and Implementation of
Encryption Standards
Presentation By:
RAghumanohAR Adusumilli
Bhagyashree Todali
2VX14LVS15 2VX14LVS26
21-12-2016VTU PG Centre, Belgavi
1
Under Guidance of
Mr. Mahesh Neelgar
Assistant Professor
Centre for PG studies
Visvesvaraya Technological University
Belgavi

Encryption
 In cryptography, encryption is the process of
encoding messages or information in such a way
that only authorized parties can read it.[1]
 In an encryption scheme, the message or
information, referred to as plain text, is encrypted
using an encryption algorithm, generating cipher
text that can only be read if decrypted.[2]
 Encryption scheme usually uses a pseudo-
random encryption key generated by an algorithm.
2

Types & Uses of Encryption
 Symmetric key encryption
 Public key encryption
 Uses of Encryption
 Military
 Mobile Phones
 Telecommunication
 E-commerce etc..
3

Encryption Standards
 Data Encryption Standard (DES, now obsolete)
 Triple-DES
 Advanced Encryption Standard
 RSA
4

Important Features
 Block size: in general larger block sizes mean greater
security.
 Key size: larger key size means greater security (larger
key space).
 Number of rounds: multiple rounds offer increasing
security.
5

Data Encryption Standard (DES)
 The Data Encryption Standard (DES) was once a
predominant symmetric-key algorithm for the encryption of
electronic data.
 Developed in the early 1970s at IBM and based on an earlier
design by Horst Feistel, the algorithm was submitted to the
National Bureau of Standards (NBS).
 in January, 1999, distributed.net and the Electronic
Frontier Foundation collaborated to publicly break a DES
key in 22 hours and 15 minutes
6

DES
 DES is the block cipher — an algorithm that takes a
fixed-length string of plaintext bits and transforms it
through a series of complicated operations into
another cipher text bit string of the same length.
 The block size is 64 bits. The key also consists of 64
bits, however, only 56 of these are actually used by the
algorithm. Eight bits are used solely for checking parity,
and are thereafter discarded.
7

8

DES
 The processing of the plaintext
proceeds in three phases :
 Initial permutation (IP)
 Feistel Rounds (16 Rounds)
 Final Permutation (FP)
9

DES: Initial Permutation
 This table specifies the input
permutation on a 64-bit block.
 The first bit of the output is taken from
the 58th bit of the input; the second bit
from the 50th bit, and so on, with the
last bit of the output taken from the 7th
bit of the input.
 This information is presented as a
table for ease of presentation: it is a
vector, not a matrix.
10

DES Rounds
 IP(x) = L0R0
 Li = Ri-1
 Ri = Li-1⊕f(Ri-1, Ki)
 y = IP-1(R16L16)
 Note that, as usual:
R16 = L15⊕f(R15, K16)
L16 = R15
11

Final Permutation
 The final permutation is the inverse of the initial
permutation; the table is interpreted similarly.
12

The Feistel function
 E is an expansion
function which takes a
block of 32 bits as input
and produces a block of
48 bits as output.
 16 bits appear twice, in
the expansion
13

S-Box
 S-boxes are the only non-linear elements in
DES design.
 S = matrix 4x16, values from 0 to 15.
 B (6 bit long) = b1b2b3b4b5b6
 b1b6  r = row of the matrix (2 bits:
0,1,2,3)
 b2b3b4b5  c = column of the matrix (4
bits: 0,1,…15)
 C (4 bit long) = Binary representation of S(r,
c).
14

DES Key Schedule
15

DES Weak keys
 DES has 4 weak keys (64-bit)
 01010101 01010101
 FEFEFEFE FEFEFEFE
 E0E0E0E0 F1F1F1F1
 1F1F1F1F 0E0E0E0E
 Using weak keys, the outcome of the Permuted Choice
1 (PC1) in the DES key schedule leads to round keys
(K1---K16) being either all zeros, all ones or alternating
zero-one patterns
 Since all the sub keys are identical, and DES is a
Feistel network, the encryption function becomes self-
inverting; that is, encrypting twice with a weak key K
produces the original plaintext.
16

Triple DES
 TDES applies the Data Encryption Standard (DES)
cipher algorithm three times to each data block.
 The original DES cipher's key size of 56 bits was
generally sufficient when that algorithm was designed, but
the availability of increasing computational power
made brute-force attacks feasible. Triple DES provides a
relatively simple method of increasing the key size of
DES to protect against such attacks, without the need to
design a completely new block cipher algorithm.
17

TDES
 Use three different keys
 Encrypt: C = EK3 [ DK2 [ EK1 [P] ] ]
 Decrypt: P = DK1 [ EK2 [ DK3 [C] ] ]
18

TDES Keying options
 The standards define three keying options:
 Keying option 1: All three keys are independent.
 Keying option 2: K1 and K2 are independent, and K3 = K1.
 Keying option 3: All three keys are identical, i.e. K1 = K2 = K3.
19

TDES Keying Options
 Keying option 1 is the strongest, with 3 × 56 = 168 independent
key bits.
 Keying option 2 provides less security, with 2 × 56 = 112 key bits.
This option is stronger than double DES, e.g. with K1 and K2,
because it protects against meet-in-the-middle attacks.
 Keying option 3 is equivalent to DES, with only 56 key bits. This
option provides backward compatibility with DES, because the
first and second DES operations cancel out.
20

Uses of TDES
 The electronic payment industry uses Triple DES and
continues to develop and promulgate standards based
upon it (e.g. EMV, Europay, VISA, Master-card).
 Microsoft OneNote, Microsoft Outlook 2007 and
Microsoft System Centre Configuration
Manager 2012 use Triple DES to password protect user
content and system data.
21

Advanced encryption standard
(AES)
 The Advanced Encryption Standard (AES), also referenced
as Rijndael[3] (its original name), is a specification for the
encryption of electronic data established by the U.S. National
Institute of Standards and Technology (NIST) in 2001.
 AES is also symmetric key algorithm.
 ES is based on a design principle known as a substitution-
permutation network, combination of both substitution and
permutation, and is fast in both software and hardware.
 AES is a variant of Rijndael which has a fixed block size of
128 bits, and a key size of 128, 192, or 256 bits.
22

AES
 AES operates on a 4×4 column-major order matrix of bytes,
termed the state.
 The key size used for an AES cipher specifies the number of
repetitions of transformation rounds that convert the input,
called the plain text, into the final output, called the cipher
text.
 10 cycles of repetition for 128-bit keys.
23

AES- Steps
 Key Expansions—round keys are derived from the cipher
key using Rijndael's key schedule.
 Initial Round
 Add Round Key
 Rounds
 Sub Bytes
 Shift Rows
 Mix Columns
 Add Round Key
 Final Round
 Sub Bytes
 Shift Rows
 Add Round Key 21-12-2016VTU PG Centre, Belgavi
24

AES
25

AES-Add Round Key
 Add Round Key: each byte of the state is combined with a
block of the round key using bitwise xor.
26

Sub Bytes
 Sub bytes: a non-linear substitution step where each
byte is replaced with another according to a lookup tab.
 In the Sub byte step, each byte a(i , j) in
the state matrix is replaced with a Sa(i , j) using an 8-
bit substitution box, the Rijndael S-box.
 The S-box used is derived from the multiplicative
inverse over GF(28).
27

AES: Shift Rows
 Shift Rows: a transposition step where the last three rows of the
state are shifted cyclically a certain number of steps.
 In shift rows step operates on the rows of the state, it cyclically
shifts the bytes in each row by a certain offset.
 For blocks of sizes 128 bits and 192 bits, row n is shifted left circular
by n-1 bytes.
 For a 256-bit block, the first row is unchanged and the shifting for the
second, third and fourth row is 1 byte, 3 bytes and 4 bytes
respectively
28

AES: Mix Columns
 Mix Columns: a mixing operation which operates on
the columns of the state, combining the four bytes in
each column.
29

Uses of AES
 AES has 10 rounds for 128-bit keys, 12 rounds for 192-bit keys,
and 14 rounds for 256-bit keys. By 2006, the best known attacks
were on 7 rounds for 128-bit keys, 8 rounds for 192-bit keys, and
9 rounds for 256-bit keys.
 Used in US Government to encrypt classified and Non-classified
data
 Mobile Phones (Black Berry etc., )
 Wi-Fi Routers
 Network Adapters
30

Implementation Results of DES
31

Implementation Results of
TDES
32

Proposed Modified TDES
33

Proposed Modified DES
34

Conclusion
 By comparing the encryption standards, it is clear that AES is
best among all the standards, We can see that DES can be
used by cascading for three times which provides more
efficiency compared to normal DES architecture.
 We developed VHDL & VERILOG code for DES, TDES and
AES compared all the technical specifications and also
working to develop the proposed designs to reduce area
which in turn reduces power dissipation and cost.
35

References
 "Encryption Basics | EFF Surveillance Self-Defense Project." Encryption
Basics | EFF Surveillance Self-Defense Project. Surveillance Self-Defense
Project, n.d. Web. 06 Nov. 2013.
 United States Department of Commerce (1999-10-25). "FIPS PUB 46-3:
Data Encryption Standard (DES)". Retrieved 2014-01-20.
 New Comparative Study Between DES, 3DES and AES within Nine
Factors. JOURNAL OF COMPUTING, VOLUME 2, ISSUE 3, MARCH
2010, ISSN 2151-9617. Retrieved 2012-12-01
 NIST Special Publication 800-78-3, Cryptographic Algorithms and Key
Sizes for Personal Identity Verification, December 2010
 Daemen, Joan; Rijmen, Vincent (March 9, 2003). "AES Proposal:
Rijndael". National Institute of Standards and Technology. p. 1. Retrieved 21
February 2013.
 Distinguisher and Related-Key Attack on the Full AES-256".Advances in
Cryptology – CRYPTO 2009. Springer Berlin / Heidelberg. pp. 231–
249.doi:10.1007/978-3-642-03356-8_14. ISBN 978-3-642-03355-1.
36

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