A New Method for Ciphering a Message Using QR Code

Abstract

In this paper, we have introduced a new data-hiding algorithm, where message is converted to QR code (Quick Response Code) and generate QR for mask (Key). QR Codes are mainly used to carry or store messages because they have higher or large storage capacity than any other normal conventional 'barcodes'. In the present work the authors have introduced the encryption technique by XORing part (series of bits) of QR message with the same part of QR mask (key) to encrypt any message and then embedding the key into the resulted QR. The resulted QR code may be sent to destination or may be saved for future use. In this encryption method authors have used bit-manipulation, byte-reshuffling and generalized this method. The ciphering method used here has been tested on different plain texts and it was found that the method is unbreakable using traditional cryptanalysis techniques like frequency analysis, plain-text attack, Differential attack, Brute-force attack, etc. The data is encrypted using a symmetric key method, then inserted in QR code, so that data cannot be easily retrieved without adequate authorization / permission.

Full text

Computer Science and Engineering 2016, 6(2): 19-24
DOI: 10.5923/j.computer.20160602.01
A New Method for Ciphering a Message Using QR Code
Sawsan K. Thamer, Basheer N. Ameen*
Computer Science Department, College of Science, Al-Nahrain University, Iraq
Abstract In this paper, we have introduced a new data-hiding algorithm, where message is converted to QR code (Quick
Response Code) and generate QR for mask (Key). QR Codes are mainly used to carry or store messages because they have
higher or large storage capacity than any other normal conventional ‘barcodes’. In the present work the authors have
introduced the encryption technique by XORing part (series of bits) of QR message with the same part of QR mask (key) to
encrypt any message and then embedding the key into the resulted QR. The resulted QR code may be sent to destination or
may be saved for future use. In this encryption method authors have used bit-manipulation, byte-reshuffling and generalized
this method. The ciphering method used here has been tested on different plain texts and it was found that the method is
unbreakable using traditional cryptanalysis techniques like frequency analysis, plain-text attack, Differential attack,
Brute-force attack, etc. The data is encrypted using a symmetric key method, then inserted in QR code, so that data cannot be
easily retrieved without adequate authorization / permission.
Keywords QR code, Cryptography, Security
1. Introduction
In today’s world, security is a big issue and securing
important data is very essential, so that the data cannot be
intercepted or misused for any kind of unauthorized use.
The hackers and intruders are always ready to get through
personal data or important data of a person or an
organization, and misuse them in various ways. For this
reason, the field of cryptography is very important and the
cryptographers are trying to introduce new cryptographic
methods to secure the data as much as possible. Keep his
valuable data like passport information, bank statements,
social security number, etc. with himself/herself all the time,
but he/she is always afraid of doing so because this
information are threatened and can be easily intercepted by
outsiders for misuse. We choose another example; a bank
manager wants to instruct his subordinates about the
process of a huge transaction. If this data is not encrypted
properly, then it can be retrieved by a hacker to reverse the
transaction process to credit a different account. For this
reason, encryption of data and hiding data from unauthentic
usage is very important. This problem can be solved by
encrypting the data and hiding it in a QR Code [1-3], which
can be kept with the person all the time and the QR Code
scanner with a software, using the method in this paper, can
be used to decode with the authentic password the
information saved in it.
* Corresponding author:
basheer_nahiz@yahoo.com (Basheer N. Ameen)
Published online at http://journal.sapub.org/computer
Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved
2. QR Code
QR code (abbreviated from Quick Response Code) is the
trademark for a type of matrix barcode (or two-dimensional
barcode) first designed for the automotive industry in Japan.
A barcode is a machine-readable optical label that contains
information about the item to which it is attached. Four
standardized encoding modes (numeric, alphanumeric and
byte/binary) could be stored as QR for efficient data store.
The QR Code system became popular outside the
automotive industry due to its fast readability and greater
storage capacity compared to standard UPC barcodes.
Applications include product tracking, item identification,
time tracking, document management, and general
marketing. [4]
A QR code consists of black modules (square dots)
arranged in a square grid on a white background, which can
be read by an imaging device (such as a camera, scanner, etc.)
and processed using Reed–Solomon error correction until the
image can be appropriately interpreted. The required data are
then extracted from patterns that are present in both
horizontal and vertical components of the image. [4]
2.1. Design
Unlike the older, one-dimensional barcodes that were
designed to be mechanically scanned by a narrow beam of
light, a QR code is detected by a 2-dimensional digital image
sensor and then digitally analyzed by a programmed
processor. The processor locates the three distinctive squares
at the corners of the QR code image, using a smaller square
(or multiple squares) near the fourth corner to normalize the

20 Sawsan K. Thamer et al.: A New Method for Ciphering a Message Using QR Code
image for size, orientation, and angle of viewing. The small
dots throughout the QR code are then converted to binary
numbers and validated with an error-correcting algorithm.
2.2. Storage
The amount of data that could be stored in the QR code
symbol depends on the data type (mode, or input character
set), version (1, …, 40, indicating the overall dimensions of
the symbol), and error correction level. The maximum
storage capacities occur for 40-L symbols (version 40, error
correction level L) as shown in Table (1) [5, 6]:
Table 1. Maximum character storage capacity (40-L)
Input mode max.
characters bits/char possible characters,
default encoding
Numeric only 7,089 3⅓ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Alphanumeric 4,296 5½ 0–9, A–Z (upper-case
only), space, $, %, *, +,
-, ., /, :
Binary/byte 2,953 8 ISO 8859-1
Here are some samples of QR code symbols:
Version 1 (21×21).
Content:"Ver1"
Version 2 (25×25). Content:
"Version 2"
Version 3 (29×29). Content:
"Version 3 QR Code"
Version 4 (33×33). Content:
"Version 4 QR Code, up to 50
char"
2.3. Error Correction
Codewords are 8 bits long and use the Reed–Solomon
error correction algorithm with four error correction levels.
The higher the error correction level, the less storage
capacity. The following table lists the approximate error
correction capability at each of the four levels as declared in
table (2):
Table 2. Errors correction levels & it’s storage capacity
Level L (Low) 7% of codewords can be restored.
Level M (Medium) 15% of codewords can be restored.
Level Q (Quartile)[7] 25% of codewords can be restored.
Level H (High) 30% of codewords can be restored.
In larger QR symbols, the message is broken up into
several Reed–Solomon code blocks. The block size is chosen
so that at most 15 errors can be corrected in each block; this
limits the complexity of the decoding algorithm. The code
blocks are then interleaved together, making it less likely that
localized damage to a QR symbol will overwhelm the
capacity of any single block.
Due to error correction, it is possible to create artistic QR
codes that still scan correctly, but contain intentional errors
to make them more readable or attractive to the human eye,
as well as to incorporate colors, logos, and other features into
the QR code block [8, 9].
It is also possible to design artistic QR codes without
reducing the error correction capacity by manipulating the
underlying mathematical constructs [10, 11].
2.4. Encoding
The format information records two things: the error
correction level and the mask pattern used for the symbol.
Masking is used to break up patterns in the data area that
might confuse a scanner, such as large blank areas or
misleading features that look like the locator marks. The
mask patterns are defined on a grid that is repeated as
necessary to cover the whole symbol. Modules
corresponding to the dark areas of the mask are inverted. The
format information is protected from errors with a BCH code,
and two complete copies are included in each QR symbol
that is show in figure (1). [12]
BCH code is the abbreviation for
(Bose-Chaudhuri-Hochquenghem) code. A multilevel,
cyclic, error-correcting, variable- length digital code used to
correct errors up to approximately 25% of the total number
of digits. Note: BCH codes are not limited to binary codes,
but may be used with multilevel phase-shift keying whenever
the number of levels is a prime number or a power of a prime
number, such as 2, 3, 4, 5, 7, 8, 11, and 13. A BCH code in 11
levels has been used to represent the 10 decimal digits plus a
sign digit.
The message dataset is placed from right to left in a zigzag
pattern, as shown in figure (2). In larger symbols, this is
complicated by the presence of the alignment patterns and
the use of multiple interleaved error-correction blocks, as
shown in figure (3).
Four-bit indicators are used to select the encoding mode
and convey other information as shown in table (3).
Encoding modes can be mixed as needed within a QR
symbol.

Computer Science and Engineering 2016, 6(2): 19-24 21
Figure 1. Meaning of format information in QR
Figure 2. Message placement within a QR
Figure 3. Larger symbol illustrating interleaved

22 Sawsan K. Thamer et al.: A New Method for Ciphering a Message Using QR Code
Table 3. Encoding modes
Indicator Meaning
0001 Numeric encoding (10 bits per 3 digits)
0010 Alphanumeric encoding (11 bits per 2 characters)
0100 Byte encoding (8 bits per character)
0000 End of message
After every indicator that selects an encoding mode is a
length field that tells how many characters are encoded in
that mode. The number of bits in the length field depends on
the encoding and the symbol version as shown in table (4).
Table 4. Number of bits per length field
Encoding Ver. 1–9 10–26 27–40
Numeric 10 12 14
Alphanumeric 9 11 13
Byte 8 16 16
Alphanumeric encoding mode stores a message more
compactly than the byte mode can, but cannot store
lower-case letters and has only a limited selection of
punctuation marks, which are sufficient for rudimentary web
addresses as shown in table (5). Two characters are coded in
an 11-bit value by this formula: V = 45 × C1 + C2
Table 5. Alphanumeric character codes
Code
Character
Code
Character
Code
Character
Code
Character
Code
Character
00 0 09 9 18 I 27 R 36 Space
01 1 10 A 19 J 28 S 37 $
02 2 11 B 20 K 29 T 38 %
03 3 12 C 21 L 30 U 39 *
04 4 13 D 22 M 31 V 40 +
05 5 14 E 23 N 32 W 41 –
06 6 15 F 24 O 33 X 42 .
07 7 16 G 25 P 34 Y 43 /
08 8 17 H 26 Q 35 Z 44 :
3. Proposed Algorithm
In our approach, new data-hiding algorithm is introduced.
Where, two QR codes are generated one for the message and
the other for the Key. Then, the two QRs are XORed in a
specific part to encrypt the message. Then the key is
embedded inside the resulted QR Code.
3.1. Algorithm of Convert Plaintext to QR_code
Step 1: write message (text).
Step 2: generate QR code for the message.
Step 3: save QR image as P.
3.2. Algorithm of Convert Key to QR_code
Step 1: write key as numbers or text.
Step 2: generate QR code for the key.
Step 3: save QR image as K.
3.3. Algorithm of get Begin Indies of Data Area in QR
Step 1: start.
Step 2: Do loop to get beginning of data area in plain.bmp
with width i as height j.
Step 3: end.
3.4. Algorithm of Encryption
Step 1: start.
Step 2: load QR image P.
Step 3: load QR image k.
Step 4: define cipher as bitmap file with dimensions width
(wd) & height (hg).
Step 5:Call function to put P(0)(0) to P(i)(j) in cipher(0)(0)
to cipher(i)(j).
Step 6: loop statement x=i
loop statement y=j
cipher(x)(y)=P(x)(y) XOR k(x)(y)
next y,x.
Step7: end.
3.5. Algorithm of Putting Key in Cipher Bitmap File
Step 1: start.
Step 2: binarization each character or number in key as
8bit.
Step 3: loop statement l<key (length)
If (key(l)=255)
Key(l)=254;
Else
Key(l)=1;
End if.
Next l
Step 4: if statement
If (key(l)=255)
Key(l)=253;
Else
Key(l)=2;
End if.
Step 5: end.
3.6. Algorithm of Getting Key from Cipher Bitmap File
Step 1: start.
Step 2: loop statement until key(l)=253 or 2
If (key(l)=254 or 1)
Str=concat(str,’1’);
Else
Str=concat(str,’0’);
End if

Computer Science and Engineering 2016, 6(2): 19-24 23
Figure 4. Encryption and decryption processes
Next l
Step 4: collect each 8bit in str and get character of this
collection.
Step 5: end.
3.7. Algorithm of Decryption
Step 1: start.
Step 2: load QR image c.
Step 3: get width (wd) & height (hg) of c.
Step 4: define plain as bitmap file with dimensions width
(wd) & height (hg).
Step 5:Call function to put cipher(0)(0) to cipher(i)(j) in
plain(0)(0) to plain(i)(j).
Step 6: loop statement x=i
loop statement y=j
plain(x)(y)=cipher(x)(y) XOR key(x)(y)
next y,x.
Step 7: end.
Figure (4) summarizes the encryption and decryption
processes.
4. Testing and Result
The test includes two processes encryption process and
decryption process.
4.1. Encryption Process
For example, choose a message “book” and a key “1”.
Figure (5) illustrates the QRs for message, key & the resulted
QR or final QR image. The final QR is unreadable.
Figure 5. Encryption process
4.2. Decryption Process
The previous example is used for the inverse operation
(decryption). Figure (6) shows the QR codes for resulted QR,
key & Message.
Figure 6. Decryption process

24 Sawsan K. Thamer et al.: A New Method for Ciphering a Message Using QR Code
5. Conclusions
This method could be used in large scope. Since QR codes
could be used for converting information to 2D barcode (QR
code), this method can be used to encrypt any type of
messages or files (numeric, URLs, alphanumeric and
byte/binary) and send it to the receiver safely. Also, the
method enables the user to store important data or
information safely as QR. The information could be
retrieved easily from the QR code using QR reader.
REFERENCES
[1] P. Kieseberg, M. Leithner, M. Mulazzani, L. Munroe, S.
Schrittwieser, M. Sinha, et al., "QR code security," in
Proceedings of the 8th International Conference on Advances
in Mobile Computing and Multimedia, 2010, pp. 430-435.
[2] S. Dey, S. Agarwal, and A. Nath, "Confidential Encrypted
Data Hiding and Retrieval Using QR Authentication System,"
in Communication Systems and Network Technologies
(CSNT), 2013 International Conference on, 2013, pp.
512-517.
[3] S. Dey, "SD-EQR: A New Technique To Use QR CodesTM
in Cryptography," arXiv preprint arXiv:1205.4829, 2012.
[4] D. Chatterjee, J. Nath, S. Dasgupta, and A. Nath, "A new
Symmetric key Cryptography Algorithm using extended
MSA method: DJSA symmetric key algorithm," in
Communication Systems and Network Technologies (CSNT),
2011 International Conference on, 2011, pp. 89-94.
[5] D. Sonawane, M. Upadhye, P. Bhogade, and S. Bajpai, "QR
based Advanced authentication for all hardware platforms,"
International Journal of Scientific and Research Publications,
vol. 4, pp. 1-4, 2014.
[6] M. Bajpai and A. P. Agrawal, "INTEGRATION OF 2D
SECURE BARCODE IN IDENTITY CARDS: WITH
ADDITIONAL SECURITY FEATURES."
[7] O. Sharaby, "Form Meets Function: Extreme Makeover QR
Code Edition," ed: Archived from the original on, 2012.
[8] H. Chan, "How to: Make your QR codes more beautiful,"
Maskable, April, vol. 18, 2011.
[9] R. Cox. (2012). QArt Codes. Available:
http://web.archive.org/web/20150321031237/http://research.
swtch.com/qart.
[10] S. Hore, T. Bhattacharya, and S. B. Chaudhuri, "A Robust
Medical Image Authentication Technique using QR Code and
DWT," International Journal of Computer Applications, vol.
83, 2013.