1. Image encryption by One time
padding

2. Introduction
 Diverse usage of images
 Need to be transmitted securely over internet
 One time pad or vernam cipher
 Large random key space
 Highly secure and efficient
 Other types: RSA, El gamal
 Triple DES, Blow fish

3. Algorithm
 Chaos function:
Generates complete random values.
Small change in an initial value produces
completely different values from each other.
Example: f(x)= P*x*(1-x)
Increase in P value causes bifurcation and reaches
point of accumulation.

4. Generation of one time pads
 Starting value for the iterations
 Number for decimal places of the mantissa that
are to be supported
 Number of iterations after which the first value
can be picked
 Number of iterations to be maintained between 2
values picked.

5. Encryption methodology
 Global parameters
Indexed key table is built. Key of length 8 has 256
indexes.
 Secret parameters
4 Conditions. Shared using Diffie hellmann or RSA.
 Uses the secret parameters and run the chaotic
function.
 Every pixel of the image is XOR’ed with the
secret key.

6. Analysis
 Key space analysis
Large key space -> secure against brute force
 Statistical analysis
Histogram analysis
Correlation coefficient analysis
 Execution time
Not computational time complex
 Key sensitivity analysis
Avalanche effect.

7. Digital Image encryption based on
chaos and improved DES

8. Introduction
 Images over Internet.
 Many image encryption algorithms
 Chaos based image encryption
 Fast and highly secure image encryption
 Problem: Limited accuracy
 DES encryption: not for image encryption
 Chaos + improved DES: better encryption system

9. DES + Chaotic encryption
 Problems:
 Low speed encryption.
 500 K image data -> 14 seconds for chaotic
 500 K image data -> 467 seconds for DES
 DES lacks key space.
 Brute force attack vulnerable
 Alternate: Triple DES and AES.

10. Improved DES + Chaotic
encryption
 Reduce DES iterations to 4 speed.
 70% improvement in speed
 Security is almost negligible
 Using logistic mapping
 Random generation of keys
 Improves key space
 Tested on computer with celeron M processor
 Proves to be stronger than other image
encryptions.

11. Image encryption based on Henon
chaotic system

12. Introduction
 Similar needs as previous papers.
 Has two stages.
 Positions are shuffled
 Grey values of the image pixels are changed.
 Then the shuffled image is encrypted by Henon’s
chaotic system

13. Arnold cat map
 Is a 2 D chaotic mapping system
 Shuffles the positions in an image.
 For an M*M image Arnold cat map is
 C,D and N are the secret keys.
 Not perfectly secure. Henon encryption system
makes it more secure.

14. Henon encryption system
 Discovered in 1978.
 3 step process:
1. Converted to one dimensional chaotic map. a=
0.3 and b=1.4 makes system secure.
2. From the 1 D, transform matrix is built.
3. Transform matrix XOR shuffled image.
 Decryption obtained by using inverse function.

15. Comparison
 Image encryption by one time padding
Uses vernam cipher. Large random key space and
images are securely transmitted
 Image encryption by chaos system + improved
DES
Uses chaos system and ¼ th size of DES along
with logistic mapping for random generation of
keys.
 Image encryption by Henon chaotic system
Shuffles the image and uses henon encryption
system to make the image secure.

16. Conclusion
 Various types of image encryption techniques.
 Few of them are widely used and few of them are
still questionable.
 One time padding, Improved DES and Henon
encryption on images.
 Widely accepted -> One time padding image
encryption.

17. References
 Image encryption on chaos and improved DES
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arn
umber=5346839
 Image encryption on one time pads
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arn
umber=5591643
 Image encryption on Henon chaotic system
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arn
umber=5054653