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Recently, Wang
Camera Sensor Networks (CSNs) are usually built with a large number of inexpensive, small and batterypowered devices. They have been used for a wide variety of applications such as environment monitoring, health monitoring, military sensing and tracking,
As a very complicated phenomenon of nonlinear system, chaos has inherent analogous cryptographic properties such as sensitive to parameter and initial state, which inspires people to apply it into cryptography [
This paper studies the security of Wang
The rest of this paper is organized as follows. Section 2 briefly reviews the Wang
In this cryptosystem, the secret key is (
Writing the value of
A binary sequence
Step 1. Get the start point
Step 2. Divide the plaintext
Step 3. Set
Step 4. Based on the method to generate binary sequences by iterating the logistic map, obtain a 64bit binary sequence
Step 5. Compute the
Step 6. Dividing the ciphertext block
Step 7. If all the plaintexts have already been encrypted, the encryption process is finished. Otherwise, calculate:
The decryption process is almost the same as the encryption one. Just need to replace
According to
In the following subsections, we will perform a chosen ciphertext attack (CCA) and a key stream attack (KSA) on Wang
A chosenciphertext attack [
In the Wang
The simulation results indicate that once
(1) Let
From
To demonstrate this procedure, we fill the chosen corresponding
(2) Decrypt
(3) Calculate
From
Therefore, we can determine the value of
(4) Using
(5) By utilizing
Some simulations are utilized to prove the validity of CCA.
In the Wang
Choose two pair of special messages (
Set
Similarly, when set
Set
From
Decrypt
Set
Encrypt the 64(
Obviously,
Encrypt another 64(
Similarly,
Go to (5) if the length of the key stream sequence is not enough; otherwise, finish the attack.
For
The key stream
Define
Obviously, the
If
By utilizing the known
Compute
As a result,
The Wang
Steps 1–4. They are the same as Wang
Step 5. Compute:
Step 6. Obtain the
Obviously, after the modified process, the feedback value
In this section, we introduce the developed architecture of the secure wireless camera sensor networks by utilizing the proposed chaotic block cipher. Each camera sensor node in the networks is batterypowered and has limited computation and wireless communication capabilities. The sink is a data collection center equipped with sufficient computation and storage capabilities. Camera sensor nodes periodically send the captured images to the sink node. Then the sink nodes transport this information secretly with the data process server via carrier networks. The proposed block cipher is mounting at the carrier network.
It is known that the entropy
When a cipher emits symbols with entropy less than
In order to resist statistical attacks, the ciphertext should possess certain random properties. A detail study has been explored and the results are summarized. The results of the Lena.bmp are used for illustration. For an ordinary image, each pixel is usually highly correlated with its adjacent pixels either in horizontal, vertical or diagonal directions. These highcorrelation properties can be quantified as their correlation coefficients for comparison. To calculate the correlation coefficients, the following formulas are used:
It is clear that there is negligible correlation between these two adjacent pixels in the encrypted image. However, the two adjacent pixels in the original image are highly correlated. The results indicate that the proposed algorithm has successfully removed the correlation of adjacent pixels in the plainimage so that neighbor pixels in the cipherimage virtually have no correlation. That is to say, the new scheme possesses prominent diffusion property.
From the cryptographical point of view, given two distinct keys, even if their difference is the minimal value under the current finite precision, the encryption and decryption results of a good cryptosystem should still be completely different. In other words, this cryptosystem should have a very high sensitivity to the secret key [
Lena.bmp is encrypted by using the secret key (
The same image is encrypted by making the slight modification in the secret key
Again, the same original image is encrypted by making the slight modification in the secret key
The same original image is encrypted by making the slight modification in the secret key
Finally, the correlation coefficients between the corresponding pixels of the four ciphertexts A, B, C and D are computed and filled into
It is clear from the
Another cryptographical property required by a good cryptosystem is that the encryption should be very sensitive to plaintext,
From the above investigation and study, we can conclude that the lack of security will discourage the use of these algorithms for secure applications. It is advisable that new chaotic cryptosystems take into account some important things: (1) the distribution of the ciphertext should be sufficiently flat in order to resist the statistics attack [
This paper has analyzed the security of a block cipher based on logistic map proposed in [
This work described here was supported in part by the National Natural Science Foundation of China (No.60971104), the Fundamental Research Funds for the Central Universities (No. SWJTU09ZT16), the Science & Technology Key Plan Project of Chengdu (No.10GGYB649GX023) and the Foundation of Southwest University for Nationalities (No.09NYB002 and Y201008).
Block diagram of Wang
System architecture of the camera sensor network.
Correlation of the adjacent pixels (1–3)are plaintext and (4–6) are ciphertext.
Bitwise XOR of two ciphertexts.
Decryption of C1 using
1  EAFA4D22D326D40C  35  10  5E0AEF19A566A729 
2  2960D4C5E768138D  36  03  D6E5053AF966B07E 
3  C716165410ACD847  12  1D  EF5FCAE1DB5FA883 
4  3C991CA5F1E8FCC6  20  2E  4246A2AAADA975E2 
Decryption of C2 using
1  F11ED8CA5F72155E  35  10  5E0AEF19A566A729 
2  8A99683495FDBAAB  36  03  D6E5053AF966B07E 
3  CC1E07D524E0E7A1  12  1D  EF5FCAE1DB5FA883 
4  D9D58D603B600C1E  20  2E  4246A2AAADA975E2 
The chosen
Chosen

Chosen
 

1  218A916626E5DA55  28  00000000000000DC  0000000000001C00 
2  BA53340E52524733  45  00000000000000ED  0000000000002D00 
3  2C2CE7EEB40BA7EC  63  00000000000000FF  0000000000003F00 
4  B19F2A8A8BBAB8BD  62  00000000000000FE  0000000000003E00 
Decrypt the chosen





1  A7F55E0AEF19A566  BB295E0AEF19A566  1CDC000000000000  16  5E0AEF19A566A729 
2  ABA16BD9AC1F83AC  ABB79D59AC1F83AC  0016F68000000000  25  B3583F075957423A 
3  2B876D414E8FBD7F  2B8762BE8E8FBD7F  00000FFFC0000000  34  3A3EF5FCAE1DB5FA 
4  6A2A9568E24C2424  6A252AE8E24C2424  000FBF8000000000  26  A389309091A8AAAB 
Entropy test result.
Test file  Lena  Text file  Video file 

Ciphertext entropy  7.9923  7.9981  7.9919 
The correlation coefficients of the adjacent pixels.
Horizontal  0.98448  0.0031261 
Vertical  0.94878  0.0057563 
Diagonal  0.96787  0.0130690 
The correlation coefficients of the ciphertexts.
Ciphertext A  Ciphertext B  0.00296 
Ciphertext A  Ciphertext C  0.00137 
Ciphertext A  Ciphertext D  0.00429 
Ciphertext B  Ciphertext C  0.00153 
Ciphertext B  Ciphertext D  0.00194 
Ciphertext C  Ciphertext D  0.00296 