year = 2001
}
-@proceedings{DBLP:conf/ih/2001,
- editor = {Ira S. Moskowitz},
- title = {Information Hiding, 4th International Workshop, IHW 2001,
- Pittsburgh, PA, USA, April 25-27, 2001, Proceedings},
- booktitle = {Information Hiding},
- publisher = {Springer},
- series = {Lecture Notes in Computer Science},
- volume = {2137},
- year = {2001},
- isbn = {3-540-42733-3},
- bibsource = {DBLP, http://dblp.uni-trier.de}
-}
@inproceedings{DBLP:conf/ih/KimDR06,
added-at = {2007-09-20T00:00:00.000+0200},
series = {Lecture Notes in Computer Science},
timestamp = {2007-09-20T00:00:00.000+0200},
title = {Modified Matrix Encoding Technique for Minimal Distortion Steganography.},
- url = {http://dblp.uni-trier.de/db/conf/ih/ih2006.html#KimDR06},
+ url = {http://dblp.uni-trier.de/db/conf/ih/ih206.html#KimDR06},
volume = 4437,
year = 2006
}
\JFC{comparer aux autres approaches}
+
\subsection{Steganalysis}
\end{table}
-\JFC{Raphael, il faut donner des résultats ici}
\ No newline at end of file
one is practically enlarged untill its size is at least twice as many larger
than the size of embedded message.
+Edge Based Image Steganography schemes
+already studied~\cite{Luo:2010:EAI:1824719.1824720,DBLP:journals/eswa/ChenCL10,DBLP:conf/ih/PevnyFB10} differ
+how they select edge pixels, and
+how they modify these ones.
+
+First of all, let us discuss about compexity of edge detetction methods.
+Let then $M$ and $N$ be the dimension of the original image.
+According to~\cite{Hu:2007:HPE:1282866.1282944},
+even if the fuzzy logic based edge detection methods~\cite{Tyan1993}
+have promising results, its complexity is in $C_3 \times O(M \times N)$
+whereas the complexity on the Canny method~\cite{Canny:1986:CAE:11274.11275}
+is in $C_1 \times O(M \times N)$ where $C_1 < C_3$.
+\JFC{Verifier ceci...}
+In experiments detailled in this article, the canny method has been retained
+but the whole approach can be updated to consider
+the fuzzy logic edge detector.
+
+Next, following~\cite{Luo:2010:EAI:1824719.1824720}, our scheme automatically
+modifies canny parameters to get a sufficiently large set of edge bits: this
+one is practically enlarged untill its size is at least twice as many larger
+than the size of embedded message.
\subsubsection{Security Considerations}
polynomial time.
+\subsubsection{Security Considerations}
+Among methods of message encryption/decryption
+(see~\cite{DBLP:journals/ejisec/FontaineG07} for a survey)
+we implement the Blum-Goldwasser cryptosystem~\cite{Blum:1985:EPP:19478.19501}
+which is based on the Blum Blum Shub~\cite{DBLP:conf/crypto/ShubBB82} Pseudo Random Number Generator (PRNG)
+for security reasons.
+It has been indeed proven~\cite{DBLP:conf/crypto/ShubBB82} that this PRNG
+has the cryptographically security property, \textit{i.e.},
+for any sequence $L$ of output bits $x_i$, $x_{i+1}$, \ldots, $x_{i+L-1}$,
+there is no algorithm, whose time complexity is polynomial in $L$, and
+which allows to find $x_{i-1}$ and $x_{i+L}$ with a probability greater
+than $1/2$.
+Thus, even if the encrypted message would be extracted,
+it would thus be not possible to retrieve the original one in a
+polynomial time.
--- /dev/null
+import Image as im
+import numpy as np
+from Image import ImageStat as imst
+from numpy import linalg as LA
+
+from math import *
+
+
+
+def sig2(mat):
+ (h,l) = mat.shape
+ L= 1
+ avx = np.empty((h,l))
+ for i in xrange(h):
+ for j in xrange(l):
+ avx[i,j] = np.average([mat[ip,jp]
+ for ip in xrange(max(0,i-L),min(h,i+L))
+ for jp in xrange(max(0,j-L),min(h,j+L))])
+
+ s2 = np.empty((h,l))
+ for i in xrange(h):
+ for j in xrange(l):
+ s2[i,j] = np.average([(mat[ip,jp]- avx[ip,jp])**2
+ for ip in xrange(max(0,i-L),min(h,i+L))
+ for jp in xrange(max(0,j-L),min(h,j+L))])
+ return s2
+
+def nvf(mat):
+ D = 75
+ (h,l) = mat.shape
+ N = np.empty((h,l))
+
+ s2 = sig2(mat)
+ sigmax = np.amax(s2)
+
+ for i in xrange(h):
+ for j in xrange(l):
+ N[i,j] = float(1)/(1+sigmax(i,j)**2)
+
+
+def wpsnr(mati,mato):
+ return 10 * log10( (float(np.amax(mati))/(LA.norm(nvf(mato-mati))))**2)
