[paper] Defending Against Statistical Steganalysis

Topic: Defending Against Statistical Steganalysis
Abstract:
The main purpose of steganography is to hide the
occurrence of communication. While most methods
in use today are invisible to an observer’s senses,
mathematical analysis may reveal statistical anoma-
lies in the stego medium. These discrepancies ex-
pose the fact that hidden communication is hap-
pening.
This paper presents improved methods for informa-
tion hiding. One method uses probabilistic em-
bedding to minimize modifications to the cover
medium. Another method employs error-correcting
codes, which allow the embedding process to choose
which bits to modify in a way that decreases the
likelihood of being detected. In addition, we can
hide multiple data sets in the same cover medium
to provide plausible deniability.
To prevent detection by statistical tests, we preserve
the statistical properties of the cover medium. After
applying a correcting transform to an image, sta-
tistical steganalysis is no longer able to detect the
presence of steganography. We present an a priori
estimate to determine the amount of data that can
be hidden in the image while still being able to main-
tain frequency count based statistics. This way, we
can quickly choose an image in which a message of
a given size can be hidden safely. To evaluate the
effectiveness of our approach, we present statistical
tests for the JPEG image format and explain how
our new method defeats them.


Niels Provos在2001年於10th USENIX Security Symposium發表的“Defending Against Statistical Steganalysis”中提出兩種資訊隱藏的方法，第一個方法是，在PRNG中選取不同的Redundant Bits位置組合，取掩護媒體改變機率最小的組合來藏資訊，讓cover medium 不要改變太多，第二個方法則是error-correcting codes,，將一半的redundant bits用來維持cover-mediun的統計資訊，priori estimate可以快速的算出在維持frequency count based statistic的情況下掩護影像可遷入的最大資訊量，如此一來可以根據message挑選出適當的掩護影像。本篇論文亦刊於2001年的CITI Tech report。

以下是細看的筆記啦

我看過的paper很少
不知道是我沒注意還是真的之前的都沒有提到
原來steganography 也是有分成classical和modern的
雖然之前有看到Modern 這個字在paper上出現
但是我都以為只是某種方法的改進
沒想到和物理有分成古典物理和近代物理一樣
steganography 也是有分成classical和modern的
真是酷斃了
好
我下一篇的paper要看這兩個的比較