On the security defects of an image encryption scheme

Abstract

This paper studies the previous termsecuritynext term of a recently-proposed chaos-based previous termimagenext term encryption scheme and points out the following problems: (1) there exist a number of invalid keys and weak keys, and some keys are partially equivalent for encryption/decryption; (2) given one chosen plain-previous termimage,next term a subkey K10 can be guessed with a smaller computational complexity than that of the simple brute-force attack; (3) given at most 128 chosen plain-previous termimages,next term a chosen-plaintext attack can possibly break the following part of the secret key: View the MathML source, which works very well when K10 is not too large; (4) when K10 is relatively small, a known-plaintext attack can be carried out with only one known plain-previous termimagenext term to recover some visual information of any other plain-previous termimagesnext term encrypted by the same key