  Recently, an image encryption scheme based on chaotic standard and logistic
maps was proposed by Patidar et al. It was later reported by Rhouma et al. that
an equivalent secret key can be reconstructed with only one
known/chosen-plaintext and the corresponding ciphertext. Patidar et al. soon
modified the original scheme and claimed that the modified scheme is secure
against Rhouma et al.'s attack. In this paper, we point out that the modified
scheme is still insecure against the same known/chosen-plaintext attack. In
addition, some other security defects existing in both the original and the
modified schemes are also reported.
