# Format preserving encryption FFX

In FFX mode the format of the ciphertext is same as plaintext. How does it ensure data integrity and authentication? Is there any bit flip attack in FFX mode? Is it malleable?

• It doesn't ensure data integrity. $\:$ It doesn't ensure authentication. $\;\;\;\;$ – user991 May 2 '15 at 8:40
• Just in case somebody gets confused: if a cipher doesn't have integrity and authentication then it doesn't automatically mean that the cipher is malleable. – Maarten Bodewes May 4 '15 at 0:09

• @MaartenBodewes : $\;\;\;$ There would need to be a suitable bijection such that [it and its inverse $\hspace{.62 in}$ can both be efficiently calculated] for that to work. $\:$ I'm pretty sure that that can't always be done. $\hspace{.5 in}$ – user991 May 4 '15 at 1:53