Sign up ×
Cryptography Stack Exchange is a question and answer site for software developers, mathematicians and others interested in cryptography. It's 100% free, no registration required.

On page 7 of NIST's views on SHA-3's security requirements and Evaluation of attacks, I see that, at least at this point, NIST planned on offering SHA-3 having eTCR security (defined on page 3):

eTCR: Find $M$ and then for a randomly chosen $r$, find $M’$ and $r’$ s.t. $H_r(M) = H_{r’}(M’), (r,M) ≠ (r’,M’)$ where $H_r$ is the randomized hash.

However, I never saw any subsequent references to the eTCR property for the SHA-3 candidates.

Does SHA-3 have an eTCR mode?

share|improve this question
This property is also known as "enhanced Target Collision Resistance". – Paŭlo Ebermann Nov 27 '12 at 18:17
Do you ask if there is a "standardized" randomized hashing mode of Keccak? – Paŭlo Ebermann Nov 27 '12 at 18:27
Yes. ${}{}{}\:$ – Ricky Demer Nov 27 '12 at 19:14
Doesn't standard CR imply you get eTCR by simply concatenating the randomness and message and then applying the hash? – David Cash Nov 28 '12 at 2:19
Yes. $\:$ Standard CR also implies you get eTCR by using zero bits of randomness $\hspace{1.5 in}$ and just applying the hash to the message. $\;\;$ – Ricky Demer Nov 28 '12 at 6:43

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.