Efficient mutual data authentication using manually authenticated strings

Question

1. What are the contributions mentioned in the paper "Efficient mutual data authentication using manually authenticated strings: extended version" ?

2. What is the simplest way to verify that h is u-almost universal?

3. what is the simplest way to prove that a protocol family is asymptotic?

4. How many bits can be used to protect authenticity?

Accepted Answer

As a solution, the authors propose an asymptotically optimal protocol family for data authentication that uses short manually authenticated out-of-band messages.. Compared to previous articles by Vaudenay and Pasini the results of this paper are more general and based on weaker security assumptions.. In addition to providing security proofs for their protocols, the authors focus also on implementation details and propose practically secure and efficient sub-primitives for applications.

Accepted Answer

If the authors compress kb in some manner, i.e., compute h(ma||mb, ka, kb) = h0(ma||mb, ka)⊕h1(mb, kb) then theresulting hash function is only εu-almost universal.

Accepted Answer

If the authors assume asymptotic optimality from the protocol family, then the authors can show that for large enough k, oob(m, rr , rs) is almost uniform w.r.t to rr and rs, and with high probability only a single value oob(m, rr, rs) leads to acceptance.

Accepted Answer

The authors explicitly assume that ≤ 30, since for sufficiently large (say 160 bits) one can use collision resistant hash functions to protect authenticity, e.g., send oob = h(m).

Accepted Answer

Since the source and destination of OOB messages together with the time uniquely reveal the corresponding Mana IV or MA–DH instance, it is straightforward to verify that honest Alice and Bob accept ma||m̂b = m̂a||mb or (sida, keya) = (sidb, keyb) with probability at most ε. Otherwise, the authors can simulate the surrounding computational context and break a stand-alone Mana IV or MA–DH protocol instance with larger probability than ε.

Accepted Answer

A protocol family is asymptotically optimal if it is possible to choose sub-primitives so that security level reaches asymptotically 2− , see App.

Accepted Answer

It is straightforward to verify that Inequality (11) forces uniform convergence w.r.t. the (dynamically changing) set of messages {m : m = m oob} or otherwise the collision attack implies εk → 2− .

Accepted Answer

Theorem 5. Let {πk} be an asymptotically optimal and correct protocol family, let probability Pr [·|πk] be taken over honest runs of πk and let two-oob denote the event that more than one value of oob lead to acceptance.

Accepted Answer

As A may totally break the Mana IV protocol on ε2 fraction public parameters pk and do nothing for other values of pk, the authors cannot get a better bound than Pr [d-forge ∧ γ ≺ β] ≤ εb · Pr [γ ≺ β] + ε2 with black-box reductions.

Accepted Answer

An execution path is almost normal (denoted as norm) if the second round is completed before A starts the third round, i.e., α, α̂, β, β̂ ≺ γ, γ̂.

Efficient mutual data authentication using manually authenticated strings

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Most frequently asked questions

1. What are the contributions mentioned in the paper "Efficient mutual data authentication using manually authenticated strings: extended version" ?

2. What is the simplest way to verify that h is u-almost universal?

3. what is the simplest way to prove that a protocol family is asymptotic?

4. How many bits can be used to protect authenticity?

5. What is the way to verify that a mana IV or MA–DH instance is?

6. What is the way to determine the security level of a protocol?

7. what is the simplest way to prove that Inequality forces uniform convergence?

8. what is the simplest way to prove that a protocol family is optimal?

9. What is the way to get a better bound?

10. What is the normal execution path for the two different protocols?

Figures

Citations

Seeing-is-believing: using camera phones for human-verifiable authentication

Usability analysis of secure pairing methods

HAPADEP: Human-Assisted Pure Audio Device Pairing

Efficient mutual data authentication using manually authenticated strings

Secure ad hoc trust initialization and key management in wireless body area networks

References

Non-Interactive and Information-Theoretic Secure Verifiable Secret Sharing

Entity authentication and key distribution

Encrypted key exchange: password-based protocols secure against dictionary attacks

A Practical Public Key Cryptosystem Provably Secure Against Adaptive Chosen Ciphertext Attack

Non-malleable cryptography

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