Cryptography that will remain secure should large-scale quantum computing become feasible. Based on hard problems with no known polynomial-time quantum algorithm (e.g., Shor's algorithm).

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Parameter choice Supersingular Isogeny DH

In “Towards quantum-resistant cryptosystems from supersingular elliptic curve isogenies” by DeFeo, Jao and Plut (PDF), the public parameters are defined as: Supersingular curve $E$, and bases $P, Q$ ...
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154 views

Quantum computing vs AES s-box equation

Do quantum computers have any affect on the ability to solve the non-linear AES s-box algebraic expression, or does solving it still fall under search algorithms (Grover's)? If quantum computer do ...
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185 views

Can Grover's algorithm be parallelized?

Using a quantum computer, Grover's algorithm can search an unordered list of length $N$ in time $\sqrt{N}$. Applied to cryptography this means that it can recover $n$ bit keys and find preimages for ...
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One-Time-Signature based codes

I'm trying to understand the sentence in bold, in the follow paragraph of A new one-time signature scheme from syndrome decoding Keygen: Given a security parameter $\lambda$, choose a suitable ...
3
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1answer
222 views

Can there be a need for 1024-bit (symmetric) encryption?

I think we are all aware of the CAESAR-competition. Now the aim of this competition is to select a (portfolio of) winner(s) which provide authenticated encryption. I'll now assume that the results ...
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How long does it take a quantum computer to brute force AES?

I understand that using Grover's algorithm it only requires $2^{64}$ lookups for a 128 bit AES encryption, leading people to say we need to increase to 256 bit keys. But how long would it actually ...
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1answer
623 views

Implementations of Ntru TLS

Has anyone come across any implementations of Ntru TLS? I'm working a project for uni that does quantum secure encryption. It relies on a mix of Ntru & AES, but I can't find an implementation of ...
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1answer
57 views

Security of MSS

I have started reading about the Merkle Signature Scheme. I am a little confused about why it is believed to be secure against quantum attacks, couldn't the hash function be attacked? What would make ...
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1answer
378 views

Supersingular Isogeny Key Exchange Software [closed]

Are there any optimised implementations of the Supersingular Isogeny Key Exchange by Defeo, Jao, and Plut. It seems like this would be a great drop-in replacement for Diffie-Hellman in both OpenSSL ...
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24 views

CMSS key sizes flexiprovider

I am study the implementation of the Coronado Merkle Signature Scheme using flexiprovider. I want to verify the Table 1 of its paper. Using the flexiprovider, I have written a example for ...
3
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2answers
312 views

Public-key cryptosystems without poly-time quantum attacks

It's well-known that Shor's algorithm can solve integer factorization, discrete logarithm and discrete log over elliptic curves in cubic time. This implies that cryptosystems like RSA, ElGamal, and ...
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3answers
245 views

Does NTRU provide Perfect Forward Secrecy?

Does NTRU provide Perfect Forward Secrecy if the world would use it in an HTTPS connection?
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2answers
187 views

Are there any quantum-resistant symmetric encryption schemes?

It seems that quite a few currently available encryption schemes will possibly be broken by quantum computing. Are there any symmetric encryption schemes that will remain unbroken (either because of ...
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2answers
156 views

PQ Key Exchange based on Elliptic Curve Isogenies

I was reading the Wikipedia article on Post Quantum Cryptography and was interested in opinions as to whether the Supersingular Elliptic Curve Isogeny Diffie-Hellman listed there would be a good Post ...
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1answer
51 views

Winternitz Signature Scheme Verfication

I am reading page 39 in this "Post Quantum Cryptography" book. Why does equation 15 hold? There is no further knowledge about f and you definitely cannot use any power laws. So, why is ...
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0answers
71 views

Name of this attack?

I am studying Merkle tree signature. Let $\sigma=(s,Y_s,\sigma_{\text{OTS}},As)$ be a signature of certain document. Here $s$ is the index of leaf, $Y_s$ is the respectively OTS public key and $A_s$ ...
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4answers
700 views

Alternative to NSA encryption algorithm

I am looking for a strong alternative to elliptic curve cryptography. It should be something that could face quantum computing attacks, but nothing created by the NSA. I heard about isogeny key ...
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2answers
247 views

Post-quantum authenticated encryption

It is well-known that the Grover's algorithm reduces cryptographic strength of symmetric ciphers to a square-root - e.g. AES-256 becomes only 2128 strong. However, these statements are always made ...
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1answer
115 views

What aspect of elliptic curve encryption paradigms makes them especially susceptible to quantum based attack algorithms?

This was a statement made during a talk at today's DFN-CERT conference but unfortunately it wasn't explained further. Can anyone shed light on why elliptic curves are susceptible to quantum based ...
4
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1answer
248 views

McEliece information set decoding attack vulnerability

Wikipedia states that McEliece is open to "information set decoding attack". What is an "information set decoding attack" and how serious is the vulnerability? (is it just a matter of choosing proper ...
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2answers
172 views

NTRU key generation

I've been experimenting with an NTRU open-source C implementation here I've noticed something (potentionally) strange with a certain set of params: NTRU_EES1087EP2 (defined here). When generating ...
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3answers
2k views

How will Cryptography be changed by Quantum Computing?

I realise this isn't a 'yes or no' question, and I apologise for asking something that could be seen as a discussion thread, but I had to ask. I'm currently doing an EPQ in CS (specifically how QC ...
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0answers
126 views

Preventing Quantum Attacks on Cryptography [duplicate]

With the advancement of technology in quantum computing, it's becoming more evident that we need to start thinking about protecting the future integrity of our cryptographic standards. What can we do ...
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1answer
84 views

Post-quantum hybrid encryption

Assume the following simplified protocol: seed = curve25519SharedKey(theirPublicKey, myPrivateKey) sharedKey = scrypt(seed, salt, sufficientlyHardWorkFactors...) cipherText = aes256(sharedKey, ...
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230 views

Are post-quantum cryptographic ciphers *also* secure if the P=NP conjecture holds true?

First of all, I only understand the P versus NP debate on a rather shallow level as I am not a computer scientist. So perhaps the answer to the question is straightforward but if not, I would be ...
5
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1answer
620 views

For a one-time pad, which MAC method is information-theoretically secure?

In the the main post about MAC methods it mentions a few methods: Authenticate And Encrypt: The sender computes a MAC of the plaintext, encrypts the plaintext, and then appends the MAC to the ...
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496 views

How dead is braid based cryptography

Braid groups has drawn the attention of cryptographers for a few years, as a promising platform for post-quantum cryptographic protocols. The security of the proposed schemes mostly relied on ...
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183 views

Is SRP post-quantum secure?

Is SRP-6a post-quantum secure? If it is not post-quantum secure, do any post-quantum secure alternatives similar to SRP-6a exist?
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216 views

Why are we advising PKI if we know that quantum computers will break them? [closed]

DNSSEC, ECDHE, RSA, even SSH and all other important specifications, protocols that we rely on and advise people to use them, they use Public key infrastructure. Question: Why do we still use, ...
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1answer
60 views

FSB Hash Functions and Convetional hash Functions

I'm reading FSB cryptographic hash function and the authors say that security of this function depends on NP-Complete Problem: "Decoding Linear Code Unlike most other cryptographic hash functions in ...
3
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3answers
223 views

Asymmetric algorithm for one time signing of small cleartext

I want to generate a key pair such that the private key can be used once to sign a small message (1024 bytes) at some indeterminate point in the future and the public key can be used to verify that ...
4
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1answer
149 views

Deterministic Rand function for Winternitz One Time Signatures

Suppose you are implementing a Generalized Merkle Signature Scheme, using the Winternitz One-Time Signature Scheme for the node signatures. Furthermore, suppose the implementation is to be stateless ...
4
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2answers
191 views

Merkle Tree High Tree

I'm reading Merkle tree signatures and I like know if the security of the that scheme depends, also, of the high of the tree or only depends that hash function is resistant to collision?
3
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1answer
130 views

Why is Lamport-Diffie secure?

Why is Lamport-Diffie secure? I note that there is a demonstration based on onewayness (in the book postquantum cryptography). But a one way function is not sufficient to ensure that it can not infer ...
2
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1answer
208 views

Generalized Merkle Signatures, SHA-3 and Sakura

Sakura specifies a tree hash mode for e.g. Keccak (SHA-3). Are there any reasons to use the Sakura tree hash mode in a Generalized Merkle Signature Scheme? It seems to me Sakura primarily solves a ...
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157 views

McEliece and cryptanalysis

What is the computational time to break McEliece on a quantum computer? I've seen that polynomial time algorithms exist, but for special conditions. What about the general case?
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143 views

Basic attacks on McEliece; finding S and P

Take a McEliece cryptosystem with public generator matrix $G' = S G P$ where $G$ is a generator of a secret code with known fast decoding (not necessarily a Goppa code over $\mathbb{F}_2$), $S$ is ...
3
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1answer
136 views

What is the quantum-resistant signature scheme with the smallest signature + pubkey?

After playing cat and mouse with an number of quantum-resistant signature schemes and coming up with nothing with small enough signatures, I'm turning to Crypto.SE. I need a quantum-resistant ...
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60 views

space complexity of quantum collision search

Is there a known way to reduce the space complexity of quantum collision search beyond what is offered by the built-in time-space tradeoff, while keeping the time complexity significantly below what ...
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132 views

FHE over the integers - Is that paper's scheme known to be insecure against quantum adversaries?

I was reading the paper Fully Homomorphic Encryption over the Integers, and started wondering if there is a known quantum attack on their main scheme, because There is an efficient quantum attack ...
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2answers
244 views

McEliece key size

There's a lot of references about McEliece key size being the barrier for proper usage of the algorithm, exactly (or roughly) how large are the keys?
4
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1answer
261 views

Long-term data protection, storage of old encrypted traffic and quantum cryptocalipse

Tony Arcieri makes an interesting point in his Imperfect Forward Secrecy article which basically boils down to: large entities such as NSA are storing encrypted internet traffic, also what's to stop ...
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120 views

Is there any restriction in using lossless compression algorithms for huge key sizes?

I'm studying McEliece and Multivariate Public Key cryptographic systems. The main problem here is the huge key size. Is there any restriction in using lossless compression algorithms to fix this ...
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2answers
441 views

How can I simulate and measure brute force hacking using RSA?

I want to implement brute force hacking using RSA. How can I simulate and measure time duration? What software (or software-based simulator) would be needed?
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1answer
175 views

Is the Couvreur et al. polynomial time attack on McEliece practical?

There's a new e-print out on arXiv titled "A Polynomial Time Attack against Algebraic Geometry Code Based Public Key Cryptosystems" by Alain Couvreur, Irene Márquez-Corbella and Ruud Pellikaan: ...
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4answers
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What security do Cryptographic Sponges offer against generic quantum attacks?

In the face of non-quantum attacker, Keccak[r=1088,c=512] with 512 bits of output provides: Collision resistance up to $2^{256}$ operations Preimage resistance up to $2^{256}$ operations Second ...
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0answers
79 views

LogSpace Merkle Traversal

I am studying LogSpace Merkle Tree Traversal algorithm in "Post Quantum Cryptography". I don't understand the Table 1 on page 58. My question is: Why within of the $2^h$ rounds for $NEED_h$ exist ...
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1answer
176 views

Merkle Signature Generation

In the section 2 (page 42) of the book "Post Quantum Cryptography", it says: Then he generates the one-time signature $\sigma_{\text{OTS}}$ of the digest using the $s$-th one-time signature key ...
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1answer
119 views

Merkle signature + PRNG?

In the section 3 (page 44) of the book "Post Quantum Cryptography", it says: Then each one-time signature key must be generated twice, once for the MSS public key generation and once during the ...