Questions tagged [hash-signature]

Hash-based digital signatures, such as Lamport one-time signatures, are digital signature schemes based on a (non-trapdoor) one-way function such as a cryptographic hash. Such schemes are expected to remain secure even against attacks using quantum computers.

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Digital signature from hashing encrypted webpage

I'm studying for the Security+ exam with the help of Total Seminars' Udemy course and in one video they claim that a digital signature is generated by encrypting a message with the sender's private ...
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Cryptographic function that can 'pack' numbers

Is there a cryptographic algorithm that can 'pack' a bunch of strings/numbers and "confirm" if a string/numbers exists (later in the code) while keeping the output hidden? For example, I have ...
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Exploiting weak hash functions in RSA-PSS

I'm just trying to understand how a Weak/broken hash can break RSA-PSS or any other signature/encryption that uses it. I know you can forge another message that has the same hash but that message ...
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Is Lamport OTS improved by using HMAC?

One problem with Lamport OTS is that the attacker can repeatedly try random inputs and there is a chance that a hash of a random input will match one of a large set of public keys, reducing the ...
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Understanding example of ECDSA P256

I am new to cryptography, I found the below Example on a nice website, but I am not able to understand the most of the terms used (H:Hash, K:Random number,E=?, Kinv=?,Rx=?=RY?,R=Private key?,D?,S? ...
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Using digital signature to reduce storage requirement

Below question is a part of my assignment and I was completely clueless about where to start from. So, I am posting it here for the purpose of getting hints/resources to help me get started. $ \ '' $...
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Best practice to hash multiple attributes

I have to generate a signature for concatenation of multiple independent values say A | B | C. Two options are : concatenate all attributes and generate the hash. Then Sign hash. $$ signature = Sign\...
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55 views

Simple: Hash Into a Prime Field

If I have some bytes, and I want to compute a secure hash into a prime field which is 300 bits long I can: Use a nice hash, like sha3_512, and then modulo my prime field (introduces some bias). ...
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Quantum Secure Signing Algorithm with a 256 bit signature & key. Am I missing anything? Can I remove tradeoff?

So I was looking at Lamport signatures and trying to figure out if there is a way to reduce the key size and signature. I stumbled across something that is tiny (125 times smaller signatures and 500 ...
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Are there any hash functions that are commutative yet secure for ordered lists?

I'm looking for a hashing function that can combine random numbers together in any order yet still find the same value. But it needs to be secure against hackers. The idea is if I'm hashing together: ...
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167 views

RSA Signing: SHA512 incompatible with PSS?

I am wrapping the RSACng class from the .Net API. Whilst unit testing, I run checks against an array of possibilities: Key Size = 1024, 2048, or 3072 bits Padding ...
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What is the public key and signature sizes for XMSS?

This is a follow-up to a recent question of mine. I am looking to find the public key and signature sizes for the XMSS signature scheme, in terms of the XMSS parameters (length $\ell$, height $h$ and ...
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XMSS^MT private key size

I'm doing some comparison on hash-based signature schemes. I am reading about one of the most recent schemes, XMSS^MT, and trying to figure out its actual public and private key sizes for concrete ...
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What's the difference between a hash chain, transaction chain and a blockchain?

Can anyone explain to me what the difference is between a hash chain, transaction chain and a blockchain?
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Advantages and disadvantages of hash-based signatures

We know hash-based signatures (Winternitz signature, HORS(T) signature) that are quantum-safe and efficient. They can be stateful or stateless, one-time or multiple-time. But why are they not widely ...
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Tuning the signature size of Sphincs+

If I only need a small number of signatures (perhaps $2^{10}$) for the lifetime of my key pair, how would I calculate the consequent signature size? Unfortunately managing state for an LMS or XMSS ...
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113 views

How secure is a hash based signature scheme after signing assuming quantum computers?

Consider a hash based signature scheme that requires taking the $k$-bit hash of an arbitrary length message to be signed (e.g. Lamport one-time signature scheme). My understanding is, assuming that ...
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Difference between XMSS and MSS-SPR

I am currently studying stateful hash based signatures. In the XMSS paper the authors claim that XMSS signatures are 4 times smaller than those of MSS-SPR. However I do not get how it is possible, ...
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How is SPHINCS Hash-based signature “stateless”?

I really hope someone can help me with these questions related to SPHINCS. I am trying to understand the concept of “stateless” vs. “stateful” signature scheme which is the basis of SPHINCS. I went ...
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Signing a message using SPHINCS Hash-based Signature scheme

I have questions on “SPHINCS: practical stateless has-based signature” by Bernstein et al. And I really hope that someone can help me with it. To help me understand it, I read the https://...
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How does the KeyGen of Merkle's improvement of Lamport's OTS work?

In his paper [1] on page 17 and 18, Merkle proposes an improvement on Lamport's OTS by only signing the 1's in the message in combination with a checksum of the amount of 0's in the message. I get the ...
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Are there any hash-based multisignature schemes?

Are there any hash-based signature schemes which would let two (or more) people sign the same message without increasing the size of the signature linearly? For my purposes, it is fine if the scheme ...
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In W-OTS, could you XOR all public keys?

Since the signatures all generate the public keys, those can be derived from sig and proven by pre-commited XOR of every pub key compared with XOR of every signature end hash.
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In W-OTS, is it trivial to forge smaller N values?

Just read about W-OTS, since the signature is the private key hashed 256-N times, is it trivial to forge a signature with a smaller vale for N when having access to original signature? I.e. just hash ...
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121 views

SPHINCS and HORST: can we sign the same message twice?

I was reading about SPHINCS which uses layers of WOTS+ trees and a bottom layer of HORST trees. HORST is a few time signature scheme, using a selection function you can sign at least twice without ...
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Basic question on hash-based signature scheme

If a hash-based signature schemes such as W-OTS is used, do we still need public key based certificates to prove ownership of a public key? I understand that hash-based signatures are one of the ...
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171 views

Does the One-Time Hash-based Signature Scheme render Ring Signatures useless?

On the Bitcoin community, to maintain privacy, they recommend using one-time spend addresses. CryptoNote, Monero et al. prefer Ring Signatures to maintain that privacy. There are some issues regarding ...
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For a hash over a finite space without size reduction, is a public permutation sufficient?

Suppose the application is a Lamport signature scheme. Is the following a secure hash $\{0,1\}^n \rightarrow \{0,1\}^n$? $$ H(x) = x \oplus P(x) $$ where $P$ is a public permutation that permutes an ...
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Why does WOTS+ need a checksum during signing operation?

I was reviewing WOTS+ scheme for consideration in our private blockchain, and noticed that it had a small overhead of calculating a checksum as seen in the following pseudocode excerpt from the ...
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How many messages before Sphincs(+) becomes insecure?

How many messages would it take until the success probability of a forger becomes $1/2$? $1/4$?
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157 views

Why is WOTS-type signature schemes OTS?

I'm sure I've missed something super trivial, but why are WOTS-type schemes one-time? I've been looking into hash-based schemes, and I feel like I understand WOTS quite well (specifically I have ...
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Can this hash-based, short signature scheme work, given a decentralized log of messages as a primitive?

Suppose we had a decentralized log of messages, i.e., an ever-growing array of information on which anyone could append arbitrary data to. Given such primitive, could a party broadcast authenticated ...
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Convert a state-dependent hash-based signature scheme into a stateless message-dependent one

Suppose we have an XMSSMT instance that is capable of signing up to 2^60 messages securely when given some state-dependent information, I could envision making it stateless as follow: Hash the ...
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162 views

Bitmasks or seed along with public key in WOTS+ post-quantum signatures

The state of the art hash-based post-quantum signature schemes, like Sphincs and XMSS, are using variations of WOTS (Winternitz OTS), like WOTS+, that require extra random bitmasks along with the ...
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449 views

eXtended Merkle Signature Scheme (XMSS) vs Leighton-Micali Signature (LMS)

Very briefly, how does eXtended Merkle Signature Scheme (XMSS) stack up against Leighton-Micali Signature (LMS)? I'm asking this in the context of my article here.
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518 views

What are the advantages and disadvantages of Merkle signatures over Lamport signatures?

I know they are both hash-based and post-quantum secure, and that Lamport signatures can form the basis for a Merkle scheme, but what do you actually gain over standard Lamport signatures by doing ...
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Smallest 256-bit security hash-based OTS?

What is the smallest hash-based OTS in terms of the sum of the public key and signature which provides 256 bits of security?
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533 views

How to use SPHINCS+?

Based on the NIST submission it looks like the SPHINCS+-256s algorithm comes in at public key sizes of 64 bytes, private key sizes of 128 bytes, and signature sizes ...
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602 views

Difference Between Gravity-SPHINCS and SPHINCS+?

What are the differences between Gravity-SPHINCS and SPHINCS+ from security and practicality standpoints? Are they just different implementations of the underlying SPHINCS algorithms or are they ...
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Blind Hash Signatures?

Is it possible to implement blind signatures with purely hash-based signature algorithms? Any whitepapers, code samples, etc on the subject would be helpful.
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What is a formal definition of strong one-time-secure signatures?

What is a formal definition of strong one-time-secure signatures? I know the Lamport's scheme is one of them, but what is the global definition of it?
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Sequential delayed release of chained HMAC keys for use as asymmetric signature

Iterative hashing of a private random seed can yield keys for use in HMAC, which if revealed publicly in reverse order and on predetermined schedule, can be used in a manner similar to other ...
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847 views

Winternitz One time signature security

There are two versions of Winternitz-One time signature scheme, $W-OTS$ and $W-OTS^+$ Security of both is as following $W-OTS$ is strongly unforgeable under chosen message attacks if $F$ is a ...
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Winternitz hash based signature signing and verification

In Winternitz hash based signature There are two functions $f: \{0,1\}^n \to \{0,1 \}^n$, a one way function and $g: \{0,1\}^* \to \{0,1 \}^n$, cryptographic hash function Key Generation steps ...
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Does still make sense to use SHA1?

I'm working with Arduino and hash-based signatures which are signature schemes that use only hash functions. Due to the constraints of an Arduino I was thinking about using SHA1 as the underlying ...
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How can I generate reasonably short temporary unlock codes?

I need a way to generate temporary unlock codes for an application to use when it can't go online to confirm that its activation subscription is still current. The application needs to able go ...
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Why do we need Collision Resistant Hash Function for the Merkle Tree Signature Scheme?

I am studying Merkle Tree Construction for digital signature. I don't quite understand why we need collision resistant hash function for Merkle tree construction. There are few papers like XMSS that ...
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Is there a signature scheme which doesn't rely on the difficulty of factoring/dlp which generates short signatures?

The Lamport signature scheme, for example, doesn't rely on the difficulty of any problem and it only depends on the existence of one-way functions. Is there an alternative scheme which also doesn't ...
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Why don't crypto-currencies use the Lamport signature scheme?

The Lamport signature scheme is faster, less complex and considerably safer than ECDSA. It's only downside - being only usable once - isn't really a downside when signing transactions, since you could ...
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Why are the bit lengths of keys and digests equal in Lamport signatures?

In Lamport's one time signature scheme: One way function to convert a pseudo random number private key to a public key takes $\{0,1\}^n$ and returns $\{0,1\}^n$. Cryptographic hash function to ...