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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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Use partial hash to verify entire hash

I've had an idea about storing parts of SHA256 hashes and I'd like to find out how secure it is, or how much less secure it is than storing the entire hash. For example, users can share this list of ...
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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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How does the user get the private/public key with HMAC based request signing?

I need to implement a HMAC signing of requests and I have read this article which explains the basics of what it is and how to achieve on theory. https://blog.andrewhoang.me/how-api-request-signing-...
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What is the expected number of messages for which Eve can forge the signature in (repeated) Lamport?

Alice and Bob use the Lamport scheme, but Alice uses the same key to sign two messages (of length $n$). Eve intercepts both these messages. What is the expected number of messages (length $n$) Eve ...
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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 do hashes really ensure uniqueness?

This might seem an impractical and unnecessary conversation, but I feel it's something I need to clarify. Especially, as I just got my first developer job in a blockchain startup. So hashes are said ...
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Does the Server Key Exchange sign a hash or text

In TLS 1.2 when using ECDHE_RSA, the ServerKeyExchange message contains a signature over the server's ECDHE public parameters. My question is: Is the signature over ...
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How to determine if a Hash function is preimage resistant?

So I'm trying to solve this problem. There are of course more but I'm trying to figure out how would I even solve this first one in order to do the rest. Any hints or help in the steps would be ...
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1answer
42 views

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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2answers
64 views

The use of Elliptic Curves as part of a blockchain transaction

As I understand it, Elliptic-Curve Cryptography is used in the verification step of a transaction (i.e. when creating a digital signature), but not in the creation and security of a 'block' (when ...
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42 views

Cryptographically secure hash function vulnerable to length extension attacks both to front and to back?

Is there any hash function where both $\text{hash}(m\|k)$ and $\text{hash}(k\|m)$ are vulnerable to length extension, but $\text{hash}(m)$ is itself secure?
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I am new to digital certificate 509V3 concept. can some one please clarify the below points [closed]

I am using RSA 2048 with SHA 256 primitive in certificate: How to verify the user certificate n + 1 with Root certificate n? why it is required to perform Certificate chain verification? How to ...
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424 views

How can one validate with a public key a JWT signature generated with a private key?

As I understand it, a JSON Web Token (JWT) consists of 3 parts: the header, specifying the hashing algorithm to use for the signature; the payload itself; and the signature, which is a hash of the ...
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1answer
124 views

Why is SubtleCrypto API generating different signature for same data?

I am trying to generate key pairs using SubtleCrypto API in javascript and then using the same to sign some data using ECDSA algorithm. Documentation for the same can be found at this link. https://...
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1answer
55 views

Is it safe to hash a packet with a shared secret to prove authenticity?

I am developing an online game, where the server is written in Node.js and the client uses Godot. The issue is that Godot has no cryptographic functionalities (it can only encrypt and decrypt files, ...
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307 views

Security of custom JSON-Object hash

I am currently implementing a signed JSON-Blob, and thus i need to create a hash of any JSON-Object possible. Currently for the hash of the JSON-Object i ended up with the following Java-Code using ...
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1answer
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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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1answer
419 views

How is public key cryptography used for digital signature?

In public key cryptography, there are two different keys used for the encryption and decryption of data . I am wondering how it is used for digital signature
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1answer
33 views

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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81 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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2answers
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Digital signatures with one-way function, can messages be longer than the signature?

Ethereum and Bitcoin both use 512 bit signatures, can the message that is being signed be longer than 512 bit?
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336 views

Does “hash than sign paradigm” apply to ECDSA cryptography?

From wikipedia https://en.wikipedia.org/wiki/Digital_signature#How_they_work and other articles I see that: "There are several reasons to sign such a hash (or message digest) instead of the whole ...
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1answer
239 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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289 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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1answer
88 views

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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1answer
187 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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434 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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2answers
79 views

Reversability of Xor'd Values In Hash?

This may be a dumb question so please forgive me if so, but is a hash function considered one-way even if you have half of an xor'd value? For example say I have the values R and C, both are randomly ...
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2answers
139 views

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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1answer
147 views

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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42 views

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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687 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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1answer
195 views

Is this Bleichenbacher '06 style signature forgery possible? (Or more like, why isn't it?)

I assume that most of you know this, but just for the sake of context; Bleichenbacher's signature forgery (https://www.ietf.org/mail-archive/web/openpgp/current/msg00999.html) basically abuses ...
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2answers
335 views

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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How to strongly reference a file that is signed twice (counter signed)

I am facing an impossible (?) problem but I'd like to find a solution that satisfies cryptographers and the users of my program. My program is able to sign a 'project' (bunch of files). For that I ...
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Rotatable hash-based duplicate check

I want to check duplicates of secret information which is also already encrypted in our database(using ECC algorithm, one of the std curves). plaintexts can be phone numbers, zip codes, etc. Since it'...
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1answer
578 views

What is the difference between signatures and VRF?

For example we have asymmetric signature scheme(RSA or ECC based) and VRF(also can be RSA/ECC based), both of them can be verified using public key of the signer/hasher and also are unique for each ...
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1answer
315 views

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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1answer
298 views

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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0answers
1k views

How to generate signature using SHA256 and verify using RsaSsaPss

I am new to digital signature concept using SHA256 hashing and verify RsaSsaPss : Could anybody please describe in simple steps? Signer feeds data to the hash function and generates hash of data. ...
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1answer
722 views

How to make cookies tamper-proof and secure by using encryption and hash / MAC

Our company has decided to ditch server side sessions in favor of storing authenticated information such as user id and access privilege information in a cookie. Before everyone jumps up and down ...
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How to authenticate indivisual value after applying homomorphic encryption using Paillier homomorphic

Assuming I have three parties in a system: Alice, Bob, and a Server. Alice and Bob needs to aggregate some messages $m1$ for Alice, and $m2$ for Bob. And send the aggregate $m1+m2$ to the Server. I ...
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1answer
474 views

Length extension attack SHA-1 message division with padding problem?

I'm was reading this example for length extension attack given here link When working out, how the extended block length be divisible by 512 (SHA block size). I'...
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1answer
461 views

What is the length of the SHA-1 message digest and how is RSASSA-PSS used for verification?

I am a newbie to cryptography and SHA-1. Currently I am configuring a SHA-1 hash function which takes default length as 128 bits. Is it okay to configure it this way, since I see in most cases SHA-1 ...
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1answer
159 views

PKCS1 v 1.5 Signature questions

I'm crash studying the public key cryptography topic and I have a few questions about how signatures are created. So are digital signatures just encrypted hashes? If that's the case then I can hash ...
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3answers
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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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1answer
223 views

birthday attack again [closed]

Suppose that we have a d-bit hashing function, and assume that the dimensionality of the input space is unbounded. The probability of finding a collision in 2d/2 steps is 1/2, and we call this a “...
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Determining Secret text

Bob has observed a ciphertext $C$ which was sent to Alice, encrypted with RSA. As usual, Alice’s public modulus is n, her public exponent is e, and her private exponent is $d$; so if the secret ...