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Questions tagged [dsa]

The Digital Signature Algorithm (DSA) is a United States Federal Government standard or FIPS for digital signatures. It was proposed by the National Institute of Standards and Technology (NIST) in August 1991 for use in their Digital Signature Standard (DSS), specified in FIPS 186, adopted in 1993. A minor revision was issued in 1996 as FIPS 186-1. The standard was expanded further in 2000 as FIPS 186-2 and again in 2009 as FIPS 186-3.

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What is TPMFail attack

Trusted Platform Module (TPM) is designed as a hardware-based root of trust to protect cryptographic keys even against system based adversaries. Although Intel's firmware based fTPM has FIPS 140-2 ...
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Signing with ECDSA

I am new to ECC. I was reading this post https://andrea.corbellini.name/2015/05/30/elliptic-curve-cryptography-ecdh-and-ecdsa/ I want to know if there is any intuition behind the following formula: $...
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DSA signature generation [duplicate]

I am trying to implement given DSA signature generation instructions in python, there are few instructions that I couldn't understand in step 3 and 4. Let m be an arbitrary length message. The ...
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Attack on DSA modification with bad hash function

Given a (bad) modification of DSA where the hash function is the identity ($H(m)=m$), I am now supposed to design an attack. So $(m, (r,s))$ are given and I should be able to create a legit signature $...
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Does the size of a ECDSA key determine the hash algorithm?

I am a bit lost in understanding what I read on authentication, signature, etc. For instance, is the size of the ECDSA keys produced by ssh-keygen -t ecdsa -b 256 ...
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What is the recommended minimum key length for ECDSA signature

I want to identify the proportion of certificates that use unrecommend ECDSA key length for TLS certificates based on some data I collected. By looking at a standard like NIST for example, I find ...
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Digital Signature Algorithm for large files - bottle-necked by hash function?

I am new to studying digital signatures like ECDSA and EdDSA, and was curious about something. Lets say hypothetically I want to create a digital signatures of millions of files, with a total size of ...
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DSA Vulnerability in ECDSA

I have implemented a ruby code where i generate private and public keys as below. However, I read few articles [1] on DSA and why it should not be used. I'm not good at cryptography. But still ...
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Encoding a message to a point of curve y^2=x^3+7 and Bitcoin Core

Where should I look at in Bitcoin Core source code to figure out how the signature process transform a message in a curve point? To sign a transaction (message) in the Bitcoin system, you need to ...
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51 views

Elliptic curve one time signatures

This is kind of an academic question, but I wonder if it's possible to build an intentionally one-time signature scheme with elliptic curves? I assume you could do it by supplying ECDSA with ...
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Is ECDSA signature strongly EUF-CMA?

I read, here, that ECDSA signature is EUF-CMA but not SUF-CMA, aka sEUF-CMA (for strong existential unforgeability under adaptively chosen message attacks; see terminology there). Specifically, the ...
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Why doesn't this replay attack work on ECDSA?

I've just started working with elliptic curves and ECSDA in particular, so my understanding of the underlying math isn't great. The thing I'm currently stuck on is trying to understand why replay ...
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Is this API for ECDSA signature verification consistent with NIST test vectors?

I'm trying to use code from "Easy ECC" package (a github project), for ECDSA-verifying a signature. The problem I'm facing is that the API assumes a public key length of N+1, which is different than ...
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How to validate the randomness of ECDSA signature generated using HSM? [migrated]

I need to programmatically(using Python) validate whether the signature generated by using HSM RnG is actually random. Didn't found much content online, hence any help would be appreciated !!
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What is the difference between: ecdsap, ecdsak, and ecdsab in the output of “openssl speed”? What do the letters P/K/B refer to?

openssl speed tests the speed of different protocols on your computer: ...
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Why can’t DSA be used for encryption?

This question at StackOverflow mentions that DSA cannot be used for encryption. But both RSA and DSA can be used to generate public and private keys, right? Then why can't I use the DSA public key to ...
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Complete Set of Test-Vectors for ECDSA secp256k1

Although there are several implementations of ECDSA secp256k1 public available over the internet (the most popular being OpenSSL), it seems that there are no complete set of test-vectors available. ...
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Are there signatures that don't have subliminal channels?

Are there signatures that don't have subliminal channels and also don't require commitments or zero-knowledge proofs? DSA or Schnorr signatures need a nonce which can leak valuable information. There ...
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ECDSA signature verification checks

From Wikipedia: Check that $Q_a$ is not equal to the identity element $O$, and its coordinates are otherwise valid. Check that $Q_a$ lies on the curve. Check that $n*Q_a = O$ Verify that $r$ and $s$ ...
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ECDSA secp256k1 attacks

Are there any known and feasible ECDSA attacks on secp256k1 which can reduce the bit security of the algorithm? For example from 256 bits of security down to 192 bits?
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ECDSA public key point uniqueness [duplicate]

I'm new to ECDSA and there is something I still not sure about. If I have a classic Certificate Authority server that delivers PEM certificates containing public key with ECDSA, I can retrieve the ...
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Elliptic curve cryptography related key attacks [closed]

This question is an extension of Families of public/private keys in elliptic curve cryptography As described above, bitcoin "type 2" deterministic wallets use a root private/public key pair, where ...
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Is it safe to reuse a ECDSA nonce for two signatures if the public keys are different?

We denote the s value of an ECDSA signature $(r, s)$ on a message $m$ as: $s=\frac{H(m)+xr}{k}$ Assume two ECDSA signatures sharing the same nonce $(r, s_1) , (r, s_2)$ on two messages $m_1, m_2$, ...
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ECDSA dA multiplication algorithm [duplicate]

I was looking at this question and i can`t understand this part: QA = dA G = 5 (5,1) = (9,16) I saw that algorithm used for this was Double-and-add algorithm but i didn't get it. Can ...
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How to generate a public key from a private ECDSA key?

Having some specific ECDSA curve and a private key, how does one calculate the public key? I am having a hard time finding the algorithm and equations for it.
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ECDSA signing process

I am trying to learn how ECDSA works. I do not have a background in maths, but have been following a guide which has built me up from finite fields, elliptic curves. I am unable to figure out how a ...
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If I have two ECDSA signatures that use the same k (nonce) but different secret keys, can the secret key be computed? [duplicate]

I have two ECDSA signatures $(r, s_1, z_1)$ and $(r, s_2, z_2)$ where $s_1 = (z_1 + r*x_1) / k$, and $s_2 = (z_2 + r*x_2) / k$. Can $x_1$ & $x_2$ be computed?
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Why do digital signatures use a hash algorithm instead of a checksum?

Based on my knowledge, all digital signature algorithms use a hash function to sign a message, and then encrypt the hash result. So why do these algorithms not use a checksum instead of a hash ...
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Lookup table for DSA/ECDSA/Schnorr multiplication

Something in common to [EC]DSA and related signature schemes like Schnorr is that the most expensive part of signing is calculating $r = g^k$ in the group for some per-signature $k$ of length $b$ bits....
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Are EdDSA algorithms encoded by ASN.1 DER standards?

Is it required, or widely practiced to encode a EdDSA signature as a ASN.1 Sequence? Why or why not? How should you encode a EdDSA signature? I cannot find mention of DER or ASN in the EdDSA RFC. ...
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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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How many unique elements are generated by a variation on the equation in DSA for r?

How many unique elements are generated from the following equation? $$i = (g^x \bmod p) \bmod n $$ where: $g$ has order $q$ $q$ and $p$ are prime numbers $q\mathop{|}p-1$ $n$ is integer number more ...
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Digital signature that is only verifiable by one specific person

I would like to digitally sign a message in such a way that the signature can only be verified by one specific person. Simply encrypting the signature will not work, because that person could then ...
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What would happen in DSA/ECDSA if there were a collision in $r$ but not $k$?

In DSA, the value of $r$ is generated as: $r = (g^k \bmod p) \bmod q$ ECDSA is similar, using the $x$ coordinate of the generator $g$ scalar-multiplied by $k$, again taken modulo $q$. It's well-...
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Are there any Secp256k1 ECDSA test examples available?

Are there any available test cases for testing elliptic curves like secp256k1 (Korblitz curves from http://www.secg.org/collateral/sec2_final.pdf)? For curves like P192 there are for example those ...
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Are DSA and ECDSA provably secure assuming DL security?

Is there proof that the DSA construction, also used by ECDSA, is secure assuming that discrete logarithms in the relevant group representation are difficult?
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DSA: why using mod p mod q and not just mod p

I'd like to know, in DSA we compute several values modulo $p$ and modulo $q$, like $r = (g^k \bmod p) \bmod q$ or $v = (g^{u_1}h^{u_2} \bmod p) \bmod q$. As far as I understand, we want to use two ...
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Why create a subkey in the digital signature algorithm

In the signing step, wikipedia, a subkey is created. A key k is randomly chosen from 1..q-1. What's the use of that k? If the k is to make less exposure to the ...
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Can I use a random number generator with seed for key derivation?

I don't know a thing about cryptography so I'm judging by what I see in APIs docs. I want to use ECDSA or ECDH in my project. And what I know so far about key derivation in this systems is that they: ...
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Known risks for publishing ECDSA public keys and signatures

For an implementation of ECDSA, I'm considering the risks of publishing public keys together with multiple signatures. From what Google tells me, a common pitfall is the use of the same random value ...
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Zero Knowledge Proof of Association

Assuming there are a group of individuals with static ecdsa keypairs, of which the public keys are in a shared database that all of them have access to, how can each participant publish an ephemeral ...
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How to find q in a corrupted ECDSA signauture

I'm doing exam papers for a crypto exam and I've been given a corrupted ECDSA signature. I'm asked to check if the signature is valid (which I know how to do), however, the q value is corrupted and so ...
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If H(m) = 0 for some m, how can a DSA signature be forged?

If we know for some message $m$ that $H(m) = 0$, how can we forge a DSA signature with only the public key? I got that $g^s*r = (g^x)^r$ where $x$ is the private key, but that's one equation with 2 ...
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Getting a key size of DSA/Elgamal certificate

I've tried to get a public key size of DSA/Elgamal PGP certificate. Using the Cleopatra I find out that there is actually two public keys - one with DSA with key ...
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Simple math ECDSA example

I'm trying to setup an ECDSA math example using just integer math and multiply (no EC). The purpose is just to help people understand why this works with out the added complication of understanding ...
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ECDSA signature of a random 32 byte number vs. the hash of the number

I'm working on an application that involves signing a 32 byte random number generated by the OS. Assuming the RNG works as intended, is it safe to sign the random number itself rather than a hash of ...
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EdDSA (Ed25519) is any random number sufficient for a good private key?

Looking at a reference implementation it shows that the key pair generation simply does: read X bytes from RNG and then derive another value from these X bytes thus producing private key with derived ...
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Performance of ECDSA, ECKCDSA and ECGDSA

It is proven that ECDSA algorithms are faster in key and signature generation compared to RSA. In addition, the signatures are much shorter. However, I would like to know the performance difference ...
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Book request about elliptic curves, RSA and DSA

I understand that this question can be hardly downvoted, but so be it if someone gives me really useful references :) I wanna learn difference (deeply) between RSA, DSA, and ECC, especially I am ...
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Is this a secure method of encrypting with authentication?

My goal is to allow two clients to send files securely over an untrusted network without the need for more than one block of information to be sent. Both clients have ECDSA keys of size 256 bits. I'd ...