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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16
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2answers
885 views

What is the intuition for ECDSA?

I understand DH and ElGamal and RSA encryption/signatures. But when I look at ECDSA (or plain DSA), it seems like the formulas are just pulled out of thin air. I can verify that the algebra used in ...
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1answer
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How do RSA and ECDSA differ in signing performance?

Signature algorithms with elliptic curves have smaller output sizes compared to RSA for the same level of security. What about the processing time to generate a signature ? I've seen figures giving ...
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Proof insecure DSA variant [duplicate]

Consider a variant of DSA in which the message space is $\mathbb Z_q$ and the hash function is replaced by the identity function. (So the second component of the signature is now $s := k^{−1} \...
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1answer
236 views

Security of Fast Two-Party ECDSA Signing

The paper "Fast Secure Two-Party ECDSA Signing" by Yehuda Lindell describes a system in which two parties, $P_1$ (with 1/2 of a share of a long-term ECDSA signing key $x_1$) and $P_2$ (with the other ...
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222 views

ECDSA Message Recovery from Two Encrypted Messages with Signatures and Public Key

I am currently working on a problem where I have two encrypted messages, their corresponding signatures, and the public key. Furthermore, the value of $r$ is the same in the two signatures. I am ...
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1answer
563 views

What is customizable in ECDSA signature and verification?

Let's say I make a signing and verification ECDSA modules. Signing module receives plain message and outputs signed message. Verification module takes signed message and checks consistency. ...
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1answer
476 views

Can a TLS certificate using ECC secp384r1 as PK algorithm uses RSA for signature

If a TLS certificate public-key algorithm is ECC secp384r1 or ECC prime256v1, is it possible to have RSA as a signature ...
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1answer
341 views

Exactly what RNG weaknesses endanger (EC)DSA?

RFC 6979 defines deterministic variants of (EC)DSA. It states in introduction One characteristic of DSA and ECDSA is that they need to produce, for each signature generation, a fresh random ...
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2answers
258 views

Why ECDSA has its form?

According to Wikipedia, if Alice wants to sign some message, she computes $s = k^{-1} (z + r d_A)$ then sends $(r, s)$ to Bob. I don't understand why they use this particular formula $s = k^{-1} (z + ...
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1answer
203 views

openSSL and ECDSA key format inspection

If I run openssl ec on a key that I have generated with openssl ecparam -genkey I get one extra prefixing 0x00 in the private ...
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Elliptic Curve Digital Signature algorithm fails

I would like to monitor step by step running of ECDSA. Parameters I am working on: The elliptic curve satisfies the equation: $y^2 = x^3 + x + 1$. I picked up the base point $G$ as: $(0, 1)$ Finally,...
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1answer
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DSA: How to calculate 224-bit $q$ for 2048-bit $p$

$p$ is a 2048 bit prime number $q$ is a 224 bit prime number I know that $q$ is a prime divisor of $p-1$, thus $p=1 \bmod q$ but I couldn't write efficient code to calculate this. I can calculate ...
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1answer
360 views

ECDSA Signing and verifying signatures between Python and JS [closed]

I create a signature on js, here jsrsasign Signatures are obtained in the format: ...
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1answer
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Why don't the TLS1.3 cipher suites mention the key exchange and digital signature algorithm in names?

Does it mean both RSA and ECDSA certificates can be used with the same cipher suite?
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1answer
1k views

When would I need DSA as opposed to RSA for digital signature?

The digital signature algorithm encrypts a hash using the senders private key and the receiver's public key. This multiple encryptions is a pretty expensive process since public key encryption is so ...
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2answers
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How does recovering the public key from an ECDSA signature work?

It is possible to recover the public key from an ECDSA signature values $(r,s)$? Please explain how this works.
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1answer
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Regarding Lattice atttacks on ECDSA with a portion of known bits of the nonce k

I am new in the field of cryptography, and I am having some troubles understanding a concept regarding the lattice dimension needed in the attack on ECDSA using several messages with L known bits of ...
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0answers
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How to prove two ECDSA public keys on two different curves are generated from the same private key [duplicate]

I wonder if I provide someone with two public keys from different elliptic curves, is there any way to prove that these two public keys are generated from the same private key without revealing the ...
2
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1answer
110 views

Encrypt your ECDSA signature with NTRU to make them quantum secure, does that work?

I have a general question about quantum security. ECDSA is suppose to be broken by quantum computers. Whilst something like NTRU is suppose to be secure. My question is: if we sign with ECDSA and ...
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0answers
48 views

Linkable ECDSA like signature [closed]

In our process of digital checks for banking - which needs to work online and offline - the receiver needs to know the chain of all generated signatures without consulting an Internet service. In this ...
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1answer
301 views

Why can we not use the group $Z_{p}^{*}$ for cryptography?

Sorry if this is a noob question, but for instance in ECDSA, we start by considering the field $\mathbb F_p$, whose the elements also form a group under multiplication. Why don't we just use this ...
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1answer
188 views

Calculating $K,N,X$ in ECDSA?

I'm confused with the parameter $n$, whether the parameter $n$ is the support point FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F or what? ...
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1answer
3k views

How does the “biased-$k$ attack” on (EC)DSA work?

I recently stumbled across Thomas Pornin's old answer about deterministic (EC)DSA again. There he states the following: Note that $k$ must be generated uniformly in the $[1, q-1]$ range (where $q$...
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1answer
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Can root and intermediate CAs use different asymmetric ciphers and key sizes?

For example, could a root CA use RSA-4096, one intermediate CA use RSA-2048, and another use ECDSA-256 (DH19)?
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2answers
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Offline authenticated encryption for pub/sub

Requirements: only publisher can create messages publisher & subscriber can both read messages and authenticate the publisher offline message transfer messages can't be read by non-participants ...
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Atomic multi-party commitments

Alice and Bob publicly choose the messages $M_A$ and $M_B$ and independently sign them (Alice privately signs $M_A$, Bob signs $M_B$). Now Alice and Bob are looking for a protocol that allows them to:...
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2answers
295 views

Max size for exponent and modulus in RSA and for y, p, q, g in DSS

I'm writing a method in Java to read SSH public key in RFC 4253 format, which, in my case, can be either RSA, or DSS. What I really need is to read exponent and <...
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1answer
155 views

Appending ECDSA signature to a message

I need to authenticate a message sent to an embedded device (which limits my options in terms of just using an existing convention). I can run ECDH/ECDSA on the device and can use SHA-256 as a hash ...
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1answer
443 views

What does ChopMD refer to in the default Go ECDSA package?

If one navigates to the ECDSA Go package page, he can observe that: This implementation derives the nonce from an AES-CTR CSPRNG keyed by ChopMD(256, SHA2-512(priv.D || entropy || hash)) While I ...
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1answer
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ECIES: ECDSA with Kmac and without MAC

I have couple of questions about ECIES. I understand how ECIES work and what I must do if I want to have ECIES with ECDSA for authentication (I understand that for full authentication I have to have ...
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1answer
625 views

ECDSA vulnerability related to recovering private key using same r [closed]

I'm considering this for bitcoin transaction as it uses ECDSA so if the signer generates two signatures suppose s1 and s2. where: I get it that any attacker who have s1 and s2 can recover its private ...
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2answers
529 views

ECIES with ECDSA

I understand how ECIES work. I have a structure of message [alice`s ephemeral public key, MAC tag, ciphertext] I do not understand what I shoud do if I want to ...
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1answer
76 views

Can ECDSA key pairs be added up or multiplied?

I have been given a public key ($y_1=x_1G$), but I don't yet know the private key ($x_1$). At a later time, I will get $x_1$ if some conditions are met. Question: Let's say I generate a new key pair ...
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1answer
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What is the difference between ECDSA and EdDSA

As I understand it, both work with elliptic curves but there seems to be a difference as EdDSA is generally recommended over ECDSA.
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0answers
89 views

Why does ECDSA transmit s and not s^-1? [duplicate]

Given: $eG=P$, $kG=(r,y)$ ECDSA signature transmits (r,s) and does this calculation: $u = \frac{z}{s}$, $v = \frac{r}{s}$ $uG+vP=(r,y)$ means the signature is valid Why do we transmit $s$ and not ...
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1answer
308 views

In ECDSA, why are u and v dividing by s?

The verification algorithm for ECDSA is: $P=e\times G$, $(r,y)=k\times G$, and $s=(z+re)\times k^{-1} \bmod n$, where $P$ is the public curve point, $G$ is the generator point, $e$ is the ...
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2answers
115 views

Private key ECDSA/TLS

Is the private key required once the certificate is hashed and signed? After a certificate is generated, public key is shared within the certificate itself. Is the private key used for any other ...
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1answer
595 views

How fast a middle-class computer can verify assymetric signatures (like ECDSA, RSA etc.)?

I have an idea for a peer-to-peer network that will require every connected peer to verify many symmetric signatures per second. In bitcoin, it's the same - every peer independently verifies ...
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2answers
2k views

BER or DER X9.62 for ECDSA signature

The signature format for ECDSA signatures can be encoded using ASN.1 integers according to X9.62 or it can comprise of two integers with the same size as the key size. In case the X9.62 format is ...
5
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3answers
1k views

Is it usual for a signed message to contain the public key of the signer?

In protocols/systems which use ECDSA, is it common for the message to contain the public key of the message signer? If not, how do recipients know that the message has been signed by the correct ...
2
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2answers
591 views

Could RSA keypairs be used for cryptocurrency addresses?

A bitcoin address is created from an ECDSA keypair. It is common to use use a hashed version of the public key as the shared address, but the original bitcoin implementation also allowed for using the ...
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1answer
491 views

ECDSA recover on arbitrary values

If I were to supply arbitrary values to an ECDSA recover function on secp256k1, is there some likelihood that the function would fail to return some value for the public key? I am specifically trying ...
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1answer
1k views

Why do we use 1024 / 160 bit primes in DSA?

I am looking at DSA's parameter generation and don't understand why for $p$ a 1024 bit prime is needed if $q$ is chosen as a $160$ bit prime. I thought that the security of DSA relates on the discrete ...
2
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1answer
539 views

Which hash function to be used with DSA 2048

I'm preparing for an examination of an Information Security course at university, but I'm not sure about an explanation I created for a specific exercise. The question is: There are now DSA ...
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1answer
832 views

What is the maximum message size when using ECDSA (specifically secp256k1?

I'm guessing that the message must conform to 256 bits but I was not able to find documentation of any message length limits.
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0answers
229 views

What public-key encryption protocol can use the same key pair as ECDSA?

Assume we wanted to use the same ECDSA public/private key pair (drawn for standard ECC parameters, perhaps P-256) for both its intended use (public-key signature), and for public-key encryption; this ...
0
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1answer
387 views

decoding a Ed25519 key per RFC8032

RFC8032 Edwards-Curve Digital Signature Algorithm (EdDSA) 5.1.3 Decoding states the following: Decoding a point, given as a 32-octet string, is a little more complicated. First, interpret ...
3
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1answer
921 views

Is there a truly safe signing algorithm?

After reading this question, I'm pretty shaken up. A determined attacker with $100 in loose change can crack any RSA key in a couple of hours. After believing that these algorithms would take millions ...
4
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1answer
563 views

How should ECDSA handle the null hash?

In ECDSA, assume your public key is $Q=(x,y)$, then when performing the verification of any message leading to a null hash value (that is $H(M)=0$), the signature $(r,s)=(x,x)$ would always lead to a ...
24
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1answer
11k views

ECDSA, EdDSA and ed25519 relationship / compatibility

I'm trying to understand the relationship between those three signature schemes (ECDSA, EdDSA and ed25519) and mainly, to what degree are they mutually compatible in the sense of key pair derivation, ...

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