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 will be the key size for rsa, ecdhe and ecdsa from the cipher suite given? [migrated]

From the cipher suites tls_rsa_with_aes_128_cbc_sha256 and tls_ecdhe_ecdsa_with_aes_128_cbc_sha256 how do I know what will be ...
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ECDSA: with knowledge of private key, can we make signatures with partially chosen content?

In ECDSA, with knowledge of private key, can we make signatures with partially chosen content? Detailing that: In ECDSA (with secp256r1 curve and SHA-256 hash), assume we know the private key, the ...
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Difference between X25519 vs. Ed25519

I am reading https://en.wikipedia.org/wiki/Curve25519 and it states Also in 2018, RFC 8446 was published as the new Transport Layer Security v1.3 standard. It requires mandatory support for X25519, ...
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Why are RSA and ECDSA sign and verification time different?

I would like to know why ECDSA signs faster than how it verifies? On the other hand, why RSA verifies faster than how it signs?
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Can you use ECDSA on pairing-friendly curves?

I'm learning about Elliptic curve cryptography. If I understand right, ECDSA and other algorithms used in ECC are dependent on the curve chosen. So, before you want to use ECDSA, you first have to ...
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Is it possible to safely implement the Signal Protocol (X3DH) without using XEdDSA

In the X3DH specification of the Signal Protocol it mentions having a signed pre-key in the key bundle. This pre-key is signed using the identity private-key. Because the identity private-key is in ...
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How Does Prime Factorization Break ECDSA?

I have heard that ECDSA will be broken in the not-to-distant future (roughly 15-25 years) by Quantum Computers running Shor's Algorithm. However, to my understanding, the only purpose of Shor's ...
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Security problems if ECDH and ECDSA use the same key [duplicate]

Hy! I want to use an EC key for ECDH and ECDSA too. Using the same key does compromise the security of the key in a cryptographic / mathematical sense? I read a lot in this theme, but I found nothing ...
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Difference and relation between ed25519, x25519 and XEd25519 [duplicate]

In my Rust implementation of a messaging system, I'm using currently two cryptographic primitives: ed25519_dalek and x25519_dalek. I use ed25519_dalek for DSA, while x25519_dalek for encryption of the ...
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What information is revealed if we send our points in Projective Coordinates?

Elliptic Curve Cryptosystem has various coordinate systems; like the Affine, Projective, and Jacobian coordinate systems. We prefer not to use the Affine coordinate system during the calculations ...
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Signature Generation Time vs Verification Time

When comparing the RSA-PSS signature algorithm with an elliptic curve based algorithm such as EdDSA, it is clear that signature verification takes less time for RSA than for EdDSA. For signature ...
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Bitcoin ECDSA signature

I am trying to use the ecdsaSign function in ecdsa.c of https://github.com/kvhnuke/Ethereum-Arduino/tree/master/Ethereum-Arduino/libs which is based on the files in the repo https://github.com/...
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What is the ChainOfFools/CurveBall Attack on ECDSA on Windows 10 CryptoAPI

What is the ChainOfFools/CurveBall Attack on ECDSA on Windows 10 CryptoAPI (Crypt32.dll) Could someone provide details?
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Is there any proof for ECDSA signature algorithm?

Related: Is there an interactive version of ECDSA signature protocol like the Schnorr identification protocol?
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Likelihood of signature collision with EdDSA

Taking EdDSA as an example, given the length of a signature is 512-bits for a given data payload, what is the probability of a collision where there is another 512-bit value that is also a valid ...
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Signing a secret key with ECDSA

Assume Alice and Bob both separately come into possession of the same randomly generated 256 bit secret key. Alice has Bob's public ECDSA key. Alice wants to verify that Bob has possession of the ...
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DSA: If signature is accepted then signature is correct

In one my classes, I have the following exercise: Prove that, in the DSA signature scheme, if a DSA signature is accepted, it is also correct. How would I go about proving this? In cryptography, ...
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ECDSA Private Key from SSS

I have all of the Shamir's secret shares required to Lagrange-interpolate f(0), which represents an ECDSA private key. The field of this object is ...
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Complexity upper bound MFC DSA with linear S-Box

in advance, excuse my eventuelly bad english. It's not my mother tongue. I work on a coolege Computer Science Project. For this, i need to know the upper bound of the complexity for the MFC( Formal ...
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Is it possible to decrypt an ECDSA private key if the same nonce is used across different private keys?

If the same nonce is used across different messages under the same private key, the private key can be easily revealed. However, let's consider another scenario. Two private keys, x1 and x2, are ...
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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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X.509 ECDSA signature field in DER format includes '00' between bit string and sequence of r and s

I created a X.509 certificate with ECDSAwithSHA256(OID=1.2.840.10045.4.3.2) by openssl. ECC parameter is secp256r1. Following is the signatureAlgorithm and signatureValue. ...
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Disk storage of RSA and DSA keys

I have generated one RSA-2048 signing key and one DSA-2048 signing key, using gpg command gpg --full-generate-keys I would expect the key to have size 2048 bits, ...
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How to properly sign and verify using DSA? Can anyone spot my mistake?

The question that I am trying to answer is as follows: 10.14. The parameters of DSA are given by p = 59,q = 29,α = 3, and Bob’s private key is d = 23. Show the process of signing (Bob) and ...
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Verify ECDSA signature without data

With RSA PKCS#1 v1.5 it is possible to verify that the signature was generated by the correct private key without actually having access to the data. You just perform the modular exponentiation with ...
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ECDH Public Key Recovery - Determine if valid key exists from just signature and message

If I have just the (r,s,v) values of the signature and the message hash, what is the most efficient way to determine if a valid public key exists? I do not need to know the public key, just that the ...
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Comparisons of ECDSA, EdDSA and BLS Signatures in Blockchain: Pros and Cons

As we know, the most used digital scheme in Blockchain is ECDSA. For now, more and more blockchain projects, I've noticed, are considering substituting EdDSA and BLS signature scheme as the new one. ...
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Why is a prime number used in ECDSA?

So I need to write a piece for school about ECDSA and how it is secure. Now I thought I had a simple question, however, I can't seem to find an answer anywhere: Why does the p in the formula need to ...
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Is it secure to use ECDSA for any arbitrary point on the Elliptic Curve as the Generator point?

My question concerns the elliptic curve $E$ over a prime field $\mathbb F_p$. To the best of my understanding, ECDSA requires a Generator point $G$ of prime order $n$, and the $r$ and $s$ values of ...
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DSA authenticity/integrity

Does checking sig with DSA implies both that the sender is verified , and the msg is original without change of any bit? (case i dont have a reference HASH for that file, only public key)
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ECDSA multiplication vs exponentiation

In Elliptic Curve Digital Signature Algorithm (ECDSA) I often see 2 different written equations of it: Elliptic curve point multiplication by a scalar, $Q_{A}=d_{A}\times G$, source Modular ...
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DSA - can $k$ be 1?

I'm learning DSA and I'm wondering if $k$ can be 1. I know that k has to be from $\mathbb{Z}_{q-1}$ but I don't know whether 1 is allowed (not talking about security concerns, purely educational). I ...
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In DSA digital signature, why does k have to be random and unique each for each signing? [duplicate]

If we repeat k, I think there is little chance for s to repeat since user's private key x is ...
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Why are in asymmetric cryptography as many keys as people involved needed?

The question: "10 friends wish to establish secure communications between themselves using asymmetric-key cryptography. How many keys need to be known by each user?" was posed by my teacher. He says ...
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What is TPMFail attack and what are the countermeasures?

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 [duplicate]

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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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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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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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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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 anyone explain ...
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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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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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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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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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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 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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