Questions tagged [ed25519]

Ed25519 is an algorithm for producing digital signatures. The algorithm is based on Edwards curves introduced by Bernstein et al. (2007) and named after mathematician Harold M. Edwards.

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How to check runtime of e.g. Ed25519 signature algorithm

As mentioned here the verification of a Ed25519 signature takes roughly 3 times as the time for the generation of a signature. Two questions on that: 1) Can I assume that this is a rule of thumb for ...
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How are all necessary parameters shared between signer and verifier in the ED25519 signature scheme?

I want to use the ED25519 signature scheme in my application which requires frequent sharing of secret data between two entities in the public domain. I know that the Schnorr signature scheme has a ...
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Using public-key signature instead of having API key

I am designing an application that will need an API key. At first I believed that generating a long, random token would be secure enough (say 32 chars string that includes 0-9, a-z and A-Z), and then ...
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Raw curve25519 public key points

I'm trying to understand curve25519, and ECC public points. I'm playing with Minisign, to better understand the fundamentals of ECC. Minisign uses curve25519 and outputs public keys as base64 ...
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Difference between Pure EdDSA (ed25519) and HashEdDSA (ed25519ph)

My question refers to EdDSA as specified in RFC 8032. I get from the RFC that ed25519 and ed25519ph are two different instances of EdDSA mainly differing in the fact that that in the case of ...
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openssh ed2215 private key format

i have generated an ed2215 private key as follows: $ ssh-keygen -o -a 100 -t ed25519 -f id_ed25519 and it looks like ...
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Onion address encoding [closed]

Could you please explain what the pipe (|) in tor specification means -- is it a bitwise or or a concatenation of the values? Encoding onion addresses [...
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ed25519 ssh public key is always 80 characters long?

I am creating some ssh keys using ed25519, something like: ...
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What is “spinal-tap grade” security?

As stated here Ed448 is different from Ed25519 because of "spinal-tap grade" security. What does this mean?
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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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723 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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Valid private keys on curve25519

Given that valid private keys on curve25519 must be less than the order of the curve which is (as I understand) already smaller than 2^256, AND a valid key must be clamped to be divisible by 8 and ...
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Is there a lower limit on message length for signature?

I was working on a tool that signs small messages (~20 bytes) when a question occurred about message size: What would be the risk of using extremely small/restricted input (say, 5 bytes of hexadecimal ...
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How to convert d into 64bit limbs? [closed]

Given a d value = -(10240/10241) How would I convert this into 64 bit limbs? I have to expand on this because of stackoverflow quality algorithm, I've tried using python to get the integer rep/hex ...
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Check if two ed25519 points are equivalent

How to check if two points are equivalent given their projective coordinates (XYTZ)? For example if I do unproject() of a point to pass from XYTZ to XY coordinates and then I come back to XYTZ ...
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Can you derive ed25519 keys from secp256k1?

Alice has a secp256k1 key pair that she used some time ago when she communicated with Bob. Bob can no longer user secp256k1 but he only uses ed25519 instead. Is there a secure algorithm that Bob can ...
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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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Converting EdDSA Keys to EC-KCDSA keys

I'm trying to create BIP32 like key derivation for EKCDSA by riding over a BIP32-EdDSA derivation Can anyone tell me if there is a glaring problem with my conversion technique? ...
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Edwards / Montgomery ECC over binary extension fields

I recentely had a discussion about the redesign of our ECC code for the library I'm collaborating on and the person I was discussing with came up with Edwards and Montgomery curves over binary ...
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Is modular Barrett reduction usable for Ed25519?

I currently try to implement Ed25519 following this draft. I have implemented every field operation except the reduction by the group order $q$ (in chapter 5). I looked for a reduction algorithm and ...
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Are the first 4 bytes of a Ed25519 public key random?

We are using the Ed25519 signature scheme (which uses Curve25519). A key pair is generated by generating the secret key from random data and then computing the 32-byte (256-bit) public key from said ...
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Curve25519 over Ed25519 for key exchange? Why?

I've been reading up on the Signal Protocol (in this PDF) and it seems to be using Curve25519 for ECDH and EdDSA (with Ed25519) for signatures. My question is why not use only Ed25519? This ...
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How does the process of creating a new secure Elliptic Curve look like?

I'm especially curious about the technique djb would have used to come up with his Curve 25519. Say I have already written down my goals, such as - Twist Secure, Speed, Side Channel resistance, etc. ...
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ED25519 Child Key Derivation

Let's say I generate a keypair for a user with go's ed25519 package: pub, private := ed25519.GenerateKey(nil) And I want to generate additional child keys as ...
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ed25519 quantum resistant? [duplicate]

Is ed25519 quantum resistant? I am using ed25519 as a cryptographic primitive for decentralized identity platform, thus this very crucial question.
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Verifying EdDSA signatures using xedDSA verify function.

I'm running into a problem where I generate signatures using a library like pynacl's (https://pynacl.readthedocs.io/en/stable/signing/) ed25519 implementation and then when I verify it using xedDSA's ...
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Is it bad to expose the public key?

I am studying about blockchain and have been focusing on encryption protocols that allow authentication. The digital signature of public and private key seems solid, I have focused on the algorithm ...
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Ed25519 threshold signature verification without knowing the single personal public keys

I read about ways to create a t-of-n threshold signature, corresponding to a collective public key of n players. (https://tools.ietf.org/html/draft-ford-cfrg-cosi-00 and Does Ed25519 support ...
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Why are NaCl secret keys 64 bytes for signing, but 32 bytes for box?

Ed25519 secret and public keys can both be represented in 32 bytes. Why does NaCl use 64 byte signing keys?
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Curve25519 / Ed25519 - Generate a private key from this term

I have 2 key pairs $(x_1, y_1)$, $(x_2, y_2)$. I also have $a = $random 256-bit array and $b = $256-bit of defined values from me. I know the values for $(x_1, y_1)$, $x_2$ and $b$. But I miss the ...
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How many points are there on the X25519 curves?

The order of the base point, $l$, is 2^252 + 27742317777372353535851937790883648493 However, the base point group is nested within other large groups, the largest of which is of size $8l$. There are ...
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does TLS 1.3 use ECDSA-Sig-Value encoded signatures for Ed25519 / Ed448?

Quoting The Transport Layer Security (TLS) Protocol Version 1.3: ECDSA algorithms Indicates a signature algorithm using ECDSA [ECDSA], the corresponding curve as defined in ANSI X9.62 [...
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Ed25519 PKCS8 private key example from IETF draft seems malformed

Malformed PKCS8 Key Algorithm Identifiers for Ed25519, Ed448, X25519 and X448 for use in the Internet X.509 Public Key Infrastructure § 10.3. Examples of Ed25519 Private Key states the following: <...
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How many qubits are required to break RSA 2048 or 4096 with a universal quantum computer?

So in the news this week, IBM have created a universal quantum computer with 5 fully functional qubits. Logic and Moore's law dictates they will be able to scale this up to a lot more qubits within a ...
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How secure is using a hash function as Key Derivation Function?

I am developing a personal project and I have the following need: given a randomly generated seed (with enough entropy) I need to generate a number $x$ of Ed25519 key pairs. These key pairs are not ...
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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 ...
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Is Deterministic Ed25519 Key Derivation from Master Key and String Secure?

I am wanting to make deterministic (i.e. always the same for the same inputs) Ed25519 key from a master Ed25519 key and a target string (e.g. a website name, ala SQRL). My algorithm takes a 32-byte ...
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Encrypt or decrypt using the private key, and decrypt using the public key?

I am currently trying to figure out if my following scheme is implementable in ECC or whether I can use existing implementation. At first I was going with libsodium but it seems that it really doesn't ...
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Ed25519 and hierarchical deterministic wallet

I'm building a solution based on the stellar codebase and using the Ed25519 curve for the signatures. One of the features I've been adding to the system is a support for hierarchical deterministic ...
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ed25519 adoption — challenges

If ed25519 is that attractive that it seems to be, can someone explain why adoption has been slow and if there are, if any, challenges with implementing ed25519. Nathan Aw
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Shor algorithm and schnorr signature in ed25519

Does the application of Shor's algorithm in any way relate/affect the schnorr signature in ed25519?
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Is it safe to use same private key in two or more EC signature algorithms?

Given two (or more) algorithms: ed25519 private key is random blob of 32 bytes public key is encoded point on Edwards 25519 curve. ECDSA with secp256k1 private key is random blob of 32 bytes ...
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Short Ed25519 keys: can I use as ID?

I am building the distributed system, where each user sends signed messages. I dont want to have a certificates system for public keys, like it is done in SSL, so I thought to use public keys ...
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Is TweetNaCl secure enough? [closed]

I decided to use TweetNaCl in my project and did some tests. For some reason, its Ed25519 signing mechanism gives me very short public and private keys, as opposed to RSA, though RSA, as I it ...
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Why does RFC8032#8.7 state that the IUF hash API should not be used for Ed25519?

RFC8032 (section 8.7) states that IUF (Init, Update, Finish) should not be used in Ed25519 API: Avoid signing large amounts of data at once (where "large" depends on the expected verifier). In ...
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Is it possible to derive an Ed25519-public-key from an Ed25519-signature?

If you have an Ed25519-signature and the signed message, can you derive the corresponding public-key or is the signature anonymous (except if you already know the public-key of course)?
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How use multiple keys to sign the same document?

I’m thinking about create one software, that will need the user to sign each document, using Ed25519. I need to create something that is secure and simple. Requering use a HSM is not viable and ...
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What are the differences between the elliptic curve equations?

I think we're all aware of the "classical" Weierstrass (short?) elliptic curve equation: $y^2\equiv x^3 + ax +b \pmod p$. Well known examples of these curves include the NIST's and Brainpool ones. ...
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Why Curve25519 for encryption but Ed25519 for signatures?

NaCl and libsodium libraries use Curve25519 for authenticated encryption (actually for sharing a key which is used for encryption) and Ed25519 for signatures. What is the purpose of using different ...
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HD (Hierarchical Deterministic) Keys using Safe Curves?

Bitcoin's HD (Hierarchical Deterministic) Keys as described in BIP32 allow for a master key to be created (a private key and a chain code) such that a tree of both public and private keys can be ...