# 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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### What is the best practices for storing ed25519 private keys which is used by nodes of my application to communicate with each other?

I am developing some kind of a P2P network where the nodes communicate with each other via TCP and each message is signed by Ed25519 private key. I use libsodium for signing and signature verification....
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### Why computation of $u*v^3*(u*v^7)^{(p-5)/8}$ is suggested instead of $(u/v)^{(p+3)/8}$

Working with Curve25519 I've faced with suggested form of computation square root candidate as: $uv^3(uv^7)^{\frac{p-5}{8}}$ instead of $\left(\frac{u}{v}\right)^{\frac{p+3}{8}}$. Why it is so? Or why ...
2answers
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### Is it possible to unscramble a scrambled ed25519 SSH key?

Let's say I generate an ed25519 SSH key with ssh-keygen -t ed25519. Then I take the private key file and randomly scramble the order of base64 encoded characters. ...
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### Is there any reason not to use EdDSA with Weierstrass curves?

I'm volunterely working for a crypto library and we're planning on adding Curve25519 support (finally). At the same point I had the idea of adding support for EdDSA in the same run. Our library is ...
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### Can the EdDSA signature scheme be customized with OpenSSL?

EdDSA has currently two signature schemes: Ed25519 and Ed448. Ed25519 is the EdDSA signature scheme using SHA-512 (SHA-2) and Curve25519 Ed448 is the EdDSA signature scheme using SHAKE256 (SHA-3) ...
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### Curve 25519 (X25519, Ed25519) Convert coordinates between Montgomery curve and twisted Edwards curve

I have some misunderstanding about EdDSA conversion coordinates between Montgomery curve and twisted Edwards curve. In https://tools.ietf.org/html/rfc7748 I see that a base point for Curve25519 is ...
0answers
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### Signal Protocol - Better way to generate one time pre keys (OTPK)

The following explains a different way (then one-time pre keys) for Bob to securely generate ephemeral keys asynchronously without a limit while still being able to delete the private key immediately ...
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### Key clamping in curve25519 not evident in generated key's binary representation

I understand with curve25519 that the private key for secret.box is clamped... I understand that this clamping process to clear ...
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### Why does curve25519 use a cofactor of 8?

This cofactor (as I understand it) effectively discards valid points that satisfy the curve equation over the finite field. Why would one wish to reduce the number of possible private keys, it seems ...
2answers
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### Which US standard includes a signature based on Ed25519?

Which standard organization (e.g. NIST or ANSI) standardizes signature Ed25519?