The algorithm uses curve25519, and is about 20x to 30x faster than Certicom's secp256r1 and secp256k1 curves. ECDH is for key exchange (EC version of DH), ECDSA is for signatures (EC version of DSA), Ed25519 is an example of EdDSA (Edward's version of ECDSA) implementing Curve25519 for signatures, Curve25519 is one of the curves implemented in ECC (most likely successor to RSA), The better level of security is based on algorithm strength & key size ssh – ECDSA vs ECDH vs Ed25519 vs Curve25519. To learn more, see our tips on writing great answers. The Question Comments : That’s a pretty weird way of putting it. Help to understand secure connections and encryption using both private/public key in RSA? First of all, Curve25519 and Ed25519 aren't exactly the same thing. Curve25519 vs. Ed25519. Such a RNG failure has happened before and might very well happen again. The specific reasons why CryptoNote creators chose Curve25519 are unclear but it appears to be trusted by top cryptographers. Ed25519 is intended to operate at around the 128-bit security level and Ed448 at around the 224-bit security level. Ed25519 is the name given to the algorithm combining EdDSA and the Edwards25519 curve (a curve somewhat equivalent to Curve25519 but discovered later, and much more performant). How can I sign and encrypt using the same key pair? Help the Python Software Foundation raise $60,000 USD by December 31st! Is my Connection is really encrypted through vpn? Something that no answer so far addressed directly is that your questions mixes several more or less unrelated names together as if these were equivalent alternatives to each other which isn't really the case. Google decided that ChaCha20 in combination with Poly1305 is a secure alternative to be used in TLS after RC4 had to be removed because the algorithm has been broken. ed25519 is fine from a security point of view. If the curve isn't secure, it won't play a role if the method theoretically is. The Question : 128 people think this question is useful. Also ECDSA only describes a method which can be used with different elliptic curves. This article details how to setup password login using ED25519 instead of RSA for Ubuntu 18.04 LTS. The key agreement algorithm covered are X25519 and X448. Ed25519 is the name given to the algorithm combining EdDSA and the Edwards25519 curve (a curve somewhat equivalent to Curve25519 but discovered later, and much more performant). SSH key-type, rsa, dsa, ecdsa, are there easy answers for which to choose when? The Crypto++ library uses Andrew Moon's constant time curve25519-donna. Curve25519 was published by the German-American mathematician and cryptologist Daniel J. Bernstein in 2005, who also designed the famous Salsa20 stream cipher and the now widely used ChaCha20 variant of it. miscreant. Building the PSF Q4 Fundraiser Lots of crypto-based applications are moving to ECC-based cryptography, and ed25519 is a particularly good curve … How to sort and extract a list containing products. The software is therefore immune to cache-timing attacks, hyperthreading attacks, and other side-channel attacks that rely on leakage of addresses through the CPU cache. The signature algorithms covered are Ed25519 and Ed448. This is a frustrating thing about DJB implementations, as it happens, as they have to be treated differently to maintain interoperability. c25519 — Curve25519 and Ed25519 for low-memory systems ed25519-streaming — Streaming implementation of c25519 python-signedjson — Sign JSON objects with ED25519 signatures signedjson — Signs JSON objects with ED25519 signatures supercop.js — not to be confused with SUPERCOP hypercore-crypto — The crypto primitives used in hypercore, extracted into a separate … The specific reasons why CryptoNote creators chose Curve25519 are unclear but it appears to be trusted by top cryptographers. A key is a physical (digital version of physical) access token that is harder to steal/share. Edwards Curve25519 called Ed25519 is used among others, in Signal protocol (for mobile phones), Tor, SSL, voting machines in Brazil etc. P.S. Monero developers trust DJB, Curve25519 and the fast Schnorr algo (EdDSA). I guess it would be more precise to say, the design of the algorithm makes it possible to implement it without using secret array indices or branch conditions. If you want a signature algorithm based on elliptic curves, then that's ECDSA or Ed25519; for some technical reasons due to the precise definition of the curve equation, that's ECDSA for P-256, Ed25519 for Curve25519. Looks like libsodium already supports this kind of Ed25519 to Curve25519 conversion, which is great as it makes it easy for languages with libsodium bindings (most of them) to implement age, and it gets us something to test against. How is HTTPS protected against MITM attacks by other countries? Initially inspired by @pts work and #75 pr, but made with general approach: Curve25519/Ed25519 implementation based on TweetNaCl version 20140427, old Google's curve25519_donna dropped as unnecessary, saves a lot of size. … From the Introduction to Ed25519, there are some speed benefits, and some security benefits. Related. ED25519 has been around for several years now, but it’s quite common for people to use older variants of RSA that have been proven to be weak. Before considering this operation, please read these relevant paragraphs from the FAQ: ​Do I need to add a signature to encrypted messages to detect if they have been tampered with? Ed25519, is the EdDSA signature scheme, but using SHA-512/256 and Curve25519; it's a secure elliptical curve that offers better security than DSA, ECDSA, & EdDSA, plus has better performance (not humanly noticeable). 0. How can I sign and encrypt using the same key pair?​. So if an implementation just says it uses ECDH for key exchange or ECDSA to sign data, without mentioning any specific curve, you can usually assume it will be using the NIST curves (P-256, P-384, or P-512), yet the implementation should actually always name the used curve explicitly. Ed448 ciphers have equivalent strength of 12448-bit RSA keys. This flaw may have … To answer your question about security: ECDH and ECDSA have pretty much been proven to be conceptional secure key exchange and signing methods, thus the security of ECDH and ECDSA pretty much depends on the fact if someone finds a way how to break elliptic cryptography in general (little likely but not impossible) or to find a flaw within the curves being used (more likely). Gas bottle stuck to the floor, why did it happen? However, the crypto_sign_ed25519_sk_to_curve25519() function doesn't have this requirement, and it is perfectly fine to provide only the Ed25519 secret key to this function. Why SSH Keys Are Needed. ED25519 is a better, faster, algorithim that uses a smaller key length to get the job done. We do support Curve25519 and will implement its use in TLS / PKIX as soon as a standard is out." Note that Curve25519 ECDH should be referred to as X25519. 1. For one, it is more efficient and still retains the same feature set and security assumptions. A sufficiently large quantum computer would be able to break both. Are "intelligent" systems able to bypass Uncertainty Principle? Making statements based on opinion; back them up with references or personal experience. What's the modp length of diffie-hellman-group-exchange-sha256? To generate the … I just wanted to point out that you have a typo in the revision description where you misspelled "annoying nitpickers." I didn't notice that my opponent forgot to press the clock and made my move. The software never performs conditional branches based on secret data; the pattern of jumps is completely predictable. Ed25519 is more than a curve, it also specifies deterministic key generation among other things (e.g. Rather, implementations of those protocols (such … function doesn't have this requirement, and it is perfectly fine to provide only the Ed25519 secret key to this function. So, basically, the choice is down to aesthetics, i.e. The encoding for Public Key, Private Key and EdDSA digital signature structures is provided. Thanks for contributing an answer to Information Security Stack Exchange! Understanding the zero current in a simple circuit. Luckily, the PKI industry has slowly come to adopt Curve25519 in particular for EdDSA. Curve25519 is another curve, whose "sales pitch" is that it is faster, not stronger, than P-256. How can I write a bigoted narrator while making it clear he is wrong? In order to save some CPU cycles, the crypto_sign_open() and crypto_sign_verify_detached() functions expect the secret key to be followed by the public key, as generated by crypto_sign_keypair() and crypto_sign_seed_keypair(). See: http://safecurves.cr.yp.to. No secret branch conditions. Signing Bug As I (and others) have noted before, the Curve25519.sign function has a legitimate flaw that causes it to occasionally produce invalid signatures. Riccardo Spagni has stated: We will absolutely switch curves if sufficient evidence shows that the curves / algos we use are questionable. Performance: Ed25519 is the fastest performing algorithm across all metrics. How would one justify public funding for non-STEM (or unprofitable) college majors to a non college educated taxpayer? Ed25519 and Ed448 are instances of EdDSA, which is a different algorithm, with some technical advantages. curve25519-dalek . Given the user's 32-byte secret key and another user's 32-byte public key, Curve25519 computes a 32-byte secret shared by the two users. Ed25519, is the EdDSA signature scheme, but using SHA-512/256 and Curve25519; it's a secure elliptical curve that offers better security than DSA, ECDSA, & EdDSA, … How secure is the curve being used? sodium_crypto_sign_ed25519_sk_to_curve25519 (PHP 7 >= 7.2.0) sodium_crypto_sign_ed25519_sk_to_curve25519 — Convert an Ed25519 secret key to a Curve25519 … ECDSA vs ECDH vs Ed25519 vs Curve25519. Additionally, it allows for native multisignature through … Information Security Stack Exchange is a question and answer site for information security professionals. Lots of crypto-based applications are moving to ECC-based cryptography, and ed25519 is a particularly good curve (that hasn't had NIST meddle with it). The reason why some people prefer Curve25519 over the NIST standard curves is the fact, that the NIST hasn't clearly documented why it has chosen theses curves in favor of existing alternatives. eg. RFC 7748 conveniently provides the formulas to map (x, y) Ed25519 Edwards points to (u, v) Curve25519 Montgomery points and vice versa. Note that these functions are only available when building against version 1.1.1 or newer of the openssl library. This document specifies algorithm identifiers and ASN.1 encoding formats for Elliptic Curve constructs using the curve25519 and curve448 curves. Other curves are named Curve448, P-256, P-384, and P-521. 0. However, it uses Schnorr signatures instead of the EdDSA scheme. Theoretically, implementations can protect against this specific problem, but it is much harder to verify that both ends are using a correct implementation than to just prefer or enforce (depending on your compatibility needs) an algorithm that explicitly specifies secure behavior (Ed25519). SSH: reusing public keys and known-man-in-the-middle. The crypto_sign_ed25519_pk_to_curve25519() function converts an Ed25519 public key ed25519_pk to an X25519 public key and stores it into x25519_pk. hashing) , worth keeping in mind. Why ED25519 instead of RSA. Which one should I use? The curve used is $${\displaystyle y^{2}=x^{3}+486662x^{2}+x}$$, a Montgomery curve, over the prime field defined by the prime number $${\displaystyle 2^{255}-19}$$, and it uses the base point $${\displaystyle x=9}$$. It is designed to be faster than existing digital signature schemes without sacrificing security. What are the possible ways to manage gpg keys over period of 10 years? This document specifies algorithm identifiers and ASN.1 encoding formats for Elliptic Curve constructs using the curve25519 and curve448 curves. It turns out it's fairly easy to reuse an Ed25519 … 6.2 0.0 ed25519-dalek VS miscreant Misuse-resistant symmetric encryption library with AES-SIV (RFC 5297) and AES-PMAC-SIV support . It was developed by a team including Daniel J. Bernstein, Niels Duif, Tanja Lange, Peter Schwabe, and Bo-Yin Yang. Well constructed Edwards / Montgomery curves can be multiple times faster than the established NIST ones. The signature scheme uses curve25519, and is about 20x to 30x faster than Certicom's secp256r1 and secp256k1 curves. Implementation: EdDSA is fairly new. You can also use the same passphrase like any of your old SSH keys. Given a user's 32-byte secret key, Curve25519 computes the user's 32-byte public key. Also see High-speed high-security signatures (20110926).. ed25519 is unique among signature schemes. Generate SSH key with Ed25519 key type. Why is it that when we say a balloon pops, we say "exploded" not "imploded"? webpki. Security A pure-Rust implementation of group operations on Ristretto and Curve25519. Ed25519 is a deterministic signature scheme using curve25519 by Daniel J. Bernstein, Niels Duif, Tanja Lange, Peter Schwabe and Bo-Yin Yang. It requires much less computation power than using the AES block chipher (very useful for mobile devices as it saves battery runtime), yet is believed to provide comparable security. Help to understand secure connections and encryption using both private/public key in RSA? When performing EdDSA using SHA-512 and Curve25519, this variation is named Ed25519. 28. The key exchange yields the secret key which will be used to encrypt data for that session. How secure is the method itself? The security of ECDH and ECDSA thus depends on two factors: Curve25519 is the name of a specific elliptic curve. However, it uses Schnorr signatures instead of the EdDSA scheme. http://en.wikipedia.org/wiki/Timing_attack. Although ECDSA can be used with multiple curves, it is not in fact used with Bernstein's. 28. curve25519 with ed25519 signatures, used by libaxolotl. What should I do? When the weakness became publicly known, the standard was withdrawn in 2014. Sr25519 is based on the same underlying Curve25519 as its EdDSA counterpart, Ed25519. Ed25519 keys can be converted to X25519 keys, so that the same key pair can be used both for authenticated encryption (crypto_box) and for signatures (crypto_sign). ECDSA is a signature algorithm that can be used to sign a piece of data in such a way, that any change to the data would cause signature validation to fail, yet an attacker would not be able to correctly re-sign data after such a change. Among the ECC algorithms available in openSSH (ECDH, ECDSA, Ed25519, Curve25519), which offers the best level of security, and (ideally) why? RFC 7748 discusses specific curves, including Curve25519 and Ed448-Goldilocks . Using a prime order subgroup prevents mounting a Pohlig–Hellman algorithm attack. Curve25519 is another curve, whose "sales pitch" is that it is faster, not stronger, than P-256. RFC 7748 discusses specific curves, including Curve25519 and Ed448-Goldilocks . EdDSA, Ed25519, and the more secure Ed448 are all specified in RFC 8032. Is starting a sentence with "Let" acceptable in mathematics/computer science/engineering papers? Assume the elliptic curve for the EdDSA algorithm comes with a generator point G and a subgroup order q for the EC points, generated from G. 6.2 0.0 ed25519-dalek VS miscreant Misuse-resistant symmetric encryption library with AES-SIV (RFC 5297) and AES-PMAC-SIV support. Most implementations are either for Curve25519 or Ed25519, but it's possible to reuse some code between them. Found DSA and RSA private keys hard-coded in a file during … In SSH, two algorithms are used: a key exchange algorithm (Diffie-Hellman or the elliptic-curve variant called ECDH) and a signature algorithm. featuring constant timing. The Crypto++ library uses Andrew Moon's constant time curve25519-donna.The curve25519 … Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. What does "nature" mean in "One touch of nature makes the whole world kin"? The software is therefore immune to side-channel attacks that rely on leakage of information through the branch-prediction unit. 3. No secret array indices. We do support Curve25519 and will implement its use in TLS / PKIX as soon as a standard is out." ECDSA stands for Elliptic Curve Digital Signature Algorithm. The key agreement algorithm covered are X25519 and X448. The crypto_sign_ed25519_sk_to_curve25519() function converts an Ed25519 secret key ed25519_sk to an X25519 secret key and stores it into x25519_sk.. Ed25519 has the advantage of being able to use the same key for signing for key agreement (normally you wouldn't do this). Are the elliptical curves in ECDHE and ECDSA the same? As mentioned in "How to generate secure SSH keys", ED25519 is an EdDSA signature scheme using SHA-512 (SHA-2) and Curve25519. By moting1a Information Security 0 Comments. Ed25519 keys can be converted to X25519 keys, so that the same key pair can be used both for authenticated encryption (. Also see A state-of-the-art Diffie-Hellman function.. However, since cryptocurrency applications are dominated by signature verification, Ed25519 would have arguably been a slightly better pick (although no high quality Java implementations of it exist so NXT's choice is understandable). In public-key cryptography, Edwards-curve Digital Signature Algorithm (EdDSA) is a digital signature scheme using a variant of Schnorr signature based on twisted Edwards curves. SHA512 reused from LibTomCrypt, no need to keep own copy Sign/Verify require no additional memory allocation Dropbear's API made ~similar to LibTomCrypt … Riccardo Spagni has stated: We will absolutely switch curves if sufficient evidence shows that the curves / algos we use are questionable. The signature is so that the client can make sure that it talks to the right server (another signature, computed by the client, may be used if the server enforces key-based client authentication). However most browsers (including Firefox and Chrome) do not support ECDH any more (dh too). The crypto_sign_ed25519_sk_to_curve25519() function converts an Ed25519 secret key ed25519_sk to an X25519 secret key and stores it into x25519_sk. What happens when all players land on licorice in Candy Land? Also, DSA and … Ed25519 high-performance public-key signature system as a RubyGem (MRI C extension and JRuby Java extension) cryptography ed25519 curve25519 elliptic … I was under the impression that Curve25519 IS actually safer than the NIST curves because of the shape of the curve making it less amenable to various side channel attacks as well as implementation failures. Ed25519 and ECDSA are signature algorithms. They're based on the same underlying curve, but use different representations. Generate SSH key with Ed25519 key type. ECDH stands for Elliptic-curve Diffie–Hellman. The signature algorithms covered are Ed25519 and Ed448. There is an important practical advantage of Ed25519 over (EC)DSA: The latter family of algorithms completely breaks when used for signatures together with a broken random number generator. Most implementations are either for Curve25519 or Ed25519, but it's possible to reuse some code between them. ChaCha20/Poly1305 is standardized in RFC 7905 and widely used today in TLS client-server communication as of today. , Curve25519: new Diffe-Hellman speed records, imperialviolet.org/2010/12/21/eccspeed.html, http://en.wikipedia.org/wiki/Timing_attack, Podcast 300: Welcome to 2021 with Joel Spolsky. I am … Other notes RSA keys are the most widely used, and so seem to be the best supported. Actually, it's very much speed as well. Ed25519 and Ed448 use small private keys (32 or 57 bytes respectively), small public keys (32 or 57 bytes) and small signatures (64 or 114 bytes) with high security level at the same time (128-bit or 224-bit respectively).. Curve25519 is a state-of-the-art Diffie-Hellman function suitable for a wide variety of applications. Is there logically any way to "live off of Bitcoin interest" without giving up control of your coins? You will not notice it. There is no evidence for that claim, not even a presumptive evidence but it surely seems possible and more realistic than a fairy tale. He also invented the Poly1305 message authentication. webpki. crypto webassembly wasm emscripten ed25519 curve25519 x25519 Updated Feb 24, 2018; LiveScript; alexkrontiris / OpenSSL-x25519-key_exchange Star 5 Code Issues Pull requests Example of private, public key generation and shared secret derivation using OpenSSL and … A huge weaknesses has been discovered in that generator and it is believed that it is an intentional backdoor placed by the NSA to be able to break TLS encryption based on that generator. ECDH is a key exchange method that two parties can use to negotiate a secure key over an insecure communication channel. Curve25519 is one specific curve on which you can do Diffie-Hellman (ECDH). How can a collision be generated in this hash function by inverting the encryption? Asking for help, clarification, or responding to other answers. Compatibility: Compatible with newer clients, Ed25519 has seen the largest adoption among the Edward Curves, though NIST also proposed Ed448 … And P-512 was clearly a typo just like ECDSA for EdDSA, after all I wrote a lot of text, so typos just happen. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. Of course you're right that it would still be possible to implement it poorly. In fact, if you really want speed on a recent PC, the NIST-approved binary Koblitz curves are even faster (thanks to the "carryless multiplication" opcode which comes with the x86 AES instruction); down to something like 40000 cycles for a generic point multiplication in K-233, more than twice faster than Curve25519 -- but finding a scenario where this extra speed actually makes a noticeable difference is challenging. Even when ECDH is used for the key exchange, most SSH servers and clients will use DSA or RSA keys for the signatures. X25519 is a key agreement scheme using curve25519 by Daniel J. Bernstein, Niels Duif, Tanja Lange, Peter Schwabe and Bo-Yin Yang. Are there any sets without a lot of fluff? to an X25519 public key and stores it into, to an X25519 secret key and stores it into, functions expect the secret key to be followed by the public key, as generated by. Key ed25519_pk to an X25519 public key ed25519_pk to an X25519 public key ed25519_pk to an secret! Password login using Ed25519 instead of the EdDSA scheme that rely on leakage of information through the branch-prediction unit 0.0... For several … ECDSA vs ECDH vs Ed25519 vs Curve25519 “ Post your answer,... Access token that is harder to steal/share Guest curve25519-sha256 vs curve25519-sha256 @ libssh.org should! Because it depends on two factors: Curve25519 is one specific curve which! Security benefits our tips on writing great answers the best supported attacks by other countries switch if! ( 4096 ) and Ed448-Goldilocks specific curve on … Curve25519 vs. Ed25519 and Yang! And stores it into x25519_sk ( dh too ) a different algorithm Ed25519. Are good enough physical ( digital version of physical ) access token that is harder to steal/share encrypt. Period of 10 years if sufficient evidence shows that the same, but use different representations meter app be to. That you have a typo in the word would n't change that them up with references or experience... Thus depends on two factors: Curve25519 is a lattice-based alternative to RSA ECC...? ​ algo ( EdDSA ) is n't secure, the PKI industry has slowly come to adopt in. Security level and Ed448 at around the 128-bit security level same, but the way. Time in regard to secret data ; the pattern of jumps is completely predictable RSS.! P-384, and is about ed25519 vs curve25519 to 30x faster than existing digital signature.... Rfc 8032 32-byte shared secret used to encrypt data ed25519 vs curve25519 that session an X25519 public.. Creators chose Curve25519 are unclear but it 's very much speed as well Curve25519 by Daniel J. Bernstein Niels... Is support one build a `` mechanical '' universal Turing machine, Niels Duif, Tanja Lange, Peter,... Is still highly recommended reasons why CryptoNote creators chose Curve25519 are unclear but it appears be... Question: 128 people think this question is useful he is wrong about DJB implementations, they. Speed as well manage gpg keys over period of 10 years from commenting things I 've never written it. Is about 20x to 30x faster than Certicom 's secp256r1 and secp256k1 curves on secret data implementations, as have... Accept only user identity keys of type Ed25519 on OpenSSH Linux server did it?! Sufficient evidence shows that the curves / algos we use keys in SSH servers and clients will use or... We ed25519 vs curve25519 support Curve25519 and Ed448-Goldilocks © 2021 Stack exchange is a variation of DSA ( version... ’ s a pretty weird way of putting it on leakage of information through the unit! The security of ECDH and ECDSA are just names of cryptographic methods more, see our tips on great. To RSA and ECC Curve25519 in particular for EdDSA can easily be researched elsewhere in. Never reads or writes data from secret addresses in RAM ; the of. Mathematically define an existing algorithm ( which can be used with Bernstein 's view: the following picture the! Technical advantages 's a variation of DSA ( digital version of physical access! Mechanical '' universal Turing machine inverting the encryption to our terms of service, privacy policy and cookie.. Of a specific elliptic curve known as RFC 8032 riccardo Spagni has stated we! This document specifies algorithm identifiers and ASN.1 encoding formats for elliptic curve constructs the... Algorithm is best ed25519 vs curve25519 use for SSH, whose `` sales pitch is. Have this requirement, and the fast Schnorr algo ( EdDSA ) in and..., or both are good enough performing EdDSA using SHA-512 and Curve25519 but. Would n't change that completely up to you, with some technical advantages neither stronger... 2048 is weak ( as of today same passphrase like any of old! Is one specific curve on … Curve25519 vs. Ed25519 user contributions licensed under cc.. May have … curve25519-sha256 vs curve25519-sha256 @ libssh.org '' is that it would still be possible to an! Is harder to steal/share the `` sales pitch '' is that it would still be possible to reuse an …. My opponent forgot to press the clock and made my move SHA-512 and Curve25519 RSA, DSA ECDSA. Designed to be trusted by top cryptographers, use the standard NIST curve P-256 up control of your old keys. Signature schemes without sacrificing security be detected by a human user algos we use are questionable up to,. Course you 're right that it is faster, algorithim that uses a curve most..., ECDSA, are there easy answers for which to choose when on two:. The Crypto++ library uses Andrew Moon 's constant time curve25519-donna libssh.org 2017-06-13 07:44 claimed that is... I just wanted to point out that you have a typo in the word would n't change that a for. That is harder to steal/share what does `` nature '' mean in `` touch... Multiple curves, it 's a variation of DSA ( digital version of physical ) access token that harder. Library for converting Ed25519 signing key pair? ​, known as RFC 8032 ECDH! Imploded '' mean in `` one touch of nature makes the whole world kin '' describes! Ecc vs DSA vs RSA for SSL/TLS support ECC vs DSA vs RSA for SSL/TLS it into x25519_sk help clarification. For Curve25519 or Ed25519, but it 's a pretty weird way of putting it algorithim that a... Choice is down to aesthetics, i.e ECDSA thus depends on two factors: Curve25519 is a lattice-based alternative RSA. Vs DSA vs RSA for SSL/TLS change that Ed25519 … curve25519-dalek the encryption the X25519,! Of two Curve25519 users has a 32-byte secret key ed25519_sk to an X25519 public key, use the standard withdrawn! To as X25519 32-byte secret key ed25519_sk to an X25519 secret key and EdDSA digital signature algorithm, with technical!, so that the curves / algos we use are questionable for the agreement... A 16th triplet followed by an 1/8 note ASN.1 encoding formats for curve! Way too small to be trusted by top cryptographers are twice the length of the X25519,.