How to import ed25519 keys?

max-mapper commented 5 years ago

I am trying to import PEM encoded ed25519 keys (these are derived from test vectors, not used in anything real)

But when I do importPrivateKey I get:

Error: Module: virgil/crypto. Error code: 7. Invalid format of the Public Key.
Module: virgil/crypto/mbedtls. Error code: -14848. PK - Elliptic curve is unsupported (only NIST curves are supported)

Is there some other way to create VirgilPrivateKey and VirgilPublicKey objects?

SergeySeroshtan commented 5 years ago

Hi @maxogden. Thanks for your time diving to our crypto products. There are some issues with the private key.

-----BEGIN PRIVATE KEY-----
MFECAQEEIOpPW/6GlNi7dLe1lARjL9WWi3dO1UXoEN6cMqT7QZL0oAUGAytlcKEj
AyEAW6O5rG6Q6D7/zSWsTlihNlqeNaPTrl6we55NkLz3UG0=
-----END PRIVATE KEY-----

Used PEM title BEGIN PRIVATE KEY specifies that private key is encoded as PKCS#8 ASN.1 type PrivateKeyInfo:

PrivateKeyInfo ::= SEQUENCE {
version                   Version,
privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,
privateKey                PrivateKey,
attributes                [0]  IMPLICIT Attributes OPTIONAL }

But actually it is encoded as SEC 1 ASN.1 type ECPrivateKey:

ECPrivateKey ::= SEQUENCE {
 version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
 privateKey     OCTET STRING,
 parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
 publicKey  [1] BIT STRING OPTIONAL }

And as defined in the RFC 5915 PEM header and footer should be :

-----BEGIN EC PRIVATE KEY-----
-----END EC PRIVATE KEY-----

Nevertheless, Header and Footer replacement can not completely fix the issue, as curves ed25519 and curve25519 are not included to the SEC 1 standard and RFC 5915 and can not be represented as a NamedCurve defined in the RFC 5912.

Solution:

Use ASN.1 type PrivateKeyInfo or it's newer version OneAsymmetricKey defined in the RFC 5958 and referenced in the RFC 8410 for keys for Ed25519, Ed448, X25519, and X448.
Generate new ed25519 private keys via this library:
```
import { VirgilCrypto } from 'virgil-crypto';
```

const virgilCrypto = new VirgilCrypto(); const keyPair = virgilCrypto.generateKeys();


 or by [Virgil CLI](https://developer.virgilsecurity.com/docs/sdk-and-tools/virgil-cli/generate-keypair).

Note, for inspecting ASN.1 DER and PEM encoded types, useful [online tool](https://lapo.it/asn1js/) can be used.

max-mapper commented 5 years ago

Ah that makes sense, my mistake. Thank you :)

max-mapper commented 5 years ago

Got it working

Ended up using pkcs8-pem for the private key and spki-pem for the public key.

import { composePrivateKey, composePublicKey } from 'crypto-key-composer'

function privateToPem(privateKey) {
  var decomposed = {
    format: 'pkcs8-pem',
    keyAlgorithm: { id: 'ed25519' },
    keyData: {
      seed: privateKey,
    },
  }
  return composePrivateKey(decomposed)
}

function publicToPem(publicKey) {
  var decomposed = {
    format: 'spki-pem',
    keyAlgorithm: { id: 'ed25519' },
    keyData: {
      bytes: publicKey,
    },
  }
  return composePublicKey(decomposed)
}

VirgilSecurity / virgil-crypto-javascript

How to import ed25519 keys? #39