[openssl-users] X25519: how to generate public key?

Olivier Meunier musicoliv at gmail.com
Tue Mar 14 14:26:19 UTC 2017

Thank you for your quick answer.

Le 14/03/2017 à 13:43, Dr. Stephen Henson a écrit :
> On Tue, Mar 14, 2017, Olivier Meunier wrote:
>> Hi,
>> using openSSL 1.1.0e, I generate my private key using:
>> openssl genpkey -algorithm x25519 -out x25519.key.pem
>> But I cannot find how to generate the public key. I tried:
>> openssl ec -in x25519.key.pem -pubout -out x25519.key.pub.pem
>> but got the errors:
>> read EC key
>> unable to load Key
>> 16084:error:0608308E:digital envelope
>> routines:EVP_PKEY_get0_EC_KEY:expecting a ec
>> key:crypto\evp\p_lib.c:319:
>> What is the right command to get the public key?
>> Thanks,
> X25519 is trteated as a distinct algorithm, not as an EC curve.
> You don't actually "generate" the public key you can extract or calculate the
> public key corresponding to a private key though.
> The pkey command can do this for any supported algorithm:
> openssl pkey -in privkey.pem -pubout -out pubkey.pem
> Steve.
> --
> Dr Stephen N. Henson. OpenSSL project core developer.
> Commercial tech support now available see: http://www.openssl.org

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