# Is it possible to re-generate ECPublic key from raw private key and curve params?

As per my understanding, in Elliptical curve cryptography, the EC PrivateKey is nothing but a bigInteger value. If you know the curve specs and you have this private BigInteger value (which I am referring as raw private key), then you can re-create PrivateKey and use it for generating the signature.

Now, my question is, if you know the raw privateKey and curve name (aka specs), can you generate the corresponding public key?

• Of course: If you know the curve $E$ and base point $P\in E$, the public key is simply computed as $Q=xP$ where $x\in\mathbb N$ is the private key. – yyyyyyy Dec 11 '15 at 14:37
• Thanks, I found the answer later on after reading this crypto.stackexchange.com/a/15307/25460 – ua741 Dec 11 '15 at 15:04
• Shall we close the question as a duplicate of the linked one or do you (ua741) want a real answer (from @yyyyyyy ?)? – SEJPM Dec 11 '15 at 18:03
• @yyyyyyy Can you please post your comment as an answer. – ua741 Dec 11 '15 at 20:52
• stackoverflow.com/questions/12480776/… is basically the same question with an answer specific to OpenSSL. – dave_thompson_085 Dec 12 '15 at 2:33