Hi,
i want to build an PHP class with some bitcoin tools for generating a bitcoin address, a WIF key compressed and uncompressed or something else.
i've generated keys with
http://brainwallet.org/#generator to test my functions. everything is ok.
now i want to create a public and private key by myself using OpenSSL for windows.
i know that i can generate an EC private key with the following commands:
openssl ecparam -name secp256k1 -noout -genkey -out key.pem
openssl ec -outform DER -in key.pem -out key.der
private key is starting at byte 9 and length is 32 bytes
public key are the last 65 bytes of the EC private key.
everything works fine and correct.
but now i want to generate a public key just from the 32 byte private key
without the whole EC private key "overhead".
it seems to be possible because
http://brainwallet.org/#generator do it (private key as hex string in secret exponent).
how can i do this with OpenSSL? is there an easy way to do this?
thx