user66581: As described here (https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses) I am trying to convert a private ECDSA key to its corresponding public key. (See step1 and step2).
I think I need some code which multiplies some coordinates on the elliptic curve. But I dont know how. Can someone help me, please?
// Unfortunately, this answer doesn't help me enough since I don't understand how to use the code. Can someone clearify that or give alternative solutions? Thanks

user13744: Yeah, you do "need some code which multiplies some coordinates on the elliptic curve" :). If you don't have extensive cryptography experience I would recommend you use library rather than trying to implement details yourself.
Googling I've found Bitcoin-lib-php. Looking at  the code it seems it seems this function does exactly what you are looking for.

66581: <p>As described here (<a href="https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses" rel="nofollow noreferrer">https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses</a>) I am trying to convert a private ECDSA key to its corresponding public key. (See step1 and step2).</p>

<p>I think I need some code which multiplies some coordinates on the elliptic curve. But I dont know how. Can someone help me, please?</p>

<p>// Unfortunately, this answer doesn't help me enough since I don't understand how to use the code. Can someone clearify that or give alternative solutions? Thanks</p>
 13744: <p>Yeah, you do "need some code which multiplies some coordinates on the elliptic curve" :). If you don't have extensive cryptography experience I would recommend you use library rather than trying to implement details yourself.</p>

<p>Googling I've found <a href="https://github.com/Bit-Wasp/bitcoin-lib-php" rel="nofollow noreferrer">Bitcoin-lib-php</a>. Looking at  <a href="https://github.com/Bit-Wasp/bitcoin-lib-php/blob/master/src/BitcoinLib.php#L506" rel="nofollow noreferrer">the code it seems it seems this function</a> does exactly what you are looking for.</p>
