Bitpay\PrivateKey::generate PHP Method

    public function generate()
    {
        if (!empty($this->hex)) {
            return $this;
        }
        do {
            $privateKey = \Bitpay\Util\SecureRandom::generateRandom(32);
            $this->hex = strtolower(bin2hex($privateKey));
        } while (Math::cmp('0x' . $this->hex, '1') <= 0 || Math::cmp('0x' . $this->hex, '0x' . Secp256k1::N) >= 0);
        $this->dec = Util::decodeHex($this->hex);
        return $this;
    }

 /**
  * Generates an uncompressed and compressed EC public key.
  *
  * @param \Bitpay\PrivateKey $privateKey
  * @return \Bitpay\PublicKey
  * @throws \Exception
  */
 public function generate(PrivateKey $privateKey = null)
 {
     if ($privateKey instanceof PrivateKey) {
         $this->setPrivateKey($privateKey);
     }
     if (!empty($this->hex)) {
         return $this;
     }
     if (is_null($this->privateKey)) {
         throw new \Exception('Please `setPrivateKey` before you generate a public key');
     }
     if (!$this->privateKey->isGenerated()) {
         $this->privateKey->generate();
     }
     if (!$this->privateKey->isValid()) {
         throw new \Exception('Private Key is invalid and cannot be used to generate a public key');
     }
     $point = new Point('0x' . substr(Secp256k1::G, 2, 64), '0x' . substr(Secp256k1::G, 66, 64));
     $R = Util::doubleAndAdd('0x' . $this->privateKey->getHex(), $point);
     $RxHex = Util::encodeHex($R->getX());
     $RyHex = Util::encodeHex($R->getY());
     $RxHex = str_pad($RxHex, 64, '0', STR_PAD_LEFT);
     $RyHex = str_pad($RyHex, 64, '0', STR_PAD_LEFT);
     $this->x = $RxHex;
     $this->y = $RyHex;
     $this->hex = sprintf('%s%s', $RxHex, $RyHex);
     $this->dec = Util::decodeHex($this->hex);
     return $this;
 }