openssl_pkey_get_public Extract public key from certificate and prepare it for use resourceopenssl_pkey_get_public mixedcertificate Returns a positive key resource identifier on success, or &false; on error. openssl_get_publickey extracts the public key from certificate and prepares it for use by other functions. certificate can be one of the following: an X.509 certificate resource a string having the format file://path/to/file.pem. The named file must contain a PEM encoded certificate/private key (it may contain both). A PEM formatted private key.