Replacing GPG with OpenSSL for public key file encryption

Hello! I'm trying to get rid of using GPG for encrypting some files since GPG requires exec for the pear crypt library and a GPG install. I've made a test implementation that uses OpenSSL public private keys generated like this: openssl genrsa -des3 -out priv.pem 2048 openssl rsa -in priv.pem -out pub.pem -outform PEM -pubout And then I encrypt the data by looping through it like this (where chunk is the length of the key used): while($data) { $chunk = substr(data, [...]); [...] openssl_public_encrypt($chunk, $encryptedBlock, $publicKey); $output .= $encryptedBlock; } How is this implementation security-wise compared to gpg for encrypting files? I don't need to keep out the NSA, but I want the files to be hard to decrypt for an intruder. Any help is highly appreciated. Thanks! Regards, Emil