Alternative to openssl_sign() and openssl_verify() with support for large files.

The default openssl_sign() and openssl_verify() functions work with in memory data, which is not suitable for signing large files that might not fit entirely in memory.

The PHPOpenSSLSignLargeFile provides alternative and compatible functions for signing large files that do not fit in memory.

bool openssl_sign_large_file(string $pathToFile, string &$signature, mixed $priv_key_id)
bool openssl_verify_large_file(string $pathToFile, string $signature, mixed $pub_key_id)

signature_alg is hardcoded as OPENSSL_ALGO_SHA1.