PG Encryption / pg_read_file

Hi Admin,

we are working on the PG Encryption using pgCrypto. We are planing to use the PGP public and private key for encryption. However to secure the key we are not using the keys directly in the SQL Query. We are planning to use the pg_read_file function, for that. However we have noticed only super user can call that function. 

Can you please suggest is there any alternative for pg_read_file function to call non super user or any other alternative to secure the key.