vatican.va/news_services/press/documentazione/documents/sp_ss_scv/insigne/sp_ss_scv_stemma-bandiera-sigillo_en.html
*The symbols of papal authority, which are the tiara (or triregnum) and the keys of St. Peter or supreme keys, “to bind and to unloose”, one in gold and the other in silver, crossed and bound with a red cord, are located directly behind the Pontiff’s personal coat of arms.
The symbolism is drawn from the Gospel and is represented by the keys given to the Apostle Peter by Christ.
Since the XIV Century, the two crossed keys have been the official insignia of the Holy See. The gold one, on the right, alludes to the power in the kingdom of the heavens, the silver one, on the left, indicates the spiritual authority of the papacy on earth. The mechanisms are turned up towards the heaven and the grips turned down, in other words into the hands of the Vicar of Christ. The cord with the bows that unites the grips alludes to the bond between the two powers.*