the locking mechanism, only limited by the length of the cable. When the cable is bent and passed through the hole, lock it at the proper length. Resistance A quantitative measure of a padlock's tensile strength and resistance to forced and surreptitious entry can be determined with tests developed by organizations such as ASTM, Sold Secure (United Kingdom), CEN (Europe), and TNO (The Netherlands). Symbolism Images of closed padlocks (sometimes physical padlocks) are sometimes used to indicate that something is secure or inaccessible. A widely known example is on the Web, where data in secure transactions is encrypted using public-key cryptography; some web browsers display a locked padlock icon while using the HTTPS protocol. Love locks are physical padlocks attached to fixtures such as bridges, gates, and monuments by sweethearts to declare their love for each other is permanent. This practice perhaps originated in Serbia. In some popular tourist locations, huge numbers of such padlocks are treated as a nuisance by local authorities. See also Mästermyr chest Pin tumbler lock References External links inventors.about.com History of Locks Locks (security device)