【71-75】certificates are （71） documents attesting to the （72） of a public key to an individualorother entity. they allow verification of the claim that a given public key does in factbelongtoa given individual. certificates help prevent someone from using a phony key to （73）someoneelse.in their simplest form， certificates contain a public key and a name. as commonly used， acertificatealso contains an （74） date， the name of the ca that issued the certificate， a serialnumber，andperhaps other information. most importantly，it contains the digital （75）of the certificateissuer.the most widely accepted format for certificates is x.509 ， thus， certificates can be readorwrittenby any application complying with x.509.
