And, because changing even one character in the message changes the message digest in an unpredictable way, the recipient can be sure that the message was not changed after the message digest was generated. Digital certificates provide the basis for secure electronic transactions as they enable all participants in a transaction to quickly and easily verify the identity of the other participants. Privacy is guaranteed through encryption. Although data can still be intercepted by a third party they will be unable to read it as they have no access to the encryption key Integrity is also ensured through encryption. If a message is received that will not decrypt properly then the recipient knows that the information has been tampered with during transmission.
Authentication is provided through digital certificates.
Digital certificates provide the basis for secure electronic transactions as they enable all participants in a transaction to quickly and easily verify the identity of the other participants. Here you can get a more detailed explanation of SSL . It uses digital certificates to ensure the identities of all parties involved in a purchase and encrypts credit card information before sending it across the Internet. Like SSL, SET allows for the merchant's identity to be authenticated via digital certificates. However, SET also allows for the merchant to request users authenticate themselves through digital certificates.