• IKP
• SET
• Secure Courier

IKP

IKP stands for Internet Keyed Payments Protocol. It was developed by IBM and defines transactions similar to credit card systems, in fact there is a third part (e.g., a bank or a credit-card system) between the seller and the buyer to authorize transactions. This protocol is based on public-key cryposystems.

SET

SET stands for Secure Electronic Transaction. It was developed by Visa and MasterCard. SET uses RSA for signatures and secret-key encryption. Secret-key is used to encrypt messages by means of DES. More information can be found at http://www.visa.com and at http://www.mastercard.com.

Secure Courier

Secure Courier is a protocol proposed by Netscape Communications Corporation. It is similar to IKP, because there is a third part involved. It uses RSA and DES cryptosystems.