SET is designed mainly to solve transactions through credit card payment among the customer and the merchant and the bank, so as to protect the secret of payment information, the integrity of payment process, the legal status of merchants and card-holders, and the operability. 它主要是为了解决用户、商家和银行之间通过信用卡支付的交易而设计的,以保证支付信息的机密、支付过程的完整、商户及持卡人的合法身份、以及可操作性。