Any system has to meet four requirements:
privacy: information must be kept from unauthorized parties.
integrity: message must not be altered or tampered with.
authentication: sender and recipient must prove their identities to each other.
non-repudiation: proof is needed that the message was indeed received.
Privacy is handled by encryption. In PKI (public key infrastructure) a message is encrypted by a public key, and decrypted by a private key. The public key is widely distributed, but only the recipient has the private key. For authentication (proving the identity of the sender, since only the sender has the particular key) the encrypted message is encrypted again, but this time with a private key. Such procedures form the basis of RSA (used by banks and governments) and PGP (Pretty Good Privacy, used to encrypt emails).
Unfortunately, PKI is not an efficient way of sending large amounts of information, and is often used only as a first step — to allow two parties to agree upon a key for symmetric secret key encryption. Here sender and recipient use keys that are generated for the particular message by a third body: a key distribution center. The keys are not identical, but each is shared with the key distribution ce
nter, which allows the message to be read. Then the symmetric keys are encrypted in the RSA manner, and rules set under various protocols. Naturally, the private keys have to be kept secret, and most security lapses indeed arise here.
结 论
目前，随着信息网络技术的急速发展，电子商务在国际贸易中的作用越来越为重要，及时了解电子商务对国际贸易的影响，并将其运用到我国的对外贸易中，对外贸易的健康、稳步、持续发展起到极大的推动及促进作用。
Conclusion
Now, with the rapid developments in information network technology, e-commerce in the growing role of international trade is important to keep abreast of the impact of electronic commerce on international trade, and its application to China's foreign trade, foreign trade, health, , steady, sustainable development, a huge contribution to promoting and facilitating role.
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