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Certificate authority

An organization that issues digital certificates and signs them with its private key.

Certificate revocation list

A list of certificates that have become invalid before their natural expiration. This may happen if somebody finds out the certificate owner's private key. The list must be stored on a highly available server.

Digital signature

A message digest that has been encrypted using a person's (called the signer) private key. The signature is sent with the message. The receiver can then calculate the digest himself and decrypt the signature using the sender's public key to obtain another digest. If the two match, the signer must be have the corresponding private key and the message could not have been altered.

Digital identity or certificate

A file that binds a public key to an identity. The file contains informations such as name, validity dates, the public key and issuer. This all is digitally signed by the issuer. The validity of the certificate can be checked as any digitally signed message. The issuer's, called the certificate authority, public key can be for example published in a newspaper. There can be several layers of certificate authorities.

Digital envelope

A term that is sometimes used of a symmetric session key that has been encrypted using the receiver's public key.

HTML

Hypertext markup language. The format into which the description of world wide web pages has been written.

HTTP

Hypertext transfer protocol. An agreement on how the HTML files are transferred through the Internet.

In-band

A way of key distribution where the key is delivered through the route which is wished to be encrypted. The idea is to distribute keys for future sessions in an encrypted session (for which the key was given in a past session).

IP

Internet protocol, an agreement about how to transfer data packets in the Internet.

Out-band

A way of key distribution where the key is delivered through some other route except that which is wished to be encrypted. The key can be sent by letter.

Session key

A key for a symmetric encryption algorithm that is specific to certain session. Because the key is different for every session, security is enchanced.

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Sivua on viimeksi päivitetty 15.11.1999 16:45.
URI: http://www.netlab.tkk.fi/opetus/s38118/s99/htyo/1/term.shtml
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