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 <<O>>  Difference Topic PubKeyCrypto (r1.2 - 23 Jan 2002 - IanClarke)
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An excellent book on this and related subjects is "Applied Cryptography" by Bruce Schneier (Amazon, Barnes and Nobel). It it aimed at a technical audience but there is also material of interest to the semi-technical.


 <<O>>  Difference Topic PubKeyCrypto (r1.1 - 08 Jan 2002 - IanClarke)
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%META:TOPICINFO{author="IanClarke" date="1010474305" format="1.0" version="1.1"}% %META:TOPICPARENT{name="WebHome"}%

Public Key Cryptography

Symmetric cryptography is the variety of cryptography most people are familiar with. There is a key which only the sender and receiver know, the crypto algorithm allows the sender to encrypt a message into a garbled "cyphertext" message that only someone else who knows the key can decode back into the original message.

The problem is that this mechanism is only as secure as the sender's ability to transmit the key securely to the receiver, which can often be an expensive task beyond the ability of most people.

Public Key cryptography offered a solution to this problem. It involves two keys, a "public" key and a "private" key. The receiver creates a public and private key-pair. The public key can be used to encrypt a message, but only the corresponding private key can be used to decrypt it. The receiver can then send his public key to the transmitter, it doesn't matter who else knows the public key. The transmitter can then encrypt the message using the public key, and send it to the receiver. Even if other people know the public key, they cannot use it to decrypt the message, only the receiver who has the private key can actually read the message.

Public Key cryptography can also be used in reverse, the transmitter can create a public and private key pair and give the public key to everyone. They can then use their private key to "sign" a message. Anyone with the public key can use it to verify that the message was signed by whoever knew the private key.

A number of algorithms are available for public-private key cryptography. Their existance has far-reaching implications, since they essentially allow almost anyone to communicate securely, even those who do not have the resources to exchange keys privately.

Freenet uses public-private key cryptography in a number of rather innovate ways to to achieve its goals.


Topic PubKeyCrypto . { View | Diffs | r1.3 | > | r1.2 | > | r1.1 | More }
Revision r1.1 - 08 Jan 2002 - 07:18 GMT - IanClarke
Revision r1.2 - 23 Jan 2002 - 05:20 GMT - IanClarke
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