68 lines
4.7 KiB
HTML
68 lines
4.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Cryptography" />
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<meta name="abstract" content="Use this information to learn what cryptography is and how digital certificates use cryptographic functions to provide security." />
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<meta name="description" content="Use this information to learn what cryptography is and how digital certificates use cryptographic functions to provide security." />
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<meta name="DC.Relation" scheme="URI" content="rzahurzahu4abunderstanddc.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzahudigsig.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzahurzahu0gmssldefco.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2000, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2000, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzahu0cm-cryptog_co" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Cryptography</title>
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</head>
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<body id="rzahu0cm-cryptog_co"><a name="rzahu0cm-cryptog_co"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Cryptography</h1>
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<div><p>Use this information to learn what cryptography is
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and how digital certificates use cryptographic functions to provide security.</p>
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<p>Cryptography is the science of keeping data secure. Cryptography allows
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you to store information or to communicate with other parties while preventing
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noninvolved parties from understanding the stored information or understanding
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the communication. Encryption transforms understandable text into an unintelligible
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piece of data (ciphertext). Decrypting restores the understandable text from
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the unintelligible data. Both processes involve a mathematical formula or
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algorithm and a secret sequence of data (the key). </p>
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<p>There are two types of cryptography:</p>
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<ul><li>In <span class="uicontrol">shared or secret key (symmetric)</span> cryptography,
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one key is a shared secret between two communicating parties. Encryption and
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decryption both use the same key.</li>
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<li>In <span class="uicontrol">public key (asymmetric)</span> cryptography, encryption
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and decryption each use different keys. A party has pair of keys consisting
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of a public key and a private key. The public key is freely distributed, typically
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within a digital certificate, while the private key is securely held by the
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owner. The two keys are mathematically related, but it is virtually impossible
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to derive the private key from the public key. An object, such as a message,
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that is encrypted with someone's public key can be decrypted only with the
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associated private key. Alternately, a server or user can use a private key
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to "sign" an object and the receiver can use the corresponding public key
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to decrypt the digital signature to verify the object's source and integrity.</li>
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</ul>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahurzahu4abunderstanddc.htm" title="View this information to better understand what digital certificates are and how they work. Learn about the different types of certificates and how you can use them as part of your security policy.">DCM concepts</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzahudigsig.htm" title="A digital signature on an electronic document or other object is created by using a form of cryptography and is equivalent to a personal signature on a written document.">Digital signatures</a></div>
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<div><a href="rzahurzahu0gmssldefco.htm" title="The Secure Sockets Layer (SSL), originally created by Netscape, is the industry standard for session encryption between clients and servers.">Secure Sockets Layer (SSL)</a></div>
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</div>
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</div>
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</body>
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</html>
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