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| {{Template:String:DEA64encrypt subtitle}}
| | #REDIRECT [[DEA64decrypt and DEA64encrypt (String functions)]] |
| This method applies the DEA (Data Encryption Algorithm) using a 64-bit symmetric key to encrypt each 64-bit block of input text. For more details about how the algorithm works, see [https://en.wikipedia.org/wiki/Data_Encryption_Standard Data Encryption Standard].
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| The length of the returned string is the same as that of the object string.
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| DEA is a two-way cipher, so encrypting a string with a key and then decrypting the result of that encryption with the same key produces the original string. That is, the following assertion should <b><i>always</i></b> hold:
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| <p class="code">[[Assert statement|assert]] %string:dea64encrypt(%key):dea64decrypt(%key) eq %string
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| </p>
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| You can use <var>RC4decrypt</var> to "document" that you are decrypting, and
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| use <var>RC4encrypt</var> to "document" that you are enrypting. In the remainder of this article, you can use <var>RC4decrypt</var> and <var>RC4encrypt</var> interchangeably.
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| ==Syntax==
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| {{Template:String:DEA64encrypt syntax}}
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| {{Template:String:DEA64decrypt syntax}}
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| ===Syntax terms===
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| <table>
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| <tr><th>%outString</th>
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| <td>A string variable to receive the encrypted or decrypted method object <var class="term">string</var>. Its length is the same as <var class="term">string</var>.</td></tr>
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| <tr><th>string</th>
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| <td>The string to which the method is applied. <var class="term">string</var> must be a multiple of eight bytes in length; its maximum is 32768 bytes. It may be null.</td></tr>
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| <tr><th>key</th>
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| <td>An 8-byte (only) string variable whose value is used to encrypt or decrypt the method object, <var class="term">string</var>.</td></tr>
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| </table>
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| ==Usage notes==
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| <ul>
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| <li>The <var>DEA64encrypt</var> and <var>DEA64decrypt</var> functions are available as of <var class="product">Model 204</var> 7.6. </li>
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| </ul>
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| ==Examples==
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| In the following example, the output string from the <var>DEA64encrypt</var> method is converted to hex using the <var>[[StringToHex (String function)|StringToHex]]</var> function to reveal its non-displayable characters, then decrypted to return the original input string:
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| <p class="code">b
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| %ls is longstring
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| %string is longstring
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| %key is longstring
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| %string = 'onetwothreefour0onetwothreefour0'
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| %key = '12345678'
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| %ls = %string:dea64encrypt(%key)
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| [[PrintText statement|printText]] {~} is {%ls:stringTohex}
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| printText {~} is: {%ls:rc4decrypt(%key)}
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| end
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| </p>
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| The result is:
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| <p class="output">%ls:stringTohex is: A54138C10468C061567574F88567E221A54138C10468C061567574F88567E221
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| %ls:dea64decrypt(%key) is: onetwothreefour0onetwothreefour0
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| </p>
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| ==See also==
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| <ul>
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| <li><var>[[DEA128encrypt (String function)|DEA128encrypt]]</var> </li>
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| <li><var>[[DEA256encrypt (String function)|DEA256encrypt]]</var> </li>
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| </ul>
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| {{Template:String:DEA64encrypt footer}}
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