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Viewing changes to lib/cryptojs/components/pad-ansix923.js

  • Committer: kapil.foss at gmail
  • Date: 2012-07-13 18:45:59 UTC
  • Revision ID: kapil.foss@gmail.com-20120713184559-2xl7be17egsrz0c9
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lib/cryptojs/components/pad-ansix923.js
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/*
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CryptoJS v3.0.2
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code.google.com/p/crypto-js
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(c) 2009-2012 by Jeff Mott. All rights reserved.
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code.google.com/p/crypto-js/wiki/License
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*/
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/**
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 * ANSI X.923 padding strategy.
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 */
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CryptoJS.pad.AnsiX923 = {
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    pad: function (data, blockSize) {
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        // Shortcuts
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        var dataSigBytes = data.sigBytes;
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        var blockSizeBytes = blockSize * 4;
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        // Count padding bytes
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        var nPaddingBytes = blockSizeBytes - dataSigBytes % blockSizeBytes;
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        // Compute last byte position
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        var lastBytePos = dataSigBytes + nPaddingBytes - 1;
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        // Pad
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        data.clamp();
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        data.words[lastBytePos >>> 2] |= nPaddingBytes << (24 - (lastBytePos % 4) * 8);
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        data.sigBytes += nPaddingBytes;
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    },
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    unpad: function (data) {
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        // Get number of padding bytes from last byte
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        var nPaddingBytes = data.words[(data.sigBytes - 1) >>> 2] & 0xff;
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        // Remove padding
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        data.sigBytes -= nPaddingBytes;
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    }
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};