var xor = require('buffer-xor')
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var Buffer = require('safe-buffer').Buffer
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var incr32 = require('../incr32')
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function getBlock (self) {
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var out = self._cipher.encryptBlockRaw(self._prev)
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incr32(self._prev)
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return out
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}
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var blockSize = 16
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exports.encrypt = function (self, chunk) {
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var chunkNum = Math.ceil(chunk.length / blockSize)
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var start = self._cache.length
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self._cache = Buffer.concat([
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self._cache,
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Buffer.allocUnsafe(chunkNum * blockSize)
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])
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for (var i = 0; i < chunkNum; i++) {
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var out = getBlock(self)
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var offset = start + i * blockSize
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self._cache.writeUInt32BE(out[0], offset + 0)
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self._cache.writeUInt32BE(out[1], offset + 4)
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self._cache.writeUInt32BE(out[2], offset + 8)
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self._cache.writeUInt32BE(out[3], offset + 12)
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}
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var pad = self._cache.slice(0, chunk.length)
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self._cache = self._cache.slice(chunk.length)
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return xor(chunk, pad)
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}
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