| 1 | var xor = require('buffer-xor')
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| 2 |
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| 3 | function incr32 (iv) {
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| 4 | var len = iv.length
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| 5 | var item
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| 6 | while (len--) {
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| 7 | item = iv.readUInt8(len)
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| 8 | if (item === 255) {
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| 9 | iv.writeUInt8(0, len)
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| 10 | } else {
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| 11 | item++
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| 12 | iv.writeUInt8(item, len)
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| 13 | break
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| 14 | }
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| 15 | }
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| 16 | }
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| 17 |
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| 18 | function getBlock (self) {
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| 19 | var out = self._cipher.encryptBlock(self._prev)
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| 20 | incr32(self._prev)
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| 21 | return out
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| 22 | }
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| 23 |
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| 24 | exports.encrypt = function (self, chunk) {
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| 25 | while (self._cache.length < chunk.length) {
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| 26 | self._cache = Buffer.concat([self._cache, getBlock(self)])
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| 27 | }
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| 28 | var pad = self._cache.slice(0, chunk.length)
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| 29 | self._cache = self._cache.slice(chunk.length)
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| 30 | return xor(chunk, pad)
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| 31 | }
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