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43 lines
917 B
43 lines
917 B
4 years ago
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var Buffer = require('safe-buffer').Buffer
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function encryptByte (self, byteParam, decrypt) {
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var pad
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var i = -1
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var len = 8
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var out = 0
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var bit, value
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while (++i < len) {
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pad = self._cipher.encryptBlock(self._prev)
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bit = (byteParam & (1 << (7 - i))) ? 0x80 : 0
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value = pad[0] ^ bit
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out += ((value & 0x80) >> (i % 8))
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self._prev = shiftIn(self._prev, decrypt ? bit : value)
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}
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return out
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}
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function shiftIn (buffer, value) {
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var len = buffer.length
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var i = -1
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var out = Buffer.allocUnsafe(buffer.length)
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buffer = Buffer.concat([buffer, Buffer.from([value])])
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while (++i < len) {
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out[i] = buffer[i] << 1 | buffer[i + 1] >> (7)
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}
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return out
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}
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exports.encrypt = function (self, chunk, decrypt) {
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var len = chunk.length
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var out = Buffer.allocUnsafe(len)
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var i = -1
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while (++i < len) {
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out[i] = encryptByte(self, chunk[i], decrypt)
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}
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return out
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}
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