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51 lines
1.8 KiB
51 lines
1.8 KiB
''' |
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Copyright (c) 2014 David Lazar <lazard@mit.edu> |
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Permission is hereby granted, free of charge, to any person obtaining a copy |
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of this software and associated documentation files (the "Software"), to deal |
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in the Software without restriction, including without limitation the rights |
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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copies of the Software, and to permit persons to whom the Software is |
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furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included in |
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all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
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THE SOFTWARE. |
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''' |
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import hashlib |
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import hmac |
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class DRBG(object): |
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def __init__(self, seed): |
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self.key = b'\x00' * 64 |
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self.val = b'\x01' * 64 |
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self.reseed(seed) |
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def hmac(self, key, val): |
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return hmac.new(key, val, hashlib.sha512).digest() |
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def reseed(self, data=b''): |
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self.key = self.hmac(self.key, self.val + b'\x00' + data) |
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self.val = self.hmac(self.key, self.val) |
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if data: |
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self.key = self.hmac(self.key, self.val + b'\x01' + data) |
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self.val = self.hmac(self.key, self.val) |
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def generate(self, n): |
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xs = b'' |
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while len(xs) < n: |
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self.val = self.hmac(self.key, self.val) |
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xs += self.val |
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self.reseed() |
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return xs[:n]
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