Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/Crypto/Random/OSRNG/rng_base.py: 64%

1# 

2# Random/OSRNG/rng_base.py : Base class for OSRNG 

3# 

4# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net> 

5# 

6# =================================================================== 

7# The contents of this file are dedicated to the public domain. To 

8# the extent that dedication to the public domain is not available, 

9# everyone is granted a worldwide, perpetual, royalty-free, 

10# non-exclusive license to exercise all rights associated with the 

11# contents of this file for any purpose whatsoever. 

12# No rights are reserved. 

13# 

14# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 

15# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 

16# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 

17# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 

18# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 

19# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 

20# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 

21# SOFTWARE. 

22# =================================================================== 

23 

24__revision__ = "$Id$" 

25 

26import sys 

27if sys.version_info[0] == 2 and sys.version_info[1] == 1: 

28 from Crypto.Util.py21compat import * 

29 

30class BaseRNG(object): 

31 

32 def __init__(self): 

33 self.closed = False 

34 self._selftest() 

35 

36 def __del__(self): 

37 self.close() 

38 

39 def _selftest(self): 

40 # Test that urandom can return data 

41 data = self.read(16) 

42 if len(data) != 16: 

43 raise AssertionError("read truncated") 

44 

45 # Test that we get different data every time (if we don't, the RNG is 

46 # probably malfunctioning) 

47 data2 = self.read(16) 

48 if data == data2: 

49 raise AssertionError("OS RNG returned duplicate data") 

50 

51 # PEP 343: Support for the "with" statement 

52 def __enter__(self): 

53 pass 

54 def __exit__(self): 

55 """PEP 343 support""" 

56 self.close() 

57 

58 def close(self): 

59 if not self.closed: 

60 self._close() 

61 self.closed = True 

62 

63 def flush(self): 

64 pass 

65 

66 def read(self, N=-1): 

67 """Return N bytes from the RNG.""" 

68 if self.closed: 

69 raise ValueError("I/O operation on closed file") 

70 if not isinstance(N, int): 

71 raise TypeError("an integer is required") 

72 if N < 0: 

73 raise ValueError("cannot read to end of infinite stream") 

74 elif N == 0: 

75 return "" 

76 data = self._read(N) 

77 if len(data) != N: 

78 raise AssertionError("%s produced truncated output (requested %d, got %d)" % (self.name, N, len(data))) 

79 return data 

80 

81 def _close(self): 

82 raise NotImplementedError("child class must implement this") 

83 

84 def _read(self, N): 

85 raise NotImplementedError("child class must implement this") 

86 

87 

88# vim:set ts=4 sw=4 sts=4 expandtab: