Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/starkbank_ecdsa-2.3.1-py3.11.egg/ellipticcurve/utils/integer.py: 82%

1# coding: utf-8 

2from hmac import new as hmacNew 

3from .binary import numberFromByteString, hexFromInt, byteStringFromHex 

4 

5try: 

6 from secrets import randbelow as _randbelow 

7except ImportError: 

8 from random import SystemRandom 

9 _systemRandom = SystemRandom() 

10 _randbelow = lambda n: _systemRandom.randrange(n) 

11 

12 

13class RandomInteger: 

14 

15 @classmethod 

16 def between(cls, min, max): 

17 """ 

18 Return integer x in the range: min <= x <= max 

19 

20 :param min: minimum value of the integer 

21 :param max: maximum value of the integer 

22 :return: 

23 """ 

24 

25 return min + _randbelow(max - min + 1) 

26 

27 @classmethod 

28 def rfc6979(cls, hashBytes, secret, curve, hashfunc): 

29 """Generate nonce values per hedged RFC 6979: deterministic k derivation 

30 with fresh random entropy mixed into K-init (RFC 6979 §3.6). Same message 

31 and key yield different signatures, while preserving RFC 6979's protection 

32 against RNG failures.""" 

33 orderBitLen = curve.nBitLength 

34 orderByteLen = (orderBitLen + 7) // 8 

35 

36 secretHex = hexFromInt(secret).zfill(orderByteLen * 2) 

37 secretBytes = byteStringFromHex(secretHex) 

38 

39 hashReduced = numberFromByteString(hashBytes, orderBitLen) % curve.N 

40 hashHex = hexFromInt(hashReduced).zfill(orderByteLen * 2) 

41 hashOctets = byteStringFromHex(hashHex) 

42 

43 extraEntropy = byteStringFromHex( 

44 hexFromInt(cls.between(0, (1 << (orderByteLen * 8)) - 1)).zfill(orderByteLen * 2) 

45 ) 

46 

47 hLen = hashfunc().digest_size 

48 V = b'\x01' * hLen 

49 K = b'\x00' * hLen 

50 

51 K = hmacNew(K, V + b'\x00' + secretBytes + hashOctets + extraEntropy, hashfunc).digest() 

52 V = hmacNew(K, V, hashfunc).digest() 

53 K = hmacNew(K, V + b'\x01' + secretBytes + hashOctets + extraEntropy, hashfunc).digest() 

54 V = hmacNew(K, V, hashfunc).digest() 

55 

56 while True: 

57 T = b'' 

58 while len(T) * 8 < orderBitLen: 

59 V = hmacNew(K, V, hashfunc).digest() 

60 T += V 

61 

62 k = numberFromByteString(T, orderBitLen) 

63 

64 if 1 <= k <= curve.N - 1: 

65 yield k 

66 

67 K = hmacNew(K, V + b'\x00', hashfunc).digest() 

68 V = hmacNew(K, V, hashfunc).digest()