Coverage for oarepo_c4gh/key/key.py: 100%

1"""An abstract Base Class for Asymmetric Secret Keys 

2 

3This module contains only the interface specification for all key 

4classes implementations. 

5 

6""" 

7 

8from typing import Protocol, abstractmethod 

9 

10 

11class Key(Protocol): 

12 """This is an abstract class, containing only abstract methods 

13 used to compute the Diffie-Hellman key exchange over the 

14 Montgomery curve Curve25519 as specified by the X25519 standard 

15 and auxilliary informative helpers. 

16 

17 """ 

18 

19 @property 

20 @abstractmethod 

21 def public_key(self) -> bytes: 

22 """The derived classes must implement providing corresponding 

23 public key in this method. 

24 

25 Returns: 

26 The 32 bytes of the public key. 

27 

28 """ 

29 ... 

30 

31 @abstractmethod 

32 def compute_write_key(self, reader_public_key: bytes) -> bytes: 

33 """Accepts the intended reader public key and computes the 

34 shared secret based on the public and secret key (this key) of 

35 the writer particular key source implementation. 

36 

37 Parameters: 

38 reader_public_key: the 32 bytes of the reader public key 

39 

40 Returns: 

41 The shared secret as 32 bytes - usable as symmetric key. 

42 

43 """ 

44 ... 

45 

46 @abstractmethod 

47 def compute_read_key(self, writer_public_key: bytes) -> bytes: 

48 """Accepts the writer public key and computes the shared 

49 secret based on the public and secret key (this key) of the 

50 reader particular key source implementation. 

51 

52 Parameters: 

53 writer_public_key: the 32 bytes of the writer public key 

54 

55 Returns: 

56 The shared secret as 32 bytes - usable as symmetric key. 

57 

58 """ 

59 ... 

60 

61 @property 

62 @abstractmethod 

63 def can_compute_symmetric_keys(self) -> bool: 

64 """A predicate returning true if this key instance can perform 

65 read/write key derivation. This is usually determined by 

66 having access to the private key (for software implementation) 

67 or some other means of working with the private key (for HSM). 

68 

69 Returns: 

70 true if it can perform symmetric key derivation 

71 

72 """ 

73 return False 

74 

75 def __bytes__(self) -> bytes: 

76 """Default converter to bytes returns the public key bytes.""" 

77 return self.public_key