Source code for pyecsca.ec.key_agreement

import hashlib
from typing import Optional, Any

from public import public

from .context import ResultAction
from .mod import Mod
from .mult import ScalarMultiplier
from .params import DomainParameters
from .point import Point


[docs]@public class ECDHAction(ResultAction): """An ECDH key exchange.""" params: DomainParameters hash_algo: Optional[Any] privkey: Mod pubkey: Point def __init__(self, params: DomainParameters, hash_algo: Optional[Any], privkey: Mod, pubkey: Point): super().__init__() self.params = params self.hash_algo = hash_algo self.privkey = privkey self.pubkey = pubkey def __repr__(self): return f"{self.__class__.__name__}({self.params}, {self.hash_algo}, {self.privkey}, {self.pubkey})"
[docs]@public class KeyAgreement(object): """An EC based key agreement primitive. (ECDH)""" mult: ScalarMultiplier params: DomainParameters pubkey: Point privkey: Mod hash_algo: Optional[Any] def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod, hash_algo: Optional[Any] = None): self.mult = mult self.params = params self.pubkey = pubkey self.privkey = privkey self.hash_algo = hash_algo self.mult.init(self.params, self.pubkey)
[docs] def perform_raw(self) -> Point: """ Perform the scalar-multiplication of the key agreement. :return: The shared point. """ point = self.mult.multiply(int(self.privkey)) return point.to_affine()
[docs] def perform(self) -> bytes: """ Perform the key agreement operation. :return: The shared secret. """ with ECDHAction(self.params, self.hash_algo, self.privkey, self.pubkey) as action: affine_point = self.perform_raw() x = int(affine_point.x) p = self.params.curve.prime n = (p.bit_length() + 7) // 8 result = x.to_bytes(n, byteorder="big") if self.hash_algo is not None: result = self.hash_algo(result).digest() return action.exit(result)
[docs]@public class ECDH_NONE(KeyAgreement): """Raw x-coordinate ECDH.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey)
[docs]@public class ECDH_SHA1(KeyAgreement): """ECDH with SHA1 of x-coordinate.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey, hashlib.sha1)
[docs]@public class ECDH_SHA224(KeyAgreement): """ECDH with SHA224 of x-coordinate.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey, hashlib.sha224)
[docs]@public class ECDH_SHA256(KeyAgreement): """ECDH with SHA256 of x-coordinate.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey, hashlib.sha256)
[docs]@public class ECDH_SHA384(KeyAgreement): """ECDH with SHA384 of x-coordinate.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey, hashlib.sha384)
[docs]@public class ECDH_SHA512(KeyAgreement): """ECDH with SHA512 of x-coordinate.""" def __init__(self, mult: ScalarMultiplier, params: DomainParameters, pubkey: Point, privkey: Mod): super().__init__(mult, params, pubkey, privkey, hashlib.sha512)