Simulator (qkdsec.sim)

BB84 QKD protocol simulator.

Two backends are available:

• "classical" — pure-Python probabilistic simulation. No extra dependencies.

• "qiskit" — real quantum circuits on IBM Qiskit Aer with depolarizing noise. Requires the sim extra: pip install qkdsec[sim].

Example

>>> from qkdsec.sim import BB84Protocol
>>> result = BB84Protocol(error_rate=0.01).run(n_bits=4096)
>>> if result.secure:
...     print(result.final_key.hex())

class qkdsec.sim.BB84Protocol(error_rate=0.01, eavesdrop=False, eavesdrop_fraction=1.0, qber_threshold=0.11, sample_fraction=0.1, backend='qiskit')

Bases: object

Full BB84 QKD protocol.

Parameters:

• error_rate (float) – Background channel error rate (without eavesdropping). Default 0.01.

• eavesdrop (bool) – Simulate an intercept-resend eavesdropper. Default False.

• eavesdrop_fraction (float) – Fraction of qubits Eve intercepts. Only used when eavesdrop=True.

• qber_threshold (float) – Maximum tolerable QBER. Protocol aborts above this. Default 0.11.

• sample_fraction (float) – Fraction of sifted bits sacrificed for QBER estimation. Default 0.10.

• backend (str) – "qiskit" — IBM Qiskit Aer simulator (requires qkdsec[sim] extra). "classical" — pure-Python probabilistic simulation (no extras).

run(n_bits=4096)

Execute the full BB84 protocol and return a BB84Result.

Return type:

BB84Result

Parameters:

n_bits (int)

class qkdsec.sim.BB84Result(final_key, key_length_bits, raw_bits, sifted_bits, qber, eavesdropper_detected, secure, backend_used='qiskit', sift_ratio=0.0, block_error_rates=None, error_variance=0.0, max_burst_length=0)

Bases: object

Parameters:

• final_key (bytes)

• key_length_bits (int)

• raw_bits (int)

• sifted_bits (int)

• qber (float)

• eavesdropper_detected (bool)

• secure (bool)

• backend_used (str)

• sift_ratio (float)

• block_error_rates (list)

• error_variance (float)

• max_burst_length (int)

backend_used: str = 'qiskit'

block_error_rates: list = None

eavesdropper_detected: bool

error_variance: float = 0.0

final_key: bytes

key_length_bits: int

max_burst_length: int = 0

qber: float

raw_bits: int

secure: bool

sift_ratio: float = 0.0

sifted_bits: int

class qkdsec.sim.BB84Protocol(error_rate=0.01, eavesdrop=False, eavesdrop_fraction=1.0, qber_threshold=0.11, sample_fraction=0.1, backend='qiskit')

Bases: object

Full BB84 QKD protocol.

Parameters:

• error_rate (float) – Background channel error rate (without eavesdropping). Default 0.01.

• eavesdrop (bool) – Simulate an intercept-resend eavesdropper. Default False.

• eavesdrop_fraction (float) – Fraction of qubits Eve intercepts. Only used when eavesdrop=True.

• qber_threshold (float) – Maximum tolerable QBER. Protocol aborts above this. Default 0.11.

• sample_fraction (float) – Fraction of sifted bits sacrificed for QBER estimation. Default 0.10.

• backend (str) – "qiskit" — IBM Qiskit Aer simulator (requires qkdsec[sim] extra). "classical" — pure-Python probabilistic simulation (no extras).

__init__(error_rate=0.01, eavesdrop=False, eavesdrop_fraction=1.0, qber_threshold=0.11, sample_fraction=0.1, backend='qiskit')

Parameters:

• error_rate (float)

• eavesdrop (bool)

• eavesdrop_fraction (float)

• qber_threshold (float)

• sample_fraction (float)

• backend (str)

run(n_bits=4096)

Execute the full BB84 protocol and return a BB84Result.

Return type:

BB84Result

Parameters:

n_bits (int)

class qkdsec.sim.BB84Result(final_key, key_length_bits, raw_bits, sifted_bits, qber, eavesdropper_detected, secure, backend_used='qiskit', sift_ratio=0.0, block_error_rates=None, error_variance=0.0, max_burst_length=0)

Bases: object

Parameters:

• final_key (bytes)

• key_length_bits (int)

• raw_bits (int)

• sifted_bits (int)

• qber (float)

• eavesdropper_detected (bool)

• secure (bool)

• backend_used (str)

• sift_ratio (float)

• block_error_rates (list)

• error_variance (float)

• max_burst_length (int)

backend_used: str = 'qiskit'

block_error_rates: list = None

eavesdropper_detected: bool

error_variance: float = 0.0

final_key: bytes

key_length_bits: int

max_burst_length: int = 0

qber: float

raw_bits: int

secure: bool

sift_ratio: float = 0.0

sifted_bits: int