Bits sent
—
Sifted key length
—
QBER
—
Eve active
—
Security
—
Alice's qubits Alice
Bob's measurements Bob
Sifted key (matching bases) Key
Alice's key string:
—
Error rate (QBER): —
Protocol legend
Bases: + = rectilinear {↑,→} × = diagonal {↗,↘}
Bit encoding: + basis: 0=→, 1=↑ × basis: 0=↗, 1=↘
Matching bases → correct measurement → sifted bit
Eve's intercept randomly disturbs ~25% of matching bits → detectable QBER ≥ 0.25
Bit encoding: + basis: 0=→, 1=↑ × basis: 0=↗, 1=↘
Matching bases → correct measurement → sifted bit
Eve's intercept randomly disturbs ~25% of matching bits → detectable QBER ≥ 0.25