| Control | ALE with control | Reduction | Annual cost | ROSI | Verdict |
|---|---|---|---|---|---|
| Passkeys for every RO user | ৳ 2.49 crore | ৳ 3.04 crore | ৳ 1.20 crore | 154% | Invest |
| Edge geo, bot and rate rules | ৳ 3.55 crore | ৳ 1.98 crore | ৳ 0.40 crore | 395% | Invest |
| Immutable backups and DR drills | ৳ 1.90 crore | ৳ 3.64 crore | ৳ 2.50 crore | 46% | Consider |
| HSM quorum on payment keys | ৳ 2.11 crore | ৳ 3.42 crore | ৳ 0.80 crore | 328% | Invest |
| Tokenisation and DLP | ৳ 1.94 crore | ৳ 3.59 crore | ৳ 1.80 crore | 99% | Invest |
| Post-quantum re-wrap of sealed data | ৳ 1.06 crore | ৳ 4.47 crore | ৳ 1.50 crore | 198% | Invest |
LEF = TEF × Vulnerability × control effect # loss events per year N ~ Poisson(LEF) # events in one simulated year loss = Σ_k [ PL_k + B_k × SL_k ], B_k ~ Bernoulli(0.4) PL_k ~ PERT(0.3·PL, PL, 3·PL) SL_k ~ PERT(0.2·SL, SL, 4·SL) (λ = 4) TEF ~ PERT(0.5·TEF, TEF, 2·TEF) Vuln ~ PERT(0.6·V, V, 1.4·V) ALE = mean over 10,000 years · VaR99 = 99th percentile ROSI = (ALE_without − ALE_with − annual cost) ÷ annual cost PERT is sampled as a scaled Beta(α, β) from two Gamma draws (Marsaglia–Tsang)