All proofs
Project-declaredLean 4.32.0 · mathlib@81a5d257

Prob Event pair collision le

OracleComp.probEvent_pair_collision_le

Plain-language statement

Per-pair collision bound: For any two positions in a loggingOracle trace with distinct inputs, the probability that their outputs are HEq-equal is ≤ 1/|C|. This is the core ROM property: distinct oracle inputs yield independent uniform outputs. The hrange hypothesis ensures |Range default| is minimal across all oracle indices, so the bound holds...

Exact Lean statement

theorem probEvent_pair_collision_le {α : Type}
    [Inhabited ι]
    (oa : OracleComp spec α)
    (n : ℕ)
    (hrange : ∀ t, Fintype.card (spec.Range default) ≤ Fintype.card (spec.Range t))
    (i j : Fin n) (hij : i ≠ j) :
    Pr[fun z => z.2.length > i.val ∧ z.2.length > j.val ∧
        z.2[i]?.bind (fun ei => z.2[j]?.map (fun ej =>
          ei.1 ≠ ej.1 ∧ HEq ei.2 ej.2)) = some true |
      (simulateQ loggingOracle oa).run] ≤
      (Fintype.card (spec.Range default) : ℝ≥0∞)⁻¹

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem probEvent_pair_collision_le {α : Type}    [Inhabited ι]    (oa : OracleComp spec α)    (n : )    (hrange :  t, Fintype.card (spec.Range default)  Fintype.card (spec.Range t))    (i j : Fin n) (hij : i  j) :    Pr[fun z => z.2.length > i.val  z.2.length > j.val         z.2[i]?.bind (fun ei => z.2[j]?.map (fun ej =>          ei.1  ej.1  HEq ei.2 ej.2)) = some true |      (simulateQ loggingOracle oa).run]       (Fintype.card (spec.Range default) : 0∞)⁻¹ := by  apply le_trans (probEvent_mono fun z _ h => h.2.2)  suffices h :  (β : Type) (ob : OracleComp spec β) (i j : ) (_ : i  j),      Pr[fun z => z.2[i]?.bind (fun ei => z.2[j]?.map (fun ej =>        ei.1  ej.1  HEq ei.2 ej.2)) = some true |        (simulateQ loggingOracle ob).run]         (Fintype.card (spec.Range default) : 0∞)⁻¹ from    h α oa i.val j.val (Fin.val_ne_of_ne hij)  intro β ob  induction ob using OracleComp.inductionOn with  | pure x => intro i j _; simp [simulateQ_pure]  | query_bind t mx ih =>    intro i j hij    rw [run_simulateQ_loggingOracle_query_bind, probEvent_bind_eq_tsum]    simp_rw [probEvent_map, Function.comp_def]    -- The matched output lives at position `k` in the log; both end cases reduce to    -- `probEvent_log_output_match_le` after extracting the sigma entry.    have key :  (u : spec.Range t) (k : ) (e : β × QueryLog spec  Prop),        ( z, e z   s v, z.2[k]? = some s, v  HEq u v)         Pr[e | (simulateQ loggingOracle (mx u)).run]           (Fintype.card (spec.Range default) : 0∞)⁻¹ := fun u k e he =>      (probEvent_mono fun z _ => he z).trans (probEvent_log_output_match_le hrange (mx u) k t u)    match i, j, hij with    | 0, 0, hij => exact absurd rfl hij    | 0, j' + 1, _ =>      simp only [List.getElem?_cons_zero, List.getElem?_cons_succ, Option.bind_some]      refine tsum_query_mul_probEvent_le_aux t mx _ _ fun u => key u j' _ fun z hev => ?_      match hz : z.2[j']? with      | none => simp [hz] at hev      | some s, v => exact s, v, rfl, by simp_all    | i' + 1, 0, _ =>      simp only [List.getElem?_cons_zero, List.getElem?_cons_succ]      refine tsum_query_mul_probEvent_le_aux t mx _ _ fun u => key u i' _ fun z hev => ?_      match hz : z.2[i']? with      | none => simp [hz] at hev      | some s, v => exact s, v, rfl, (by simp_all : v ≍ u).symm    | i' + 1, j' + 1, hij =>      simp only [List.getElem?_cons_succ]      exact tsum_query_mul_probEvent_le_aux t mx _ _ fun u => ih u i' j' (by lia)
Project
VCVio
License
Apache-2.0
Commit
2ceb2d825ee3
Source
VCVio/OracleComp/QueryTracking/Birthday.lean:151-199

Reuse this declaration

Bring the exact result into your workflow

The import identifies the source module. Your project still needs the pinned package dependency shown on this page.

What this badge means

This completion status comes from the project or community source. It has not yet been represented here as an independent rebuild and axiom audit.

Continue in this project

Related declarations

Project-declaredLean 4.32.0

Expected Cost Nat eq sum tail probs of pathwise Cost At Most

AddWriterT.expectedCostNat_eq_sum_tail_probs_of_pathwiseCostAtMost

Plain-language statement

Finite tail-sum formula for natural-valued writer cost under a pathwise upper bound. If every execution path of oa incurs cost at most n, then the tail probabilities vanish above n, so the infinite tail sum truncates to Finset.range n.

program verificationseparation logiccryptography

Source project: VCVio

Person-level attribution pending.

View proof record
Project-declaredLean 4.32.0

IND CPA advantage to Real le sum step signed Advantage Real abs

AsymmEncAlg.IND_CPA_advantage_toReal_le_sum_step_signedAdvantageReal_abs

Plain-language statement

Planned generic one-time-to-many-time lift: bounded multi-query IND-CPA advantage is at most the sum of the extracted one-time signed advantages over the first q fresh LR queries.

program verificationseparation logiccryptography

Source project: VCVio

Person-level attribution pending.

View proof record