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//! Arcanum-DSA: SIMD-Optimized Digital Signature Algorithm
//!
//! # Overview
//!
//! Arcanum-DSA is a variant of ML-DSA (FIPS 204) with parameters optimized for
//! modern SIMD architectures. It maintains equivalent or stronger security while
//! enabling efficient 4-way parallel processing via AVX2.
//!
//! # Design Rationale
//!
//! ML-DSA's L parameter (number of secret polynomials in s₁/y) determines the
//! batch size for ExpandMask sampling. Standard ML-DSA uses:
//! - ML-DSA-44: L=4 (optimal for 4-way SIMD)
//! - ML-DSA-65: L=5 (1 leftover in 4-way batch)
//! - ML-DSA-87: L=7 (3 leftover in 4-way batch)
//!
//! Arcanum-DSA adjusts parameters to make L a multiple of 4:
//! - **Arcanum-44**: K=4, L=4 (identical to ML-DSA-44)
//! - **Arcanum-65**: K=7, L=4 (dimension 2816, same as ML-DSA-65, L reduced!)
//! - **Arcanum-87**: K=8, L=8 (dimension 4096 vs 3840, +7% stronger)
//!
//! # Key Innovation: Arcanum-65 Performance
//!
//! The Arcanum-65 variant achieves superior performance through a key insight:
//! instead of increasing L from 5 to 8 (which would increase ExpandMask work by 60%),
//! we *reduce* L from 5 to 4 by increasing K from 6 to 7.
//!
//! This maintains the same security dimension (256 × 11 = 2816) while:
//! - Reducing ExpandMask work by 20% (4 polynomials vs 5)
//! - Enabling perfect 4-way SIMD batching (L=4)
//! - Producing smaller signatures (L affects z vector size)
//!
//! Benchmark results show Arcanum-65 at 0.48x-0.99x the time of ML-DSA-65.
//!
//! # Security Equivalence
//!
//! Security is primarily determined by:
//! 1. Lattice dimension: N×(K+L) where N=256
//! 2. Secret coefficient bound η
//! 3. Challenge weight τ
//!
//! | Variant | Dimension | vs ML-DSA | Security Level |
//! |---------|-----------|-----------|----------------|
//! | Arcanum-44 | 2048 | Same | NIST Level 2 |
//! | Arcanum-65 | 2816 | Same | NIST Level 3 |
//! | Arcanum-87 | 4096 | +7% | NIST Level 5 |
//!
//! # Size Trade-offs
//!
//! | Variant | Public Key | Secret Key | Signature |
//! |---------|------------|------------|-----------|
//! | Arcanum-44 | 1312 B | 2560 B | 2420 B |
//! | Arcanum-65 | 2272 B (+16%) | 4448 B (+10%) | 2670 B (-19%) |
//! | Arcanum-87 | 2592 B | 4992 B (+2%) | 5267 B (+14%) |
//!
//! Note: Arcanum-65 has *smaller* signatures than ML-DSA-65 (2670 vs 3309 bytes)
//! due to L=4 vs L=5, at the cost of a larger public key.
//!
//! # When to Use
//!
//! - **Use Arcanum-DSA** when: Performance is critical, FIPS compliance not required
//! - **Use ML-DSA** when: FIPS 204 compliance required, interoperability needed
//!
//! # Security Analysis
//!
//! ## Constant-Time Considerations
//!
//! Arcanum-DSA inherits ML-DSA's timing characteristics:
//!
//! | Operation | Timing | Notes |
//! |-----------|--------|-------|
//! | ExpandA | Variable | Public seed, not security-sensitive |
//! | ExpandS | Variable | Low rejection rate (~7-44%), no useful leakage |
//! | ExpandMask | Constant | No rejection sampling, fixed squeeze |
//! | SampleInBall | Variable | Public challenge hash |
//! | Sign loop | Variable | Known property, proven secure |
//! | NTT/INTT | Constant | No data-dependent branches |
//! | Coefficient ops | Constant | Standard arithmetic |
//!
//! The signing loop's variable iteration count is a known property of
//! Fiat-Shamir lattice signatures. The security proof accounts for this
//! leakage; the masking polynomial y ensures z = y + cs₁ doesn't reveal s₁.
//!
//! ## Parameter Security
//!
//! Parameters are validated at compile-time (see `params.rs`):
//! - SIMD alignment (L % 4 == 0)
//! - Security dimension (≥ ML-DSA equivalent)
//! - Algebraic consistency (BETA = TAU × ETA)
//! - Sampling efficiency (GAMMA1 power of 2)
//! - Valid coefficient bounds (ETA ∈ {2, 4})
//!
//! ## SIMD Implementation Security
//!
//! The 4-way parallel Keccak implementation (`expand_mask_x4`):
//! - Uses identical logic to sequential version (bit extraction)
//! - No timing variation based on coefficient values
//! - Buffer sizes validated to prevent under-read
//! - Nonce overflow checked (would cause incorrect signatures)
//!
//! # Agent-Optimized TDD Methodology
//!
//! This module follows agent-optimized TDD where tests serve as:
//! 1. **Executable specifications** - Tests define behavior unambiguously
//! 2. **Property invariants** - Mathematical properties that must hold
//! 3. **Boundary conditions** - Edge cases agents might miss
//! 4. **Regression guards** - Prevent breaking working code
//!
//! Tests are written BEFORE implementation and serve as the source of truth.
// Re-export parameter types
pub use ;
// Re-export API types
pub use ;