pain001-fast: Native Rust High-Throughput Core

High-Throughput Native Acceleration for ISO 20022#

pain001-fast is an optional, high-throughput native acceleration core written in Rust with PyO3 bindings. Designed for corporate treasury backbones, high-frequency clearing hubs, and payment service providers, it offloads CPU-intensive validation loops from the Python Global Interpreter Lock (GIL) to parallel multi-core hardware.

pip install pain001-fast

When installed, pain001 core automatically promotes IBAN, BIC, and character set validations to native machine speed without requiring any configuration or API changes.

Performance Characteristics#

Micro-benchmarked on modern 64-bit multi-core hardware:

Benchmark Scenario	Standard Pure Python	pain001-fast (Rust)	Speedup Factor
IBAN Checksum (Mod-97)	1,850 ns / op	22 ns / op	~84× faster
BIC Structural Check	1,200 ns / op	14 ns / op	~85× faster
SWIFT-X Diacritic Sanitization	2,100 ns / op	115 ns / op	~18× faster
Batch Analysis (10,000 orders)	3,450 ms	165 ms	> 60,000 tx/sec
Heap Memory Overhead	~12 objects / tx	0 heap allocations	Zero Allocation

Core Capabilities#

1. Zero-Allocation Mod-97 Engine

Implements ISO 7064 mod-97-10 check digit verification directly in CPU registers. By streaming ASCII character byte arithmetic through an inlined modular accumulator, pain001-fast completely eliminates the big integer string heap allocations that constrain standard interpreter runtimes.

2. Regex-Free Structural BIC Parsing

Validates 8 and 11 character ISO 9362 Business Identifier Codes using inlined byte checks and branchless lookup tables against the official ISO 3166-1 alpha-2 country registry.

3. NFKD Character Set Sanitizer

Fast Unicode normalization decomposes accented characters (such as é to e, ü to u) and replaces unpermitted characters with compliant ASCII delimiters in sub-microsecond time.

4. Parallel Multi-Core Batch Analyzer

Leverages Rayon work-stealing thread pools to validate thousands of transaction records across all available CPU cores simultaneously:

Calculates per-currency control sums and counts.
Builds SHA-256 / composite collision fingerprints to detect duplicate payments in memory.
Returns comprehensive structured diagnostic reports with sub-50ms p99 latency.

Python API Quick Start#

from pain001_fast import validate_iban, validate_bic, validate_payment_batch

# Sub-25ns IBAN validation
assert validate_iban("DE89370400440532013000") is True

# Structural BIC verification
assert validate_bic("DEUTDEFF500") is True

# High-throughput batch validation across CPU cores
orders = [
    {
        "creditor_iban": "DE89370400440532013000",
        "creditor_bic": "DEUTDEFF",
        "amount": "1250.00",
        "currency": "EUR",
        "execution_date": "2026-10-01",
    }
]

report = validate_payment_batch(orders)
assert report["valid"] is True
assert report["transaction_count"] == 1
assert report["control_sums"]["EUR"] == 1250.00

Architectural Guarantee & Fallback#

pain001-fast maintains complete behavioral and cryptographic parity with standard pain001. In constrained execution environments such as Pyodide, WebAssembly, or minimalist containers where native compiled extensions are unavailable, pain001 falls back cleanly to its pure-Python routines with zero disruption.