verda-ecc 0.1.0

Bit-level Reed-Solomon / BCH / CRC error-correcting codes (IT++ wrapper) with bit-vector I/O

verda-ecc

Bit-level Reed-Solomon / BCH / CRC error-correcting codes with native bit-vector (bvec) I/O, wrapping IT++ via pybind11. Built as a self-contained wheel (IT++ + OpenBLAS statically linked) — no system libitpp, no patchelf, no per-Python .so checked into git.

Why not a byte-oriented ECC library?

The Verda watermark encodes/decodes on non-byte-aligned codeword lengths (e.g. 31- and 127-bit BCH) and needs bit-error correction, not byte-symbol correction. Mainstream libraries operate on byte symbols: reedsolo is GF(2^8), bchlib takes bytearrays, crcmod produces byte CRCs. IT++ provides true bit-vector coding, so we wrap the known-good IT++ implementation rather than reimplement.

API

from verda_ecc import ECCHandler

ecc = ECCHandler()
cw  = ecc.bch_encode(bits, n=127, t=6)      # numpy int32 bit-array in/out
msg = ecc.bch_decode(cw, n=127, t=6)
cw  = ecc.rs_encode(bits, m=5, t=7)
crc = ecc.crc_encode(bits, crc_len=16)

Composites: encode_with_crc_and_{bch,rs} / decode_with_{bch,rs}_and_crc.

Bit-identical guarantee

tests/golden.json freezes the deployed IT++ build's exact output for every parameter set. tests/test_golden.py asserts a fresh build reproduces it byte-for-byte (encode + decode round-trips). The wheel does not ship unless this passes — the acceptance gate against silent build drift.

License

GPL-3.0-or-later (inherited from IT++). Pure coding theory; no Verda IP.