---
title: "ECDSA on sect571r1: which blockchains use it"
url: "https://hardyindex.com/algorithms/ecdsa-sect571r1"
---

# ECDSA on sect571r1

The Elliptic Curve Digital Signature Algorithm over sect571r1, a 571-bit binary-field curve defined in SEC 2 and known to NIST as B-571. Nexus's original coin layer, before signature chains, signs with it. A larger curve raises the classical cost of attack but not the quantum one: Shor's algorithm on a cryptographically relevant quantum computer recovers the private key from the public key.

- **Quantum status:** Broken by Shor's algorithm on a cryptographically relevant quantum computer.
- **Standard:** SEC 2 (SECG, final).
- **Family:** elliptic curve.
- **Also known as:** sect571r1, B-571.

## Rated chains using it

- [Nexus](https://hardyindex.com/chains/nexus.md): account signatures, mainnet, opt-in, sect571r1, legacy UTXO outputs. The legacy CheckSig builds an elliptic-curve key on the default curve, NID_sect571r1 (src/LLC/eckey.cpp lines 271 to 276). Legacy transactions are still accepted in Tritium blocks; how much supply remains in legacy outputs is unmeasured. Source (source code or release): https://github.com/Nexusoft/LLL-TAO/blob/5.1.6/src/Legacy/signature.cpp#L146-L163

## Sources

- [SEC 2: Recommended Elliptic Curve Domain Parameters](https://www.secg.org/sec2-v2.pdf), Standards for Efficient Cryptography Group. Accessed 23 October 2026.