--- title: Is eCash quantum-safe? chain: eCash ticker: XEC hardy_score: 8.5 rank: 60 of 80 tier: "5: Exposed" url: "https://hardyindex.com/chains/ecash" updated: 2026-10-22 reviewed: 2026-11-13 methodology_version: 1.8 --- # Is eCash quantum-safe? **Hardy Score 8.5 / 100. Rank 60 of 80. Tier 5: Exposed. Last editorial review 22 October 2026; sources checked 13 November 2026.** No. eCash, run by the Bitcoin ABC node, protects XEC with ECDSA and Schnorr signatures on the secp256k1 curve, both broken by Shor's algorithm. Its Avalanche layer, which finalises blocks and, since the November 2025 upgrade, transactions before they are mined, uses the same curve: stake proofs, delegations and votes are all Schnorr signatures on secp256k1. We found no post-quantum proposal, roadmap item or research programme from Bitcoin ABC or the eCash project. The published eCash roadmap lists Schnorr signatures as complete and names nothing post-quantum, and none of the posts on the eCash blog mentions quantum computing. eCash became a separate currency from Bitcoin Cash in a chain split on 15 November 2020, and Bitcoin Cash had split from Bitcoin on 1 August 2017, so eCash carries Bitcoin's early history, including the original pay-to-public-key outputs, about 2 million coins by Deloitte's count, whose public keys are already on-chain. > This is a security-readiness assessment, not investment advice. ## Summary Signs with ECDSA and Schnorr on secp256k1, finalises blocks with Avalanche votes signed by the same curve, has no post-quantum proposal, and as a fork of Bitcoin Cash inherits the early pay-to-public-key coins whose keys have been on-chain since 2009. ## Where we are making a judgement call Two judgement calls carry this profile, and one fact belongs beside them. First, exposure inherits the measured pre-fork pay-to-public-key outputs eCash shares with Bitcoin and Bitcoin Cash, under v1.8's inheritance rule. A reader who scores eCash on its own key-hash address model, as Litecoin and Dogecoin are scored, would give exposure 4, adding 2.0 points to a Hardy Score of 8.5. A measurement of eCash itself would replace the inherited figure and could move the score either way: some inherited coins have moved on this chain since the splits, and the keys of staked coins published in Avalanche proofs are unmeasured. Second, migration scores 2 on eCash's record of scheduled upgrades. The eCash project says Avalanche lets nodes agree on upgrades without chain splits, which a reader could treat as a governance mechanism worth more; we do not, because it is a way to activate changes, not a route for moving holders to new keys, and nothing has been proposed for it to carry. A reader who weighs the record at nothing without a quantum plan would score 1, taking 1.5 points off. Third, the fact: a consensus rule in the Bitcoin ABC node, in force since the November 2020 split and raised to 32% in November 2023, sends that share of every block reward to a single fund address hard-coded in the node. The address is pay-to-script-hash, so it is controlled by whatever script stands behind it, and the sources we read do not say what that script is or who controls it. It does not change any score here. ## Score breakdown | # | Dimension | Score | Weight | Contribution | |---:|---|---:|---:|---:| | 1 | Signature scheme | 0/10 | 30% | 0.0 | | 2 | Deployment stage | 1/10 | 25% | 2.5 | | 3 | NIST alignment | 0/10 | 15% | 0.0 | | 4 | Migration path | 2/10 | 15% | 3.0 | | 5 | Exposure | 2/10 | 10% | 2.0 | | 6 | Verification | 2/10 | 5% | 1.0 | | | **Hardy Score** | | | **8.5** | ### 1. Signature scheme: 0/10 Anchor band 0: Classical signatures only on mainnet, with nothing post-quantum protecting live funds. Short-lived devnets and one-off benchmarks sit here: they demonstrate research rather than something a user can hold keys on. eCash spends are authorised by ECDSA or by the Schnorr variant on secp256k1 that the Bitcoin ABC specification added to OP_CHECKSIG and OP_CHECKDATASIG in May 2019 and to OP_CHECKMULTISIG in November 2019. Avalanche stake proofs and votes are Schnorr signatures on the same curve. Nothing post-quantum protects XEC on mainnet. Source: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/schnorr.md ### 2. Deployment stage: 1/10 Anchor band 1: Tier 5: Exposed. Tier 5: Exposed. The signatures securing XEC and finalising its blocks are quantum-vulnerable, and neither the eCash roadmap nor the Bitcoin ABC repository holds a post-quantum plan, proposal or research programme for them. The roadmap lists Schnorr signatures as complete and names no post-quantum item. Source: https://e.cash/roadmap ### 3. NIST alignment: 0/10 Anchor band 0 to 2: No post-quantum scheme named for the chain’s fund-protecting signatures, or a proprietary scheme with no public cryptanalysis. No post-quantum scheme has been named for eCash's spend signatures or for the Avalanche signatures that finalise blocks, so there is nothing to assess against a NIST standard. Placement in the band: The floor of the band rather than a 1 or a 2: no scheme of any kind has been named for eCash's fund-protecting signatures, standardised or otherwise, so there is nothing for the band's upper values to credit. Source: https://e.cash/roadmap ### 4. Migration path: 2/10 Anchor band 0 to 2: No agreed migration path, or the proposals on the table would strand or freeze holder funds. No migration plan exists. eCash has shown it can coordinate consensus changes on a fixed schedule: the November 2023 upgrade added the staking reward output to the coinbase, the November 2025 upgrade enabled Avalanche pre-consensus and 64-bit script integers, and Bitcoin ABC 0.34.0 prepares the next upgrade for 15 November 2026. None of them touched the signature scheme. Placement in the band: The top of the band rather than a 0 or a 1: upgrades activated on a published twice-yearly schedule, the latest in November 2025, are direct evidence that the chain can ship protocol changes. Not a 3, because nobody with authority over eCash has acknowledged quantum migration as a problem to solve. Source: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.32.0.md ### 5. Exposure: 2/10 Anchor band 0 to 2: Public keys are exposed for effectively all accounts, or a large, measured share of total supply sits in exposed addresses. Under v1.8's inheritance rule, published measurements of the history eCash shares with Bitcoin apply to it until one specific to eCash exists. Its chain carries Bitcoin's blocks to August 2017 and Bitcoin Cash's to November 2020, including the original pay-to-public-key outputs that Deloitte puts at about 2 million coins, roughly a tenth of supply, with keys already on-chain. Placement in the band: The top of the band rather than a 1: the pre-fork pay-to-public-key share is the part inherited with certainty, while Bitcoin's larger address-reuse figures were measured on its history after the splits and do not transfer. Not a 3, because a measured tenth of supply with keys on-chain is a large share. Source: https://www.deloitte.com/nl/en/services/risk-advisory/perspectives/quantum-computers-and-the-bitcoin-blockchain.html ### 6. Verification: 2/10 Anchor band 0 to 2: No post-quantum component exists, or the claims rest on marketing. No post-quantum component protects eCash, so there is nothing post-quantum to review or audit. Under v1.8 the openness of the Bitcoin ABC node earns nothing here, because it is classical code that a quantum computer would break. Placement in the band: The top of the band rather than a 0 or a 1: there is no post-quantum component to verify, but nothing about eCash is marketed as quantum-safe, so its position does not rest on marketing. Source: https://github.com/Bitcoin-ABC/bitcoin-abc ## Nearest chains in the ranking The chains eCash sits among, out of 80 rated. The last column is the gap in Hardy points from eCash. | Rank | Chain | Tier | Hardy | vs XEC | |---:|---|---|---:|---:| | 56 | [Celestia](https://hardyindex.com/chains/celestia) | 5: Exposed | 8.5 | level | | 57 | [Chiliz Chain](https://hardyindex.com/chains/chiliz) | 5: Exposed | 8.5 | level | | 58 | [Conflux](https://hardyindex.com/chains/conflux) | 5: Exposed | 8.5 | level | | 59 | [dYdX Chain](https://hardyindex.com/chains/dydx) | 5: Exposed | 8.5 | level | | 60 | **eCash** | 5: Exposed | 8.5 | this chain | | 61 | [Filecoin](https://hardyindex.com/chains/filecoin) | 5: Exposed | 8.5 | level | | 62 | [GateChain](https://hardyindex.com/chains/gatechain) | 5: Exposed | 8.5 | level | | 63 | [Gnosis Chain](https://hardyindex.com/chains/gnosis) | 5: Exposed | 8.5 | level | | 64 | [Injective](https://hardyindex.com/chains/injective) | 5: Exposed | 8.5 | level | ## Signature scheme - **On mainnet today:** ECDSA and Schnorr on secp256k1 for spends; Schnorr on secp256k1 for Avalanche stake proofs, delegations and votes; proof of work for block production - **Post-quantum scheme:** None deployed or proposed. - **NIST standard:** None adopted - **Readiness tier:** Tier 5: Exposed. The signatures securing funds on mainnet today are quantum-vulnerable, and no public post-quantum plan, proposal or research programme addressing them could be found. ## Cryptography in use - **Account signatures:** [ECDSA on secp256k1](https://hardyindex.com/algorithms/ecdsa-secp256k1.md). Mainnet, default. Spend signatures. OP_CHECKSIG accepts ECDSA or Schnorr since May 2019, and OP_CHECKMULTISIG does too since November 2019. Source (specification or proposal): https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/schnorr.md - **Account signatures:** [Schnorr signatures on secp256k1](https://hardyindex.com/algorithms/schnorr-secp256k1.md). Mainnet, default. The Schnorr variant activated in May 2019, before the split from Bitcoin Cash; not BIP-340. Source (specification or proposal): https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/schnorr.md - **Validator consensus:** [Schnorr signatures on secp256k1](https://hardyindex.com/algorithms/schnorr-secp256k1.md). Mainnet, mandatory. Avalanche proofs sign each stake with the staked coin's key, and delegations and poll responses carry 64-byte Schnorr signatures. Avalanche finalises blocks and, since November 2025, transactions. Source (specification or proposal): https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/avalanche.md A role not listed here is not evidenced either way. See https://hardyindex.com/algorithms.md. ## Roadmap - **1 August 2017** (shipped): Bitcoin Cash splits from Bitcoin at the August 2017 hard fork, which the Bitcoin ABC node still records at block 478,558. eCash descends from that chain, so it shares Bitcoin's history, and every public key revealed in it, up to this point. Source: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/src/kernel/chainparams.cpp - **15 November 2020** (shipped): eCash and Bitcoin Cash become separate currencies in a chain split at the November 2020 upgrade, which activated the ASERT difficulty algorithm and a coinbase rule funding infrastructure development. Coins unmoved since before the split exist on both chains. Source: https://e.cash/blog/splitting-ecash-bch - **15 November 2023** (shipped): The staking reward output is added to the coinbase, paying 10% of the block reward to an address selected from the Avalanche network. Not post-quantum work, but evidence of coordinated consensus change. Source: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.28.0.md - **15 November 2025** (shipped): Avalanche pre-consensus is enabled, so nodes vote to finalise transactions before they are mined, alongside 64-bit script integers. The votes are Schnorr signatures on secp256k1. Source: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.32.0.md - **No published position** (proposed): No post-quantum roadmap item, proposal or research programme for eCash's signatures was found on the eCash roadmap, the eCash blog or in the Bitcoin ABC repository at the time of writing. Source: https://e.cash/roadmap ## If holders never migrate **No stated policy.** Neither Bitcoin ABC nor the eCash project has published a policy on coins that stay behind ECDSA or Schnorr keys, including the inherited early pay-to-public-key outputs. As of 22 October 2026. ## Exposure eCash inherits two histories. Its chain carries every Bitcoin block to the Bitcoin Cash split of 1 August 2017 and every Bitcoin Cash block to its own split on 15 November 2020, and the eCash project describes it as tracing back to Bitcoin's genesis block. Each original pay-to-public-key output mined in Bitcoin's early years therefore exists here too, with its public key on-chain, and every address reused before November 2020 has revealed its key on this chain as well. Under the v1.8 inheritance rule, the measured pre-fork share applies until a measurement of eCash exists: Deloitte found that the pay-to-public-key supply has stayed practically constant at about 2 million coins, which places it in the early history that predates both splits. This follows the treatment of Bitcoin Cash and Bitcoin SV. One eCash-specific exposure is unmeasured: an Avalanche proof lists each staked coin with its public key and a signature by that key, and proofs are relayed between nodes, so the keys behind staked coins are public while the coins stay unspent. No measurement specific to eCash has been published, so coins that moved after the splits, staked coins and address reuse since are unmeasured. ## Frequently asked questions ### Is eCash quantum-safe? No. eCash, run by the Bitcoin ABC node, protects XEC with ECDSA and Schnorr signatures on the secp256k1 curve, both broken by Shor's algorithm. Its Avalanche layer, which finalises blocks and, since the November 2025 upgrade, transactions before they are mined, uses the same curve: stake proofs, delegations and votes are all Schnorr signatures on secp256k1. We found no post-quantum proposal, roadmap item or research programme from Bitcoin ABC or the eCash project. The published eCash roadmap lists Schnorr signatures as complete and names nothing post-quantum, and none of the posts on the eCash blog mentions quantum computing. eCash became a separate currency from Bitcoin Cash in a chain split on 15 November 2020, and Bitcoin Cash had split from Bitcoin on 1 August 2017, so eCash carries Bitcoin's early history, including the original pay-to-public-key outputs, about 2 million coins by Deloitte's count, whose public keys are already on-chain. ### Is eCash quantum-safe? No. eCash signs spends with ECDSA and Schnorr on the secp256k1 curve, and its Avalanche finality layer signs with Schnorr on the same curve. A sufficiently large quantum computer would break both. We found no post-quantum proposal, roadmap item or research programme from Bitcoin ABC or the eCash project. ### Does Avalanche finality protect eCash against a quantum attacker? No. Avalanche stake proofs, delegations and votes are all Schnorr signatures on secp256k1, which Shor's algorithm breaks as it breaks ECDSA. An attacker able to forge those keys could vote with other people's stake as well as spend other people's coins. ### Does eCash inherit Bitcoin's exposed coins? Yes, for the history it shares. eCash's chain contains Bitcoin's blocks up to August 2017 and Bitcoin Cash's up to November 2020, so the original pay-to-public-key outputs from Bitcoin's early years, about 2 million coins by Deloitte's count, exist on eCash with their public keys on-chain. Under the index's inheritance rule that measured share applies here until someone measures eCash itself. ### What would move eCash up the index? A formal proposal or public research programme from Bitcoin ABC on eCash's own signatures would meet the Tier 4 floor. eCash already upgrades on a published twice-yearly schedule, so a post-quantum signature in a scheduled upgrade, with a route for holders to move their coins, would raise several of the six scores. ## What this rating means if you hold eCash Plain-language guidance from the same publication, with no product recommendation attached. - [Is my crypto safe from quantum computers?](https://hardyindex.com/guides/is-my-crypto-safe-from-quantum-computers.md) - [How to protect your crypto from quantum computers](https://hardyindex.com/guides/how-to-protect-crypto-from-quantum-computers.md) - [All guides](https://hardyindex.com/guides.md) ## Sources 1. [Bitcoin ABC node software](https://github.com/Bitcoin-ABC/bitcoin-abc): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 2. [2019-MAY-15 Schnorr Signature specification](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/schnorr.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 3. [2019-NOV-15 Network Upgrade Specification](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/2019-11-15-upgrade.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 4. [2019-NOV-15 Schnorr OP_CHECKMULTISIG specification](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/schnorrmultisig.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 5. [Avalanche protocol documentation (doc/avalanche.md)](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/avalanche.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 6. [Avalanche proof structure (src/avalanche/proof.h)](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/src/avalanche/proof.h): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 7. [Bitcoin ABC chain parameters (src/kernel/chainparams.cpp)](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/src/kernel/chainparams.cpp): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 8. [2020-NOV-15 Network Upgrade Specification](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/standards/2020-11-15-upgrade.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 9. [Miner fund consensus rule (src/minerfund.cpp)](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/src/minerfund.cpp): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 10. [Bitcoin ABC 0.28.0 release notes](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.28.0.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 11. [Bitcoin ABC 0.32.0 release notes](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.32.0.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 12. [Bitcoin ABC 0.34.0 release notes](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/release-notes/release-notes-0.34.0.md): Bitcoin ABC (GitHub) (primary, checked 22 October 2026) 13. [eCash Roadmap](https://e.cash/roadmap): eCash (primary, checked 22 October 2026) 14. [eCash Technology](https://e.cash/tech): eCash (primary, checked 22 October 2026) 15. [Splitting eCash and BCH coins using Electrum ABC and Electron Cash](https://e.cash/blog/splitting-ecash-bch): eCash (primary, checked 22 October 2026) 16. [What is eCash?](https://e.cash/blog/what-is-ecash): eCash (primary, checked 22 October 2026) 17. [Quantum computers and the Bitcoin blockchain](https://www.deloitte.com/nl/en/services/risk-advisory/perspectives/quantum-computers-and-the-bitcoin-blockchain.html): Deloitte (primary, checked 22 October 2026) ## How to cite this rating A rating is only true as of the day it was reviewed, so both forms carry the review date and the methodology version. If you are quoting the score, quote those too. The Hardy Index (2026). eCash: quantum readiness assessment. Hardy Score 8.5 of 100, Tier 5: Exposed. Methodology v1.8. Last reviewed 22 October 2026; sources checked 13 November 2026. https://hardyindex.com/chains/ecash ```bibtex @misc{hardyindex_ecash_2026, author = {{The Hardy Index}}, title = {eCash: quantum readiness assessment}, year = {2026}, howpublished = {\url{https://hardyindex.com/chains/ecash}}, note = {Hardy Score 8.5 of 100, Tier 5: Exposed. Methodology v1.8}, urldate = {2026-11-13} } ``` --- Methodology: https://hardyindex.com/methodology (v1.8). Cite as: The Hardy Index, "eCash", https://hardyindex.com/chains/ecash, as of 13 November 2026.