# ZIP 143: Transaction Signature Validation for Overwinter

Status: Final

Owners: Jack Grigg, Daira-Emma Hopwood

Snapshot: a34cfc091434275120ff017c92c3b50d3cef623a

Source date: 2026-10-16T02:56:04+01:00

[Source revision](https://github.com/zcash/zips/commit/a34cfc091434275120ff017c92c3b50d3cef623a)

[Official source](https://zips.z.cash/zip-0143) · [Source file](https://github.com/zcash/zips/blob/a34cfc091434275120ff017c92c3b50d3cef623a/zips/zip-0143.rst)

## Document parts

[Part 1](https://zip-tools-web.harpocrates.workers.dev/zip/143) · [Part 2](https://zip-tools-web.harpocrates.workers.dev/zip/143?part=2)

Reading part 2 of 2. Follow all parts for the complete proposal.

1. [Information on BCP 14 — "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels" and "RFC 8174: Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"](https://www.rfc-editor.org/info/bcp14)[↩︎](/zip/143#fnref1)

2. [ZIP 200: Network Upgrade Mechanism](/zip/200)[↩︎](/zip/143#fnref2)

3. [ZIP 201: Network Peer Management for Overwinter](/zip/201)[↩︎](/zip/143#fnref3)

4. [OP_CHECKSIG. Bitcoin Wiki](https://en.bitcoin.it/wiki/OP_CHECKSIG)[↩︎](/zip/143#fnref4)

5. [Zcash Protocol Specification, Version 2021.2.16. Section 4.7.1: Sending Notes (Sprout)](protocol/protocol.pdf#sproutsend)[↩︎](/zip/143#fnref5)

6. - [CVE-2013-2292](https://nvd.nist.gov/vuln/detail/CVE-2013-2292)
   
   - [New Bitcoin vulnerability: A transaction that takes at least 3 minutes to verify](https://bitcointalk.org/?topic=140078)
   
   - [The Megatransaction: Why Does It Take 25 Seconds?](https://rusty.ozlabs.org/?p=522)
   
   
   
   [↩︎](/zip/143#fnref6)

7. [SIGHASH_WITHINPUTVALUE: Super-lightweight HW wallets and offline data](https://bitcointalk.org/index.php?topic=181734.0)[↩︎](/zip/143#fnref7)

8. [BIP 143: Transaction Signature Verification for Version 0 Witness Program](https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki)[↩︎](/zip/143#fnref8)

9. [BUIP-HF Digest for replay protected signature verification across hard forks, version 1.2](https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/abc/replay-protected-sighash.md)[↩︎](/zip/143#fnref9)

10. [ZIP 202: Version 3 Transaction Format for Overwinter](/zip/202)[↩︎](/zip/143#fnref10)

11. [ZIP 202: Version 3 Transaction Format for Overwinter](/zip/202)[↩︎](/zip/143#fnref11)

12. [ZIP 201: Network Peer Management for Overwinter](/zip/201)[↩︎](/zip/143#fnref12)

13. ["BLAKE2: simpler, smaller, fast as MD5", Section 2.8](https://blake2.net/blake2.pdf)[↩︎](/zip/143#fnref13)

14. [ZIP 200: Network Upgrade Mechanism](/zip/200)[↩︎](/zip/143#fnref14)

15. [OP_CHECKSIG. Bitcoin Wiki](https://en.bitcoin.it/wiki/OP_CHECKSIG)[↩︎](/zip/143#fnref15)

16. [ZIP 202: Version 3 Transaction Format for Overwinter](/zip/202)[↩︎](/zip/143#fnref16)

17. [ZIP 202: Version 3 Transaction Format for Overwinter](/zip/202)[↩︎](/zip/143#fnref17)

18. In the original algorithm, a `uint256` of `0x0000......0001` is committed if the input index for a `SINGLE` signature is greater than or equal to the number of outputs. In this ZIP a `0x0000......0000` is commited, without changing the semantics.[↩︎](/zip/143#fnref18)

19. [ZIP 203: Transaction Expiry](/zip/203)[↩︎](/zip/143#fnref19)

20. [ZIP 143 Test Vectors](https://github.com/zcash-hackworks/zcash-test-vectors/blob/master/zcash_test_vectors/zip_0143.py)[↩︎](/zip/143#fnref20)

21. [SignatureHash Test Vectors](https://github.com/zcash/zcash/blob/master/src/test/data/sighash.json)[↩︎](/zip/143#fnref21)

22. [ZIP 201: Network Peer Management for Overwinter](/zip/201)[↩︎](/zip/143#fnref22)

23. [ZIP 201: Network Peer Management for Overwinter](/zip/201)[↩︎](/zip/143#fnref23)

## Citation relationships

Cites: [ZIP 200](https://zip-tools-web.harpocrates.workers.dev/zip/200), [ZIP 201](https://zip-tools-web.harpocrates.workers.dev/zip/201), [ZIP 202](https://zip-tools-web.harpocrates.workers.dev/zip/202), [ZIP 203](https://zip-tools-web.harpocrates.workers.dev/zip/203)

Cited by: [ZIP 200](https://zip-tools-web.harpocrates.workers.dev/zip/200), [ZIP 201](https://zip-tools-web.harpocrates.workers.dev/zip/201), [ZIP 202](https://zip-tools-web.harpocrates.workers.dev/zip/202), [ZIP 243](https://zip-tools-web.harpocrates.workers.dev/zip/243), [ZIP 244](https://zip-tools-web.harpocrates.workers.dev/zip/244)