{"id":"GHSA-7f6p-phw2-8253","summary":"Taurus multi-party-sig has OT-based ECDSA protocol implementation flaws","details":"Coinbase researchers reported 2 security issues in our implementation of the oblivious transfer (OT) based protocol [DKLS](https://eprint.iacr.org/2018/499.pdf):\n\n### 1. Secret share recovery attack\n\nIf the base OT setup of the protocol is reused for another execution of the OT extension, then a malicious participant can extract a bit of the secret of another participant. By repeating the execution they can eventually recover the whole secret.\n\nTherefore, unlike our comments suggested, you **must not reuse an OT setup** for multiple protocol executions. \n\nWe're adding a warning in the code:\n\nhttps://github.com/taurushq-io/multi-party-sig/blob/9e4400fccee89be6195d0a12dd0ed052288d5040/internal/ot/extended.go#L114\n\n### 2. Invalid security proof due to incorrect operator\n\nThe original 2018 version of the DKLS had a typo in the OT extension protocol when computing the check value in the OT extension: the paper noted a XOR whereas it should be a field multiplication. This erroneous behavior was implemented [in our code](https://github.com/taurushq-io/multi-party-sig/blob/4d84aafb57b437da1b933db9a265fb7ce4e7c138/internal/ot/extended.go#L188). \n\nThe proof of security fails in this case. No concrete attack is known, however.\n\nThe [2023 update](https://eprint.iacr.org/2018/499.pdf) of the DKLS paper reported that typo and updated the protocol definition.\n\n~As of 20241124, patching is in progress (branch [otfix](https://github.com/taurushq-io/multi-party-sig/tree/otfix)), but not merged to the main branch yes as the tests fail to pass. We're troubleshooting the issue and will merge into the main branch when it's resolved.~\n\nAs of 20250128, a patched version is available in https://github.com/taurushq-io/multi-party-sig/releases/tag/v0.7.0-alpha-2025-01-28, thanks to https://github.com/taurushq-io/multi-party-sig/pull/119.\n\n### Workarounds\n\nDo not reuse an OT setup in the event that an abort is detected, to eliminate the secret recovery attack.\n  \n\n### Credits\n\nThanks to the Coinbase researchers Yi-Hsiu Chen and Samuel Ranellucci for discovering these issues and providing a comprehensive write-up. Thank you to Yehuda Lindell for coordinating the disclosure.\nThanks to Jay Prakash for clarifying the risk of the base setup reuse.\nThanks to @cronokirby for writing the corrected code.\n\n\n","aliases":["GO-2024-3288"],"modified":"2025-01-28T18:06:15Z","published":"2024-11-25T15:11:11Z","database_specific":{"cwe_ids":[],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2024-11-25T15:11:11Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/taurushq-io/multi-party-sig/security/advisories/GHSA-7f6p-phw2-8253"},{"type":"WEB","url":"https://eprint.iacr.org/2018/499.pdf"},{"type":"PACKAGE","url":"https://github.com/taurushq-io/multi-party-sig"},{"type":"WEB","url":"https://github.com/taurushq-io/multi-party-sig/blob/4d84aafb57b437da1b933db9a265fb7ce4e7c138/internal/ot/extended.go#L188"},{"type":"WEB","url":"https://github.com/taurushq-io/multi-party-sig/blob/9e4400fccee89be6195d0a12dd0ed052288d5040/internal/ot/extended.go#L114"},{"type":"WEB","url":"https://github.com/taurushq-io/multi-party-sig/tree/otfix"}],"affected":[{"package":{"name":"github.com/taurusgroup/multi-party-sig","ecosystem":"Go","purl":"pkg:golang/github.com/taurusgroup/multi-party-sig"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.7.0-alpha-2025-01-28"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 0.6.0-alpha-2021-09-21","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7f6p-phw2-8253/GHSA-7f6p-phw2-8253.json"}}],"schema_version":"1.9.0"}