An issue was discovered in fastecdsa before 2.1.2. When using the NIST P-256 curve in the ECDSA implementation, the point at infinity is mishandled. This means that for an extreme value in k and s^-1, the signature verification fails even if the signature is correct. This behavior is not solely a usability problem. There are some threat models where an attacker can benefit by successfully guessing users for whom signature verification will fail.
{ "vanir_signatures": [ { "digest": { "function_hash": "93520763919975657384232032081005663602", "length": 830.0 }, "signature_version": "v1", "signature_type": "Function", "source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1", "id": "CVE-2020-12607-66ce0194", "deprecated": false, "target": { "file": "src/curveMath.c", "function": "pointZZ_pDouble" } }, { "digest": { "function_hash": "114807553560984464700912165694170755712", "length": 1007.0 }, "signature_version": "v1", "signature_type": "Function", "source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1", "id": "CVE-2020-12607-765a86e6", "deprecated": false, "target": { "file": "src/curveMath.c", "function": "pointZZ_pMul" } }, { "digest": { "function_hash": "237713034721248222028732838030589999764", "length": 794.0 }, "signature_version": "v1", "signature_type": "Function", "source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1", "id": "CVE-2020-12607-9ebef2d1", "deprecated": false, "target": { "file": "src/curveMath.c", "function": "pointZZ_pAdd" } }, { "digest": { "threshold": 0.9, "line_hashes": [ "295440111576572506065665976290646547187", "196854035119909962313773951870531590818", "317871309843992884374969037078204491522", "104375746076562032098332227659040301528", "65416599458374717787017732325794096570", "177423792026663125093054846541122329542", "218619352812740939546316886251052461695", "40930251885493100673819922373020214212", "243540426651314462511606196020035304659", "273798193599705150604646108665496793181", "170054887755278315323162088544007563571", "197353946011006447932649302589988372905", "234408837222518631626031317531483544714", "74221276442437195587473428445690813998" ] }, "signature_version": "v1", "signature_type": "Line", "source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1", "id": "CVE-2020-12607-adb032bc", "deprecated": false, "target": { "file": "src/curveMath.c" } } ] }