Sample

Handle bcryptjs parameter asymmetries in hash salt defaults, selective 60-character error throwing in compare, fallback random precedence, and custom Base64 encoding

sha256:9e53fd13103b399494311358bf94c04682964ebb0f7c6cc08d8077e3ab99f3db

Case

Goal

Handle bcryptjs parameter asymmetries in hash salt defaults, selective 60-character error throwing in compare, fallback random precedence, and custom Base64 encoding HOW

Packages

bcryptjs 3.0.3

Environment

node

Created

2026-08-17T15:40:43Z

Commonly assumed

bcrypt.compareSync returns boolean false for any non-matching password hash and hash defaults to 10 rounds when the salt parameter is omitted

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

• assert compareSync returns boolean false for mismatched hashes whose length is not 60, but throws an uncaught Error on 60-character invalid or unsupported revision strings, while async hash rejects with Illegal arguments unless rounds or salt is explicitly supplied
• assert hashSync defaults to 10 rounds producing a 60-character $2b$10$ hash when salt is omitted, whereas async hash without salt rejects with 'Illegal arguments: string, undefined'
• assert setRandomFallback does not override crypto.getRandomValues or node:crypto when available, only executing if native crypto is absent
• assert genSaltSync(0) evaluates 0 || 10 and produces 10 rounds, while rounds 1 to 3 are silently clamped to 4 and rounds above 31 are clamped to 31
• assert compareSync and async compare throw 'Invalid salt version' on 60-character non-bcrypt strings and 'Invalid salt revision' on $2x$, but return false on length mismatches
• assert $2a$, $2b$, and $2y$ 60-character hashes verify with compareSync, whereas legacy $2$ produces a 59-character hash that fails compareSync and causes getSalt to throw
• assert encodeBase64 and decodeBase64 use bcrypt's non-standard alphabet where index 0 is '.' rather than 'A', causing standard RFC 4648 Base64 'AAAA' to decode to [8, 32, 130]
• assert async functions return a Promise when callback is omitted, but return undefined when a callback is passed
• assert truncates measures UTF-8 byte length with boundary at 72 bytes across multibyte characters and surrogate pairs, causing passwords sharing their initial 72 bytes to collide under compareSync
• assert embedded null bytes in passwords are preserved during UTF-8 array conversion rather than terminating early, producing distinct hashes for 'secret' and 'secret\x00'
• assert getRounds returns NaN without throwing on empty or malformed strings, while getSalt strictly requires length 60 and extracts 29 characters without format validation
• assert bcryptjs 3 defines an exports map restricting subpaths so requiring 'bcryptjs/package.json' throws ERR_PACKAGE_PATH_NOT_EXPORTED

Files

• NOTES.md
• csx.json
• package-lock.json
• package.json
• src/index.mjs
• test/contract.mjs

Download the source artifact (tar.gz)

Origin Seeder

csx-seed

Verification receipts

• node 22 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9