golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c: bcrypt.InvalidHashPrefixError

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify golang.org/x/crypto/bcrypt.InvalidHashPrefixError in pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c
Demonstrate these symbols/APIs:
  - golang.org/x/crypto/bcrypt.InvalidHashPrefixError

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:ca4e5e2e486555a7d32e0354e0712e10855e68910184906537ee633e75fc177a","contract":["bcrypt.InvalidHashPrefixError('#').Error() returns \"crypto/bcrypt: bcrypt hashes must start with '$', but hashedSecret started with '#'\"","bcrypt.CompareHashAndPassword returns bcrypt.InvalidHashPrefixError('#') when given a full-length hash starting with '#' instead of '$'","bcrypt.Cost returns bcrypt.InvalidHashPrefixError('!') when given a full-length hash starting with '!'"],"goal":"verify golang.org/x/crypto/bcrypt.InvalidHashPrefixError in pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c","kind":"HOW","packages":["pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c"],"schemaVersion":1,"symbols":["golang.org/x/crypto/bcrypt.InvalidHashPrefixError"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c","symbols":["golang.org/x/crypto/bcrypt.InvalidHashPrefixError"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.21

require golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c h1:9HhBz5L/UjnK9XLtiZhYAdue5BVKep3PMmS2LuPDt8k=
golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

package main

import (
	"fmt"
	"golang.org/x/crypto/bcrypt"
)

func main() {
	err := bcrypt.InvalidHashPrefixError('#')
	fmt.Println(err.Error())

	cmpErr := bcrypt.CompareHashAndPassword([]byte("#2a$10$abcdefghijklmnopqrstuuABCDEFGHIJKLMNOPQRSTUVWXYZ01234"), []byte("password"))
	if prefixErr, ok := cmpErr.(bcrypt.InvalidHashPrefixError); ok {
		fmt.Printf("prefix=%c msg=%s\n", byte(prefixErr), prefixErr.Error())
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/crypto/bcrypt.InvalidHashPrefixError in pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/crypto@v0.0.0-20201203163018-be400aefbc4c"
  ],
  "symbols": [
    "golang.org/x/crypto/bcrypt.InvalidHashPrefixError"
  ]
}

package main

import (
	"errors"
	"os"

	"golang.org/x/crypto/bcrypt"
)

func main() {
	directErr := bcrypt.InvalidHashPrefixError('#')
	expectedMsg := "crypto/bcrypt: bcrypt hashes must start with '$', but hashedSecret started with '#'"
	if directErr.Error() != expectedMsg {
		os.Exit(1)
	}

	var asErr error = directErr
	if byte(directErr) != '#' || asErr.Error() != expectedMsg {
		os.Exit(1)
	}

	cmpErr := bcrypt.CompareHashAndPassword([]byte("#2a$10$abcdefghijklmnopqrstuuABCDEFGHIJKLMNOPQRSTUVWXYZ01234"), []byte("password"))
	if cmpErr == nil {
		os.Exit(1)
	}

	var target bcrypt.InvalidHashPrefixError
	if !errors.As(cmpErr, &target) {
		os.Exit(1)
	}
	if target != bcrypt.InvalidHashPrefixError('#') {
		os.Exit(1)
	}
	if target.Error() != expectedMsg {
		os.Exit(1)
	}

	costErr, err := bcrypt.Cost([]byte("!2a$10$abcdefghijklmnopqrstuuABCDEFGHIJKLMNOPQRSTUVWXYZ01234"))
	if costErr != 0 || err != bcrypt.InvalidHashPrefixError('!') {
		os.Exit(1)
	}
}