golang.org/x/crypto v0.48.0: bcrypt.ErrHashTooShort

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.ErrHashTooShort in pkg:golang/golang.org/x/crypto@v0.48.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/crypto@v0.48.0
Demonstrate these symbols/APIs:
  - golang.org/x/crypto/bcrypt.ErrHashTooShort

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:cbbc53bc5baef57889b400697b7a8bf343c4c59731e38073df62d08a50a153d3","contract":["bcrypt.CompareHashAndPassword returns ErrHashTooShort when hash is shorter than minHashSize","bcrypt.CompareHashAndPassword returns ErrHashTooShort for empty hash","bcrypt.Cost returns ErrHashTooShort when hash is shorter than minHashSize","errors.Is identifies ErrHashTooShort from CompareHashAndPassword error","bcrypt.ErrHashTooShort error message equals 'crypto/bcrypt: hashedSecret too short to be a bcrypted password'","bcrypt.CompareHashAndPassword returns nil for matching password and does not match ErrHashTooShort"],"goal":"verify golang.org/x/crypto/bcrypt.ErrHashTooShort in pkg:golang/golang.org/x/crypto@v0.48.0","kind":"HOW","packages":["pkg:golang/golang.org/x/crypto@v0.48.0"],"schemaVersion":1,"symbols":["golang.org/x/crypto/bcrypt.ErrHashTooShort"]},"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@v0.48.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/crypto@v0.48.0","symbols":["golang.org/x/crypto/bcrypt.ErrHashTooShort"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/crypto v0.48.0

golang.org/x/crypto v0.48.0 h1:/VRzVqiRSggnhY7gNRxPauEQ5Drw9haKdM0jqfcCFts=
golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=

package main

import (
	"errors"
	"fmt"
	"log"

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

func main() {
	password := []byte("example-password")

	// Generate a valid bcrypt hash
	hash, err := bcrypt.GenerateFromPassword(password, bcrypt.DefaultCost)
	if err != nil {
		log.Fatalf("failed to generate password hash: %v", err)
	}

	// Comparing against a valid hash succeeds
	if err := bcrypt.CompareHashAndPassword(hash, password); err != nil {
		log.Fatalf("unexpected error comparing valid hash: %v", err)
	}
	fmt.Println("Password comparison succeeded with valid hash.")

	// Attempting to compare against a truncated/short hash triggers ErrHashTooShort
	shortHash := []byte("$2a$10$tooshort")
	err = bcrypt.CompareHashAndPassword(shortHash, password)
	if err != nil {
		if errors.Is(err, bcrypt.ErrHashTooShort) {
			fmt.Println("Detected hash too short via ErrHashTooShort as expected.")
		} else {
			log.Fatalf("unexpected error: %v", err)
		}
	}

	// Cost inspection also returns ErrHashTooShort on short hashes
	_, err = bcrypt.Cost(shortHash)
	if errors.Is(err, bcrypt.ErrHashTooShort) {
		fmt.Println("Detected hash too short during Cost check as expected.")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/crypto/bcrypt.ErrHashTooShort in pkg:golang/golang.org/x/crypto@v0.48.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/crypto@v0.48.0"
  ],
  "symbols": [
    "golang.org/x/crypto/bcrypt.ErrHashTooShort"
  ]
}

package main

import (
	"errors"
	"fmt"
	"os"

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

func main() {
	password := []byte("contract-test-password")

	hash, err := bcrypt.GenerateFromPassword(password, bcrypt.MinCost)
	if err != nil {
		fmt.Fprintf(os.Stderr, "setup failed: %v\n", err)
		os.Exit(1)
	}

	shortHash := []byte("$2a$10$tooshort")

	// 1. bcrypt.CompareHashAndPassword returns ErrHashTooShort when hash is shorter than minHashSize
	errShort := bcrypt.CompareHashAndPassword(shortHash, password)
	if errShort == nil || !errors.Is(errShort, bcrypt.ErrHashTooShort) {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected ErrHashTooShort, got %v\n", errShort)
		os.Exit(1)
	}

	// 2. bcrypt.CompareHashAndPassword returns ErrHashTooShort for empty hash
	errEmpty := bcrypt.CompareHashAndPassword([]byte(""), password)
	if !errors.Is(errEmpty, bcrypt.ErrHashTooShort) {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected ErrHashTooShort, got %v\n", errEmpty)
		os.Exit(1)
	}

	// 3. bcrypt.Cost returns ErrHashTooShort when hash is shorter than minHashSize
	_, errCost := bcrypt.Cost(shortHash)
	if !errors.Is(errCost, bcrypt.ErrHashTooShort) {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: expected ErrHashTooShort, got %v\n", errCost)
		os.Exit(1)
	}

	// 4. errors.Is identifies ErrHashTooShort from CompareHashAndPassword error
	if !errors.Is(errShort, bcrypt.ErrHashTooShort) {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: errors.Is failed to identify ErrHashTooShort\n")
		os.Exit(1)
	}

	// 5. bcrypt.ErrHashTooShort error message equals 'crypto/bcrypt: hashedSecret too short to be a bcrypted password'
	expectedMsg := "crypto/bcrypt: hashedSecret too short to be a bcrypted password"
	if bcrypt.ErrHashTooShort.Error() != expectedMsg {
		fmt.Fprintf(os.Stderr, "assertion 5 failed: expected %q, got %q\n", expectedMsg, bcrypt.ErrHashTooShort.Error())
		os.Exit(1)
	}

	// 6. bcrypt.CompareHashAndPassword returns nil for matching password and does not match ErrHashTooShort
	errMatch := bcrypt.CompareHashAndPassword(hash, password)
	if errMatch != nil {
		fmt.Fprintf(os.Stderr, "assertion 6 failed: expected nil for matching password, got %v\n", errMatch)
		os.Exit(1)
	}
	if errors.Is(errMatch, bcrypt.ErrHashTooShort) {
		fmt.Fprintf(os.Stderr, "assertion 6 failed: nil should not match ErrHashTooShort\n")
		os.Exit(1)
	}

	fmt.Println("All contract assertions passed.")
}