golang.org/x/crypto v0.39.0: blowfish.NewCipher

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 blowfish.NewCipher in pkg:golang/golang.org/x/crypto@v0.39.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/crypto@v0.39.0
Demonstrate these symbols/APIs:
  - blowfish.NewCipher

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:e8d32b89400768b067e4f5cdbac303b35b536068ad7b0b8d9a6e2c978b0f7416","contract":["blowfish.NewCipher accepts key lengths from 1 to 56 bytes inclusive and returns a *blowfish.Cipher with BlockSize() == 8","Encrypt and Decrypt on an 8-byte block round-trip to the original plaintext","blowfish.NewCipher returns blowfish.KeySizeError when key length is 0 or greater than 56"],"goal":"verify blowfish.NewCipher in pkg:golang/golang.org/x/crypto@v0.39.0","kind":"HOW","packages":["pkg:golang/golang.org/x/crypto@v0.39.0"],"schemaVersion":1,"symbols":["blowfish.NewCipher"]},"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@v0.39.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/crypto@v0.39.0","symbols":["blowfish.NewCipher"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.24.0

require golang.org/x/crypto v0.39.0

golang.org/x/crypto v0.39.0 h1:SHs+kF4LP+f+p14esP5jAoDpHU8Gu/v9lFRK6IT5imM=
golang.org/x/crypto v0.39.0/go.mod h1:L+Xg3Wf6HoL4Bn4238Z6ft6KfEpN0tJGo53AAPC632U=

{
  "schemaVersion": 1,
  "goal": "verify blowfish.NewCipher in pkg:golang/golang.org/x/crypto@v0.39.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/crypto@v0.39.0"
  ],
  "symbols": [
    "blowfish.NewCipher"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"

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

func main() {
	// Test valid 16-byte key encryption and decryption round-trip
	key := []byte("0123456789abcdef")
	c, err := blowfish.NewCipher(key)
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected no error for 16-byte key, got: %v\n", err)
		os.Exit(1)
	}
	if c.BlockSize() != blowfish.BlockSize || c.BlockSize() != 8 {
		fmt.Fprintf(os.Stderr, "expected BlockSize 8, got: %d\n", c.BlockSize())
		os.Exit(1)
	}

	plaintext := []byte("8byteblk")
	ciphertext := make([]byte, blowfish.BlockSize)
	c.Encrypt(ciphertext, plaintext)
	if bytes.Equal(ciphertext, plaintext) {
		fmt.Fprintln(os.Stderr, "expected ciphertext to differ from plaintext")
		os.Exit(1)
	}

	decrypted := make([]byte, blowfish.BlockSize)
	c.Decrypt(decrypted, ciphertext)
	if !bytes.Equal(decrypted, plaintext) {
		fmt.Fprintf(os.Stderr, "round-trip failed: got %x, want %x\n", decrypted, plaintext)
		os.Exit(1)
	}

	// Test boundary valid key lengths: 1 byte (min) and 56 bytes (max)
	if _, err := blowfish.NewCipher([]byte{0x42}); err != nil {
		fmt.Fprintf(os.Stderr, "expected 1-byte key to succeed, got: %v\n", err)
		os.Exit(1)
	}
	maxKey := bytes.Repeat([]byte{0x11}, 56)
	if _, err := blowfish.NewCipher(maxKey); err != nil {
		fmt.Fprintf(os.Stderr, "expected 56-byte key to succeed, got: %v\n", err)
		os.Exit(1)
	}

	// Test invalid key lengths: 0 bytes and 57 bytes return KeySizeError
	if _, err := blowfish.NewCipher([]byte{}); err == nil {
		fmt.Fprintln(os.Stderr, "expected error for empty key, got nil")
		os.Exit(1)
	} else if kse, ok := err.(blowfish.KeySizeError); !ok || int(kse) != 0 {
		fmt.Fprintf(os.Stderr, "expected KeySizeError(0), got %T (%v)\n", err, err)
		os.Exit(1)
	}

	tooLongKey := bytes.Repeat([]byte{0x22}, 57)
	if _, err := blowfish.NewCipher(tooLongKey); err == nil {
		fmt.Fprintln(os.Stderr, "expected error for 57-byte key, got nil")
		os.Exit(1)
	} else if kse, ok := err.(blowfish.KeySizeError); !ok || int(kse) != 57 {
		fmt.Fprintf(os.Stderr, "expected KeySizeError(57), got %T (%v)\n", err, err)
		os.Exit(1)
	}
}