golang.org/x/crypto v0.48.0: sha3.New256

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 sha3.New256 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:
  - sha3.New256
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:ad0a0b6df7dcbf2d2669a2602cc1d22d81e51b4c93c5e0f6c9e4ed02d8ba4b51","contract":["sha3.New256 returns a hash.Hash with Size 32 and BlockSize 136","sha3.New256 streaming hash computes 32-byte SHA3-256 digest matching NIST FIPS 202 test vector for empty input","sha3.New256 streaming hash computes 32-byte SHA3-256 digest matching NIST FIPS 202 test vector for standard test input","sha3.New256 incremental writes produce identical digest to single-write computation","sha3.New256 Reset clears accumulated state to compute a new digest independently"],"goal":"verify sha3.New256 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":["sha3.New256"]},"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":["sha3.New256"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/crypto v0.48.0

require golang.org/x/sys v0.41.0 // indirect

golang.org/x/crypto v0.48.0 h1:/VRzVqiRSggnhY7gNRxPauEQ5Drw9haKdM0jqfcCFts=
golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=
golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=

package main

import (
	"fmt"

	"golang.org/x/crypto/sha3"
)

func main() {
	hasher := sha3.New256()
	hasher.Write([]byte("Hello, "))
	hasher.Write([]byte("CodeSampleX!"))
	digest := hasher.Sum(nil)
	fmt.Printf("SHA3-256: %x\n", digest)
}

{
  "schemaVersion": 1,
  "goal": "verify sha3.New256 in pkg:golang/golang.org/x/crypto@v0.48.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/crypto@v0.48.0"
  ],
  "symbols": [
    "sha3.New256"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"os"

	"golang.org/x/crypto/sha3"
)

func main() {
	// 1. sha3.New256 returns a hash.Hash with Size 32 and BlockSize 136
	hasher := sha3.New256()
	if hasher.Size() != 32 {
		fmt.Fprintf(os.Stderr, "sha3.New256 Size() mismatch: got %d, want 32\n", hasher.Size())
		os.Exit(1)
	}
	if hasher.BlockSize() != 136 {
		fmt.Fprintf(os.Stderr, "sha3.New256 BlockSize() mismatch: got %d, want 136\n", hasher.BlockSize())
		os.Exit(1)
	}

	// 2. sha3.New256 streaming hash computes 32-byte SHA3-256 digest matching NIST FIPS 202 test vector for empty input
	expectedEmpty, _ := hex.DecodeString("a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a")
	emptyHasher := sha3.New256()
	emptyDigest := emptyHasher.Sum(nil)
	if !bytes.Equal(emptyDigest, expectedEmpty) {
		fmt.Fprintf(os.Stderr, "sha3.New256 empty input mismatch: got %x, want %x\n", emptyDigest, expectedEmpty)
		os.Exit(1)
	}

	// 3. sha3.New256 streaming hash computes 32-byte SHA3-256 digest matching NIST FIPS 202 test vector for standard test input
	expectedAbc, _ := hex.DecodeString("3a985da74fe225b2045c172d6bd390bd855f086e3e9d525b46bfe24511431532")
	abcHasher := sha3.New256()
	abcHasher.Write([]byte("abc"))
	abcDigest := abcHasher.Sum(nil)
	if !bytes.Equal(abcDigest, expectedAbc) {
		fmt.Fprintf(os.Stderr, "sha3.New256 'abc' mismatch: got %x, want %x\n", abcDigest, expectedAbc)
		os.Exit(1)
	}

	// 4. sha3.New256 incremental writes produce identical digest to single-write computation
	chunkHasher := sha3.New256()
	chunkHasher.Write([]byte("The quick "))
	chunkHasher.Write([]byte("brown fox "))
	chunkHasher.Write([]byte("jumps over "))
	chunkHasher.Write([]byte("the lazy dog"))
	chunkDigest := chunkHasher.Sum(nil)

	singleHasher := sha3.New256()
	singleHasher.Write([]byte("The quick brown fox jumps over the lazy dog"))
	singleDigest := singleHasher.Sum(nil)

	if !bytes.Equal(chunkDigest, singleDigest) {
		fmt.Fprintf(os.Stderr, "sha3.New256 chunked write mismatch: got %x, want %x\n", chunkDigest, singleDigest)
		os.Exit(1)
	}

	// 5. sha3.New256 Reset clears accumulated state to compute a new digest independently
	resetHasher := sha3.New256()
	resetHasher.Write([]byte("some initial data that should be discarded"))
	resetHasher.Reset()
	resetHasher.Write([]byte("abc"))
	resetDigest := resetHasher.Sum(nil)
	if !bytes.Equal(resetDigest, expectedAbc) {
		fmt.Fprintf(os.Stderr, "sha3.New256 Reset mismatch: got %x, want %x\n", resetDigest, expectedAbc)
		os.Exit(1)
	}

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