golang.org/x/crypto v0.56.0: pbkdf2.Key

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 pkg:golang/golang.org/x/crypto@v0.56.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/crypto@v0.56.0
Demonstrate these symbols/APIs:
  - pbkdf2.Key

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:sha256:163c48b020a160ec86af5fab7b209514cb52901e6992cc6755382783f5a643b5","contract":["pbkdf2.Key derives key bytes matching requested length","pbkdf2.Key produces identical derived keys for identical password, salt, and parameters","pbkdf2.Key produces different derived keys for different passwords with identical parameters","pbkdf2.Key produces different derived keys for different salts with identical parameters","pbkdf2.Key matches RFC 6070 test vector for SHA-1 with 1 iteration","pbkdf2.Key matches RFC 6070 test vector for SHA-1 with 4096 iterations","pbkdf2.Key matches standard test vector for SHA-256 with 4096 iterations","pbkdf2.Key correctly handles null bytes inside password and salt"],"goal":"verify pkg:golang/golang.org/x/crypto@v0.56.0","kind":"HOW","packages":["pkg:golang/golang.org/x/crypto@v0.56.0"],"schemaVersion":1,"symbols":["pbkdf2.Key"]},"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@v0.56.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/crypto@v0.56.0","symbols":["pbkdf2.Key"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/crypto v0.56.0

golang.org/x/crypto v0.56.0 h1:GUh5Ii4J5jtcseSMiRqr1jXCNHoxjeV9Fmekc2oLy6Y=
golang.org/x/crypto v0.56.0/go.mod h1:OMW5y6CY9l38uPLmxU6l6pwcXp1obtLo3e6gT7gQR2I=

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"

	"golang.org/x/crypto/pbkdf2"
)

func main() {
	password := []byte("example-password")
	salt := []byte("example-salt")
	iterations := 4096
	keyLength := 32

	derivedKey := pbkdf2.Key(password, salt, iterations, keyLength, sha256.New)
	fmt.Printf("Derived key (%d bytes): %s\n", len(derivedKey), hex.EncodeToString(derivedKey))
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/golang.org/x/crypto@v0.56.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/crypto@v0.56.0"
  ],
  "symbols": [
    "pbkdf2.Key"
  ]
}

package main

import (
	"bytes"
	"crypto/sha1"
	"crypto/sha256"
	"fmt"
	"os"

	"golang.org/x/crypto/pbkdf2"
)

func main() {
	pass := []byte("example-secret-passphrase")
	salt := []byte("example-cryptographic-salt")

	// 1. pbkdf2.Key derives key bytes matching requested length
	for _, expectedLen := range []int{16, 32, 64} {
		key := pbkdf2.Key(pass, salt, 1000, expectedLen, sha256.New)
		if len(key) != expectedLen {
			fmt.Fprintf(os.Stderr, "Key length mismatch: expected %d, got %d\n", expectedLen, len(key))
			os.Exit(1)
		}
	}

	// 2. pbkdf2.Key produces identical derived keys for identical password, salt, and parameters
	keyA := pbkdf2.Key(pass, salt, 2048, 32, sha256.New)
	keyB := pbkdf2.Key(pass, salt, 2048, 32, sha256.New)
	if !bytes.Equal(keyA, keyB) {
		fmt.Fprintf(os.Stderr, "Deterministic derivation failed: identical inputs yielded different keys\n")
		os.Exit(1)
	}

	// 3. pbkdf2.Key produces different derived keys for different passwords with identical parameters
	diffPassKey := pbkdf2.Key([]byte("another-secret-passphrase"), salt, 2048, 32, sha256.New)
	if bytes.Equal(keyA, diffPassKey) {
		fmt.Fprintf(os.Stderr, "Different passwords unexpectedly produced identical keys\n")
		os.Exit(1)
	}

	// 4. pbkdf2.Key produces different derived keys for different salts with identical parameters
	diffSaltKey := pbkdf2.Key(pass, []byte("different-salt-value"), 2048, 32, sha256.New)
	if bytes.Equal(keyA, diffSaltKey) {
		fmt.Fprintf(os.Stderr, "Different salts unexpectedly produced identical keys\n")
		os.Exit(1)
	}

	// 5. pbkdf2.Key matches RFC 6070 test vector for SHA-1 with 1 iteration
	expectedRfcSha1Iter1 := []byte{
		0x0c, 0x60, 0xc8, 0x0f, 0x96, 0x1f, 0x0e, 0x71,
		0xf3, 0xa9, 0xb5, 0x24, 0xaf, 0x60, 0x12, 0x06,
		0x2f, 0xe0, 0x37, 0xa6,
	}
	actualRfcSha1Iter1 := pbkdf2.Key([]byte("password"), []byte("salt"), 1, 20, sha1.New)
	if !bytes.Equal(actualRfcSha1Iter1, expectedRfcSha1Iter1) {
		fmt.Fprintf(os.Stderr, "RFC 6070 SHA-1 (iter=1) mismatch: got %x, want %x\n", actualRfcSha1Iter1, expectedRfcSha1Iter1)
		os.Exit(1)
	}

	// 6. pbkdf2.Key matches RFC 6070 test vector for SHA-1 with 4096 iterations
	expectedRfcSha1Iter4096 := []byte{
		0x4b, 0x00, 0x79, 0x01, 0xb7, 0x65, 0x48, 0x9a,
		0xbe, 0xad, 0x49, 0xd9, 0x26, 0xf7, 0x21, 0xd0,
		0x65, 0xa4, 0x29, 0xc1,
	}
	actualRfcSha1Iter4096 := pbkdf2.Key([]byte("password"), []byte("salt"), 4096, 20, sha1.New)
	if !bytes.Equal(actualRfcSha1Iter4096, expectedRfcSha1Iter4096) {
		fmt.Fprintf(os.Stderr, "RFC 6070 SHA-1 (iter=4096) mismatch: got %x, want %x\n", actualRfcSha1Iter4096, expectedRfcSha1Iter4096)
		os.Exit(1)
	}

	// 7. pbkdf2.Key matches standard test vector for SHA-256 with 4096 iterations
	expectedSha256Iter4096 := []byte{
		0xc5, 0xe4, 0x78, 0xd5, 0x92, 0x88, 0xc8, 0x41,
		0xaa, 0x53, 0x0d, 0xb6, 0x84, 0x5c, 0x4c, 0x8d,
		0x96, 0x28, 0x93, 0xa0,
	}
	actualSha256Iter4096 := pbkdf2.Key([]byte("password"), []byte("salt"), 4096, 20, sha256.New)
	if !bytes.Equal(actualSha256Iter4096, expectedSha256Iter4096) {
		fmt.Fprintf(os.Stderr, "SHA-256 (iter=4096) mismatch: got %x, want %x\n", actualSha256Iter4096, expectedSha256Iter4096)
		os.Exit(1)
	}

	// 8. pbkdf2.Key correctly handles null bytes inside password and salt
	expectedNullBytes := []byte{
		0x56, 0xfa, 0x6a, 0xa7, 0x55, 0x48, 0x09, 0x9d,
		0xcc, 0x37, 0xd7, 0xf0, 0x34, 0x25, 0xe0, 0xc3,
	}
	actualNullBytes := pbkdf2.Key([]byte("pass\x00word"), []byte("sa\x00lt"), 4096, 16, sha1.New)
	if !bytes.Equal(actualNullBytes, expectedNullBytes) {
		fmt.Fprintf(os.Stderr, "Null-byte handling mismatch: got %x, want %x\n", actualNullBytes, expectedNullBytes)
		os.Exit(1)
	}

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