Swift Passphrase Generator

A modern Swift package for generating cryptographically secure passphrases using the EFF Large Wordlist (7,776 words). Create memorable yet strong passphrases — like correct-horse-battery-staple — with control over word count, separator, and capitalization style. Perfect for password managers, onboarding flows, and any app that needs human-friendly secrets.

Features

• 🔐 Cryptographically secure — Word selection uses SecRandomCopyBytes for true, unbiased randomness.
• 📖 EFF Large Wordlist — Ships with the 7,776-word list curated by the Electronic Frontier Foundation (~12.92 bits per word).
• 🎯 Sensible defaults — generate() returns a 4-word, hyphen-separated, lowercase passphrase (~52 bits of entropy).
• ⚙️ Configurable — Choose word count (2–10), separator, and casing style.
• 🔤 Five casing styles — Lowercase, uppercase, capitalize, sentence case, and alternating.
• 📦 Batch generation — generateMultiple produces 1–1000 passphrases in one call.
• 📝 Custom word lists — Supply your own words for non-English or specialized passphrases.
• 📊 Entropy calculation — entropy(wordCount:wordListSize:) reports passphrase strength in bits.
• ℹ️ Wordlist metadata — wordListInfo() exposes name, size, and per-word entropy.
• 🛡️ Safe bounds — Word counts and batch sizes are automatically clamped.

Requirements

• iOS 13.0+ / macOS 10.15+ / tvOS 13.0+ / watchOS 6.0+
• Swift 6.1+
• Xcode 16.0+

Installation

Swift Package Manager

dependencies: [
    .package(url: "https://github.com/arraypress/swift-passphrase-generator.git", from: "1.0.0")
]

Usage

Quick start

import PassphraseGenerator

let passphrase = PassphraseGenerator.generate()
// "correct-horse-battery-staple"

Custom options

import PassphraseGenerator

let passphrase = PassphraseGenerator.generate(
    wordCount: 5,
    separator: ".",
    casing: .capitalize
)
// "Aluminum.Beacon.Cluster.Devoted.Examine"

Casing styles

import PassphraseGenerator

PassphraseGenerator.generate(casing: .lowercase)     // correct-horse-battery-staple
PassphraseGenerator.generate(casing: .uppercase)     // CORRECT-HORSE-BATTERY-STAPLE
PassphraseGenerator.generate(casing: .capitalize)    // Correct-Horse-Battery-Staple
PassphraseGenerator.generate(casing: .sentenceCase)  // Correct-horse-battery-staple
PassphraseGenerator.generate(casing: .alternating)   // correct-HORSE-battery-STAPLE

Generating multiple passphrases

import PassphraseGenerator

// Defaults: 10 passphrases, 4 words, "-", lowercase
let many = PassphraseGenerator.generateMultiple(count: 5)

// Custom configuration
let custom = PassphraseGenerator.generateMultiple(
    count: 3,
    wordCount: 5,
    separator: ".",
    casing: .capitalize
)

// Using a custom word list
let words = ["apple", "banana", "cherry", "dog", "elephant"]
let fromCustom = PassphraseGenerator.generateMultiple(
    count: 3,
    wordCount: 3,
    customWords: words
)

Custom word lists

import PassphraseGenerator

let words = ["apple", "banana", "cherry", "dog", "elephant"]
let passphrase = PassphraseGenerator.generate(
    wordCount: 3,
    separator: "_",
    casing: .uppercase,
    customWords: words
)
// "APPLE_CHERRY_DOG"

Measuring strength

import PassphraseGenerator

let bits = PassphraseGenerator.entropy(wordCount: 4, wordListSize: 7776)
// ~51.7

let info = PassphraseGenerator.wordListInfo()
print(info.wordCount)        // 7776
print(info.entropyPerWord)   // ~12.92

Models

Type	Description
CasingStyle	.lowercase, .uppercase, .capitalize, .sentenceCase, .alternating.
WordListInfo	Wordlist name, wordCount, entropyPerWord, and description.

How It Works

Each word is chosen by drawing four cryptographically secure random bytes via SecRandomCopyBytes and reducing them modulo the word-list size, giving a uniform, unbiased selection. The built-in EFF Large Wordlist is loaded once and cached for thread-safe reuse. Word counts are clamped to 2–10 and batch sizes to 1–1000 for security and performance.

Testing

swift test

The test suite covers default and custom generation, casing styles, batch generation, custom word lists, and entropy calculations.

License

MIT License — see LICENSE file for details.

Author

Created by David Sherlock (ArrayPress) in 2026.