random-swift

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A Swift package for cryptographically secure random number generation, offering utilities for secure random bytes, array initialization, and buffer operations.
GiacomoLeopizzi/random-swift

Random

A Swift package for generating cryptographically secure random bytes and numbers. Built using swift-nio and swift-nio-ssl.

Features

  • Secure random number generation suitable for cryptographic applications.
  • Utilities to generate secure random bytes and fill buffers with random data.
  • Extensions to integrate with common Swift and NIO types.

Installation

Add the Random package to your Package.swift:

// swift-tools-version:6.0
import PackageDescription

let package = Package(
    name: "YourProject",
    dependencies: [
        .package(url: "https://github.com/GiacomoLeopizzi/random-swift", from: "1.0.0"),
    ],
    targets: [
        .target(
            name: "YourTarget",
            dependencies: [
                .product(name: "Random", package: "random-swift")
            ]
        ),
    ]
)

Usage

1. Generating Secure Random Numbers

Use SecureRandomNumberGenerator to generate cryptographically secure random numbers:

import Random

var generator = SecureRandomNumberGenerator()
let randomValue = generator.next() // Generates a secure random UInt64

2. Creating an Array of Secure Random Bytes

Generate an array filled with secure random bytes:

import Random

let randomBytes = [UInt8](withSecureRandom: 16) // An array of 16 secure random bytes

3. Writing Secure Random Bytes to a ByteBuffer

import Random
import NIO

var buffer = ByteBuffer()
buffer.writeSecureRandomBytes(count: 32) // Writes 32 secure random bytes into the buffer

4. Filling Buffers with Secure Random Bytes

Using UnsafeMutableRawBufferPointer

import Random

var rawBuffer = UnsafeMutableRawBufferPointer.allocate(byteCount: 16, alignment: 1)

defer {
    rawBuffer.deallocate()
}

let success = rawBuffer.fillWithSecureRandomBytes()
assert(success, "Failed to fill buffer with secure random bytes")

Using UnsafeMutableBufferPointer

import Random

var buffer = UnsafeMutableBufferPointer<UInt8>.allocate(capacity: 16)

defer {
    buffer.deallocate()
}

let success = buffer.fillWithSecureRandomBytes()
assert(success, "Failed to fill buffer with secure random bytes")

5. Extending Pointers

UnsafeMutablePointer

Write secure random bytes to the memory pointed to by a pointer:

import Random

let pointer = UnsafeMutablePointer<UInt8>.allocate(capacity: 16)

defer {
    pointer.deallocate()
}

pointer.writeSecureRandomBytes(count: 16)

UnsafeMutableRawPointer

import Random

let rawPointer = UnsafeMutableRawPointer.allocate(byteCount: 16, alignment: 1)

defer {
    rawPointer.deallocate()
}

rawPointer.writeSecureRandomBytes(count: 16)

6. Using SecureRandomNumberGenerator with Collections

SecureRandomNumberGenerator conforms to the RandomNumberGenerator protocol, meaning it can be used to generate secure random values for standard Swift collection APIs like randomElement(using:).

Example: Picking a Random Character from a String

import Random

let alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
var generator = SecureRandomNumberGenerator()

if let char = alphabet.randomElement(using: &generator) {
    print("Random character: \(char)")
}

Example: Shuffling an Array Securely

import Random

var numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
var generator = SecureRandomNumberGenerator()

numbers.shuffle(using: &generator)

print("Shuffled array: \(numbers)")

Example: Generating a Secure Random Password

import Random

let characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()"
var generator = SecureRandomNumberGenerator()

let passwordLength = 16
let password = String((0..<passwordLength).compactMap { _ in characters.randomElement(using: &generator) })

print("Secure random password: \(password)")

API Reference

SecureRandomNumberGenerator

A cryptographically secure random number generator. Conforms to the RandomNumberGenerator protocol.

  • next() -> UInt64: Generates a secure random UInt64.

Extensions

Array

  • init(withSecureRandom elementsCount: Int): Initializes an array with cryptographically secure random bytes.

ByteBuffer

  • writeSecureRandomBytes(count: Int): Writes secure random bytes into the ByteBuffer.

UnsafeMutableBufferPointer

  • fillWithSecureRandomBytes() -> Bool: Fills the buffer with secure random bytes.

UnsafeMutableRawBufferPointer

  • fillWithSecureRandomBytes() -> Bool: Fills the raw buffer with secure random bytes.

UnsafeMutablePointer

  • writeSecureRandomBytes(count: Int): Writes secure random bytes to the memory pointed to by the pointer.

UnsafeMutableRawPointer

  • writeSecureRandomBytes(count: Int): Writes secure random bytes to the raw pointer memory.

Contributing

Contributions are welcome! Feel free to submit a pull request or open an issue for any improvements or bug fixes.

Description

  • Swift Tools 6.0.0
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Dependencies

Last updated: Wed May 21 2025 13:19:50 GMT-0900 (Hawaii-Aleutian Daylight Time)