CryptoKit for Swift: Complete Guide with Examples

What is CryptoKit and why is it needed?

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CryptoKit is a framework for cryptographic operations developed by Apple and built directly into the Swift ecosystem. It is available starting from iOS 13, macOS 10.15, watchOS 6, and tvOS 13. Unlike third-party libraries, CryptoKit is a native solution, which guarantees high performance, security, and full integration with the Secure Enclave key management system.

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Why is CryptoKit needed? In modern application development, data security comes to the forefront. CryptoKit provides developers with a simple yet powerful interface for:

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• Data hashing (SHA-256, SHA-384, SHA-512)
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• Symmetric encryption (AES-GCM, ChaCha20-Poly1305)
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• Asymmetric encryption (Curve25519, P-256, P-384, P-521)
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• Digital signatures (EdDSA, ECDSA)
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• Generating cryptographically secure random numbers
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• Key exchange (Elliptic Curve Diffie-Hellman)
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The library is designed to minimize developer errors: it uses secure implementations by default, automatically manages memory, and does not allow the use of outdated or insecure algorithms (e.g., MD5 or SHA-1 for signatures).

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Installing CryptoKit

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Since CryptoKit is part of the Apple standard library, no installation via package managers (CocoaPods, Swift Package Manager, or Carthage) is required. All you need is a project with a minimum deployment target of iOS 13+ or macOS 10.15+.

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Important: If you are developing for older OS versions, CryptoKit is not available. In that case, use CommonCrypto (C-level) or third-party libraries (e.g., CryptoSwift).

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To check CryptoKit availability in code, use:

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import CryptoKit\n\nif #available(iOS 13.0, macOS 10.15, *) {\n    // Your CryptoKit code\n} else {\n    // Fallback to CommonCrypto\n}

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Quick Start with Code Example

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Let's look at a simple example: string hashing and symmetric encryption.

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import CryptoKit\nimport Foundation\n\n// 1. Hashing\nlet inputString = "Hello, CryptoKit!"\nlet inputData = Data(inputString.utf8)\nlet hash = SHA256.hash(data: inputData)\nprint("SHA256 hash: \\(hash.compactMap { String(format: "%02x", $0) }.joined())")\n\n// 2. Symmetric encryption (AES-GCM)\nlet key = SymmetricKey(size: .bits256) // Generate a 256-bit key\nlet plaintext = "Secret message".data(using: .utf8)!\n\ndo {\n    let sealedBox = try AES.GCM.seal(plaintext, using: key)\n    print("Encrypted data: \\(sealedBox.ciphertext.base64EncodedString())")\n    \n    // Decryption\n    let openedBox = try AES.GCM.open(sealedBox, using: key)\n    let decryptedString = String(data: openedBox, encoding: .utf8)!\n    print("Decrypted message: \\(decryptedString)")\n} catch {\n    print("Encryption error: \\(error)")\n}

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Main CryptoKit Methods and Functions

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Below are 10 key CryptoKit functions with detailed descriptions, parameters, and examples.

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1. SHA256.hash(data:)

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Description: Computes a SHA-256 hash of the provided data. Returns a SHA256Digest object.

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Parameters:

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• data: Data — the source data to hash.
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Example:

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let data = "Sample data".data(using: .utf8)!\nlet digest = SHA256.hash(data: data)\nprint(digest.description) // Output: SHA256 digest: 8f4343... (64 characters)

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2. SHA384.hash(data:)

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Description: Similar to SHA256, but uses a 384-bit digest. More secure but slower.

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Parameters: same a