PrismEncryptedStore
Transparent encryption wrapper. Encrypts with AES-GCM before delegating to inner store. Decrypts on load.
import CryptoKit
let key = SymmetricKey(size: .bits256)
let defaults = PrismDefaultsStore()
let secure = PrismEncryptedStore(wrapping: defaults, key: key)
// Values encrypted at rest
try secure.save("api-key-secret", forKey: "apiKey")
let apiKey = try secure.load(String.self, forKey: "apiKey") // decrypted
// Also accepts raw key data
let secure2 = PrismEncryptedStore(wrapping: defaults, keyData: keyData)
Async Variant
let disk = PrismDiskStore(directory: .applicationSupport)
let secureDisk = PrismEncryptedAsyncStore(wrapping: disk, key: key)
try await secureDisk.save(credentials, forKey: "creds")
Security
- Algorithm: AES-GCM (authenticated encryption)
- Nonce: Auto-generated per encryption
- Format: Combined nonce + ciphertext + tag
- Wrong key →
PrismStorageError.decryptionFailed
PrismCompressedStore
Transparent compression wrapper. Compresses before save, decompresses on load.
let store = PrismCompressedStore(
wrapping: PrismDefaultsStore(),
algorithm: .lzfse // default
)
// Large payloads compressed transparently
let bigPayload = Array(0..<10_000)
try store.save(bigPayload, forKey: "data")
let loaded = try store.load([Int].self, forKey: "data")
Algorithms
| Algorithm | Speed | Ratio | Use Case |
|---|
.lzfse | Fast | Good | Default — Apple optimized |
.lz4 | Fastest | Lower | Real-time, low latency |
.zlib | Medium | Better | Cross-platform compatibility |
.lzma | Slow | Best | Archival, max compression |
Async Variant
let compressedDisk = PrismCompressedAsyncStore(
wrapping: PrismDiskStore(),
algorithm: .lzma
)
Combining Layers
Stack encryption + compression for maximum efficiency:
let base = PrismDefaultsStore()
let compressed = PrismCompressedStore(wrapping: base, algorithm: .lzfse)
let secure = PrismEncryptedStore(wrapping: compressed, key: key)
// Data flow: value → JSON → compress → encrypt → store
try secure.save(sensitiveData, forKey: "payload")
Compress before encrypting. Encrypted data has high entropy and compresses poorly.
