39 lines
1.9 KiB
Swift
39 lines
1.9 KiB
Swift
import CryptoSwift
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internal typealias EncryptionResult = (ciphertext: Data, symmetricKey: Data, ephemeralPublicKey: Data)
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enum EncryptionUtilities {
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internal static let gcmTagSize: UInt = 16
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internal static let ivSize: UInt = 12
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/// - Note: Sync. Don't call from the main thread.
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internal static func encrypt(_ plaintext: Data, usingAESGCMWithSymmetricKey symmetricKey: Data) throws -> Data {
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if Thread.isMainThread {
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#if DEBUG
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preconditionFailure("It's illegal to call encrypt(_:usingAESGCMWithSymmetricKey:) from the main thread.")
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#endif
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}
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let iv = Data.getSecureRandomData(ofSize: ivSize)!
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let gcm = GCM(iv: iv.bytes, tagLength: Int(gcmTagSize), mode: .combined)
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let aes = try AES(key: symmetricKey.bytes, blockMode: gcm, padding: .noPadding)
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let ciphertext = try aes.encrypt(plaintext.bytes)
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return iv + Data(bytes: ciphertext)
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}
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/// - Note: Sync. Don't call from the main thread.
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internal static func encrypt(_ plaintext: Data, using hexEncodedX25519PublicKey: String) throws -> EncryptionResult {
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if Thread.isMainThread {
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#if DEBUG
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preconditionFailure("It's illegal to call encrypt(_:forSnode:) from the main thread.")
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#endif
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}
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let x25519PublicKey = Data(hex: hexEncodedX25519PublicKey)
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let ephemeralKeyPair = Curve25519.generateKeyPair()
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let ephemeralSharedSecret = try Curve25519.generateSharedSecret(fromPublicKey: x25519PublicKey, privateKey: ephemeralKeyPair.privateKey)
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let salt = "LOKI"
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let symmetricKey = try HMAC(key: salt.bytes, variant: .sha256).authenticate(ephemeralSharedSecret.bytes)
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let ciphertext = try encrypt(plaintext, usingAESGCMWithSymmetricKey: Data(bytes: symmetricKey))
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return (ciphertext, Data(bytes: symmetricKey), ephemeralKeyPair.publicKey)
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}
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}
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