39 lines
1.1 KiB
Swift
39 lines
1.1 KiB
Swift
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import Foundation
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import CryptoKit
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extension SignedMessage {
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/// The message encoded to data
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var encoded: Data {
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mac + message.encoded
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}
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var bytes: [UInt8] {
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Array(encoded)
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}
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/**
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Create a message from received bytes.
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- Parameter data: The sequence of bytes
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- Note: The sequence must contain at least `Message.length` bytes, or the function will crash.
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*/
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init(decodeFrom data: Data) throws {
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guard data.count == SignedMessage.size else {
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print("Invalid signed message size \(data.count)")
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throw MessageResult.invalidMessageSizeFromDevice
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}
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let count = SHA256.byteCount
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self.mac = data.prefix(count)
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self.message = try Message(decodeFrom: data.dropFirst(count))
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}
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/**
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Check if the message contains a valid authentication code
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- Parameter key: The key used to sign the message.
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- Returns: `true`, if the message is valid.
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*/
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func isValid(using key: SymmetricKey) -> Bool {
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HMAC<SHA256>.isValidAuthenticationCode(mac, authenticating: message.encoded, using: key)
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}
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}
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