50 lines
2.1 KiB
Swift
50 lines
2.1 KiB
Swift
import CryptoSwift
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import Curve25519Kit
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public final class DiffieHellman : NSObject {
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public static let ivSize: UInt = 16
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public enum Error : LocalizedError {
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case decryptionFailed
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case sharedSecretGenerationFailed
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public var errorDescription: String {
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switch self {
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case .decryptionFailed: return "Couldn't decrypt data"
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case .sharedSecretGenerationFailed: return "Couldn't generate a shared secret."
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}
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}
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}
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private override init() { }
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public static func encrypt(_ plaintext: Data, using symmetricKey: Data) throws -> Data {
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let iv = Data.getSecureRandomData(ofSize: ivSize)!
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let cbc = CBC(iv: iv.bytes)
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let aes = try AES(key: symmetricKey.bytes, blockMode: cbc)
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let ciphertext = try aes.encrypt(plaintext.bytes)
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let ivAndCiphertext = iv.bytes + ciphertext
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return Data(ivAndCiphertext)
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}
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public static func encrypt(_ plaintext: Data, publicKey: Data, privateKey: Data) throws -> Data {
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guard let symmetricKey = try? Curve25519.generateSharedSecret(fromPublicKey: publicKey, privateKey: privateKey) else { throw Error.sharedSecretGenerationFailed }
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return try encrypt(plaintext, using: symmetricKey)
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}
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public static func decrypt(_ ivAndCiphertext: Data, using symmetricKey: Data) throws -> Data {
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guard ivAndCiphertext.count >= ivSize else { throw Error.decryptionFailed }
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let iv = ivAndCiphertext[..<ivSize]
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let ciphertext = ivAndCiphertext[ivSize...]
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let cbc = CBC(iv: iv.bytes)
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let aes = try AES(key: symmetricKey.bytes, blockMode: cbc)
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let plaintext = try aes.decrypt(ciphertext.bytes)
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return Data(plaintext)
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}
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public static func decrypt(_ ivAndCiphertext: Data, publicKey: Data, privateKey: Data) throws -> Data {
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guard let symmetricKey = try? Curve25519.generateSharedSecret(fromPublicKey: publicKey, privateKey: privateKey) else { throw Error.sharedSecretGenerationFailed }
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return try decrypt(ivAndCiphertext, using: symmetricKey)
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}
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}
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