73 lines
3.4 KiB
Swift
73 lines
3.4 KiB
Swift
// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.
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import Foundation
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import Sodium
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import SessionUtilitiesKit
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extension MessageSender {
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internal static func encryptWithSessionProtocol(
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_ plaintext: Data,
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for recipientHexEncodedX25519PublicKey: String,
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using dependencies: SMKDependencies = SMKDependencies()
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) throws -> Data {
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guard let userEd25519KeyPair: Box.KeyPair = dependencies.storage.read({ db in Identity.fetchUserEd25519KeyPair(db) }) else {
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throw MessageSenderError.noUserED25519KeyPair
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}
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let recipientX25519PublicKey = Data(hex: recipientHexEncodedX25519PublicKey.removingIdPrefixIfNeeded())
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let verificationData = plaintext + Data(userEd25519KeyPair.publicKey) + recipientX25519PublicKey
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guard let signature = dependencies.sign.signature(message: Bytes(verificationData), secretKey: userEd25519KeyPair.secretKey) else {
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throw MessageSenderError.signingFailed
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}
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let plaintextWithMetadata = plaintext + Data(userEd25519KeyPair.publicKey) + Data(signature)
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guard let ciphertext = dependencies.box.seal(message: Bytes(plaintextWithMetadata), recipientPublicKey: Bytes(recipientX25519PublicKey)) else {
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throw MessageSenderError.encryptionFailed
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}
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return Data(ciphertext)
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}
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internal static func encryptWithSessionBlindingProtocol(
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_ plaintext: Data,
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for recipientBlindedId: String,
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openGroupPublicKey: String,
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using dependencies: SMKDependencies = SMKDependencies()
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) throws -> Data {
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guard SessionId.Prefix(from: recipientBlindedId) == .blinded else { throw MessageSenderError.signingFailed }
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guard let userEd25519KeyPair: Box.KeyPair = dependencies.storage.read({ db in Identity.fetchUserEd25519KeyPair(db) }) else {
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throw MessageSenderError.noUserED25519KeyPair
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}
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guard let blindedKeyPair = dependencies.sodium.blindedKeyPair(serverPublicKey: openGroupPublicKey, edKeyPair: userEd25519KeyPair, genericHash: dependencies.genericHash) else {
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throw MessageSenderError.signingFailed
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}
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let recipientBlindedPublicKey = Data(hex: recipientBlindedId.removingIdPrefixIfNeeded())
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/// Step one: calculate the shared encryption key, sending from A to B
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guard let enc_key: Bytes = dependencies.sodium.sharedBlindedEncryptionKey(
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secretKey: userEd25519KeyPair.secretKey,
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otherBlindedPublicKey: recipientBlindedPublicKey.bytes,
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fromBlindedPublicKey: blindedKeyPair.publicKey,
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toBlindedPublicKey: recipientBlindedPublicKey.bytes,
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genericHash: dependencies.genericHash
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) else {
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throw MessageSenderError.signingFailed
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}
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/// Inner data: msg || A (i.e. the sender's ed25519 master pubkey, *not* kA blinded pubkey)
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let innerBytes: Bytes = (plaintext.bytes + userEd25519KeyPair.publicKey)
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/// Encrypt using xchacha20-poly1305
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let nonce: Bytes = dependencies.nonceGenerator24.nonce()
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guard let ciphertext = dependencies.aeadXChaCha20Poly1305Ietf.encrypt(message: innerBytes, secretKey: enc_key, nonce: nonce) else {
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throw MessageSenderError.encryptionFailed
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}
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/// data = b'\x00' + ciphertext + nonce
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return Data(Bytes(arrayLiteral: 0) + ciphertext + nonce)
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}
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}
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