91 lines
3.8 KiB
Swift
91 lines
3.8 KiB
Swift
// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.
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import Foundation
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import GRDB
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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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_ db: Database,
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plaintext: Data,
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for recipientHexEncodedX25519PublicKey: String,
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using dependencies: Dependencies
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) throws -> Data {
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guard let userEd25519KeyPair: KeyPair = 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
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let signature = try? dependencies.crypto.perform(
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.signature(message: Bytes(verificationData), secretKey: userEd25519KeyPair.secretKey)
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)
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else { throw MessageSenderError.signingFailed }
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let plaintextWithMetadata = plaintext + Data(userEd25519KeyPair.publicKey) + Data(signature)
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guard
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let ciphertext = try? dependencies.crypto.perform(
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.seal(
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message: Bytes(plaintextWithMetadata),
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recipientPublicKey: Bytes(recipientX25519PublicKey)
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)
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)
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else { throw MessageSenderError.encryptionFailed }
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return Data(ciphertext)
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}
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internal static func encryptWithSessionBlindingProtocol(
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_ db: Database,
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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: Dependencies
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) throws -> Data {
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guard
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SessionId.Prefix(from: recipientBlindedId) == .blinded15 ||
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SessionId.Prefix(from: recipientBlindedId) == .blinded25
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else { throw MessageSenderError.signingFailed }
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guard let userEd25519KeyPair: KeyPair = Identity.fetchUserEd25519KeyPair(db) else {
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throw MessageSenderError.noUserED25519KeyPair
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}
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guard
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let blindedKeyPair = dependencies.crypto.generate(
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.blindedKeyPair(serverPublicKey: openGroupPublicKey, edKeyPair: userEd25519KeyPair, using: dependencies)
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)
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else { throw MessageSenderError.signingFailed }
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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
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let enc_key: Bytes = try? dependencies.crypto.perform(
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.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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using: dependencies
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)
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),
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let nonce: Bytes = try? dependencies.crypto.perform(.generateNonce24())
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else { throw MessageSenderError.signingFailed }
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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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guard
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let ciphertext = try? dependencies.crypto.perform(
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.encryptAeadXChaCha20(message: innerBytes, secretKey: enc_key, nonce: nonce, using: dependencies)
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)
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else { throw MessageSenderError.encryptionFailed }
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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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