Merge pull request #9 from ddtch/sensor-refactoring

sensor-refactoring

Sources/RNLibreToolsiOS13/LibreToolsResources/AbstractLibre2.swift

@@ -0,0 +1,110 @@
+//
+//  AbstractLibre2.swift
+//  LibreWrapper
+//
+//  Created by Yury Dymov on 4/2/22.
+//
+
+import CoreNFC
+import Foundation
+
+let libre2DumpMap = [
+    0x000:  (40,  "Extended header"),
+    0x028:  (32,  "Extended footer"),
+    0x048:  (296, "Body right-rotated by 4"),
+    0x170:  (24,  "FRAM header"),
+    0x188:  (296, "FRAM body"),
+    0x2b0:  (24,  "FRAM footer"),
+    0x2c8:  (34,  "Keys"),
+    0x2ea:  (10,  "MAC address"),
+    0x26d8: (24,  "Table of enabled NFC commands")
+]
+
+class AbstractLibre2: AbstractLibre {
+
+    override var fram: Data {
+        didSet {
+            encryptedFram = Data()
+            if UInt16(fram[0...1]) != crc16(fram[2...23]) {
+                encryptedFram = fram
+                if fram.count >= 344 {
+                    if let decryptedFRAM = try? decryptFRAM(data: fram) {
+                        fram = decryptedFRAM
+                    }
+                }
+            }
+            parseFRAM()
+        }
+    }
+
+    private let libre2Secret: UInt16 = 0x1b6a
+
+    private func getFramArg(block: Int) -> UInt16 {
+        return UInt16(patchInfo[5], patchInfo[4]) ^ 0x44
+    }
+
+    private func decryptFRAM(data: Data) throws -> Data {
+        var result = [UInt8]()
+
+        for i in 0 ..< 43 {
+            let input = prepareVariables(id: uid, x: UInt16(i), y: getFramArg(block: i))
+            let blockKey = processCrypto(input: input)
+
+            result.append(data[i * 8 + 0] ^ UInt8(truncatingIfNeeded: blockKey[0]))
+            result.append(data[i * 8 + 1] ^ UInt8(truncatingIfNeeded: blockKey[0] >> 8))
+            result.append(data[i * 8 + 2] ^ UInt8(truncatingIfNeeded: blockKey[1]))
+            result.append(data[i * 8 + 3] ^ UInt8(truncatingIfNeeded: blockKey[1] >> 8))
+            result.append(data[i * 8 + 4] ^ UInt8(truncatingIfNeeded: blockKey[2]))
+            result.append(data[i * 8 + 5] ^ UInt8(truncatingIfNeeded: blockKey[2] >> 8))
+            result.append(data[i * 8 + 6] ^ UInt8(truncatingIfNeeded: blockKey[3]))
+            result.append(data[i * 8 + 7] ^ UInt8(truncatingIfNeeded: blockKey[3] >> 8))
+        }
+        return Data(result)
+    }
+
+    override var activationCommand: NFCCommand {
+        return nfcCommand(.activate)
+    }
+
+    override func activate(tag: NFCISO15693Tag) async throws {
+        try await super.activate(tag: tag)
+        logger.info("NFC: \(type) should be activated and warming up")
+    }
+
+    override func nfcCommand(_ code: Subcommand, parameters: Data = Data(), secret: UInt16 = 0) -> NFCCommand {
+        let secret = secret != 0 ? secret : libre2Secret
+
+        var parameters = parameters
+        if code.rawValue < 0x20 {
+            parameters += usefulFunction(id: uid, x: UInt16(code.rawValue), y: secret)
+        }
+
+        return super.nfcCommand(code, parameters: parameters, secret: secret)
+    }
+
+    override func readBlocks(tag: NFCISO15693Tag, from start: Int, count blocks: Int, requesting: Int = 3) async throws -> (Int, Data) {
+        guard securityGeneration >= 1 else {
+            logger.error("readBlocks() B3 command not supported by \(type)")
+            throw LibreError.commandNotSupported("B3")
+        }
+
+        return try await super.readBlocks(tag: tag, from: start, count: blocks, requesting: requesting)
+    }
+
+    private func usefulFunction(id: SensorUid, x: UInt16, y: UInt16) -> Data {
+        let blockKey = processCrypto(input: prepareVariables(id: id, x: x, y: y))
+        let low = blockKey[0]
+        let high = blockKey[1]
+
+        // https://github.com/ivalkou/LibreTools/issues/2: "XOR with inverted low/high words in usefulFunction()"
+        let r1 = low ^ 0x4163
+        let r2 = high ^ 0x4344
+
+        return Data([
+            UInt8(truncatingIfNeeded: r1),
+            UInt8(truncatingIfNeeded: r1 >> 8),
+            UInt8(truncatingIfNeeded: r2),
+            UInt8(truncatingIfNeeded: r2 >> 8)
+        ])
+    }
+}

Sources/RNLibreToolsiOS13/LibreToolsResources/Libre1.swift

@@ -0,0 +1,23 @@
+//
+//  Libre1.swift
+//  LibreWrapper
+//
+//  Created by Yury Dymov on 4/2/22.
+//
+
+import Foundation
+
+final class Libre1: AbstractLibre {
+
+    override var type: SensorType {
+        return .libre1
+    }
+
+    override var framBlocksToRead: Int {
+        return 244
+    }
+
+    override var activationCommand: NFCCommand {
+        return NFCCommand(code: 0xA0, parameters: backdoor, description: "activate")
+    }
+}

Sources/RNLibreToolsiOS13/LibreToolsResources/Libre14US.swift

@@ -0,0 +1,58 @@
+//
+//  Libre14Usd.swift
+//  LibreWrapper
+//
+//  Created by Yury Dymov on 4/2/22.
+//
+
+import Foundation
+
+final class Libre14US: AbstractLibre {
+
+    override var type: SensorType {
+        return .libreUS14day
+    }
+
+    override var fram: Data {
+        didSet {
+            encryptedFram = Data()
+            if UInt16(fram[0...1]) != crc16(fram[2...23]) {
+                encryptedFram = fram
+                if fram.count >= 344 {
+                    if let decryptedFRAM = try? decryptFRAM(data: fram) {
+                        fram = decryptedFRAM
+                    }
+                }
+            }
+            parseFRAM()
+        }
+    }
+
+    private func getFramArg(block: Int) -> UInt16 {
+        if block < 3 || block >= 40 {
+            // For header and footer it is a fixed value.
+            return 0xcadc
+        }
+        return UInt16(patchInfo[5], patchInfo[4])
+    }
+
+    private func decryptFRAM(data: Data) throws -> Data {
+        var result = [UInt8]()
+
+        for i in 0 ..< 43 {
+            let input = prepareVariables(id: uid, x: UInt16(i), y: getFramArg(block: i))
+            let blockKey = processCrypto(input: input)
+
+            result.append(data[i * 8 + 0] ^ UInt8(truncatingIfNeeded: blockKey[0]))
+            result.append(data[i * 8 + 1] ^ UInt8(truncatingIfNeeded: blockKey[0] >> 8))
+            result.append(data[i * 8 + 2] ^ UInt8(truncatingIfNeeded: blockKey[1]))
+            result.append(data[i * 8 + 3] ^ UInt8(truncatingIfNeeded: blockKey[1] >> 8))
+            result.append(data[i * 8 + 4] ^ UInt8(truncatingIfNeeded: blockKey[2]))
+            result.append(data[i * 8 + 5] ^ UInt8(truncatingIfNeeded: blockKey[2] >> 8))
+            result.append(data[i * 8 + 6] ^ UInt8(truncatingIfNeeded: blockKey[3]))
+            result.append(data[i * 8 + 7] ^ UInt8(truncatingIfNeeded: blockKey[3] >> 8))
+        }
+        return Data(result)
+    }
+}
+