Initial implementation of using YubiKey for decryption (#533)

passKit/Helpers/YubiKeyAPDU.swift

@@ -0,0 +1,54 @@
+//
+//  YubiKeyAPDU.swift
+//  passKit
+//
+//  Copyright © 2022 Bob Sun. All rights reserved.
+//
+
+import YubiKit
+
+public enum YubiKeyAPDU {
+    public static func selectOpenPGPApplication() -> YKFSelectApplicationAPDU {
+        let selectOpenPGPAPDU = YKFSelectApplicationAPDU(data: Data([0xD2, 0x76, 0x00, 0x01, 0x24, 0x01]))!
+        return selectOpenPGPAPDU
+    }
+
+    public static func verify(password: String) -> YKFAPDU {
+        let pw1: [UInt8] = Array(password.utf8)
+        var apdu: [UInt8] = []
+        apdu += [0x00] // CLA
+        apdu += [0x20] // INS: VERIFY
+        apdu += [0x00] // P1
+        apdu += [0x82] // P2: PW1
+        apdu += withUnsafeBytes(of: UInt8(pw1.count).bigEndian, Array.init)
+        apdu += pw1
+        let verifyApdu = YKFAPDU(data: Data(apdu))!
+        return verifyApdu
+    }
+
+    public static func decipher(data: Data) -> YKFAPDU {
+        var apdu: [UInt8] = []
+        apdu += [0x00] // CLA
+        apdu += [0x2A, 0x80, 0x86] // INS, P1, P2: PSO.DECIPHER
+        // Lc, An extended Lc field consists of three bytes:
+        // one byte set to '00' followed by two bytes not set to '0000' (1 to 65535 dec.).
+        apdu += [0x00] + withUnsafeBytes(of: UInt16(data.count + 1).bigEndian, Array.init)
+        // Padding indicator byte (00) for RSA or (02) for AES followed by cryptogram Cipher DO 'A6' for ECDH
+        apdu += [0x00]
+        apdu += data
+        apdu += [0x02, 0x00]
+        let decipherApdu = YKFAPDU(data: Data(apdu))!
+
+        return decipherApdu
+    }
+
+    public static func get_application_related_data() -> YKFAPDU {
+        var apdu: [UInt8] = []
+        apdu += [0x00] // CLA
+        apdu += [0xCA] // INS: GET DATA
+        apdu += [0x00]
+        apdu += [0x6E] // P2: application related data
+        apdu += [0x00]
+        return YKFAPDU(data: Data(apdu))!
+    }
+}