Key: Use C implementation instead

Swift compiles so slowly and it's unclear all of the insane type punning
was even correct.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

WireGuard/Shared/Model/Key.swift

@@ -5,143 +5,55 @@ import Foundation
 
 extension Data {
     func isKey() -> Bool {
-        return self.count == 32
+        return self.count == WG_KEY_LEN
     }
 
     func hexKey() -> String? {
-        if self.count != 32 {
+        if self.count != WG_KEY_LEN {
             return nil
         }
-        var nibble1, nibble2: UInt
+        var out = Data(repeating: 0, count: Int(WG_KEY_LEN_HEX))
-        var hex: [UInt8] = Array(repeating: 0, count: 64)
+        out.withUnsafeMutableBytes { outBytes in
-
+            self.withUnsafeBytes { inBytes in
-        for i in 0..<32 {
+                key_to_hex(outBytes, inBytes)
-            let n = UInt(self[i])
-            nibble1 = 87 + (n >> 4)
-            nibble1 += (((UInt(bitPattern: Int(n >> 4) - 10)) >> 8) & 217)
-            nibble2 = 87 + (n & 0xf)
-            nibble2 += (((UInt(bitPattern: Int(n & 0xf) - 10)) >> 8) & 217)
-            hex[i * 2] = UInt8(truncatingIfNeeded: nibble1)
-            hex[i * 2 + 1] = UInt8(truncatingIfNeeded: nibble2)
             }
-        return String(bytes: hex, encoding: .ascii)
         }
-
+        out.removeLast()
-    private func decodeHex(c: UInt8) -> (UInt8, UInt8) {
+        return String(data: out, encoding: .ascii)
-        var alpha0, alpha, num0, num, val, ret: UInt8
-
-        num = c ^ 48
-        num0 = UInt8(truncatingIfNeeded: UInt(bitPattern: Int(num) - 10) >> 8)
-
-        alpha = UInt8(truncatingIfNeeded: Int(c & 223) - 55)
-        alpha0 = UInt8(truncatingIfNeeded: (UInt(bitPattern: Int(alpha) - 10) ^ UInt(bitPattern: Int(alpha) - 16)) >> 8)
-
-        ret = UInt8(truncatingIfNeeded: UInt(bitPattern: Int(num0 | alpha0) - 1) >> 8)
-        val = (num0 & num) | (alpha0 & alpha)
-
-        return (val, ret)
     }
 
     init?(hexKey hexString: String) {
-        let hex = [UInt8](hexString.utf8)
+        if hexString.utf8.count != WG_KEY_LEN_HEX - 1 {
-        if hex.count != 64 {
             return nil
         }
-        self.init(repeating: 0, count: 32)
+        self.init(repeating: 0, count: Int(WG_KEY_LEN))
 
-        var ret: UInt8 = 0
+        if !self.withUnsafeMutableBytes { key_from_hex($0, hexString) } {
-        for i in stride(from: 0, to: 64, by: 2) {
-            var v1, v2, r: UInt8
-
-            (v1, r) = decodeHex(c: hex[i])
-            ret |= r
-
-            (v2, r) = decodeHex(c: hex[i + 1])
-            ret |= r
-
-            self[i / 2] = (v1 << 4) | v2
-        }
-
-        if 1 & (UInt8(truncatingIfNeeded: Int(ret) - 1) >> 8) != 0 {
             return nil
         }
     }
 
-
-    private func encodeBase64<T: RandomAccessCollection>(dest: inout ArraySlice<UInt8>, src: T) where T.Index == Int, T.Element == UInt8 {
-        let a = Int((src[src.startIndex + 0] >> 2) & 63)
-        let b = Int(((src[src.startIndex + 0] << 4) | (src[src.startIndex + 1] >> 4)) & 63)
-        let c = Int(((src[src.startIndex + 1] << 2) | (src[src.startIndex + 2] >> 6)) & 63)
-        let d = Int(src[src.startIndex + 2] & 63)
-
-        for (i, x) in [a, b, c, d].enumerated() {
-            var y: Int = x + 65
-            y += ((25 - x) >> 8) & 6
-            y -= ((51 - x) >> 8) & 75
-            y -= ((61 - x) >> 8) & 15
-            y += ((62 - x) >> 8) & 3
-            dest[dest.startIndex + i] = UInt8(y)
-        }
-    }
-
     func base64Key() -> String? {
-        if self.count != 32 {
+        if self.count != WG_KEY_LEN {
             return nil
         }
-        var base64: [UInt8] = Array(repeating: 0, count: 44)
+        var out = Data(repeating: 0, count: Int(WG_KEY_LEN_BASE64))
-
+        out.withUnsafeMutableBytes { outBytes in
-        for i in 0..<(32 / 3) {
+            self.withUnsafeBytes { inBytes in
-            encodeBase64(dest: &base64[(i * 4)..<(i * 4 + 4)], src: self[(i * 3)..<(i * 3 + 3)])
+                key_to_base64(outBytes, inBytes)
             }
-        encodeBase64(dest: &base64[40..<44], src: [self[30], self[31], 0])
-        base64[43] = 61
-
-        return String(bytes: base64, encoding: .ascii)
         }
-
+        out.removeLast()
-    private func decodeBase64<T: RandomAccessCollection>(src: T) -> Int where T.Index == Int, T.Element == UInt8 {
+        return String(data: out, encoding: .ascii)
-        var val: Int = 0
-        for i in 0..<4 {
-            let n = Int(src[src.startIndex + i])
-            var a: Int = -1
-            var b: Int
-            b = ((((65 - 1) - n) & (n - (90 + 1))) >> 8)
-            a += b & (n - 64)
-            b = ((((97 - 1) - n) & (n - (122 + 1))) >> 8)
-            a += b & (n - 70)
-            b = ((((48 - 1) - n) & (n - (57 + 1))) >> 8)
-            a += b & (n + 5)
-            b = ((((43 - 1) - n) & (n - (43 + 1))) >> 8)
-            a += b & 63
-            b = ((((47 - 1) - n) & (n - (47 + 1))) >> 8)
-            a += b & 64
-            val |= a << (18 - 6 * i)
-        }
-        return val
     }
 
     init?(base64Key base64String: String) {
-        let base64 = [UInt8](base64String.utf8)
+        if base64String.utf8.count != WG_KEY_LEN_BASE64 - 1 {
-        if base64.count != 44 || base64[43] != 61 {
             return nil
         }
-        self.init(repeating: 0, count: 32)
+        self.init(repeating: 0, count: Int(WG_KEY_LEN))
 
-        var ret: UInt8 = 0
+        if !self.withUnsafeMutableBytes { key_from_base64($0, base64String) } {
-        var val: Int
-        for i in 0..<(32/3) {
-            val = decodeBase64(src: base64[(i * 4)..<(i * 4 + 4)])
-            ret |= UInt8(UInt32(val) >> UInt32(31))
-            self[i * 3 + 0] = UInt8((val >> 16) & 0xff)
-            self[i * 3 + 1] = UInt8((val >> 8) & 0xff)
-            self[i * 3 + 2] = UInt8(val & 0xff)
-        }
-        val = decodeBase64(src: [base64[40], base64[41], base64[42], 65])
-        ret |= UInt8((UInt32(val) >> 31) | UInt32(val & 0xff))
-        self[30] = UInt8((val >> 16) & 0xff)
-        self[31] = UInt8((val >> 8) & 0xff)
-
-        if 1 & (UInt8(truncatingIfNeeded: Int(ret) - 1) >> 8) != 0 {
             return nil
         }
     }

WireGuard/Shared/Model/key.c

@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ *
+ * This is a specialized constant-time base64/hex implementation that resists side-channel attacks.
+ */
+
+#include <string.h>
+#include "key.h"
+
+static inline void encode_base64(char dest[static 4], const uint8_t src[static 3])
+{
+	const uint8_t input[] = { (src[0] >> 2) & 63, ((src[0] << 4) | (src[1] >> 4)) & 63, ((src[1] << 2) | (src[2] >> 6)) & 63, src[2] & 63 };
+
+	for (unsigned int i = 0; i < 4; ++i)
+		dest[i] = input[i] + 'A'
+			  + (((25 - input[i]) >> 8) & 6)
+			  - (((51 - input[i]) >> 8) & 75)
+			  - (((61 - input[i]) >> 8) & 15)
+			  + (((62 - input[i]) >> 8) & 3);
+
+}
+
+void key_to_base64(char base64[static WG_KEY_LEN_BASE64], const uint8_t key[static WG_KEY_LEN])
+{
+	unsigned int i;
+
+	for (i = 0; i < WG_KEY_LEN / 3; ++i)
+		encode_base64(&base64[i * 4], &key[i * 3]);
+	encode_base64(&base64[i * 4], (const uint8_t[]){ key[i * 3 + 0], key[i * 3 + 1], 0 });
+	base64[WG_KEY_LEN_BASE64 - 2] = '=';
+	base64[WG_KEY_LEN_BASE64 - 1] = '\0';
+}
+
+static inline int decode_base64(const char src[static 4])
+{
+	int val = 0;
+
+	for (unsigned int i = 0; i < 4; ++i)
+		val |= (-1
+			    + ((((('A' - 1) - src[i]) & (src[i] - ('Z' + 1))) >> 8) & (src[i] - 64))
+			    + ((((('a' - 1) - src[i]) & (src[i] - ('z' + 1))) >> 8) & (src[i] - 70))
+			    + ((((('0' - 1) - src[i]) & (src[i] - ('9' + 1))) >> 8) & (src[i] + 5))
+			    + ((((('+' - 1) - src[i]) & (src[i] - ('+' + 1))) >> 8) & 63)
+			    + ((((('/' - 1) - src[i]) & (src[i] - ('/' + 1))) >> 8) & 64)
+			) << (18 - 6 * i);
+	return val;
+}
+
+bool key_from_base64(uint8_t key[static WG_KEY_LEN], const char *base64)
+{
+	unsigned int i;
+	volatile uint8_t ret = 0;
+	int val;
+
+	if (strlen(base64) != WG_KEY_LEN_BASE64 - 1 || base64[WG_KEY_LEN_BASE64 - 2] != '=')
+		return false;
+
+	for (i = 0; i < WG_KEY_LEN / 3; ++i) {
+		val = decode_base64(&base64[i * 4]);
+		ret |= (uint32_t)val >> 31;
+		key[i * 3 + 0] = (val >> 16) & 0xff;
+		key[i * 3 + 1] = (val >> 8) & 0xff;
+		key[i * 3 + 2] = val & 0xff;
+	}
+	val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' });
+	ret |= ((uint32_t)val >> 31) | (val & 0xff);
+	key[i * 3 + 0] = (val >> 16) & 0xff;
+	key[i * 3 + 1] = (val >> 8) & 0xff;
+
+	return 1 & ((ret - 1) >> 8);
+}
+
+void key_to_hex(char hex[static WG_KEY_LEN_HEX], const uint8_t key[static WG_KEY_LEN])
+{
+	unsigned int i;
+
+	for (i = 0; i < WG_KEY_LEN; ++i) {
+		hex[i * 2] = 87U + (key[i] >> 4) + ((((key[i] >> 4) - 10U) >> 8) & ~38U);
+		hex[i * 2 + 1] = 87U + (key[i] & 0xf) + ((((key[i] & 0xf) - 10U) >> 8) & ~38U);
+	}
+	hex[i * 2] = '\0';
+}
+
+bool key_from_hex(uint8_t key[static WG_KEY_LEN], const char *hex)
+{
+	uint8_t c, c_acc, c_alpha0, c_alpha, c_num0, c_num, c_val;
+	volatile uint8_t ret = 0;
+
+	if (strlen(hex) != WG_KEY_LEN_HEX - 1)
+		return false;
+
+	for (unsigned int i = 0; i < WG_KEY_LEN_HEX - 1; i += 2) {
+		c = (uint8_t)hex[i];
+		c_num = c ^ 48U;
+		c_num0 = (c_num - 10U) >> 8;
+		c_alpha = (c & ~32U) - 55U;
+		c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8;
+		ret |= ((c_num0 | c_alpha0) - 1) >> 8;
+		c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
+		c_acc = c_val * 16U;
+
+		c = (uint8_t)hex[i + 1];
+		c_num = c ^ 48U;
+		c_num0 = (c_num - 10U) >> 8;
+		c_alpha = (c & ~32U) - 55U;
+		c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8;
+		ret |= ((c_num0 | c_alpha0) - 1) >> 8;
+		c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
+		key[i / 2] = c_acc | c_val;
+	}
+
+	return 1 & ((ret - 1) >> 8);
+}

WireGuard/Shared/Model/key.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#ifndef KEY_H
+#define KEY_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#define WG_KEY_LEN (32)
+#define WG_KEY_LEN_BASE64 (45)
+#define WG_KEY_LEN_HEX (65)
+
+void key_to_base64(char base64[static WG_KEY_LEN_BASE64], const uint8_t key[static WG_KEY_LEN]);
+bool key_from_base64(uint8_t key[static WG_KEY_LEN], const char *base64);
+
+void key_to_hex(char hex[static WG_KEY_LEN_HEX], const uint8_t key[static WG_KEY_LEN]);
+bool key_from_hex(uint8_t key[static WG_KEY_LEN], const char *hex);
+
+#endif

WireGuard/WireGuard.xcodeproj/project.pbxproj

@@ -41,6 +41,10 @@
 		6B62E460220A6FA900EF34A6 /* PrivateDataConfirmation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B62E45E220A6FA900EF34A6 /* PrivateDataConfirmation.swift */; };
 		6B707D8421F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B707D8321F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift */; };
 		6B707D8621F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B707D8321F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift */; };
+		6BD5C97B220D1AE200784E08 /* key.c in Sources */ = {isa = PBXBuildFile; fileRef = 6BD5C979220D1AE100784E08 /* key.c */; };
+		6BD5C97C220D1AE200784E08 /* key.c in Sources */ = {isa = PBXBuildFile; fileRef = 6BD5C979220D1AE100784E08 /* key.c */; };
+		6BD5C97D220D1AE200784E08 /* key.c in Sources */ = {isa = PBXBuildFile; fileRef = 6BD5C979220D1AE100784E08 /* key.c */; };
+		6BD5C97E220D1AE200784E08 /* key.c in Sources */ = {isa = PBXBuildFile; fileRef = 6BD5C979220D1AE100784E08 /* key.c */; };
 		6F4DD16B21DA558800690EAE /* TunnelListRow.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F4DD16A21DA558800690EAE /* TunnelListRow.swift */; };
 		6F4DD16C21DA558F00690EAE /* NSTableView+Reuse.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F4DD16721DA552B00690EAE /* NSTableView+Reuse.swift */; };
 		6F4DD16E21DBEA0700690EAE /* ManageTunnelsRootViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F4DD16D21DBEA0700690EAE /* ManageTunnelsRootViewController.swift */; };
@@ -248,6 +252,8 @@
 		6B5C5E26220A48D30024272E /* Keychain.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Keychain.swift; sourceTree = "<group>"; };
 		6B62E45E220A6FA900EF34A6 /* PrivateDataConfirmation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PrivateDataConfirmation.swift; sourceTree = "<group>"; };
 		6B707D8321F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "TunnelConfiguration+UapiConfig.swift"; sourceTree = "<group>"; };
+		6BD5C979220D1AE100784E08 /* key.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = key.c; sourceTree = "<group>"; };
+		6BD5C97A220D1AE200784E08 /* key.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = key.h; sourceTree = "<group>"; };
 		6F4DD16721DA552B00690EAE /* NSTableView+Reuse.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "NSTableView+Reuse.swift"; sourceTree = "<group>"; };
 		6F4DD16A21DA558800690EAE /* TunnelListRow.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TunnelListRow.swift; sourceTree = "<group>"; };
 		6F4DD16D21DBEA0700690EAE /* ManageTunnelsRootViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ManageTunnelsRootViewController.swift; sourceTree = "<group>"; };
@@ -484,6 +490,8 @@
 		6F7774E6217201E0006A79B3 /* Model */ = {
 			isa = PBXGroup;
 			children = (
+				6BD5C979220D1AE100784E08 /* key.c */,
+				6BD5C97A220D1AE200784E08 /* key.h */,
 				5F9696AF21CD7128008063FE /* TunnelConfiguration+WgQuickConfig.swift */,
 				6FFA5D942194454A0001E2F7 /* NETunnelProviderProtocol+Extension.swift */,
 				5F4541B121CBFAEE00994C13 /* String+ArrayConversion.swift */,
@@ -1097,6 +1105,7 @@
 				6FFA5D902194370D0001E2F7 /* Endpoint.swift in Sources */,
 				5FF7B96321CC95DE00A7DD74 /* InterfaceConfiguration.swift in Sources */,
 				6FFA5D9321943BC90001E2F7 /* DNSResolver.swift in Sources */,
+				6BD5C97C220D1AE200784E08 /* key.c in Sources */,
 				6FFA5D912194370D0001E2F7 /* DNSServer.swift in Sources */,
 				6FFA5D8921942F320001E2F7 /* PacketTunnelSettingsGenerator.swift in Sources */,
 				6F5D0C1D218352EF000F85AD /* PacketTunnelProvider.swift in Sources */,
@@ -1125,6 +1134,7 @@
 				6FDB3C3B21DCF47400A0C0BF /* TunnelDetailTableViewController.swift in Sources */,
 				6FB1BDD721D50F5300A991BF /* WireGuardAppError.swift in Sources */,
 				5F52D0BD21E3785C00283CEA /* ConfTextStorage.swift in Sources */,
+				6BD5C97D220D1AE200784E08 /* key.c in Sources */,
 				5F52D0C221E378C000283CEA /* highlighter.c in Sources */,
 				6F4DD16E21DBEA0700690EAE /* ManageTunnelsRootViewController.swift in Sources */,
 				6F4DD16C21DA558F00690EAE /* NSTableView+Reuse.swift in Sources */,
@@ -1187,6 +1197,7 @@
 				6FB1BDAA21D4F53300A991BF /* IPAddressRange.swift in Sources */,
 				6FB1BDAB21D4F53300A991BF /* Endpoint.swift in Sources */,
 				6FB1BDAC21D4F53300A991BF /* DNSServer.swift in Sources */,
+				6BD5C97E220D1AE200784E08 /* key.c in Sources */,
 				6FB1BDAD21D4F53300A991BF /* InterfaceConfiguration.swift in Sources */,
 				6FB1BDAE21D4F53300A991BF /* PeerConfiguration.swift in Sources */,
 				6FB1BDAF21D4F53300A991BF /* FileManager+Extension.swift in Sources */,
@@ -1240,6 +1251,7 @@
 				6FBA103B21D6B4290051C35F /* ErrorPresenterProtocol.swift in Sources */,
 				6FDEF802218646BA00D8FBF6 /* ZipArchive.swift in Sources */,
 				5F45419021C2D53800994C13 /* SwitchCell.swift in Sources */,
+				6BD5C97B220D1AE200784E08 /* key.c in Sources */,
 				6FB1017921C57DE600766195 /* MockTunnels.swift in Sources */,
 				6B707D8421F918D4000A8F73 /* TunnelConfiguration+UapiConfig.swift in Sources */,
 				6FDEF806218725D200D8FBF6 /* SettingsTableViewController.swift in Sources */,

WireGuard/WireGuard/WireGuard-Bridging-Header.h

@@ -4,3 +4,4 @@
 #include "wireguard-go-version.h"
 #include "ringlogger.h"
 #include "highlighter.h"
+#include "key.h"

WireGuard/WireGuardNetworkExtension/WireGuardNetworkExtension-Bridging-Header.h

@@ -1,3 +1,4 @@
 #include "../../wireguard-go-bridge/wireguard.h"
 #include "wireguard-go-version.h"
 #include "ringlogger.h"
+#include "key.h"