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>

1 files changed, 23 insertions, 111 deletions

diff --git a/WireGuard/Shared/Model/Key.swift b/WireGuard/Shared/Model/Key.swift
index 17e25a0..3f11452 100644
--- a/WireGuard/Shared/Model/Key.swift
+++ b/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 hex: [UInt8] = Array(repeating: 0, count: 64)
-
-        for i in 0..<32 {
-            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)
+        var out = Data(repeating: 0, count: Int(WG_KEY_LEN_HEX))
+        out.withUnsafeMutableBytes { outBytes in
+            self.withUnsafeBytes { inBytes in
+                key_to_hex(outBytes, inBytes)
+            }
         }
-        return String(bytes: hex, encoding: .ascii)
-    }
-
-    private func decodeHex(c: UInt8) -> (UInt8, UInt8) {
-        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)
+        out.removeLast()
+        return String(data: out, encoding: .ascii)
     }
 
     init?(hexKey hexString: String) {
-        let hex = [UInt8](hexString.utf8)
-        if hex.count != 64 {
+        if hexString.utf8.count != WG_KEY_LEN_HEX - 1 {
             return nil
         }
-        self.init(repeating: 0, count: 32)
-
-        var ret: UInt8 = 0
-        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
-        }
+        self.init(repeating: 0, count: Int(WG_KEY_LEN))
 
-        if 1 & (UInt8(truncatingIfNeeded: Int(ret) - 1) >> 8) != 0 {
+        if !self.withUnsafeMutableBytes { key_from_hex($0, hexString) } {
             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)
-
-        for i in 0..<(32 / 3) {
-            encodeBase64(dest: &base64[(i * 4)..<(i * 4 + 4)], src: self[(i * 3)..<(i * 3 + 3)])
-        }
-        encodeBase64(dest: &base64[40..<44], src: [self[30], self[31], 0])
-        base64[43] = 61
-
-        return String(bytes: base64, encoding: .ascii)
-    }
-
-    private func decodeBase64<T: RandomAccessCollection>(src: T) -> Int where T.Index == Int, T.Element == UInt8 {
-        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)
+        var out = Data(repeating: 0, count: Int(WG_KEY_LEN_BASE64))
+        out.withUnsafeMutableBytes { outBytes in
+            self.withUnsafeBytes { inBytes in
+                key_to_base64(outBytes, inBytes)
+            }
         }
-        return val
+        out.removeLast()
+        return String(data: out, encoding: .ascii)
     }
 
     init?(base64Key base64String: String) {
-        let base64 = [UInt8](base64String.utf8)
-        if base64.count != 44 || base64[43] != 61 {
+        if base64String.utf8.count != WG_KEY_LEN_BASE64 - 1 {
             return nil
         }
-        self.init(repeating: 0, count: 32)
-
-        var ret: UInt8 = 0
-        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)
+        self.init(repeating: 0, count: Int(WG_KEY_LEN))
 
-        if 1 & (UInt8(truncatingIfNeeded: Int(ret) - 1) >> 8) != 0 {
+        if !self.withUnsafeMutableBytes { key_from_base64($0, base64String) } {
             return nil
         }
     }