CRC16

CryptoSwift/Array<UInt8>+Extension.swift

@@ -39,7 +39,11 @@ extension Array where Element: _UInt8Type {
     public func crc32() -> [UInt8]? {
         return Hash.crc32(Element.arrayValue(self)).calculate()
     }
-    
+
+    public func crc16() -> [UInt8]? {
+        return Hash.crc16(Element.arrayValue(self)).calculate()
+    }
+
     public func encrypt(cipher: Cipher) throws -> [UInt8]? {
         return try cipher.encrypt(Element.arrayValue(self))
     }

CryptoSwift/CRC.swift

@@ -8,7 +8,7 @@
 
 final class CRC {
     
-    private let table:[UInt32] = [0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
+    private static let table32:[UInt32] = [0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
         0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
         0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
         0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
@@ -41,16 +41,58 @@ final class CRC {
         0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
         0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d]
     
+    private static let table16:[UInt16] = [0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
+        0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
+        0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
+        0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
+        0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
+        0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
+        0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
+        0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
+        0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
+        0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
+        0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
+        0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
+        0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
+        0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
+        0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
+        0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
+        0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
+        0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
+        0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
+        0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
+        0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
+        0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
+        0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
+        0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
+        0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
+        0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
+        0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
+        0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
+        0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
+        0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
+        0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
+        0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040]
+    
     func crc32(message:[UInt8]) -> UInt32 {
         var crc:UInt32 = 0xffffffff
         
         for chunk in BytesSequence(chunkSize: 256, data: message) {
             for b in chunk {
                 let idx = Int((crc ^ UInt32(b)) & 0xff)
-                crc = (crc >> 8) ^ table[idx]
+                crc = (crc >> 8) ^ CRC.table32[idx]
             }
         }
-        
         return crc ^ 0xffffffff
     }
+    
+    func crc16(message:[UInt8]) -> UInt16 {
+        var crc:UInt16 = 0x0000
+        for chunk in BytesSequence(chunkSize: 256, data: message) {
+            for b in chunk {
+                crc = (crc >> 8) ^ CRC.table16[Int((crc ^ UInt16(b)) & 0xFF)]
+            }
+        }
+        return crc
+    }
 }

CryptoSwift/Foundation/NSData+Extension.swift

@@ -65,6 +65,11 @@ extension NSData {
         return NSData.withBytes(result)
     }
 
+    public func crc16() -> NSData? {
+        guard let result = Hash.crc16(self.arrayOfBytes()).calculate() else { return nil }
+        return NSData.withBytes(result)
+    }
+
     public func encrypt(cipher: Cipher) throws -> NSData? {
         let encrypted = try cipher.encrypt(self.arrayOfBytes())
         return NSData.withBytes(encrypted)

CryptoSwift/Hash.swift

@@ -11,6 +11,7 @@ public enum Hash {
     case sha1(Array<UInt8>)
     case sha224(Array<UInt8>), sha256(Array<UInt8>), sha384(Array<UInt8>), sha512(Array<UInt8>)
     case crc32(Array<UInt8>)
+    case crc16(Array<UInt8>)
     
     public func calculate() -> [UInt8]? {
         switch self {
@@ -28,6 +29,8 @@ public enum Hash {
             return SHA2(bytes, variant: .sha512).calculate64()
         case crc32(let bytes):
             return CRC().crc32(bytes).bytes()
+        case crc16(let bytes):
+            return UInt32(CRC().crc16(bytes)).bytes(2)
         }
     }
 }

CryptoSwift/String+Extension.swift

@@ -37,6 +37,10 @@ extension String {
         return self.utf8.lazy.map({ $0 as UInt8 }).crc32()?.toHexString()
     }
 
+    public func crc16() -> String? {
+        return self.utf8.lazy.map({ $0 as UInt8 }).crc16()?.toHexString()
+    }
+
     public func encrypt(cipher: Cipher) throws -> String? {
         return try self.utf8.lazy.map({ $0 as UInt8 }).encrypt(cipher)?.toHexString()
     }

CryptoSwiftTests/HashTests.swift

@@ -193,6 +193,11 @@ final class CryptoSwiftTests: XCTestCase {
         }
     }
     
+    func testCRC16() {
+        let result = CRC().crc16([49,50,51,52,53,54,55,56,57] as [UInt8])
+        XCTAssert(result == 0xBB3D, "CRC16 failed")
+    }
+    
     func testChecksum() {
         let data:NSData = NSData(bytes: [49, 50, 51] as [UInt8], length: 3)
         XCTAssert(data.checksum() == 0x96, "Invalid checksum")

README.md

@@ -31,6 +31,7 @@ Good mood
 - [SHA384](http://tools.ietf.org/html/rfc6234)
 - [SHA512](http://tools.ietf.org/html/rfc6234)
 - [CRC32](http://en.wikipedia.org/wiki/Cyclic_redundancy_check) (well, kind of hash)
+- [CRC16](http://en.wikipedia.org/wiki/Cyclic_redundancy_check) (well, kind of hash)
 
 #####Cipher
 - [AES-128, AES-192, AES-256](http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf)