Swift － 常用 － 加密/解密

（1）首先创建桥接头文件bridge.h来包含需要引用的Objective-C头文件，并在项目中配置

#import <CommonCrypto/CommonHMAC.h>

（2）下面是一个封装类，同时对String进行扩展。（除了SHA1，还可以使用其它算法比如MD5，SHA224等）

//HMAC.swift
import Foundation

enum CryptoAlgorithm {
    case MD5, SHA1, SHA224, SHA256, SHA384, SHA512

    var HMACAlgorithm: CCHmacAlgorithm {
        var result: Int = 0
        switch self {
        case .MD5:      result = kCCHmacAlgMD5
        case .SHA1:     result = kCCHmacAlgSHA1
        case .SHA224:   result = kCCHmacAlgSHA224
        case .SHA256:   result = kCCHmacAlgSHA256
        case .SHA384:   result = kCCHmacAlgSHA384
        case .SHA512:   result = kCCHmacAlgSHA512
        }
        return CCHmacAlgorithm(result)
    }
    
    var digestLength: Int {
        var result: Int32 = 0
        switch self {
        case .MD5:      result = CC_MD5_DIGEST_LENGTH
        case .SHA1:     result = CC_SHA1_DIGEST_LENGTH
        case .SHA224:   result = CC_SHA224_DIGEST_LENGTH
        case .SHA256:   result = CC_SHA256_DIGEST_LENGTH
        case .SHA384:   result = CC_SHA384_DIGEST_LENGTH
        case .SHA512:   result = CC_SHA512_DIGEST_LENGTH
        }
        return Int(result)
    }
}

extension String  {
    var md5: String! {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = Int(CC_MD5_DIGEST_LENGTH)
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        CC_MD5(str!, strLen, result)
        return stringFromBytes(result, length: digestLen)
    }
    
    var sha1: String! {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = Int(CC_SHA1_DIGEST_LENGTH)
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        CC_SHA1(str!, strLen, result)
        return stringFromBytes(result, length: digestLen)
    }
    
    var sha256String: String! {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = Int(CC_SHA256_DIGEST_LENGTH)
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        CC_SHA256(str!, strLen, result)
        return stringFromBytes(result, length: digestLen)
    }
    
    var sha512String: String! {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = CC_LONG(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = Int(CC_SHA512_DIGEST_LENGTH)
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        CC_SHA512(str!, strLen, result)
        return stringFromBytes(result, length: digestLen)
    }
    
    func stringFromBytes(bytes: UnsafeMutablePointer<CUnsignedChar>, length: Int) -> String{
        let hash = NSMutableString()
        for i in 0..<length {
            hash.appendFormat("%02x", bytes[i])
        }
        bytes.dealloc(length)
        return String(format: hash as String)
    }
    
    func hmac(algorithm: CryptoAlgorithm, key: String) -> String {
        let str = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let strLen = Int(self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        let digestLen = algorithm.digestLength
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(digestLen)
        let keyStr = key.cStringUsingEncoding(NSUTF8StringEncoding)
        let keyLen = Int(key.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
        
        CCHmac(algorithm.HMACAlgorithm, keyStr!, keyLen, str!, strLen, result)
        
        let digest = stringFromResult(result, length: digestLen)
        
        result.dealloc(digestLen)
        
        return digest
    }
    
    private func stringFromResult(result: UnsafeMutablePointer<CUnsignedChar>, length: Int) -> String {
        let hash = NSMutableString()
        for i in 0..<length {
            hash.appendFormat("%02x", result[i])
        }
        return String(hash)
    }
}

（3）测试样例

let str = "welcome to hangge.com"
let key = "67FG"
let hmacStr = str.hmac(.SHA1, key: key)
let pwd = str.d5
         
print("原始字符串：\(str)")
print("key：\(key)")
print("HMAC运算结果：\(hmacStr)")
print("md5运算结果：\(pwd)")
         
/**** 输出 ******
原始字符串：welcome to hangge.com
key：67FG
HMAC运算结果：79a5f5b138b5646289a9648de035c80e9c5c14c7
md5运算结果：0d5ca19da68a37af5900c8ebf5356c6e
*****/