HMAC是密钥相关的哈希运算消息认证码（Hash-based Message Authentication Code）。 HMAC运算利用哈希算法，以一个密钥和一个消息为输入，生成一个消息摘要作为输出。也就是说HMAC通过将哈希算法(SHA1, MD5)与密钥进行计算生成摘要。
Objectice-C
在上个 Objectice-C 项目中，使用的 HMAC 和 SHA1 进行加密。如下代码：
+ (NSString *)hmacsha1:(NSString *)text key:(NSString *)secret {
NSData *secretData = [secret dataUsingEncoding:NSUTF8StringEncoding];
NSData *clearTextData = [text dataUsingEncoding:NSUTF8StringEncoding];
unsigned char result[20];
// SHA1加密
CCHmac(kCCHmacAlgSHA1, [secretData bytes], [secretData length], [clearTextData bytes], [clearTextData length], result);
char base64Result[32];
size_t theResultLength = 32;
// 转为Base64
Base64EncodeData(result, 20, base64Result, &theResultLength,YES);
NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
NSString *base64EncodedResult = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
return base64EncodedResult;
}
swift
最近用 swift 重构项目,用 Swift 重写了 HMAC 的 SHA1 加密方式。
使用
// 使用HMAC和SHA加密
let hmacResult:String = "myStringToHMAC".hmac(HMACAlgorithm.SHA1, key: "myKey")
代码
使用下面代码时，需要在 OC 桥接文件xxx-Bridging-Header中 #import <CommonCrypto/CommonHMAC.h>
extension String {
func hmac(algorithm: HMACAlgorithm, key: String) -> String {
let cKey = key.cStringUsingEncoding(NSUTF8StringEncoding)
let cData = self.cStringUsingEncoding(NSUTF8StringEncoding)
var result = [CUnsignedChar](count: Int(algorithm.digestLength()), repeatedValue: 0)
CCHmac(algorithm.toCCHmacAlgorithm(), cKey!, strlen(cKey!), cData!, strlen(cData!), &result)
var hmacData:NSData = NSData(bytes: result, length: (Int(algorithm.digestLength())))
var hmacBase64 = hmacData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding76CharacterLineLength)
return String(hmacBase64)
}
}
enum HMACAlgorithm {
case MD5, SHA1, SHA224, SHA256, SHA384, SHA512
func toCCHmacAlgorithm() -> 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)
}
func digestLength() -> Int {
var result: CInt = 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)
}
}
