ios - 使用 CCHmac() 生成 HMAC swift sdk8.3

Question

在 SDK8.3 之前，我是这样生成我的 hmac 的。现在我在 CCHmac() 函数上遇到错误。由于我是初学者，所以我无法弄清楚如何解决它。预先感谢您的帮助!

xcode warning: cannot involke 'CCHmac' with an argument list of type (UInt32, [CChar]?, UInt, [CChar]?, UInt, inout[(CUnsignedChar)]

func generateHMAC(key: String, data: String) -> String {

    let cKey = key.cStringUsingEncoding(NSUTF8StringEncoding)
    let cData = data.cStringUsingEncoding(NSUTF8StringEncoding)

    var result = [CUnsignedChar](count: Int(CC_SHA512_DIGEST_LENGTH), repeatedValue: 0)
    CCHmac(CCHmacAlgorithm(kCCHmacAlgSHA512), cKey, strlen(cKey!), cData, strlen(cData!), &result)


    let hash = NSMutableString()
    for var i = 0; i < result.count; i++ {
        hash.appendFormat("%02hhx", result[i])
    }

    return hash as String
}

Answer 1

问题是 strlen 返回一个 UInt，而 CCHmac 的长度参数是 Int。

虽然您可以进行一些强制转换，但您也可以只使用两个数组的 count 属性，而不是调用 strlen。

func generateHMAC(key: String, data: String) -> String {

    var result: [CUnsignedChar]
    if let cKey = key.cStringUsingEncoding(NSUTF8StringEncoding),
           cData = data.cStringUsingEncoding(NSUTF8StringEncoding)
    {
        let algo  = CCHmacAlgorithm(kCCHmacAlgSHA512)
        result = Array(count: Int(CC_SHA512_DIGEST_LENGTH), repeatedValue: 0)

        CCHmac(algo, cKey, cKey.count-1, cData, cData.count-1, &result)
    }
    else {
        // as @MartinR points out, this is in theory impossible 
        // but personally, I prefer doing this to using `!`
        fatalError("Nil returned when processing input strings as UTF8")
    }

    let hash = NSMutableString()
    for val in result {
        hash.appendFormat("%02hhx", val)
    }

    return hash as String
}