重叠访问'salt'，但修改需要独占访问；考虑复制到本地变量中

Question

我正在开发一个高度安全的iOS应用，其中包含敏感数据，我试图使用AES256加密系统来保护数据安全。

我按照这里的教程进行了操作。https:/code.tutsplus.comtutorialssecuring-ios-data-at-rest-encryption--cms-28786。

Xcode 11 (Swift 5)告诉我 "对'salt'的访问是重叠的，但修改需要独占访问，可以考虑复制到本地变量"

请你告诉我如何解决这个问题好吗？

谢谢你的帮助。

这是我的代码。

var key = Data(repeating:0, count:kCCKeySizeAES256)
    var salt = Data(count: 8)
    salt.withUnsafeMutableBytes {
        (saltBytes: UnsafeMutablePointer<UInt8>) in//-> Void in
        let saltStatus = SecRandomCopyBytes(kSecRandomDefault, salt.count, saltBytes)
        if saltStatus == errSecSuccess
        {
            let passwordData = password.data(using:String.Encoding.utf8)!
            key.withUnsafeMutableBytes { (keyBytes : UnsafeMutablePointer<UInt8>) in
                let derivationStatus = CCKeyDerivationPBKDF(CCPBKDFAlgorithm(kCCPBKDF2), password, passwordData.count, saltBytes, salt.count, CCPseudoRandomAlgorithm(kCCPRFHmacAlgSHA512), 14271, keyBytes, key.count)
                if derivationStatus != Int32(kCCSuccess)
                {
                    setupSuccess = false
                }
            }
        }
        else
        {
            setupSuccess = false
        }
    }

Answer 1

最后，我解决了我的问题，修改了我的代码，像这样。

salt.withUnsafeMutableBytes { (saltBuffer: UnsafeMutableRawBufferPointer) in  
let saltBytes = saltBuffer.bindMemory(to: UInt8.self)  
let saltStatus = SecRandomCopyBytes(kSecRandomDefault, saltBytes.count, saltBytes.baseAddress!)  
if saltStatus == errSecSuccess {  
    let passwordData = password.data(using: .utf8)!  
    key.withUnsafeMutableBytes { (keyBuffer: UnsafeMutableRawBufferPointer) in  
        let keyBytes = keyBuffer.bindMemory(to: UInt8.self)  
        let derivationStatus = CCKeyDerivationPBKDF(CCPBKDFAlgorithm(kCCPBKDF2), password, passwordData.count, saltBytes.baseAddress!, saltBytes.count, CCPseudoRandomAlgorithm(kCCPRFHmacAlgSHA512), 14271, keyBytes.baseAddress!, keyBytes.count)  
        if derivationStatus != Int32(kCCSuccess) {  
            setupSuccess = false  
        }  
    }  
} else {  
    setupSuccess = false  
}  

}