带有数字签名的 Swift 签名字符串

Posted 2023-04-12

【中文标题】带有数字签名的 Swift 签名字符串

【英文标题】：Swift sign string with digital signature

【发布时间】：2018-05-22 22:21:57

【问题描述】：

我有一个项目，我需要使用私人数字签名（有密码）对字符串（原始或 base64 编码）进行签名。我在互联网上搜索，发现私有数字证书是 x.509 格式（RSA）。在 xcode 中，我将 UIFileSharingEnabled 设置为 Enabled 并使用 Itunes 上传了该 rsa.p12 证书。接下来，我从文档目录中以（数据或字符串）格式获取证书。我的问题是如何使用数字签名加密任何文本？ 我尝试使用这个库 https://github.com/TakeScoop/SwiftyRSA/issues 但这个库不支持 x.509 证书。

【问题讨论】：

有人知道如何签署文件而不是字符串吗？

【参考方案1】：

我刚刚找到了编码字符串文本的代码，它可以工作

 func signRequestorId(requestorID: String) -> String? 

    let name = "RSA256_4f1826090c554a439c419043270d40f7d.p12"
    guard let certificateData = CustomFileManager.getFile(by: name) else 
        return nil
    

    var status: OSStatus

    let certificateKey = "123456"
    let options = [kSecImportExportPassphrase as String : certificateKey]

    var optItems: CFArray?
    status = SecPKCS12Import(certificateData as CFData, options as CFDictionary, &optItems)
    if status != errSecSuccess 
        print("Cannot sign the device id info: failed importing keystore.")
        return nil
    
    guard let items = optItems else 
        return nil
    

    // Cast CFArrayRef to Swift Array
    let itemsArray = items as [AnyObject]
    // Cast CFDictionaryRef as Swift Dictionary
    guard let myIdentityAndTrust = itemsArray.first as? [String : AnyObject] else 
        return nil
    

    // Get our SecIdentityRef from the PKCS #12 blob
    let outIdentity = myIdentityAndTrust[kSecImportItemIdentity as String] as! SecIdentity
    var myReturnedCertificate: SecCertificate?
    status = SecIdentityCopyCertificate(outIdentity, &myReturnedCertificate)
    if status != errSecSuccess 
        print("Failed to retrieve the certificate associated with the requested identity.")
        return nil
    

    // Get the private key associated with our identity
    var optPrivateKey: SecKey?
    status = SecIdentityCopyPrivateKey(outIdentity, &optPrivateKey)
    if status != errSecSuccess 
        print("Failed to extract the private key from the keystore.")
        return nil
    
    // Unwrap privateKey from optional SecKeyRef
    guard let privateKey = optPrivateKey else 
        return nil
    

    // Retrieve the digital signature and sign the requestor

    // Get the maximum size of the digital signature
    var signedBytesSize: size_t = SecKeyGetBlockSize(privateKey)
    var signedBytes: UnsafeMutablePointer<UInt8>

    // alloc a buffer to hold the signature
    signedBytes = UnsafeMutablePointer<UInt8>.allocate(capacity: signedBytesSize)
    memset(signedBytes, 0x0, signedBytesSize)
    // We're calling alloc here, so we need to destroy and deinit
    defer 
        signedBytes.deinitialize()
        signedBytes.deallocate(capacity: signedBytesSize)
    

    // Sign data
    let requestorData = requestorID.data(using: String.Encoding.utf8)!
    // Generate a digital signature for our requestor from our cert
    let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: requestorData.count)
    let stream = OutputStream(toBuffer: buffer, capacity: requestorData.count)

    stream.open()
    requestorData.withUnsafeBytes( (p: UnsafePointer<UInt8>) -> Void in
        stream.write(p, maxLength: requestorData.count)
    )

    stream.close()

    let weidformat = UnsafePointer<UInt8>(buffer)

    status = SecKeyRawSign(privateKey, .PKCS1, weidformat,
                           requestorData.count, signedBytes, &signedBytesSize)

    if status != errSecSuccess 
        print("Cannot sign the device id info: failed obtaining the signed bytes.")
        return nil
    

    let encryptedBytes = NSData(bytes: signedBytes, length: signedBytesSize)
    let signedRequestorId = encryptedBytes.base64EncodedString(options: [])

    print(signedRequestorId)
    return signedRequestorId

你还需要按名称获取文档的函数

static func getFile(by name: String)-> Data?
    let documentsUrl =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
    let destinationUrl = documentsUrl!.appendingPathComponent("\(name)")

    let isFileFound = FileManager.default.fileExists(atPath: destinationUrl.path)
    if isFileFound 
        let documentContent = FileManager.default.contents(atPath: destinationUrl.path)
        return documentContent
    
    return nil

enter code here