如何导出使用 SecKeyGeneratePair 生成的 public 密钥 <SecKey> 以便在服务器上使用？

Question

我使用 SecKeyGeneratePair 生成了一个 keeper。

        var publicKeyPtr, privateKeyPtr: Unmanaged<SecKey>?

        let publicKeyParameters: [String: AnyObject] = [
            kSecAttrIsPermanent: true,
            kSecAttrApplicationTag: "com.example.site.public"
        ]
        let privateKeyParameters: [String: AnyObject] = [
            kSecAttrIsPermanent: true,
            kSecAttrApplicationTag: "com.example.site.private"
        ]
        let parameters: [String: AnyObject] = [
            kSecAttrKeyType: kSecAttrKeyTypeRSA,
            kSecAttrKeySizeInBits: 2048,
            kSecPublicKeyAttrs.takeUnretainedValue() as String: publicKeyParameters,
            kSecPrivateKeyAttrs.takeUnretainedValue() as String: privateKeyParameters
        ]
        let result = SecKeyGeneratePair(parameters, &publicKeyPtr, &privateKeyPtr)
        let publicKey = publicKeyPtr!.takeRetainedValue()
        let privateKey = privateKeyPtr!.takeRetainedValue()
        let blockSize = SecKeyGetBlockSize(publicKey)

如果我打印出 publicKey，我可以看到模数，我很确定这就是我需要的：

publicKey: <SecKeyRef algorithm id: 1, key type: RSAPublicKey, version: 3, block size: 2048 bits, exponent: {hex: 10001, decimal: 65537}, modulus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addr: 0x144841a00>

但我不知道如何导出密钥以便将其发送到我的服务器以供在那里使用。

据我了解。 Keychain中保存了一个SecKey，是一个指向它的指针，块大小就是key在内存中的长度。所以理论上我可以将其提取为 NSData，然后将其转换为我的服务器可以读取的内容。从理论上讲，我认为这会奏效，但在实践中我却碰壁了。将不胜感激所有帮助。

Answer 1

SecItemCopyMatching 适合你：

var dataPtr:Unmanaged<AnyObject>?
let query: [String:AnyObject] = [
    kSecClass: kSecClassKey,
    kSecAttrApplicationTag: "com.example.site.public",
    kSecReturnData: kCFBooleanTrue
]
let qResult = SecItemCopyMatching(query, &dataPtr)

// error handling with `qResult` ...

let publicKeyData = dataPtr!.takeRetainedValue() as NSData

// convert to Base64 string
let base64PublicKey = publicKeyData.base64EncodedStringWithOptions(nil)

Swift 4:

var dataPtr:CFTypeRef?
let query: [String: Any] = [
    kSecClass as String: kSecClassKey,
    kSecAttrApplicationTag as String: "com.example.site.public",
    kSecReturnData as String: true
]

let qResult = SecItemCopyMatching(query as CFDictionary, &dataPtr)

// error handling with `qResult` ...

let data = dataPtr as! Data
let base64PublicKey = data.base64EncodedString()

请注意，数据的大小为 270，与密钥的块大小不同。参见 this question on the crypto.stackexchange.com。

如何导出使用 SecKeyGeneratePair 生成的 public 密钥 <SecKey> 以便在服务器上使用？

How do I export a public key <SecKey> that was generated using SecKeyGeneratePair to be used on a server?

public-key-encryption

swift

ios8

Swift 4: