在iOS(Swift)中生成后，是否获取RSA密钥对作为String

Question

在iOS中生成RSA密钥对并将其作为String的最佳方法是什么。我见过几个可以生成的libs，但我无法将私钥作为String。有人知道在String中获取私钥的lib或方法吗？

目前我以这种方式生成密钥对

var statusCode: OSStatus
var publicKey: SecKey?
var privateKey: SecKey?
let publicKeyAttr: [NSObject: NSObject] = [kSecAttrIsPermanent:true as NSObject, kSecAttrApplicationTag:"publicTag" as NSObject]
let privateKeyAttr: [NSObject: NSObject] = [kSecAttrIsPermanent:true as NSObject, kSecAttrApplicationTag:"privateTag" as NSObject]
var keyPairAttr = [NSObject: NSObject]()
keyPairAttr[kSecAttrKeyType] = kSecAttrKeyTypeRSA
keyPairAttr[kSecAttrKeySizeInBits] = 2048 as NSObject?
keyPairAttr[kSecPublicKeyAttrs] = publicKeyAttr as NSObject?
keyPairAttr[kSecPrivateKeyAttrs] = privateKeyAttr as NSObject?
statusCode = SecKeyGeneratePair(keyPairAttr as CFDictionary, &publicKey, &privateKey)
if statusCode == noErr && publicKey != nil && privateKey != nil {
print(publicKey!)
print(privateKey!)
} else {
print("Error generating key pair: (statusCode)")
}

它在SecKey中。如何将它们转换为String？或者还有别的办法吗？

Answer 1

以下是使用SecItemCopyMatching:的代码

let PublicKeyTag = "publicTag"
let PrivateKeyTag = "privateTag"
let publicKeyAttr: [NSString: Any] = [
kSecAttrIsPermanent: NSNumber(value: true),
kSecAttrApplicationTag: PublicKeyTag
]
let privateKeyAttr: [NSString: Any] = [
kSecAttrIsPermanent: NSNumber(value: true),
kSecAttrApplicationTag: PrivateKeyTag
]
let keyPairAttr: [NSString: Any] = [
kSecAttrKeyType: kSecAttrKeyTypeRSA,
kSecAttrKeySizeInBits: 2048 as NSObject,
kSecPublicKeyAttrs: publicKeyAttr,
kSecPrivateKeyAttrs: privateKeyAttr
]
var publicKey: SecKey?
var privateKey: SecKey?
var statusCode: OSStatus
statusCode = SecKeyGeneratePair(keyPairAttr as CFDictionary, &publicKey, &privateKey)
if statusCode == noErr && publicKey != nil && privateKey != nil {
print(publicKey!)
print(privateKey!)
} else {
print("Error generating key pair: (statusCode)")
}
var dataPtr: AnyObject?
let query: [NSString: Any] = [
kSecClass: kSecClassKey,
kSecAttrApplicationTag: PrivateKeyTag,
kSecReturnData: NSNumber(value: true)
]
statusCode = SecItemCopyMatching(query as CFDictionary, &dataPtr)
let privateKeyData = dataPtr as! Data
let privateKeyString = privateKeyData.base64EncodedString(options: [])
print(privateKeyString)

privateKeyData似乎包含ASN.1编码的信息。最终结果是Base64编码的。

Answer 2

如果下面的方法对任何人都有帮助，请尝试它。在代码中添加以下方法，并输入SecKey类型的参数。

func secKeyToString(key:SecKey) {
var error:Unmanaged<CFError>?
if let cfData = SecKeyCopyExternalRepresentation(key, &error) {
let base64KeyString = (cfData as Data).base64EncodedString()
print("Sec key in string:(base64KeyString)")
}
}

您还可以使用相同的代码库创建SecKey类的扩展，并返回以64为基编码的字符串，如下所示：扩展SecKey｛

func toString()-> String{
var error:Unmanaged<CFError>?
let cfData = SecKeyCopyExternalRepresentation(self, &error)
let base64KeyString = (cfData as! Data).base64EncodedString()
return base64KeyString
}
}

使用以下方法：

//publicSecKey is your public key in SecKey format
let keyInStringFormat = publicSecKey.toString()
print("public key in string:(keyInStringFormat)")