如何使用swift进行RSA加解密呢？

一.这四个方面:加载公钥/加载私钥/RSA加密/RSA解密

• 1.加载公钥

    @objc public func publicKey(fileFullPath: NSString, block :@escaping YKRSASignBlock ) {
        
        if !FileManager.default.fileExists(atPath: fileFullPath as String){
            block(NSError.init(domain: "file not exist at the full path ", code: -1, userInfo: nil),nil)
        }

        let certificateData = NSData(contentsOfFile: fileFullPath as String);
        
        let myCertificate: SecCertificate = SecCertificateCreateWithData(kCFAllocatorDefault, certificateData!)!
        let policy = SecPolicyCreateBasicX509()
        var trust: SecTrust?
        var status: OSStatus = SecTrustCreateWithCertificates(myCertificate, policy, &trust)
        
        if status == noErr {
            var trustResult:SecTrustResultType = SecTrustResultType(rawValue: 0)!
            status = SecTrustEvaluate(trust!, &trustResult)
            let secKey =  SecTrustCopyPublicKey(trust!)
            self.publicSecKey = secKey
            block(nil, secKey)
        }else{
            
            block(NSError(domain: "load error", code: Int(status), userInfo: nil), nil)
        }
    }

• 2.加载私钥

    @objc public func privateKey(fileFullPath: NSString, password: NSString, block :@escaping YKRSASignBlock ) {
        
        if !FileManager.default.fileExists(atPath: fileFullPath as String){
            block(NSError.init(domain: "file not exist at the full path ", code: -1, userInfo: nil),nil)
        }
        
        let p12Data = NSData(contentsOfFile: fileFullPath as String);
        
        guard p12Data != nil else {
            return
        }
        
        let options = [kSecImportExportPassphrase: password]  as [String : Any]
        var items : CFArray?
        var status: OSStatus = SecPKCS12Import(p12Data!, options as CFDictionary, &items)
        var privateKey:SecKey?
        
        if status == noErr {
            
            let resArray:Array = (items as Array?)!
            let identityDict: Dictionary = resArray.first as! Dictionary<String, AnyObject>
            let identity = identityDict[ kSecImportItemIdentity as String]
//            let identityDict = CFArrayGetValueAtIndex(items, 0)
//            let secImportItemIdentity = unsafeBitCast(kSecImportItemIdentity, to: UnsafeRawPointer.self)
//            let identityApp:SecIdentity = CFDictionaryGetValue(identityDict.unsafelyUnwrapped as! CFDictionary, secImportItemIdentity) as! SecIdentity
            status = SecIdentityCopyPrivateKey(identity as! SecIdentity, &privateKey)
            if status == noErr {
                self.privateSecKey = privateKey
                 block(nil, self.privateSecKey)
                return
            }
        }
        block(NSError(domain: "load error", code: Int(status), userInfo: nil), nil)
    }

• 3.使用RSA加密

@objc public func encrypt(source: NSString) -> NSString? {
        
        guard source.length > 0 && self.publicSecKey != nil else {
            return ""
        }
        
        let data: NSData = (source.data(using: String.Encoding.utf8.rawValue)! as NSData)
        var resData:NSData? = nil
        
//        if #available(iOS 10.0, *) {
//            var error: Unmanaged<CFError>?
//            resData =  SecKeyCreateEncryptedData(self.publicSecKey!, SecKeyAlgorithm.rsaEncryptionPKCS1, data as CFData, &error)
//
//            print("res = \(String(describing: error?.takeUnretainedValue().localizedDescription))")
//        } else
        //{
            // Fallback on earlier versions
            
        let blockLen =  SecKeyGetBlockSize(self.publicSecKey!)
        var outBuf = [UInt8](repeating: 0, count: blockLen)
        var outBufLen:Int = blockLen
        
        let status: OSStatus = SecKeyEncrypt(self.publicSecKey!, SecPadding.PKCS1, data.bytes.assumingMemoryBound(to: UInt8.self), data.length, &outBuf, &outBufLen)
            
        if status == noErr {
            resData = NSData(bytes: outBuf, length: outBufLen)
        }

        if resData != nil {
            
            let resString = resData!.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: NSData.Base64EncodingOptions.lineLength64Characters.rawValue))

            return resString as NSString
        }
        
        return nil
    }

• 4.使用RSA解密

    @objc public func decrypt(source: NSString) -> NSString? {
        
        guard source.length > 0 && self.privateSecKey != nil else {
            return ""
        }
        
        let data: Data = (NSData(base64Encoded: (source as String), options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)! as Data)
        
        
        let blockLen =  SecKeyGetBlockSize(self.privateSecKey!)
        
        let outBuf = UnsafeMutablePointer<UInt8>.allocate(capacity: blockLen)
        
        defer {
            outBuf.deallocate()
        }
        
        var outLen: Int = blockLen
        var status: OSStatus = noErr
        
        var resData:NSData? = nil
        
//        if #available(iOS 10.0, *) {
//            var error: Unmanaged<CFError>?
//            resData =  SecKeyCreateDecryptedData(self.privateSecKey!, SecKeyAlgorithm.rsaEncryptionPKCS1, data as CFData, &error)
//
//            print("res = \(String(describing: error?.takeUnretainedValue().localizedDescription))")
//        } else {
//            // Fallback on earlier versions
//            //let status = SecKeyEncrypt(seckey, SecPadding.PKCS1, chunkData, chunkData.count, outBuf, &encryptedDataLength)
//
//        }
        
        data.withUnsafeBytes { (bytes:UnsafePointer<UInt8>) -> Void in
            status = SecKeyDecrypt(self.privateSecKey!, SecPadding.PKCS1, bytes, data.count, outBuf, &outLen)
            
            print("status = \(status)")
        }
        
        if status == noErr {
            resData = NSData(bytes: outBuf, length: outLen)
        }
        
        if resData != nil  {
            return String(data: (resData! as Data), encoding: String.Encoding.utf8) as NSString?
        }
        
        return nil
    }
    

二.问题。

• 1.返回的为什么是NSString?混编
• 2.为什么不支持超过128字节数据加解密？别急，见下一篇
• 3.为什么不使用新版的RSA加解密？新版的只支持iOS10以上