uniqueidentifier | 易学教程

Host-based Card Emulation with Fixed Card ID

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Android 4.4 introduced Host-based Card Emulation (HCE). As you know, all NFC cards come with a fixed card ID ( NfcAdapter.EXTRA_ID ). My office door access usually detects the NFC card ID for the authorization. After flashing my phone to KitKat, I tried to scan my phone with the access reader. But whenever the screen turns off and on again, I get a different card ID. I did try keeping the phone screen on, and registering the emulated card ID to the door access system. It managed to grant the access to open the door. But this won't work after the screen turns off and on again. Ever since KitKat

App rejected, but I don't use UDID

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Today we received a feedback about our submission and we do not understand the reported problem: "Apps are not permitted to access the UDID and must not use the uniqueIdentifier method of UIDevice. Please update your apps and servers to associate users with the Vendor or Advertising identifiers introduced in iOS 6.". We know about the rejections about udid, but our App do not use this! After read this, our team reevaluated the App and we do not found occurrences from "UIDevice uniqueIdentifier". We also revised all used libraries and really we do not find any call from UDID. Someone have ideas

How are hash functions like MD5 unique?

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问题 I\'m aware that MD5 has had some collisions but this is more of a high-level question about hashing functions. If MD5 hashes any arbitrary string into a 32-digit hex value, then according to the Pigeonhole Principle surely this can not be unique, as there are more unique arbitrary strings than there are unique 32-digit hex values. 回答1: You're correct that it cannot guarantee uniqueness, however there are approximately 3.402823669209387e+38 different values in a 32 digit hex value (16^32).

Generating a globally unique identifier in Java

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问题 Summary: I\'m developing a persistent Java web application, and I need to make sure that all resources I persist have globally unique identifiers to prevent duplicates. The Fine Print: I\'m not using an RDBMS, so I don\'t have any fancy sequence generators (such as the one provided by Oracle) I\'d like it to be fast, preferably all in memory - I\'d rather not have to open up a file and increment some value It needs to be thread safe (I\'m anticipating that only one JVM at a time will need to

How to get a unique device ID in Swift?

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How can I get a devices unique ID in Swift? I need an ID to use in the database and as the API-key for my web service in my social app. Something to keep track of this devices daily use and limit its queries to the database. Thanks! You can use this (Swift 3): UIDevice.current.identifierForVendor!.uuidString For older versions: UIDevice.currentDevice().identifierForVendor or if you want a string: UIDevice.currentDevice().identifierForVendor!.UUIDString There is no longer a way to uniquely identify a device after the user uninstalled the app(s). The documentation says: The value in this

What's a good way to uniquely identify a computer?

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I'm developing some desktop software for a client to resell. The client wants to restrict the software so that the registration code will be specific to one and only one computer. Besides using the MAC from the network card, does anyone have any other techniques (that work on both Windows and Mac OS X) for uniquely identifying a computer? Another solution is to use a licensing technology with a dongle . This is a small device that plugs into USB or another I/O port on the host, and serves as a unique, physical key to activate the software. A third solution is to provide a license manager .

Android Unique Serial Number

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问题 I am developing an android application that targets Android 4.0 (API 14) and above. I am looking for a serial number that is unique per device and that persists for ever (dies with the device, does not change after factory resets). I have found lots of results on the web concerning unique identifiers for android devices, but very little on the android.os.Build.SERIAL number. So far, I eliminated the use of the ANDROID_ID because it might change after factory resets. I also eliminated the use

Any way to identify browser tab in JavaScript?

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问题 I need to be able to identify what tab I am in within the browser. Isn\'t there some bit of information I can get from the browser to identify the tab? I don\'t need to know anything about any other tabs, I just need an id for the tab I am in. It could be a random or sequenced number, or a date-time stamp, as long as it remains the same for the life of the tab. I have a client side app that makes a BOSH over HTTP connection to a remote server, and if I open it in multiple tabs, each instance

How to detect the original MAC address after it has been spoofed?

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问题 We are using the following code for retrieving active MAC address of a windows pc. private static string macId() { return identifier(\"Win32_NetworkAdapterConfiguration\", \"MACAddress\", \"IPEnabled\"); } private static string identifier(string wmiClass, string wmiProperty, string wmiMustBeTrue) { string result = \"\"; System.Management.ManagementClass mc = new System.Management.ManagementClass(wmiClass); System.Management.ManagementObjectCollection moc = mc.GetInstances(); foreach (System

C# guid and SQL uniqueidentifier

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问题 I want to create a GUID and store it in the DB. In C# a guid can be created using Guid.NewGuid(). This creates a 128 bit integer. SQL Server has a uniqueidentifier column which holds a huge hexidecimal number. Is there a good/preferred way to make C# and SQL Server guids play well together? (i.e. create a guid using Guid.New() and then store it in the database using nvarchar or some other field ... or create some hexidecimal number of the form that SQL Server is expecting by some other means)