Generating Keys for Encryption and Decryption.; 3 minutes to read +7; In this article. Creating and managing keys is an important part of the cryptographic process. Symmetric algorithms require the creation of a key and an initialization vector (IV). The key must be kept secret from anyone who should not decrypt your data. Dec 24, 2012 How to Generate a Sequence of Unique Random Integers. Another refinement: Instead of generating an arbitrary 32-bit integer for each element and hoping it’s unique, we could generate a random index in the range 0, N) where N is the number of remaining unused values. The index would tell us which free slot to take next. At the first glance it seems to be satisfied Unique key as its using current time and hashing to generate key but GetHashCode doesn’t procduce unique code everytime. Althought Microsoft is using Double Hashing algorithms with N Number of collision resolving double hash function but during my experimentation I found lot of collisions. Generating Unique Token in C# Generating Unique Token that Expires after 24 Hours in C# C# Tutorial ASP.NET MVC, C# There are two possible approaches; either you create a unique value and store somewhere along with the creation time, for example in a database, or you put the creation time inside the token so that you can decode it later and see when it was created. GUIDs are used in enterprise software development in C#, Java, and C as database keys, component identifiers, or just about anywhere else a truly unique identifier is required. GUIDs are also used to identify all interfaces and objects in COM programming. More Information About GUIDs.
You can create a unique constraint in SQL Server 2019 (15.x) by using SQL Server Management Studio or Transact-SQL to ensure no duplicate values are entered in specific columns that do not participate in a primary key. Creating a unique constraint automatically creates a corresponding unique index.
Note
See Primary key, foreign key, and unique key in Azure Synapse Analytics for information on unique constraints in Azure Synapse Analytics.
In This Topic
Before you begin:
To create a unique constraint, using:
Requires ALTER permission on the table.
In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design.
On the Table Designer menu, click Indexes/Keys.
In the Indexes/Keys dialog box, click Add.
In the grid under General, click Type and choose Unique Key from the drop-down list box to the right of the property. Watch dogs 2 license key generator browser.
On the File menu, click Savetable name.
In Object Explorer, connect to an instance of Database Engine.
On the Standard bar, click New Query.
Copy and paste the following example into the query window and click Execute. The example creates the table TransactionHistoryArchive4
and creates a unique constraint on the column TransactionID
.
In Object Explorer, connect to an instance of Database Engine.
On the Standard bar, click New Query.
Copy and paste the following example into the query window and click Execute. The example creates a unique constraint on the columns PasswordHash
and PasswordSalt
in the table Person.Password
.
In Object Explorer, connect to an instance of Database Engine.
On the Standard bar, click New Query.
Copy and paste the following example into the query window and click Execute. The example creates a table and defines a unique constraint on the column TransactionID
.
For more information, see ALTER TABLE (Transact-SQL), CREATE TABLE (Transact-SQL), and table_constraint (Transact-SQL).