Sql Server 2014 Generate Hash Key
Creates an asymmetric key in the database.
This feature is incompatible with database export using Data Tier Application Framework (DACFx). You must drop all asymmetric keys before exporting.
Syntax
May 16, 2018 In SQL Server 2012, we have an enhancement in this function and now it supports SHA2256, SHA2512 algorithms that can generate 32 and 64 bytes hash codes for the respective input. Beginning with SQL Server 2016, all algorithms other than SHA2256, and SHA2512 are deprecated. Speed of the Hash function. SQL Server exposes a series of hash functions that can be used to generate a hash based on one or more columns. The most basic functions are CHECKSUM and BINARYCHECKSUM. These two functions each take a column as input and outputs a 32-bit integer. Inside SQL Server, you will also find the HASHBYTES function. Using hash values in SSIS to determine when to insert or update rows. By: Koen Verbeeck Updated. And if that will be for Oracle databases, can we create the third table in SQL Server Database? Decause the access is limited in both Oracle DBs. Compare a hash summary of key fileds to hash value stored in database. If the hash values. Dec 20, 2013 Memory Optimized Indexes Hash vs Range Indexes – SQL Server 2014 December 20, 2013 Leave a comment Go to comments In SQL Server 2014 for In-Memory tables there are lot of changes in DDLs compared with normal Disk Based Tables. Getting Started with Hashing in SQL Server. You can concatenate them and generate hash key on the concatenated value and then you can use this hash key as a. Sep 24, 2018 How to use HASHBYTES function in sql server for multiple columns – Learn more on the SQLServerCentral forums.
Arguments
asym_key_name
Is the name for the asymmetric key in the database. Asymmetric key names must comply with the rules for identifiers and must be unique within the database.
When you create a login, SQL Server add a 4 bytes salt key to it (i.e. Password '12345678' + key 0x1234abcd) and hash it using SHA algorithm. Because the salt key is randomly generated, each hash will be different unless it use the same key twice. (1 out of 65k possible salt keys) You can see the salt key at the beginning of the hash.
AUTHORIZATION database_principal_name
Specifies the owner of the asymmetric key. The owner cannot be a role or a group. If this option is omitted, the owner will be the current user.
FROM asym_key_source
Specifies the source from which to load the asymmetric key pair.
FILE = 'path_to_strong-name_file'
Specifies the path of a strong-name file from which to load the key pair. Limited to 260 characters by MAX_PATH from the Windows API.
Note
This option is not available in a contained database.
EXECUTABLE FILE = 'path_to_executable_file'
Specifies the path of an assembly file from which to load the public key. Limited to 260 characters by MAX_PATH from the Windows API.
Note
This option is not available in a contained database.
ASSEMBLY assembly_name
Specifies the name of a signed assembly that has already been loaded into the database from which to load the public key.
PROVIDER provider_name
Specifies the name of an Extensible Key Management (EKM) provider. The provider must be defined first using the CREATE PROVIDER statement. For more information about external key management, see Extensible Key Management (EKM).
ALGORITHM = <algorithm>
Five algorithms can be provided; RSA_4096, RSA_3072, RSA_2048, RSA_1024, and RSA_512.
RSA_1024 and RSA_512 are deprecated. To use RSA_1024 or RSA_512 (not recommended) you must set the database to database compatibility level 120 or lower.
PROVIDER_KEY_NAME = 'key_name_in_provider'
Specifies the key name from the external provider.
Microsoft streets and trips 2013 key generator. CREATION_DISPOSITION = CREATE_NEW
Creates a new key on the Extensible Key Management device. PROVIDER_KEY_NAME must be used to specify key name on the device. If a key already exists on the device the statement fails with error.
CREATION_DISPOSITION = OPEN_EXISTING
Maps a SQL Server asymmetric key to an existing Extensible Key Management key. PROVIDER_KEY_NAME must be used to specify key name on the device. If CREATION_DISPOSITION = OPEN_EXISTING is not provided, the default is CREATE_NEW.
ENCRYPTION BY PASSWORD = 'password'
Specifies the password with which to encrypt the private key. If this clause is not present, the private key will be encrypted with the database master key. password is a maximum of 128 characters. password must meet the Windows password policy requirements of the computer that is running the instance of SQL Server.
Remarks
An asymmetric key is a securable entity at the database level. In its default form, this entity contains both a public key and a private key. When executed without the FROM clause, CREATE ASYMMETRIC KEY generates a new key pair. When executed with the FROM clause, CREATE ASYMMETRIC KEY imports a key pair from a file, or imports a public key from an assembly or DLL file.
By default, the private key is protected by the database master key. If no database master key has been created, a password is required to protect the private key.
The private key can be 512, 1024, or 2048 bits long.
Permissions
Sql Server Hash Column
Requires CREATE ASYMMETRIC KEY permission on the database. If the AUTHORIZATION clause is specified, requires IMPERSONATE permission on the database principal, or ALTER permission on the application role. Only Windows logins, SQL Server logins, and application roles can own asymmetric keys. Groups and roles cannot own asymmetric keys.
Examples
A. Creating an asymmetric key
The following example creates an asymmetric key named PacificSales09 by using the RSA_2048 algorithm, and protects the private key with a password.
B. Creating an asymmetric key from a file, giving authorization to a user
Hash Key Sql Server
The following example creates the asymmetric key PacificSales19 from a key pair stored in a file, and assigns ownership of the asymmetric key to user Christina. The private key is protected by the database master key, which must be created prior to creating the asymmetric key.
C. Creating an asymmetric key from an EKM provider
The following example creates the asymmetric key EKM_askey1 from a key pair stored in an Extensible Key Management provider called EKM_Provider1, and a key on that provider called key10_user1.
See Also
ALTER ASYMMETRIC KEY (Transact-SQL)
DROP ASYMMETRIC KEY (Transact-SQL)
ASYMKEYPROPERTY (Transact-SQL)
ASYMKEY_ID (Transact-SQL)
Choose an Encryption Algorithm
Encryption Hierarchy
Extensible Key Management Using Azure Key Vault (SQL Server)
The CHECKSUM function returns the checksum value computed over a table row, or over an expression list. Use CHECKSUM to build hash indexes.
Syntax
Arguments
*
This argument specifies that the checksum computation covers all table columns. CHECKSUM returns an error if any column has a noncomparable data type. Noncomparable data types include:
- cursor
- image
- ntext
- text
- XML
Another noncomparable data type is sql_variant with any one of the preceding data types as its base type.
expression
An expression of any type, except a noncomparable data type.
Return types
int
Remarks
CHECKSUM computes a hash value, called the checksum, over its argument list. Use this hash value to build hash indexes. A hash index will result if the CHECKSUM function has column arguments, and an index is built over the computed CHECKSUM value. This can be used for equality searches over the columns.
The CHECKSUM function satisfies hash function properties: CHECKSUM applied over any two lists of expressions will return the same value, if the corresponding elements of the two lists have the same data type, and if those corresponding elements have equality when compared using the equals (=) operator. Null values of a specified type are defined to compare as equal for CHECKSUM function purposes. If at least one of the values in the expression list changes, the list checksum will probably change. However, this is not guaranteed.Therefore, to detect whether values have changed, we recommend use of CHECKSUM only if your application can tolerate an occasional missed change. Otherwise, consider using HASHBYTES instead. With a specified MD5 hash algorithm, the probability that HASHBYTES will return the same result, for two different inputs, is much lower compared to CHECKSUM.
The expression order affects the computed CHECKSUM value. The order of columns used for CHECKSUM(*) is the order of columns specified in the table or view definition. This includes computed columns.
The CHECKSUM value depends on the collation. The same value stored with a different collation will return a different CHECKSUM value.
CHECKSUM () does not guarantee unique results.
Examples
These examples show the use of CHECKSUM to build hash indexes.
To build the hash index, the first example adds a computed checksum column to the table we want to index. It then builds an index on the checksum column.
This example shows the use of a checksum index as a hash index. This can help improve indexing speed when the column to index is a long character column. The checksum index can be used for equality searches.
Index creation on the computed column materializes the checksum column, and any changes to the ProductName value will propagate to the checksum column. Alternatively, we could build an index directly on the column we want to index. However, for long key values, a regular index will probably not perform as well as a checksum index.
See also
CHECKSUM_AGG (Transact-SQL)
HASHBYTES (Transact-SQL)
BINARY_CHECKSUM (Transact-SQL)