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sp_describe_parameter_encryption (Transact-SQL)

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Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance

Analyzes the specified Transact-SQL statement and its parameters, to determine which parameters correspond to database columns that are protected by using the Always Encrypted feature. Returns encryption metadata for the parameters that correspond to encrypted columns.

Syntax

sp_describe_parameter_encryption
    [ @tsql = ] N'tsql'
    [ , [ @params = ] N'@parameter_name data_type [ , ... n ]' ]
[ ; ]

Arguments

[ @tsql = ] 'tsql'

One or more Transact-SQL statements. @tsql might be nvarchar(n) or nvarchar(max).

[ @params = ] N'@parameter_name data_type [ ,... n ]'

@params provides a declaration string for parameters for @tsql, which is similar to sp_executesql. Parameters might be nvarchar(n) or nvarchar(max).

A string that contains the definitions of all parameters that are embedded in the Transact-SQL_batch. The string must be either a Unicode constant or a Unicode variable. Each parameter definition consists of a parameter name and a data type. n is a placeholder that indicates additional parameter definitions. n is a placeholder that indicates additional parameter definitions. Every parameter specified in the statement must be defined in @params. If the Transact-SQL statement or batch in the statement doesn't contain parameters, @params isn't required. NULL is the default value for this parameter.

Return value

0 indicates success. Anything else indicates failure.

Result set

sp_describe_parameter_encryption returns two result sets:

  • The result set describing cryptographic keys configured for database columns, the parameters of the specified Transact-SQL statement correspond to.

  • The result set describing how particular parameters should be encrypted. This result set references the keys described in the first result set.

Each row of the first result set describes a pair of keys: an encrypted column encryption key, and its corresponding column master key (CMK).

Column name Data type Description
column_encryption_key_ordinal int ID of the row in the resultset.
database_id int Database ID.
column_encryption_key_id int The column encryption key ID.

Note: this ID denotes a row in the sys.column_encryption_keys catalog view.
column_encryption_key_version int Reserved for future use. Currently, always contains 1.
column_encryption_key_metadata_version binary(8) A timestamp representing the creation time of the column encryption key.
column_encryption_key_encrypted_value varbinary(4000) The encrypted value of the column encryption key.
column_master_key_store_provider_name sysname The name of the provider for the key store that contains the CMK, which was used to produce the encrypted value of the column encryption key.
column_master_key_path nvarchar(4000) The key path of the CMK, which was used to produce the encrypted value of the column encryption key.
column_encryption_key_encryption_algorithm_name sysname The name of the encryption algorithm used to produce the encryption value of the column encryption key.

Each row of the second result set contains encryption metadata for one parameter.

Column name Data type Description
parameter_ordinal int ID of the row in the result set.
parameter_name sysname Name of one of the parameters specified in the @params argument.
column_encryption_algorithm tinyint Code indicating the encryption algorithm configured for the column the parameter corresponds to. The currently supported value is 2 for AEAD_AES_256_CBC_HMAC_SHA_256.
column_encryption_type tinyint Code indicating the encryption type configured for the column, the parameter corresponds to. The supported values are:

0 - plaintext (the column isn't encrypted)
1 - deterministic encryption
2 - randomized encryption.
column_encryption_key_ordinal int Code of the row in the first result set. The referenced row describes the column encryption key configured for the column, the parameter corresponds to.
column_encryption_normalization_rule_version tinyint Version number of the type normalization algorithm.

Remarks

A SQL Server client driver, supporting Always Encrypted, automatically calls sp_describe_parameter_encryption to retrieve encryption metadata for parameterized queries issued by the application. Then, the driver uses the encryption metadata to encrypt the values of parameters that correspond to database columns protected with Always Encrypted. It substitutes the plaintext parameter values submitted by the application, with the encrypted parameter values, before sending the query to the database engine.

Permissions

Require the VIEW ANY COLUMN ENCRYPTION KEY DEFINITION and VIEW ANY COLUMN MASTER KEY DEFINITION permissions in the database.

Examples

The following example truncates the value for ENCRYPTED_VALUE, for display purposes.

CREATE COLUMN MASTER KEY [CMK1]
WITH (
    KEY_STORE_PROVIDER_NAME = N'MSSQL_CERTIFICATE_STORE',
    KEY_PATH = N'CurrentUser/my/A66BB0F6DD70BDFF02B62D0F87E340288E6F9305'
);
GO

CREATE COLUMN ENCRYPTION KEY [CEK1]
WITH VALUES (
    COLUMN_MASTER_KEY = [CMK1],
    ALGORITHM = 'RSA_OAEP',
    ENCRYPTED_VALUE = 0x016E00000163007500720072<...> -- truncated in this example
);
GO

CREATE TABLE t1 (
    c1 INT ENCRYPTED WITH (
        COLUMN_ENCRYPTION_KEY = [CEK1],
        ENCRYPTION_TYPE = Randomized,
        ALGORITHM = 'AEAD_AES_256_CBC_HMAC_SHA_256'
        ) NULL,
);

EXEC sp_describe_parameter_encryption
    N'INSERT INTO t1 VALUES(@c1)',
    N'@c1 INT';

Here's the first result set:

Column Value
column_encryption_key_ordinal 1
database_id 5
column_encryption_key_id 1
column_encryption_key_version 1
column_encryption_key_metadata_version 0x99EDA60083A50000
column_encryption_key_encrypted_value 0x016E00000163007500720072<...>
column_master_key_store_provider_name MSSQL_CERTIFICATE_STORE
column_master_key_path CurrentUser/my/A66BB0F6DD70BDFF02B62D0F87E340288E6F9305
column_encryption_key_encryption_algorithm_name RSA_OAEP

Here's the second result set:

Column Value
parameter_ordinal 1
parameter_name @c1
column_encryption_algorithm 1
column_encryption_type 1
column_encryption_key_ordinal 1
column_encryption_normalization_rule_version 1

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