(SQL Server) HMAC Hex String

Demonstrates how to compute an HMAC using a hexidecimal key and data.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- This example assumes the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @crypt int
    -- Use "Chilkat_9_5_0.Crypt2" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Crypt2', @crypt OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Set the MAC algorithm to HMAC
    EXEC sp_OASetProperty @crypt, 'MacAlgorithm', 'hmac'

    -- Our HMAC key will be the bytes represented in the following hex string.
    -- In other words, the HMAC key is composed of the bytes 0x41, 0xC2, 0x1C, ...
    -- (It is not composed of the us-ascii string '4', '1', 'C', ...)
    DECLARE @keyHex nvarchar(4000)
    SELECT @keyHex = '41C21CB9D7A02FC5D4FADB9E4755B9DE'
    DECLARE @success int
    EXEC sp_OAMethod @crypt, 'SetMacKeyEncoded', @success OUT, @keyHex, 'hex'

    -- Our desire is to HMAC the bytes represented in the following string:
    DECLARE @dataHex nvarchar(4000)
    SELECT @dataHex = 'C22078065B01460001000000010062043BF5B18228C8E02D17BCFE4E00561FA6DEC216EA97195CEB579942E275C21932258E3CD391E507FF4E7FD4C787A8447DA111C54A9C1795E7FF4C0BAA2EDA'

    -- We'll need to decode the hex to binary:
    DECLARE @bd int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT

    EXEC sp_OAMethod @bd, 'AppendEncoded', @success OUT, @dataHex, 'hex'

    -- Do the HMAC-SHA256 hash and return as a hex string:
    EXEC sp_OASetProperty @crypt, 'EncodingMode', 'hex'
    EXEC sp_OASetProperty @crypt, 'HashAlgorithm', 'sha-256'
    DECLARE @macHex nvarchar(4000)
    EXEC sp_OAMethod @crypt, 'MacBdENC', @macHex OUT, @bd

    PRINT @macHex

    EXEC @hr = sp_OADestroy @crypt
    EXEC @hr = sp_OADestroy @bd


END
GO