SQL Server

Generating Repeatable Random Data for Testing/Debugging

See more PRNG Examples

Demonstrates how to use the Fortuna PRNG to generate random-looking but repeatable non-random data for the purpose of testing and debugging. SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @success int
    SELECT @success = 0

    -- This example assumes the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    SELECT @success = 0

    DECLARE @fortuna int
    EXEC @hr = sp_OACreate 'Chilkat.Prng', @fortuna OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Normally an application would seed the PRNG with entropy from
    -- some real random source.  However, sometimes we want the same
    -- random sequence of bytes for testing and debugging purposes.
    -- This a reason why GetEntropy and AddEntropy are two different methods.
    -- An application could omit the call to GetEntropy, and instead pass
    -- non-random data to AddEntropy. For example:

    -- Seed the PRNG with non-entropy, so we get a repeatable sequence.
    -- Note: AddEntropy can be called any number of times.
    EXEC sp_OAMethod @fortuna, 'AddEntropy', @success OUT, '01020304', 'hex'
    EXEC sp_OAMethod @fortuna, 'AddEntropy', @success OUT, 'hello world', 'ascii'

    -- Generate some random data:
    DECLARE @strRandHex nvarchar(4000)
    EXEC sp_OAMethod @fortuna, 'GenRandom', @strRandHex OUT, 16, 'hex'
    DECLARE @strRandBase64 nvarchar(4000)
    EXEC sp_OAMethod @fortuna, 'GenRandom', @strRandBase64 OUT, 22, 'base64'
    DECLARE @strRandBase58 nvarchar(4000)
    EXEC sp_OAMethod @fortuna, 'GenRandom', @strRandBase58 OUT, 32, 'base58'


    PRINT 'hex random bytes: ' + @strRandHex

    PRINT 'base64 random bytes: ' + @strRandBase64

    PRINT 'base58 random bytes: ' + @strRandBase58

    -- Try it again with a different object to verify that the same results are obtained:
    DECLARE @fortuna2 int
    EXEC @hr = sp_OACreate 'Chilkat.Prng', @fortuna2 OUT

    EXEC sp_OAMethod @fortuna2, 'AddEntropy', @success OUT, '01020304', 'hex'
    EXEC sp_OAMethod @fortuna2, 'AddEntropy', @success OUT, 'hello world', 'ascii'

    EXEC sp_OAMethod @fortuna2, 'GenRandom', @strRandHex OUT, 16, 'hex'
    EXEC sp_OAMethod @fortuna2, 'GenRandom', @strRandBase64 OUT, 22, 'base64'
    EXEC sp_OAMethod @fortuna2, 'GenRandom', @strRandBase58 OUT, 32, 'base58'


    PRINT 'hex random bytes: ' + @strRandHex

    PRINT 'base64 random bytes: ' + @strRandBase64

    PRINT 'base58 random bytes: ' + @strRandBase58

    EXEC @hr = sp_OADestroy @fortuna
    EXEC @hr = sp_OADestroy @fortuna2


END
GO