Question

I’m playing around with Asymmetric Encryption and Decryption, but I don’t understand the results I’m getting when I use VerifySignedByAsymKey().

Why does this:

CREATE ASYMMETRIC KEY myasymkey 
WITH ALGORITHM = RSA_2048 
ENCRYPTION BY PASSWORD = '123pass!'; 
GO

Select VerifySignedByAsymKey(AsymKey_ID('myasymkey'), 
    'Greg', 
    EncryptByAsymKey(AsymKey_ID('myasymkey'), 'Greg'));
GO

Produce 0? I was expecting it to be 1.

Answer 1

You’ve only encrypted the data, not signed it.

See SignByAsymKey(). The following example returns 1:

declare @clear varchar(128)
set @clear = 'Greg'
Select VerifySignedByAsymKey(AsymKey_ID('myasymkey'), @clear, 
       SignByAsymKey(AsymKey_ID('myasymkey'), @clear, N'123pass!'))