RSA Encryption -- Same Key Different Results

The RSA encryption algorithm produces different results for each call, even when encrypting the same data with the same key. Decryption however, will produce the correct results. This example demonstrates.

Download Chilkat RSA Public-Key Encryption ActiveX

CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @rsa int
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsa OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @success int

    EXEC sp_OAMethod @rsa, 'UnlockComponent', @success OUT, 'Anything for 30-day trial'
    IF @success <> 1
      BEGIN
        PRINT 'RSA component unlock failed'
        RETURN
      END

    --  RSA public key in XML format:
    DECLARE @publicKey nvarchar(4000)

    SELECT @publicKey = '<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>'

    DECLARE @privateKey nvarchar(4000)

    SELECT @privateKey = '<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent><P>4cpW9fvG99Jsz8/AO7PDHTl+pPRAglksrR2kClLV2g9DEeFe/bvmCxLUgMCJ+0eGQ1zA6aA7McKr13zTQ7jKpQ==</P><Q>4cCS/kFlq/P1ExF37Fkh4pCodOEGutepLEG7Q/KljT3ZGlAY+2l8fGu4f+hrkUuGoFl7NOMaJflULoPIgQaq/Q==</Q><DP>lkjcSsvzqh3YKRXJiLNkyf3rypV8noYGU4+oEOsDxilkZfFRDafUPUiiQrRk4ui/d/SzvozU+ZDuWfaOk8PatQ==</DP><DQ>SYCD25i7W8Mwdibn3uIecEAdOQDTSh5RjIFSUYs9b8FFYJXXrHPp/jCsf6jS7RmkGa1Iui1/JAIL8KEjtS7QmQ==</DQ><InverseQ>EDAJa3TpNdPQ3GIdBpnTgFTQY5A60DcszsUW/iCYoXQdPVJ9BLBxVTe9jiLzGuNuzLkVBwQlCy0Bf84hACRV9A==</InverseQ><D>cMFdDYKkddlRNczaugOmOH8b1egpx2liSPs6GYZ2gFObAXJiPK8m+r6c2ckls7hrlUP0DZhi4cG6Tn7xANb0Ek17P7QquVhQYOmFy/YHzm+IJbcwwq7pJHhZBhtcjyXqfUZ+BADGE//GQbrSVwVltpOj5KcxG88NAprLn2MMxfE=</D></RSAKeyValue>'

    EXEC sp_OAMethod @rsa, 'ImportPublicKey', NULL, @publicKey

    --  Encrypt a string and return the encrypted data base64-encoded:
    EXEC sp_OASetProperty @rsa, 'EncodingMode', 'base64'

    DECLARE @plainText nvarchar(4000)

    SELECT @plainText = 'RSA gives different results with each call, weird but OK'

    DECLARE @usePrivateKey int

    SELECT @usePrivateKey = 0
    DECLARE @encryptedStr1 nvarchar(4000)

    EXEC sp_OAMethod @rsa, 'EncryptStringENC', @encryptedStr1 OUT, @plainText, @usePrivateKey
    PRINT @encryptedStr1

    --  Do it again. The results are different...
    DECLARE @encryptedStr2 nvarchar(4000)

    EXEC sp_OAMethod @rsa, 'EncryptStringENC', @encryptedStr2 OUT, @plainText, @usePrivateKey
    PRINT @encryptedStr2

    --  Now decrypt both strings, and the results are correct
    --  in both cases:
    DECLARE @rsa2 int
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsa2 OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OAMethod @rsa2, 'ImportPrivateKey', NULL, @privateKey
    EXEC sp_OASetProperty @rsa2, 'EncodingMode', 'base64'
    SELECT @usePrivateKey = 1

    DECLARE @decryptedStr1 nvarchar(4000)

    EXEC sp_OAMethod @rsa2, 'DecryptStringENC', @decryptedStr1 OUT, @encryptedStr1, @usePrivateKey
    PRINT @decryptedStr1

    DECLARE @decryptedStr2 nvarchar(4000)

    EXEC sp_OAMethod @rsa2, 'DecryptStringENC', @decryptedStr2 OUT, @encryptedStr2, @usePrivateKey
    PRINT @decryptedStr2


END
GO