(SQL Server) RSA Encrypt and Decrypt Strings

SQL Server sample code to RSA public-key encrypt and decrypt strings using public and private keys.

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
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example assumes the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

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

    -- This example also generates the public and private
    -- keys to be used in the RSA encryption.
    -- Normally, you would generate a key pair once,
    -- and distribute the public key to your partner.
    -- Anything encrypted with the public key can be
    -- decrypted with the private key.  The reverse is 
    -- also true: anything encrypted using the private
    -- key can be decrypted using the public key.

    -- Generate a 1024-bit key.  Chilkat RSA supports
    -- key sizes ranging from 512 bits to 4096 bits.
    DECLARE @success int
    EXEC sp_OAMethod @rsa, 'GenerateKey', @success OUT, 1024
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END

    -- Keys are exported in XML format:
    DECLARE @publicKey nvarchar(4000)
    EXEC sp_OAMethod @rsa, 'ExportPublicKey', @publicKey OUT
    DECLARE @privateKey nvarchar(4000)
    EXEC sp_OAMethod @rsa, 'ExportPrivateKey', @privateKey OUT

    DECLARE @plainText nvarchar(4000)
    SELECT @plainText = 'Encrypting and decrypting should be easy!'

    -- Start with a new RSA object to demonstrate that all we
    -- need are the keys previously exported:
    DECLARE @rsaEncryptor int
    -- Use "Chilkat_9_5_0.Rsa" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsaEncryptor OUT

    -- Encrypted output is always binary.  In this case, we want
    -- to encode the encrypted bytes in a printable string.
    -- Our choices are "hex", "base64", "url", "quoted-printable".
    EXEC sp_OASetProperty @rsaEncryptor, 'EncodingMode', 'hex'

    -- We'll encrypt with the public key and decrypt with the private
    -- key.  It's also possible to do the reverse.
    EXEC sp_OAMethod @rsaEncryptor, 'ImportPublicKey', @success OUT, @publicKey

    DECLARE @usePrivateKey int
    SELECT @usePrivateKey = 0
    DECLARE @encryptedStr nvarchar(4000)
    EXEC sp_OAMethod @rsaEncryptor, 'EncryptStringENC', @encryptedStr OUT, @plainText, @usePrivateKey

    PRINT @encryptedStr

    -- Now decrypt:
    DECLARE @rsaDecryptor int
    -- Use "Chilkat_9_5_0.Rsa" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsaDecryptor OUT

    EXEC sp_OASetProperty @rsaDecryptor, 'EncodingMode', 'hex'
    EXEC sp_OAMethod @rsaDecryptor, 'ImportPrivateKey', @success OUT, @privateKey

    SELECT @usePrivateKey = 1
    DECLARE @decryptedStr nvarchar(4000)
    EXEC sp_OAMethod @rsaDecryptor, 'DecryptStringENC', @decryptedStr OUT, @encryptedStr, @usePrivateKey


    PRINT @decryptedStr

    EXEC @hr = sp_OADestroy @rsa
    EXEC @hr = sp_OADestroy @rsaEncryptor
    EXEC @hr = sp_OADestroy @rsaDecryptor


END
GO