SQL Server

Select the S/MIME Encryption Algorithm

Demonstrates the Chilkat Email.Pkcs7CryptAlg property, which selects the underlying symmetric encryption algorithm used when an email is sent encrypted with PKCS#7 public-key (S/MIME) encryption. Possible values are aes, aes-gcm, des, 3des, and rc2; the default is aes. This example selects AES and pairs it with a 256-bit key length.

Background: S/MIME encryption is hybrid. The message body is encrypted with a fast symmetric algorithm (the one this property chooses, such as AES) using a randomly generated one-time key; then that one-time key is itself encrypted with each recipient's public key. This gives the speed of symmetric encryption with the key-distribution convenience of public-key cryptography. Modern choices like aes are strongly preferred — older options such as des and rc2 are considered weak.

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--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    --  Demonstrates the Email.Pkcs7CryptAlg property, which selects the symmetric encryption
    --  algorithm used when an email is sent encrypted with PKCS#7 (S/MIME) public-key
    --  encryption.  Possible values: aes, aes-gcm, des, 3des, rc2.  The default is aes.

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

    EXEC sp_OASetProperty @email, 'Subject', 'Encrypted email'
    EXEC sp_OASetProperty @email, 'Body', 'This message will be S/MIME encrypted when sent.'

    --  Select AES with a 256-bit key for the symmetric encryption.
    EXEC sp_OASetProperty @email, 'Pkcs7CryptAlg', 'aes'
    EXEC sp_OASetProperty @email, 'Pkcs7KeyLength', 256


    EXEC sp_OAGetProperty @email, 'Pkcs7CryptAlg', @sTmp0 OUT
    PRINT 'Pkcs7CryptAlg = ' + @sTmp0

    EXEC sp_OAGetProperty @email, 'Pkcs7KeyLength', @iTmp0 OUT
    PRINT 'Pkcs7KeyLength = ' + @iTmp0

    EXEC @hr = sp_OADestroy @email


END
GO