SQL Server

Set the S/MIME Encryption Key Length

Demonstrates the Chilkat Email.Pkcs7KeyLength property, which sets the key length of the symmetric algorithm used for PKCS#7 (S/MIME) encryption. The allowed values depend on Pkcs7CryptAlg: for aes use 128, 192, or 256; for 3des use 192; for des use 40; for rc2 use 40, 56, 64, or 128. The default is 128, and an unsupported algorithm/key-length combination causes encryption to fail. This example pairs AES with a 192-bit key.

Background: Key length is the size, in bits, of the secret key a symmetric cipher uses — a longer key means exponentially more possible keys and thus more resistance to brute-force attack. But length is only meaningful within a given algorithm: AES-128 is already very strong, and a key size must be one the chosen cipher actually supports, which is why Pkcs7KeyLength and Pkcs7CryptAlg have to agree.

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--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    --  Demonstrates the Email.Pkcs7KeyLength property, which sets the key length (in bits)
    --  of the symmetric algorithm used for PKCS#7 (S/MIME) encryption.  The allowed values
    --  depend on Pkcs7CryptAlg; for aes they are 128, 192, or 256.  The default is 128.

    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, 'Pkcs7CryptAlg', 'aes'
    EXEC sp_OASetProperty @email, 'Pkcs7KeyLength', 192


    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