Why does EFS uses two ways of encryption?

Discussion in 'Computer Security' started by Pamela, Aug 31, 2004.

  1. Pamela

    Pamela Guest

    Hi,


    EFS uses an asymetric encryption but it also uses an FEK which is symetric
    encryption.
    In fact the FEK is encrypted by the asymetric encryption.

    Wouldn't it be possible that the asymetric method is directly used to
    encrypt the file?

    thx


    Pamela
     
    Pamela, Aug 31, 2004
    #1
    1. Advertisements

  2. Pamela

    Felix Tiede Guest

    AFAIK asymmetric encryption/decryption is slower than the symmetric method.
    Because of that many encryption systems use a temporary session key to
    symmetrically encrypt data and then use the asymmetric key to encrypt the
    session key.

    So it *would* be possible to encrypt a file with an asymmetric method, but
    it would cost more CPU time.

    Greetings,
    Felix

    -----BEGIN PGP SIGNATURE-----
    Version: GnuPG v1.2.4 (GNU/Linux)
    Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

    iD8DBQFBNH1pDH+mFzdSOa0RApWfAJwM1gjge1D79RrX3eNGsuh8+qWl7gCfdc54
    xRRwlu8ir6CQRPtGp75HrjE=
    =kbp+
    -----END PGP SIGNATURE-----
     
    Felix Tiede, Aug 31, 2004
    #2
    1. Advertisements

  3. Pamela

    Celtic Leroy Guest

    In addition, the method of using a symmetric key to encrypt the data,
    and the asymmetric key to encrypt the symmetric key, is when the data
    is being transported across a live internet session...as in shttp,
    SSL, sessions. Speed is a major factor in this type of communication.
    In testing the time factors though, I found that (with Ghz processors)
    the difference is not significant until you start moving large amounts
    of data (in excess of 10Mb).

    Regards,
    Leroy
     
    Celtic Leroy, Aug 31, 2004
    #3
  4. Pamela

    Pamela Guest

    thank you both


    Greetz


    Pam


     
    Pamela, Sep 1, 2004
    #4
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.