> -----Original Message-----
> From: Daniel Crichton [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, 18 April 2000 8:44 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Crypto - mail attachments, docs
>
>
> On 18 Apr 2000, at 10:50, SAGI MINI wrote:
>
> > Does anyone have/using any product for the following purposes:
> >
> > 1. Software to perform encryption/decryption on the e-mail
> attachments,
> > documents, or the e-mail contents. The software should also
> be able to
> > identify if the encrypted file has been tampered before
> open by the receiver and
> > perform decryption. I have one that perform 128-bit
> encryption but its to costly
> > to implement.
I wouldn't do what you're suggesting with the message verification. The most
common way to do this would be to sign the encrypted message - don't do
that. Read some crypto stuff to find out why (or just trust me).
If the ciphertext has been garbled then you'll get plaintext errors - one or
more bits of the plaintext will come out wrong. If you sign the message
_before_ you encrypt then the signature and the message won't match and the
tampering will be detected.
In terms of products - PGP and S/MIME are probably the biggest contenders.
If you use M$ mail stuff you probably have S/MIME built in. S/MIME 3 and
later is pretty good - just don't use an old version. PGP is "better" (IMO)
but is an add-on. GPG is like PGP but free - only *nix users need apply (at
this stage) though.
> How about PGP? Up to 2048-bit encryption, free for
> non-commercial use,
> commercial licenses are fairly cheap (well, they were before
> NAI bought the
> software!).
Really minor point:
PGP uses a symmetric block cipher (choice of 3DES, CAST5 or IDEA, from
memory) to do the actual payload encryption. The _key_ is encrypted with RSA
for which you can go higher than 2048 bits if you are really paranoid.
However in the "size queen" debate, your "biggest" key is 3DES with 168
bits.
> Dan
>
> ---
> D.C. Crichton email: [EMAIL PROTECTED]
> Senior Systems Analyst tel: +44 (0)121 706 6000
> Computer Manuals Ltd. fax: +44 (0)121 606 0477
>
Cheers,
--
Ben Nagy
Network Consultant, Volante IT
PGP Key ID: 0x1A86E304 Mobile: +61 414 411 520
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