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Re: paging IO and 192-bit (or any non-aligned on page size) encryption

David_J._CraigDavid_J._Craig Member Posts: 1,885
Stream ciphers are secure if the key string is longer than the data stream
and the cipher stream is not repeated for multiple blocks. I am NOT an
expert, nor do I desire to be one, on encryption. I have implemented
encryption in several environments and one problem with some block
encryption methods is that multiple blocks of the same plaintext will show a
repeating pattern. This can make finding the encryption key easier,
especially if the data is binary zeroes. Using CBC or some other method
that allows real random access, but prevents repeating blocks is the best
solution. Using a hash of the byte or block offset can provide a good seed.
Many encryption algorithms, including DES, have variations that permit such
seeding.

"Dejan Maksimovic" wrote in message news:xxxxx@ntfsd...
>
> > Stream ciphers are not as secure, I think, but they work at the byte
level.
>
> SORT of. ECB mode itself is unsecure, and any encryption that
relies
> on it (even taking sector number or something else into account) is not
secure
> enough, because a skilled hacker can easily bypass it.
> That's why other modes exist.
> Stream ciphers (except SEAL IIRC) are not applicable because they
are
> NOT random access, but require previous bytes to be processed first -
meaning
> on every read you have to read in the previous bytes and process them
before
> the current block.
>
> --
> Kind regards, Dejan M. MVP for DDK
> http://www.alfasp.com E-mail: xxxxx@alfasp.com
> Alfa Transparent File Encryptor - Transparent file encryption services.
> Alfa File Protector - File protection and hiding library for Win32
developers.
> Alfa File Monitor - File monitoring library for Win32 developers.
>
>
>
>
>
>
>
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