Re: Newbie : openssh and RC4

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Threaded View (ludovic LECLERC) writes:

]I'm using an old openssh version (v.2.3) and openssl version (0.9.7)
]on Linux system. I wanted to remove RC4 support from openssl, for
]legal reason cause I don't want cipher using key size more then 56
]bits (...).

What legal reason is that? If, as your domain name suggests it is french
law, I would check that the legal reason you advance is real. After all
there are another 10million french using the stock version of ssl.
I think befor you try to cure a disease by amputation, you ensure that
the disease exists.

]The problem is that it seems openssh needs RC4 functions from openssl
]: in arc4random() and arc4random_stir() [bsd_arc4random.c].
]Does this mean RC4 support cannot be removed from openssl ?...

]thanks for your help.

Re: Newbie : openssh and RC4

    NKG> ??? You can compile OpenSSH without the SSL libraries, I believe,

I assume you mean "OpenSSL" here, rather than "SSL" (since OpenSSH does
not actually use the SSL protocol) -- and I know of no such option;
OpenSSH takes all its crypto primitives from OpenSSL.  It wouldn't do much
without it.

    NKG> but considering that OpenSSH itself uses 1024 bit keys, I don't
    NKG> think you come out ahead.....

I don't know what you mean by "OpenSSH itself" -- presumably, some build
of OpenSSH without OpenSSL, which I don't think exists.  In any event,
this is comparing apples and oranges, Nico.  1024 and similar bit lengths
are used by public-key algorithms for authentication and key agreement,
which are not generally restricted by crypto-as-munitions laws.  In
talking about RC4 and 128-bit keys, the OP is referring to restrictions on
actual (symmetric) encryption algorithms.

  Richard Silverman

Re: Newbie : openssh and RC4

    NKG> The crypto regulations are *weird*, and need not make
    NKG> computational sense. With the former limits of "80 bits" for
    NKG> using SSL keys overseas, I was always surprused that PGP and
    NKG> OpenSSH using far longer key lengths didn't get in more
    NKG> grief.

They do make sense; again, your surprise comes because you are comparing
the wrong lengths.  The 80 bits restriction refers to key lengths on the
symmetric encryption ciphers.  You are comparing this to key lengths of
the public-key algorithms, to which this restriction does not apply.

The regulations generally do not apply to authentication/signature
schemes.  And the authorities involved don't care if you have a secure
public-key cipher to encrypt your bulk data key, as long as that bulk key
is short enough to be broken by brute force if need be.

  Richard Silverman

Re: Newbie : openssh and RC4

Quoted text here. Click to load it

Again, my question is more : is there any simple solution (patch ?) to have
an openssh that doesn't need RC4 functions from openssl ?...


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