[Bug 592] "Bad decrypted len" error in OpenSSH using smart-card stored public-key

[bugzilla-daemon at mindrot.org]

http://bugzilla.mindrot.org/show_bug.cgi?id=592

           Summary: "Bad decrypted len" error in OpenSSH using smart-card
                    stored public-key
           Product: Portable OpenSSH
           Version: -current
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P2
         Component: sshd
        AssignedTo: openssh-bugs at mindrot.org
        ReportedBy: sth at hq.bsbg.net


I think lines between 250-252 in  file ssh-rsa.c in OpenSSH source code should 
be commented!

REASON:
 Using "SecureNetTerm Client" ( http://www.securenetterm.com/ ) with
 "SecureKeyAgent" ver. 5.4.2.4 ( same situation: Putty + SecureKeyAgent ) to
 connect to OpenSSH server "OpenSSH ver. 3.6.1" using public key from Smart
 Card certificate causes the following errors in "/var/log/auth/errors":
     . . .
     sshd[1224] error: bad decrypted len: 36 != 20 + 15
     sshd[1227] error: bad decrypted len: 36 != 20 + 15
     . . .

I sent a letter about this to SecureNetTerm and here is the answer:
OpenSSH 3.6.1 is a little braindead when it comes to proper operation of
Certificates. All you have to do is edit the OpenSSL file ssh-rsa.c and 
comment out lines 250-252. This is a redundant length check that is not 
technically correct.  The OpenSSH team is aware of the problem but don't care 
since they have no idea how to use certificates.

The length check is not redundant since the result might be
too small for example ... 

I commented out lines 250-252 and problem disapeared.

Please fix this issue because otherwise we could not use Smart-card 
certificates with OpenSSH server at all :(


Best regards
    Stefan Hadjistoytchev



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