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Re: Crypt::CBC losing its RandomIV

by jimbojones (Friar)
on Mar 17, 2006 at 21:07 UTC ( #537576=note: print w/ replies, xml ) Need Help??


in reply to Crypt::CBC losing its RandomIV

Hi

Haven't had time to get deep into this problem, but one thought: you have both filehandles in binmode and you are reading encrypted data that may not have "\n" characters. Perhaps you should do a $fh_cipher->read instead of $fh_cipher->getline?

HTH, J


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Re^2: Crypt::CBC losing its RandomIV
by Solostian (Beadle) on Mar 20, 2006 at 16:50 UTC
    I just got to a point where I don't get errors anymore. Here's what I did.

    First, I modified the way I create the Crypt::CBC object to:
    my $cipher = Crypt::CBC->new(-key => $self->{SYMMKEY}, -cipher => 'Twofish', -salt => 1) or die "Unable to create cipher:\n$@\n";

    My undertsanding is that CBC is now using a random Salt instead of a random IV. Correct me if I am wrong.

    Doing that solved the decryption error I was getting. It was replaced by an EOCD error during the unzip operation.

    I then followed your suggestion and replaced the getline with read:
    # $fh_cipher->write($cipher->crypt($fh_plain->getline)) until ($fh_pla +in->eof); do { $fh_plain->read($buf, length($self->{SYMMKEY})); $fh_cipher->write($cipher->crypt($buf)) } until ($fh_plain->eof);
    and:
    # $fh_plain->write($cipher->crypt($fh_cipher->getline)) until ($fh_cip +her->eof); do { $fh_cipher->read($buf, length($self->{SYMMKEY})); $fh_plain->write($cipher->crypt($buf)) } until ($fh_cipher->eof);
    That got rid of the EOCD error. My app now runs as expected. Thanks for the tip!

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