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    SubjectRe: [PATCH] Initial Vector Fix for loop.c.
    > That leaves the question of what the default behaviour should be.  If
    > we have to switch to 512Byte in the long run anyway, there is little
    > point in postponing the pain. Make it the default, and old behaviour
    > depends on the flag.

    In my opinion it doesn't make much difference. crypto-loop
    has broken beyond belief[1] IV anyways, so they will
    eventually need to change it. Or just use CBC, which is simpler
    and compatible and has nearly equivalent security to the easily
    predictable IV :-) And when they change it they can as well set the flag.

    Also I think Clemens is exaggerating the problem too.
    The old 2.2 behaviour of using absolute IVs caused quite
    some problems, but the relative IVs used in 2.4 are
    not that bad because it is near always used with 4K
    blocks (there are exceptions to this, but they're quite
    rare assuming your file systems are all big enough
    and you don't use a S390)


    [1] the problem is that it is too predictable. consider block 0,
    which is usually filled with zeros. It also has IV==0. This means
    it it 100% equivalent to CBC and worse even has known plain text.
    Same problem applies to other blocks - the layout of most
    installations generated by standard installers is quite predictible.
    Fixing it is simple, but requires a new secret per file system.

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