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Re: 5.5.3 clarification

2000-11-06 08:43:33
Regarding the 2 octet checksum (that is encrypted), how do we encrypt:

If you're asking whether there is a CFB resync before the checksum, then
the answer is no.

Perhaps Hal would be willing to change the wording to something like:

    With V4 keys, a simpler method is used.  All secret MPI values 
    (including their MPI bitcount prefixes) and the checksum are
    encrypted in CFB mode, without any resynchronization.

16 bit checksum = 16 most significant bits (sum of Secret MPI's ASCII 
values MOD 65536)

Actually, it's mod 2^16, which means the *least* significant bits.
It's raw binary data; there is no character set involved.
The description of the checksum in the spec looks pretty airtight to me.

this also assumes a big endian system.

The checksumming itself doesn't depend on the encoding system -- you're
adding individual octets (not 16-bit things).  The result is indeed
encoded most-significant-octet-first, like all other multi-octet numbers.

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