panteltje@yahoo.com writes:

Hello all,

In conjunction to reading Applied Cryptography 2nd Ed., I'm also using Cryptool as a
learning aid. In learning modern encryption algorithms I figured I'd start with the
DES, my logic being that it will give me a good foundation for learning the rest of
the algorithms.

However, I do have a question about the "circular shift" of the key after it has been
reduced to 48 bits and then split into two 28 bit halves.

Cryptool has some animated illustrations of some of the classic ciphers, and also for
DES.

This is what it shows for the first 'R' and 'L' half of the 28 bits before and after
the left circular shift, on the first round of the 16, which would make it a 1 bit
shift.

(I have aligned the shift for simplicity)

For the 'R' half:

1 0 1 1 1 1 1
1 0 0 1 1 0 0
0 1 1 1 1 0 0
1 1 1 1 0 0 0

In many ways I still see myself as an outsider so I see things perhaps
in a slightly different way.

I would like to thank sci.crypt for an educational year over a goodly
range of topics. It is an amazing gift to the public that professors,
doctors and genuine experts give their time to deal with the "small
matters" raised by non-experts.

I also thank Rodger Schlafly who puts out his crypto mini-faq every
month but rarely gets thanked for his efforts. And JS, DG, BU and JP
(who seems to be no more) - even if I disagreed with you in an OT
thread, I respected your intellect and you did change me.

Merry Christmas Sci.crypt and best wishes for the new year

In many ways I still see myself as an outsider so I see things perhaps
in a slightly different way.

I would like to thank sci.crypt for an educational year over a goodly
range of topics. It is an amazing gift to the public that professors,
doctors and genuine experts give their time to deal with the "small
matters" raised by non-experts.

I also thank Rodger Schlafly who puts out his crypto mini-faq every
monthly but rarely gets thanked for his efforts. And JS, DG, BU and JP
(who seems to be no more) - even if I disagreed with you in an OT
thread, I respected your intellect.

Merry Christmas Sci.crypt and best wishes for the new year

"Tom St Denis" gmail.com> writes:

A lot more than the point of archiving this whole discussion, or most of
the discussions on netnews.

ggr@network.ucsd.edu (Greg Rose) writes:

bobandcarole wrote:

In article ,
Unruh wrote:

I beg your pardon? They most certainly are
dependent on the data format. They have to take
input as a byte-stream (actually a bit stream if
you want to get technical) and turn it into 32-bit
lumps for the algorithms to work on.

Rivest used little-endian for MD5, but the NSA
reversed that to be big-endian for the SHA family.

In programming, a serialized object is one that has been turned into a
string - a string that can be saved in a database, in a *.txt file, or
whatever. Is ASN.1 basically just a serialization technique?

Also, wikipedia.org provides an example of a ASN.1 using DER:

http://en.wikipedia.org/wiki/Asn.1#Example_encoded_in_DER

The first byte represents SEQUENCE and the second byte represents the
length of everything else. How does at ASN.1 decoder know that just
one byte is being used? If I had 256 bytes of data, the length would
be two bytes (0x01, 0x00). How would an ASN.1 decoder know this?

Section 8.1.3 of
<http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf>
suggests the length field ends when a bytes "first" digit is a 0 and
that only the last seven bits are actually used to store the number.
Does this mean that 256 would be represented as 1000 0010 0000 0000 =
0x82, 0x00? (I assume the most significant bit comes first)

"Tom St Denis" gmail.com> writes:

No, you do it with ease, you do not have to try.

In far fewer words than you used here you could have summarized that
discussion.