Re:[ntfsd] encrypt file without aligned

NTFSD
1

Hi,idlee.
I have ever considered this algorithm.
Considering a special scenario:
A Write Operation:
pagingio==TRUE;
offset:4097;
length:[15 bytes of data];
using this algorithm , we should read 4096th byte. So we should send
IRP_MJ_READ to the lower device. But the pagingresource was exclusively held
by cache manager,deadlock occurs.

David J. Craig,

i have found your mail as follow:

Let me try a diagram:

[Data nnnnnnnn bytes mod 16] [15 bytes of data]

  1. Encrypt the Data nnnnnnnn bytes mod 16 first.
  2. Take one byte from the end of the data encrypted in 1. and add to the
    front of the 15 byte remainder.
  3. Encrypt that 16 byte packet.
  4. Write it to the file overlaying the one byte you took out.
  5. Do the decryption in reverse order doing the last 16 bytes first and
    then the mod 16 pieces of the file.

In my opinion,you means that the last block which is not aligned should be
encryptd with aligned by the block before last block,when encrype is over ,
the cipher of the last block overlaying the cipher of the block before last

block whitch is use to make the last block aligned,

e.g.
algorithm: alignd to 8,
buffer: 1234567890123
first block: 12345678
second block: 90123

when encrypt:
first block is aligned to 8,so no more process require just encrypt.
but the second(last) block is not aligned to 8,so use first
block(the block before last block)add to last block aligned to 8,
when encrypt second(last) block the block is became 67890123, so encrypt
it.

join the two blocks cipher:

block 1 block 2

buffer: 12345678 67890123
cipher: XNBJE*** ***NJUEA

join the cipher,
cipher part 1: XNBJE***
cipher part 2: ***NJUEA

result: XNBJE***NJUEA

my algorithm is block related,that means the cipher of buffer 678 in first
block is
not the same in second (last) block ,what can i do???

and if the algorithm is not 1:1,e.g 1:1.1 or even 1:2 ,how to deal with the
file size???

thank you,

ildee

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to $subst(‘List.Name’) as:
$subst(‘Recip.EmailAddr’)
To unsubscribe send a blank email to $subst(‘Email.UnSub’)

–http://www.eyou.com
–Îȶ¨¿É¿¿µÄµç×ÓÐÅÏä ÓïÒôÓʼþ Òƶ¯ÊéÇ© ÈÕÀú·þÎñ ÍøÂç´æ´¢…ÒÚÓÊδ¾¡

–http://vip.eyou.com
–¿ì¿ìµÇ¼ÒÚÓÊVIPÐÅÏä ×¢²áÄúÖÐÒâµÄÓû§Ãû