Does NTFS store the hash or CRC32 of every inode/file, how to acesss it?
I know how to read a file, pass these bytes to a hashing algorithm such as MD5SUM, SHA256 or CRC32, and get the hash.
Here I'm asking something slightly different:
Each time we write/modify a file on a NTFS partition, does it re-compute a hash or CRC32 and store this information in the NTFS metadata / FAT / MFT (Master File Table) (I don't remember the exact name)?
Note: the important thing is that I just want to read the stored hash/CRC stored in the filesystem (i.e. read a few bytes, should be a few milliseconds maximum), and not recompute the hash (that would take many seconds for a 10 GB file).
If so, how to access this CRC or hash for a specific file, using Python? Is there something like:
import ntfsutil
ntfsutil.getCRC('d:/big50GBfile.dat') # done in < 10 ms
python windows filesystems ntfs ntfs-mft
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
|
show 4 more comments
I know how to read a file, pass these bytes to a hashing algorithm such as MD5SUM, SHA256 or CRC32, and get the hash.
Here I'm asking something slightly different:
Each time we write/modify a file on a NTFS partition, does it re-compute a hash or CRC32 and store this information in the NTFS metadata / FAT / MFT (Master File Table) (I don't remember the exact name)?
Note: the important thing is that I just want to read the stored hash/CRC stored in the filesystem (i.e. read a few bytes, should be a few milliseconds maximum), and not recompute the hash (that would take many seconds for a 10 GB file).
If so, how to access this CRC or hash for a specific file, using Python? Is there something like:
import ntfsutil
ntfsutil.getCRC('d:/big50GBfile.dat') # done in < 10 ms
python windows filesystems ntfs ntfs-mft
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
1
No.
– user2357112
Nov 24 '18 at 11:06
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:notepad c:test.txt:secretwill create a stream namedsecret! Funny that this is so rarely used...
– Basj
Nov 25 '18 at 11:12
|
show 4 more comments
I know how to read a file, pass these bytes to a hashing algorithm such as MD5SUM, SHA256 or CRC32, and get the hash.
Here I'm asking something slightly different:
Each time we write/modify a file on a NTFS partition, does it re-compute a hash or CRC32 and store this information in the NTFS metadata / FAT / MFT (Master File Table) (I don't remember the exact name)?
Note: the important thing is that I just want to read the stored hash/CRC stored in the filesystem (i.e. read a few bytes, should be a few milliseconds maximum), and not recompute the hash (that would take many seconds for a 10 GB file).
If so, how to access this CRC or hash for a specific file, using Python? Is there something like:
import ntfsutil
ntfsutil.getCRC('d:/big50GBfile.dat') # done in < 10 ms
python windows filesystems ntfs ntfs-mft
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
I know how to read a file, pass these bytes to a hashing algorithm such as MD5SUM, SHA256 or CRC32, and get the hash.
Here I'm asking something slightly different:
Each time we write/modify a file on a NTFS partition, does it re-compute a hash or CRC32 and store this information in the NTFS metadata / FAT / MFT (Master File Table) (I don't remember the exact name)?
Note: the important thing is that I just want to read the stored hash/CRC stored in the filesystem (i.e. read a few bytes, should be a few milliseconds maximum), and not recompute the hash (that would take many seconds for a 10 GB file).
If so, how to access this CRC or hash for a specific file, using Python? Is there something like:
import ntfsutil
ntfsutil.getCRC('d:/big50GBfile.dat') # done in < 10 ms
python windows filesystems ntfs ntfs-mft
python windows filesystems ntfs ntfs-mft
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
asked Nov 24 '18 at 10:06
BasjBasj
6,17632106233
6,17632106233
1
No.
– user2357112
Nov 24 '18 at 11:06
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:notepad c:test.txt:secretwill create a stream namedsecret! Funny that this is so rarely used...
– Basj
Nov 25 '18 at 11:12
|
show 4 more comments
1
No.
– user2357112
Nov 24 '18 at 11:06
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:notepad c:test.txt:secretwill create a stream namedsecret! Funny that this is so rarely used...
– Basj
Nov 25 '18 at 11:12
1
1
No.
– user2357112
Nov 24 '18 at 11:06
No.
– user2357112
Nov 24 '18 at 11:06
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:
notepad c:test.txt:secret will create a stream named secret! Funny that this is so rarely used...– Basj
Nov 25 '18 at 11:12
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:
notepad c:test.txt:secret will create a stream named secret! Funny that this is so rarely used...– Basj
Nov 25 '18 at 11:12
|
show 4 more comments
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1
No.
– user2357112
Nov 24 '18 at 11:06
@user2357112 So the only way is to re-compute the hash/checksum each time I need it? NTFS cannot be configured to store checksums? PS: prime number sequence in your pseudo (nearly), is it on purpose? :)
– Basj
Nov 24 '18 at 11:41
NTFS doesn't do file checksums. (Also, the 2 3 5 7 11 thing was pure luck, but it's part of the reason I never changed my default username.)
– user2357112
Nov 24 '18 at 18:36
You could cache the checksum and corresponding last-write timestamp in an alternate data stream, e.g. "big50GBfile.dat:md5". This "md5" stream will be lost if the file is copied to a file system that doesn't support named streams (e.g. FAT32).
– eryksun
Nov 25 '18 at 1:51
@eryksun Wow, this is the first time I hear about streams, very cool! howtogeek.com/howto/windows-vista/…. For future ref:
notepad c:test.txt:secretwill create a stream namedsecret! Funny that this is so rarely used...– Basj
Nov 25 '18 at 11:12