Encryption help - Command line

[William Saywell]

Hi,

I need to add all the files in a folder to a self-extracting exe archive using AES256 encryption, and also set a password.

I tried

"c:\program files\7-zip\7z.exe" a -sfx7z.sfx -tzip encrypted.exe * -ppassword -mem=AES256

Which creates a nice self-extracting exe but I can open it with 7-zipithout needing a password.

I've obviously got something wrong in the -m command, but the help file isn't very helpful as to how exactly it should be done.

Suggestions welcomed!

Thanks,

William

[fernando]

I do not know what you make of file encrypted.exe
Switch -tzip is not compatable with switch -sfx
7z format and switch -p will encrypt with AES256

Do like:
"c:\program files\7-zip\7z.exe" a -ppassword -sfx7z.sfx encrypted.exe *

Or for encrypt filnames also, do like:
"c:\program files\7-zip\7z.exe" a -mhe=on -ppassword -sfx7z.sfx encrypted.exe *

See:

$ 7z a -mhe=on -ppassword -sfx7z.sfx encrypted.exe *

7-Zip 4.61 beta  Copyright (c) 1999-2008 Igor Pavlov  2008-11-23
Scanning

Creating archive encrypted.exe

Compressing  example1.dat

Everything is Ok

$ 7z l -slt encrypted.exe

7-Zip 4.61 beta  Copyright (c) 1999-2008 Igor Pavlov  2008-11-23

Enter password:password

Listing archive: encrypted.exe

Method = LZMA 7zAES
Solid = -
Blocks = 1
Physical Size = 1588089
Headers Size = 201
Offset = 139776
----------

Path = example1.dat
Size = 1605444
Packed Size = 1587888
Modified = 2008-11-29 10:37:45
Attributes = ....A
CRC = D806AB22
Encrypted = +
Method = LZMA:21 7zAES:19
Block = 0

$

[William Saywell]

Thanks.

Are you sure that "7z format and switch -p will encrypt with AES256" is correct, and it's not just setting a password for extraction rather than actually encrypting the files? 

The 7-zip help makes no mention of this - the only mention of AES256 seems to be in the -m section, with em=AES256 (though it doesn't describe the correct syntax for using -m and em=AES256).

It's important, as the files to be created MUST be encrypted by AES256.

Regards,

William

[William Saywell]

OK, I've found confirmation via Google!
If only the documentation was as good as the application!

Next question:

Is it possible to suppress the dialogue box asking which directory to extract into?
I need it to extract to the directory it's in - ie the default setting.
Thanks again,

William

[fernando]

Do like:
"c:\program files\7-zip\7z.exe" a -ppassword -sfx encrypted.exe *

Or for encrypt filnames also, do like:
"c:\program files\7-zip\7z.exe" a -mhe=on -ppassword -sfx encrypted.exe *

[William Saywell]

Thanks - that works well.

William