May 27, 2011

MD5, SHA1 checksum with Example to check the hash value for Integrity

What is hashing, everyone talks about hashing, data integrity etc.

let me explain with an example.

Download some file source or executable with md5 and sha1, for example purpose we used OpenSSL
Downloaded openssl-1.0.0d.tar.gz, MD5 and SHA1

Now we will compute md5 and sha1 from our side and verify, whether downloaded file is not modified by any other user.

Download FCIV(File Checksum Integrity Verifier) in windows. In Linux, use md5sum, sha1sum to check the integrity of the file.

I have tried the following commands in Windows

// Computing md5 of the file
E:\> fciv.exe -add openssl-1.0.0d.tar.gz
40b6ea380cc8a5bf9734c2f8bf7e701e openssl-1.0.0d.tar.gz

// Comparing with the downloaded md5 file
E:\> type openssl-1.0.0d.tar.gz.md5

// Computing sha1 of the file
E:\> fciv.exe -add openssl-1.0.0d.tar.gz -sha1
32ca934f380a547061ddab7221b1a34e4e07e8d5 openssl-1.0.0d.tar.gz

// Comparing with the downloaded sha1 file
E:\> type openssl-1.0.0d.tar.gz.sha1

Now, we can say that, file integrity was maintained.

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May 18, 2011

Boot Windows XP, Vista, 7 from USB Pen Drive

Hi everyone,
I was thinking that, How can I get rid of carrying DVD to install OS on friend's laptop. When I googled, I got some useful info and want to share with you ppl.

Please use the following commands to make USB Bootable with Windows OS

STEP 1: Make USB Ready to made bootable

1) Run Diskpart, In Windows Vista and 7 it has come default, I think in Windows XP you need to install Diskpart.
2) New Window with Diskpart as prompt will be opened.
3) See the connected disks by running
    DISKPART> list disk
4) Select the USB disk with its name of the list disk command output. The output usually comes as disk 0, disk 1 etc.
   DISKPART> select disk 1
5) Clean the disk by typing the command
   DISKPART> clean
6) Make the disk partition as primary
   DISKPART> create partition primary
7) Select the partition
   DISKPART> select partition 1
8) Activate the partition
   DISKPART> active
9) Format the partition with NTFS filesystem
   DISKPART> format fs=NTFS
10) Type following command to exit
   DISKPART> assign
   DISKPART> exit

Now the disk is formatted and ready to made bootable

STEP 2: Make USB Bootable

Make USB drive as bootable by executing following commads
1) Insert or mount the Windows OS disk
     Ex: DVD Drive path say G:
2) Use the bootsect.exe to make the USB bootable.
  a) Open CommandPrompt
  b) Change the directory to G:
      cmd> G:
  c) Change to boot directory
      G:> cd boot
  d) Run the following command to make USB Bootable, assume USB drive is H:
      G:/boot> bootsect /nt60 h:
3) Close the command prompt
     G:/boot> exit

STEP 3: Copy OS to USB

Say Example Windows OS DVD drive is G: and USB Drive is H:
Run the following commands to copy the contents from DVD to USB
i) cmd> G:
ii) G:> copy *.* h: /Y /V (or) xcopy /s *.* h:/

STEP 4: Install Windows OS from USB Drive

Please restart and boot from the USB drive to install Windows OS


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