How to Use MD5

On 2010年09月14日, in linux, by netoearth

Posted by Nikesh Jauhari

Using an MD5 checksum you can do exactly that- verify the integrity of data. This can be used in a number of different situations and in any number of different ways, but it is a simple and effective way to verify large amounts of data.

Message-Digest algorithm 5 is a cryptographic hash function with a 128-bit value which can be found all over, especially on the internet. A checksum is a kind of redundancy check which can verify the integrity of data in a number of ways. The most basic form of checksum will verify the size of a set amount of data, assuming that if the data has the correct number of bytes it was transferred without a problem. Using MD5, a unique string of letters and numbers can be put together so signify the data which is in question. Here is a sample string:


The goal of this would be to identify data which needs to be backed up, and then create a MD5 checksum. With this done the data can be copied into place and the MD5 checksum can be reviewed so as to verify the data was copied without incident.

How to use MD5 in Linux?

With any Linux distribution checking an MD5 checksum is easy and quick. No installations or add-ons should be necessary.

Generate a MD5 checksum:
1) Enter the console
2) Type: ” md5sum xxxxxx.iso >″
(note: any file extension can be used)

Verify a MD5 checksum:
1) Enter the console
2) Type: “md5sum -c xxxxxx.iso.md5″
(this is supposing the MD5 and the file being verified are in the same directory)

That is really all there is to it! In just a few minutes you can be an MD5 expert and will have taken control of this powerful tool. MD5 checksums are very useful for the verification of data and for passwords, but it should be noted that tools are available that can decompile MD5 sums so that they are not always a perfectly secure way to store a password. Even so, they are a very useful tool for data redundancy, protection, and recovery.

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