SHA-1 and MD5

[aheyn]

Hi All,

A while ago I installed HashTab (HashTab... is the coolest thing ever! - adds a tab "File Hashes" that then works out the CRC, MD5 and SHA-1 of the file), and have used it alot to compare files to make sure they are identical etc.

My question is - as I understand it, CRC -> MD5 -> SHA are more and more comprehensive in terms of hashing, and length etc (remember reading ages ago someone spoofed an MD5 hash or something). So the question is, if the SHA-1s matched on two files, then is it DEFINITE that the MD5s will also match up? I.e. I can just use the SHA-1 and not also need to check the MD5 or CRC.

Thanks!


Cheers
Andrew

 

[K3VL4R]

Yes. They are the same file. You cannot change 1 bit of data on it without the hash changing as well. If you are ever in doubt, you could just check two or three of the hash formats for reassurance.

 

[antt]

Both SHA-1 and MD5 can suffer from collisions, but in very rare cases. Check both the SHA-1 and the MD5 together, and you will know the file has not been tampered with.