SHA-1 checksums provide an assurance that a document downloaded from this site or others is in fact the original, unmodified document.

All that is necessary is to compare the 40-character checksum given on these download pages from that generated by a SHA-1 checksum program. If they match, the file is original and untampered with. If they don't match, the file may have been modified somewhere.

For Linux and Unix systems, the command sha1sum is provided for this purpose. Simply type

sha1sum -b <filename>

at a command prompt and compare the result to the published value.

For Windows systems, you'll need to get a program to make the check. A recommended program is sha1sum.exe, which can be downloaded from our site sha1sum.exe, or for better security (by using multiple source), from the gnupg site ( ftp://ftp.gnupg.org/gcrypt/binary/sha1sum.exe). To use the Windows version of sha1sum.exe, open a command prompt, and type

sha1sum <filename>

at a command prompt and compare the result to the published value.