On 2012-4-23 07:27 , Ryan Schmidt wrote: > > On Apr 22, 2012, at 16:21, Joshua Root wrote: > >> On 2012-4-23 06:51 , Ryan Schmidt wrote: >>> No, I'm trying to protect against the gzip compression of the tar archive >>> varying from generation to generation. gzip compression uses entropy -- >>> random numbers. If you have two identical tar archives, and gzip compress >>> them with the same settings, the resulting gzip files will not be byte for >>> byte identical, and thus they'll have different checksums: >>> >>> $ sha1sum *.tar >>> 92bfe8b02b49b977a18c9f8e8d301a0ef159fe51 1.tar >>> 92bfe8b02b49b977a18c9f8e8d301a0ef159fe51 2.tar >>> $ gzip 1.tar >>> $ gzip 2.tar >>> $ sha1sum *.tar.gz >>> 39c6beda6851d98295f770a11b8ea122647ae4c8 1.tar.gz >>> 7a95ea746e698d367ec155e4387972051e1a2e38 2.tar.gz >>> $ >> >> Nonsense. The gzip files in the above example differ because they >> contain files with different names. > > Oh. Well, here's a test with the same file names: > > $ sha1sum */file.tar > 92bfe8b02b49b977a18c9f8e8d301a0ef159fe51 1/file.tar > 92bfe8b02b49b977a18c9f8e8d301a0ef159fe51 2/file.tar > $ gzip 1/file.tar > $ gzip 2/file.tar > $ sha1sum */file.tar.gz > 238d08d9c64af0622abdd6a074b5c3c0b784a238 1/file.tar.gz > e398dbc43e65f5bb165876bcb1819b302fe251fd 2/file.tar.gz > $
WFM: % openssl sha1 1/file.tar 2/file.tar SHA1(1/file.tar)= 7937656d0860ca9286a24246a199cf2fddeb6e49 SHA1(2/file.tar)= 7937656d0860ca9286a24246a199cf2fddeb6e49 % gzip 1/file.tar % gzip 2/file.tar % openssl sha1 1/file.tar.gz 2/file.tar.gz SHA1(1/file.tar.gz)= 78020f5e126da22be27ac9eda2633db59b725480 SHA1(2/file.tar.gz)= 78020f5e126da22be27ac9eda2633db59b725480 Do your two input files also have identical timestamps? _______________________________________________ macports-dev mailing list macports-dev@lists.macosforge.org http://lists.macosforge.org/mailman/listinfo.cgi/macports-dev
