edited tags

Link

edited Jun 24, 2013 at 22:38

hash md5 length-extension

Tweeted twitter.com/#!/StackCrypto/status/250203630697852928

occurred Sep 24, 2012 at 12:02

edited body

Source Link

edited Sep 19, 2012 at 8:38

If I know

H = md5( SECRET_KEY | DATA )

then I can calculate

H' = md5( SECRET_KEY | DATA | DATA' )

That's length-extension attack. But is the opposite possible, e? E.g. if I know

H = md5( SECRET_KEY | DATA )

can I find

H'' = md5( SECRET_KEY )

where DATA is known and lenght of DATA is known too???

Basically, can I find md5 of the KEY without DATA (once again, DATA is known, H is known, but SECRET_KEY is unknown)?

If I know

H = md5( SECRET_KEY | DATA )

then I can calculate

H' = md5( SECRET_KEY | DATA | DATA' )

That's length-extension attack. But is the opposite possible, e.g. if I know

H = md5( SECRET_KEY | DATA )

can I find

H'' = md5( SECRET_KEY )

where DATA is known and lenght of DATA is known too???

Basically, can I find md5 of the KEY without DATA (once again, DATA is known, H is known, but SECRET_KEY is unknown)?

If I know

H = md5( SECRET_KEY | DATA )

then I can calculate

H' = md5( SECRET_KEY | DATA | DATA' )

That's length-extension attack. But is the opposite possible? E.g. if I know

H = md5( SECRET_KEY | DATA )

can I find

H'' = md5( SECRET_KEY )

where DATA is known and lenght of DATA is known too???

Basically, can I find md5 of the KEY without DATA (once again, DATA is known, H is known, but SECRET_KEY is unknown)?

Source Link

asked Sep 19, 2012 at 8:27

md5: is reverse length-extension attack possible?

If I know

H = md5( SECRET_KEY | DATA )

then I can calculate

H' = md5( SECRET_KEY | DATA | DATA' )

That's length-extension attack. But is the opposite possible, e.g. if I know

H = md5( SECRET_KEY | DATA )

can I find

H'' = md5( SECRET_KEY )

where DATA is known and lenght of DATA is known too???

Basically, can I find md5 of the KEY without DATA (once again, DATA is known, H is known, but SECRET_KEY is unknown)?

md5

Return to Question