Computers & Electronics

Crack password to Open Office 2.0 .ods file?

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  • Aug 18th, 2009 8:51 pm
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[OP]
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Jan 27, 2008
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Guelph

Crack password to Open Office 2.0 .ods file?

I tried Open Office Calc Password recovery. It said: "recovered!" after 2 hours and gave me a bogus password like ***h***n***

Windows or Linux, doesn't matter. Just really need to remember/brute force this document.
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[OP]
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Guelph
nobody eh?
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Deal Addict
Jul 28, 2005
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Openoffice uses strong encryption. Brute force will be useless unless you are positive that it is an extremely easy password.
[OP]
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Guelph
I am positive that it is just letters a-z

I also have access to very fast computers.
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attonbitusira wrote:
Aug 17th, 2009 2:36 pm
I also have access to very fast computers.
All the computers on the planet couldn't crack a random 128-bit encryption key this century unless they got very lucky.

Open Office appears to use 128-bit Blowfish encryption so you're going to have to hope that whoever encrypted it used a short password with only lower-case a-z if you want any chance of breaking it.
[OP]
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Guelph
Where did you find documentation on the encryption used?
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Member
Jun 3, 2009
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Ottawa
I've been reading that 128-bit is getting easier to crack and 256-bit is becoming necessary. Supposedly PS3's can rip through password cracking esp. if you have 5-10 PS3's.
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saltyvinegar wrote:
Aug 17th, 2009 7:02 pm
I've been reading that 128-bit is getting easier to crack and 256-bit is becoming necessary. Supposedly PS3's can rip through password cracking esp. if you have 5-10 PS3's.
Actually, the latest research from earlier this month shows there may be a problem with 256-bit AES that doesn't exist in 128 or 196 bit keys. It's only a theoretical attack with little or no practical applications. But for better security the latest recommendation is to move to 128 or 196 bit keys.

http://www.theregister.co.uk/2009/08/03 ... to_attack/




Second of all, if you are trying to brute force 128-bit keys, a couple of PS3 is nothing. The only known attack of 128-bit AES is brute force. And from http://www.nist.gov/public_affairs/releases/aesq&a.htm
16. What is the chance that someone could use the "DES Cracker"-like hardware to crack an AES key?

In the late 1990s, specialized "DES Cracker" machines were built that could recover a DES key after a few hours. In other words, by trying possible key values, the hardware could determine which key was used to encrypt a message.

Assuming that one could build a machine that could recover a DES key in a second (i.e., try 2^55 keys per second), then it would take that machine approximately 149 thousand-billion (149 trillion) years to crack a 128-bit AES key. To put that into perspective, the universe is believed to be less than 20 billion years old.
Even if you took all of the computers in the world and tried to brute force AES, it would likely still take many thousands of years.
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saltyvinegar wrote:
Aug 17th, 2009 7:02 pm
I've been reading that 128-bit is getting easier to crack and 256-bit is becoming necessary.
The main reason for switching to 256-bit keys is quantum computing: cracking a 256-bit key on a quantum computer would take a similar amount of time to cracking a 128-bit key on a conventional computer.

As for PS3s, a 128-bit key has around 200 billion billion billion billion possible combinations: even if a PS3 could test a billion billion keys per second (while I don't know much about the hardware it's safe to say that's way more than it could possibly do based simply on the clock speed and transistor count), you'd be looking at millions of years to try all those combinations.
[OP]
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Guelph
I was banking on using rainbow tables but there's no way.
Even Open Office 2.0 documents salt the key.

Forget it. I give up!

Thanks for the help everyone.
"blackbox 2.2 aluminus"[INDENT]
Core i5 2500K / Asus P8P67 / 16 GB DDR3
GTX 580 / Samsung 27"
Intel 320 120GB / Win7Pro64
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