CONFidence 2015: How to Steal Bitcoins - Daniel Shearer, Nick Zeeb

1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2

Credit: fail0verflow 27C3 http://events.ccc.de/congress/2010/Fahrplan/attachments/1780_27c3_console_hacking_2010.pdf

Alice

Bob

2

1

Alice

Bob

2

1

Alice

Bob

2

1

Alice

Bob

2.1

1.0

Alice

Bob

2

1

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

Alice

Bob

2.1

1.0

Alice

Bob

2

1

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send25 coins to meMyself

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

I send1 coin to Alice Bob

I send1 coin to Bob Alice

I send1 coin to Alice Bob

1+ 8302

934902843093572

X

I send1 coin to Alice Bob

Cat

Alice

Bob

1

0

Cat 0

Alice

Bob

I send1 cointo BobAlice

I send1 cointo CatAlice

Alice

Bob

0

1

Cat 0

Alice

Bob

1

0

Cat 0

Alice

Bob

0

0

Cat 1

I send1 cointo BobAlice

Credit: fail0verflow 27C3 http://events.ccc.de/congress/2010/Fahrplan/attachments/1780_27c3_console_hacking_2010.pdf

Transaction Malleability

For every ECDSA signature (R,S),

the signature (R, -S mod N)

is a valid signature of the same message.

Alice

I send1 cointo BobAlice

I send1 cointo Bob-Alice

I send1 cointo BobAlice

We send1 cointo BobAlice, Cat

● Trick people into sending them to you● Malware● Cross Site Scripting● Bad Randomness● Watch TV● 51% Attack● Double Spending● Transaction Malleability

How to Steal Bitcoins…

More Links

Block Chain● https://blockchain.info/● https://blockchain.info/charts

ECDSA● http://rdist.root.org/2010/11/19/dsa-requirements-for-random-k-value/● http://www.nilsschneider.net/2013/01/28/recovering-bitcoin-private-keys.html

TOR Attack● http://arxiv.org/abs/1410.6079

TLS Certificate Revocation● https://github.com/ChristopherA/revocable-self-signed-tls-certificates-hack