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Transaction malleability in cryptocurrencies

14 September 2016 Dmitry Meshkov 5 mins read

Transaction malleability in cryptocurrencies - Input Output HongKong

Transaction malleability in cryptocurrencies

In this article I'm going to provide a brief review of protection methods against replay attacks, arising from signature malleability of elliptic curve cryptography.


Most cryptocurrencies are based on public-key cryptography. Each owner transfers coins to the next one digitally signing the transaction Tx containing the public key of the next owner.

Thus everyone can verify that the sender wants to send her coins to the recipient, but a problem arises - how to prevent the inclusion of transactin Tx in the blockchain twice? Without such a protection an unscrupulous recipient may repeat Tx as long as the sender has enough coins at his balance, making it impossible to reuse the same address for more then 1 transaction. In particular the adversary can withdraw some coins from an exchange and repeat this transaction until there are no coins left on exchange (such attacks have already been…