Algorand: Scaling Byzantine Agreements for Cryptocurrencies
Speaker
Yossi Gilad
MIT CSAIL, Boston University
Host
CSAIL Security Seminar
Algorand: Scaling Byzantine Agreements for Cryptocurrencies
Abstract
Algorand is a new cryptocurrency that confirms transactions
with latency on the order of a minute while scaling to many
users. Algorand ensures that users never have divergent
views of confirmed transactions, even if some of the users
are malicious and the network is temporarily partitioned.
In contrast, existing cryptocurrencies allow for temporary
forks and therefore require a long time, on the order of an
hour, to confirm transactions with high confidence.
Algorand uses a new Byzantine Agreement (BA) protocol
to reach consensus among users on the next set of transactions.
To scale the consensus to many users, Algorand
uses a novel mechanism based on Verifiable Random Functions
that allows users to privately check whether they are
selected to participate in the BA to agree on the next set
of transactions, and to include a proof of their selection in
their network messages. In Algorand’s BA protocol, users
do not keep any private state except for their private keys,
which allows Algorand to replace participants immediately
after they send a message. This mitigates targeted attacks
on chosen participants after their identity is revealed.
We implement Algorand and evaluate its performance on
1,000 EC2 virtual machines, simulating up to 500,000 users.
Experimental results show that Algorand confirms transactions
in under a minute, achieves 125× Bitcoin’s throughput,
and incurs almost no penalty for scaling to more users.
Bio
Yossi Gilad is a postdoctoral researcher at MIT and Boston University. His research interests include designing, building, and analyzing secure and scalable networked systems.
Prior to this position he was a postdoctoral researcher at the Hebrew University of Jerusalem, and a research staff member at IBM Research. He is a recipient of the IETF/IRTF Applied Networking Research Prize (2017), the IBM Research Inventor Recognition Award (2015), and the Check Point Institute Information Security Prize (2013-2014).
Abstract
Algorand is a new cryptocurrency that confirms transactions
with latency on the order of a minute while scaling to many
users. Algorand ensures that users never have divergent
views of confirmed transactions, even if some of the users
are malicious and the network is temporarily partitioned.
In contrast, existing cryptocurrencies allow for temporary
forks and therefore require a long time, on the order of an
hour, to confirm transactions with high confidence.
Algorand uses a new Byzantine Agreement (BA) protocol
to reach consensus among users on the next set of transactions.
To scale the consensus to many users, Algorand
uses a novel mechanism based on Verifiable Random Functions
that allows users to privately check whether they are
selected to participate in the BA to agree on the next set
of transactions, and to include a proof of their selection in
their network messages. In Algorand’s BA protocol, users
do not keep any private state except for their private keys,
which allows Algorand to replace participants immediately
after they send a message. This mitigates targeted attacks
on chosen participants after their identity is revealed.
We implement Algorand and evaluate its performance on
1,000 EC2 virtual machines, simulating up to 500,000 users.
Experimental results show that Algorand confirms transactions
in under a minute, achieves 125× Bitcoin’s throughput,
and incurs almost no penalty for scaling to more users.
Bio
Yossi Gilad is a postdoctoral researcher at MIT and Boston University. His research interests include designing, building, and analyzing secure and scalable networked systems.
Prior to this position he was a postdoctoral researcher at the Hebrew University of Jerusalem, and a research staff member at IBM Research. He is a recipient of the IETF/IRTF Applied Networking Research Prize (2017), the IBM Research Inventor Recognition Award (2015), and the Check Point Institute Information Security Prize (2013-2014).