Below, we answer some frequently raised questions.
We update frequently.
Is there a public Algorand token sale?
Any public token sale will be announced on our website. At the moment, we are not running any public token sale.
How does Algorand choose a block proposer for each round?
In Algorand, every user selects herself as a block proposer using Algorand’s hallmark cryptographic sortition mechanism1 that depends on the amount of stake the user holds in the system. Cryptographic sortition is based on a Verifiable Random Function (VRF) for which each user holds a personal secret key2. At the beginning of each round, each user samples a VRF, using her secret key, computed on a seed from previous rounds. She checks if the output string of the VRF is within a specific range to decide if she’s chosen as the block proposer for the round. For users with more stake in the system, the range is higher than for users with less stake. As a result, users with more stake are selected more frequently to become block proposers. If the user’s output falls within her range, she has a “winning ticket’’, proving to everyone that she can propose a block in the current round. The block proposed by the user and the winning ticket are propagated through the network.
1Cryptographic sortition in blockchains was pioneered by Algorand, since the first version of its white paper (citation: https://arxiv.org/pdf/1607.01341v1.pdf –page 12 “Main Desiderata in Verifier Selection”).
2VRFs were co-invented by Algorand founder: Verifiable Random Functions. S. Micali, M. Rabin and S. Vadhan. 40th Foundations of Computer Science (FOCS), New York, Oct 1999. Available at https://people.csail.mit.edu/silvio/Selected%20Scientific%20Papers/Pseudo%20Randomness/Verifiable_Random_Functions.pdf
How are the certifying committees of the proposed block chosen for each round?
Algorand uses cryptographic sortition to select a committee to certify each proposed block. This mechanism is similar to the selection of block proposers, except that a different seed is used as the input to the VRF by the users. Users that are self-selected to serve on the committee propagate their messages (votes) through the network, together with a universally verifiable proof that they have been so selected.
What happens when an Algorand block proposer is not online at a round when she is supposed to propose a block?
Recall that Algorand uses cryptographic sortition to select a block proposer for each round. In fact, multiple candidate block proposers are self-selected for each round. That is, the protocol parameters are set such that a small number (e.g., 30) of users will have the output of their VRF functions fall in a range to be block proposers. Each candidate block proposer propagates her candidate block and the “winning ticket’’ for the round. The candidate whose hashed “winning ticket’’ is lowest is then chosen as the ultimate block proposer for the round, and the certifying committees members run an agreement on her proposed block. Thus, if some candidate block proposers are not online, the block proposer will be the one whose hashed winning ticket is smallest among all candidates block proposers who are online.
What are the hashes in the Algorand roadmap?
Algorand is deeply committed to continuous innovation. The hashes are commitments to selected new innovations the Algorand team will unveil and deploy in the future. Hashes are computed as follows: SHA256(SHA256(msg) || SHA256(nonce)).