LibraryConsensus2017Design paperCorpus record
ALGORAND: The Efficient and Democratic Ledger
Algorand. Silvio Micali.
Micali's ledger design: a proof-of-stake protocol that elects a small, unpredictable committee to certify each block, and replaces participants so a corruptor cannot find them in time.
Algorand picks a small, unpredictable committee for each step, lets that committee vote, and replaces it before an adversary can learn who to corrupt.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 4
- Records linked
- 5
Code
Source, repository, and what is actually hosted
- arXiv:1607.01341https://arxiv.org/pdf/1607.01341
- The source URL is not a GitHub repository. No code remote is invented.
- Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
- Add to a reading list
01 Claim ledger
What the paper is allowed to say
Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.
Claim 01 · Paper model
Committees, not the whole network
Asking every holder to vote on every block is a broadcast storm. Algorand samples a committee whose votes stand for the stake, and it does this again for the next step.
Claim 02 · Paper model
The committee is secret until it speaks
A verifier locally computes a cryptographic sortition result. Nobody else knows they were chosen until the message, with its proof, is already on the wire.
Claim 03 · Paper model
Player replaceability
Once a step's message is out, that voter's power for the step is spent. Corrupting them afterwards does not let the adversary rewrite the step. The next committee is a new draw.
Claim 04 · Paper model
The adversary is assumed adaptive but not instant
The proof allows the adversary to corrupt players after seeing messages, as long as corruption is not faster than the step. That bound is the security claim. It is not a slogan about democracy.
Claim 05 · Paper model
Forks are not the steady state
The protocol is built to agree on one block with overwhelming probability, rather than to let forks race. Finality in the paper is a probability statement about the committee, not a social convention about six blocks.
02 Three cuts
Observation, model, falsifier
A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.
01 Committees, not the whole network
Observation
What the study says
Asking every holder to vote on every block is a broadcast storm. Algorand samples a committee whose votes stand for the stake, and it does this again for the next step.
Model
What has to hold
Enough stake is online and participating. Offline stake does not vote, and the paper's liveness depends on participation.
Falsifier
What would retire it
Is the committee known before it votes?
02 The committee is secret until it speaks
Observation
What the study says
A verifier locally computes a cryptographic sortition result. Nobody else knows they were chosen until the message, with its proof, is already on the wire.
Model
What has to hold
The adversary cannot corrupt a newly revealed voter before the step completes.
Falsifier
What would retire it
Is the committee known before it votes?
03 Player replaceability
Observation
What the study says
Once a step's message is out, that voter's power for the step is spent. Corrupting them afterwards does not let the adversary rewrite the step. The next committee is a new draw.
Model
What has to hold
The adversary cannot corrupt a newly revealed voter before the step completes.
Falsifier
What would retire it
Is the committee known before it votes?
04 The adversary is assumed adaptive but not instant
Observation
What the study says
The proof allows the adversary to corrupt players after seeing messages, as long as corruption is not faster than the step. That bound is the security claim. It is not a slogan about democracy.
Model
What has to hold
The adversary cannot corrupt a newly revealed voter before the step completes.
Falsifier
What would retire it
Are votes weighted by stake or by account?
05 Forks are not the steady state
Observation
What the study says
The protocol is built to agree on one block with overwhelming probability, rather than to let forks race. Finality in the paper is a probability statement about the committee, not a social convention about six blocks.
Model
What has to hold
Honest stake exceeds the paper's threshold, often two thirds in the Byzantine setting it argues.
Falsifier
What would retire it
Is the committee known before it votes?
03 Sequence
One action, as an operating tape
- 01Each online account holds a participation key and a stake weight.
- 02For a given round and step, the account runs cryptographic sortition against a shared seed and learns whether it has a vote, and of what weight.
- 03If selected, it gossips a signed vote with the sortition proof. Others can verify the proof without a private channel.
- 04A committee of proposers offers candidate blocks. A committee of voters reduces them until one block has a quorum.
- 05The seed for the next round is updated from the round's output so the next committee cannot be predicted far in advance.
04 Load-bearing
The argument, and where a pitch drops it
Secrecy has to last only one step
The cut
The design does not need anonymous accounts. It needs the adversary to learn a voter only when that voter's message is already useful to everyone. That is a narrower, more achievable secrecy. Systems that publish the committee in advance have dropped it.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
Committee designs still need an account of who can censor inclusion. Certification is not the same as open membership of every transaction.
Stake-weighted sampling can still be captured
The cut
A committee represents stake only if the draw is uniform and the seed is unbiased. A large holder who can predict or grind the seed can aim corruption at the people who will matter. Sortition is not a decoration on top of a weak beacon.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
Sortition only helps if the underlying stake and keys are what the paper assumes.
Democracy in the title is a stake democracy
The cut
Votes are weighted by stake, not by person. The paper is explicit about this. A marketing line about 'one user, one vote' is a different protocol.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
Sortition only helps if the underlying stake and keys are what the paper assumes.
05 Register
What has to be true
Stake and threshold · Not re-measured
Honest stake exceeds the paper's threshold, often two thirds in the Byzantine setting it argues.
Adversary · Not re-measured
The adversary cannot corrupt a newly revealed voter before the step completes.
Stake and threshold · Not re-measured
Enough stake is online and participating. Offline stake does not vote, and the paper's liveness depends on participation.
Cryptography · Not re-measured
The random seed is unpredictable and unbiasable within the round structure.
06 Divergence
What happened after the paper
The Algorand network implemented the idea with participation keys, a relay topology, and later performance work. Those operational choices are not theorems in the 2017 paper. Committee size and timing parameters are where the proof meets the network.
A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.
07 Pre-mortem
What to check before you use the idea
- 0 of 4 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.
08 Anatomy
The paper, in the order a builder needs
The problem it names
Classical Byzantine agreement is expensive if every holder talks to every other holder. Bitcoin-style longest chain is permissionless but slow to become confident. Algorand wants a committee that is large enough to represent stake and small enough to finish quickly, without publishing the committee in advance.
What the design proposes
- Cryptographic sortition lets a holder learn privately, from their own key and a public seed, whether they were selected.
- A verifier can check the selection proof after the message appears. Before that, the holder is not a target.
- Player replaceability means the next step draws a new committee. Bribing the last one does not carry forward.
How the mechanism is specified
- The ledger is a sequence of certified blocks, not a race of forks that the heaviest chain wins later.
- Safety is argued from the stake-weighted honesty of the selected sets.
- The 2017 systems paper by Gilad, Hemo, Micali, Vlachos and Zeldovich is the implementation companion, not a different project.
What this page does not treat as proven
- Sortition only helps if the underlying stake and keys are what the paper assumes.
- The paper is not a description of later Algorand product features or relay networks.
- Committee designs still need an account of who can censor inclusion. Certification is not the same as open membership of every transaction.
Why the desk still reads it
The idea worth stealing, carefully, is replaceability: do not leave a standing set of signers who can be found and pressured. A venture that publishes its validator set on a webpage has not adopted this property.
09 Lexicon
Terms, opened into the record
- Cryptographic sortition
- A local lottery, proved to everyone else, that selects a voter with probability proportional to stake.
- Player replaceability
- The property that a voter matters only for the message they already sent. Later corruption cannot change that step.
- Committee
- The small stake-weighted sample whose votes decide a step, then is discarded.
- Adaptive adversary
- An attacker who can choose whom to corrupt as the protocol runs, not only at the start.
10 Repository
Every linked record on this page
Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.
Concepts
This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.
Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.