LibraryConsensus2020Design paperCorpus record
Streamlet: Textbook Streamlined Blockchains
Streamlet. Benjamin Y. Chan and Elaine Shi.
A deliberately small consensus protocol: epochs, a leader, a vote, and a rule that three adjacent certified blocks on the same chain become final. The point is to show how little machinery the last few years of BFT designs actually need.
Streamlet finalises a block when three certified blocks sit in a row on the longest certified chain. A leader proposes, a quorum certifies, and the protocol is short enough to re-derive. The replica set is known. One third faulty is still the bound.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 4
- Records linked
- 6
Code
Source, repository, and what is actually hosted
- ePrint 2020/088https://eprint.iacr.org/2020/088
- 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
Longest certified chain
The leader extends the longest chain of blocks that already have a quorum certificate. Uncertified tips do not count as the place to build.
Claim 02 · Paper model
One vote, not three phases
The paper's streamlining is to drop the classical pre-prepare, prepare, commit theatre down to a single vote that produces a certificate. The safety argument is then carried by the three-in-a-row rule.
Claim 03 · Paper model
Three in a row
Certificates in three consecutive epochs finalise the prefix. That rule is the entire finality gadget. If a design needs a paragraph of extra cases, it is no longer the textbook version.
Claim 04 · Paper model
Known replicas
Leaders are elected from a fixed set. Streamlet does not solve membership.
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 Longest certified chain
Observation
What the study says
The leader extends the longest chain of blocks that already have a quorum certificate. Uncertified tips do not count as the place to build.
Model
What has to hold
Quorum certificates are actually checked. A client that trusts a leader's word is not running Streamlet.
Falsifier
What would retire it
Is the voter set known in advance?
02 One vote, not three phases
Observation
What the study says
The paper's streamlining is to drop the classical pre-prepare, prepare, commit theatre down to a single vote that produces a certificate. The safety argument is then carried by the three-in-a-row rule.
Model
What has to hold
The set of replicas is known and signatures identify them.
03 Three in a row
Observation
What the study says
Certificates in three consecutive epochs finalise the prefix. That rule is the entire finality gadget. If a design needs a paragraph of extra cases, it is no longer the textbook version.
Model
What has to hold
Epochs progress. A stalled clock is outside the happy path.
04 Known replicas
Observation
What the study says
Leaders are elected from a fixed set. Streamlet does not solve membership.
Model
What has to hold
The set of replicas is known and signatures identify them.
Falsifier
What would retire it
Is the voter set known in advance?
03 Sequence
One action, as an operating tape
- 01An epoch begins and a leader is determined.
- 02The leader proposes a block on the longest certified chain.
- 03Replicas vote if the proposal is timely and well formed. A quorum certificate freezes that vote.
- 04Anyone who sees three consecutive certified blocks finalises the chain up to the first of them.
- 05A bad leader is skipped by the next epoch. Safety does not depend on this leader having been honest.
04 Load-bearing
The argument, and where a pitch drops it
A baseline, not a product
The cut
The authors wrote Streamlet so the reader can see what the previous five years of BFT had condensed to. Quoting it as a novel consensus for a public chain skips the permissioned assumption.
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
Citing Streamlet does not make an open membership chain into a permissioned quorum.
Partial synchrony is still there
The cut
Safety holds through asynchrony in the usual BFT way. Liveness needs a long enough synchronous period with honest leaders. A network that is never timely does not get the liveness theorem.
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
A later client, parameter or reward formula is a different object from this paragraph.
05 Register
What has to be true
Model · Not re-measured
Fewer than one third of replicas are faulty.
Cryptography · Not re-measured
The set of replicas is known and signatures identify them.
Model · Not re-measured
Epochs progress. A stalled clock is outside the happy path.
Stake and threshold · Not re-measured
Quorum certificates are actually checked. A client that trusts a leader's word is not running Streamlet.
06 Divergence
What happened after the paper
Streamlet is the short citation next to PBFT, Tendermint and HotStuff. Use it to test whether a new whitepaper has a new idea or a new vocabulary for certify-then-finalise.
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
PBFT is correct and hard to re-derive. Streamlet asks for a protocol a reader can hold in their head, with the same style of quorum and a partial-synchrony assumption, without the classical message types.
What the design proposes
- Each epoch has a leader who proposes one block extending the longest certified chain.
- A block is certified when a quorum of two thirds votes for it.
- Three certified blocks in a row, with consecutive epochs, finalise the middle one's parent chain.
How the mechanism is specified
- The quorum intersection argument is the familiar one: two quorums share an honest replica if fewer than one third are faulty.
- The paper assumes a known replica set. It does not elect that set.
- Liveness needs a period of synchrony and honest leaders. Safety does not wait for that period.
What this page does not treat as proven
- A textbook protocol is not a production client. Timeouts, networking and signature aggregation are left as engineering.
- Simplicity does not remove the one-third bound.
- Citing Streamlet does not make an open membership chain into a permissioned quorum.
Why the desk still reads it
Read it before reading a new BFT whitepaper. If the new paper cannot say what it changed relative to 'certify, then three in a row', it may be renaming Streamlet.
09 Lexicon
Terms, opened into the record
- Certified block
- A block that has gathered a quorum of votes for the proposal in its epoch.
- Three-chain rule
- The Streamlet finality rule: three adjacent certified blocks commit the prefix.
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.
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.