Blocks To Currencies

How to Design Cryptographic & Blockchain Systems

46 modules

186 lessons

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Part 1

Course Setup and the Incremental Ladder

Course Setup and the Incremental LadderSign in
Why "Blocks to Currencies"Sign in
How to Use This CourseSign in
The Incremental Ladder (Step 0 -> Step 7)Sign in
The Course LensesSign in
Diagram Legend and Notation TypesSign in

Part 2

Mental Models: Ledgers, States, and Blocks

Mental Models: Ledgers, States, and BlocksSign in
Ledger as State HistorySign in
Blocks as Batched TransitionsSign in
Global vs Local ViewsSign in

Part 3

Cryptographic Primitives Overview

Cryptographic Primitives OverviewSign in
Hash PropertiesSign in
Symmetric vs AsymmetricSign in
Signatures and AuthenticationSign in

Part 4

Distributed Systems Fundamentals

Distributed Systems FundamentalsSign in
Nodes, Messages, TimeoutsSign in
Asynchrony and Impossibility (High-Level)Sign in
Replicated State MachinesSign in

Part 5

Peer-to-Peer and Overlay Networks

Peer-to-Peer and Overlay NetworksSign in
Overlay TopologiesSign in
Gossip and BroadcastSign in
Discovery and ChurnSign in

Part 6

Diagramming Cryptographic & Blockchain Systems

Diagramming Cryptographic & Blockchain SystemsSign in
Protocol Message Sequence ChartsSign in
Ledger and Block Structure DiagramsSign in
Economic Flow DiagramsSign in

Part 7

Hashes, Commitments, and Integrity

Hashes, Commitments, and IntegritySign in
Hash Chains and Merkle TreesSign in
Commitments IntuitionSign in
Content Addressing and ProofsSign in

Part 8

Public-Key Cryptography and Signatures

Public-Key Cryptography and SignaturesSign in
Signing and VerificationSign in
Addresses as Derived IdentifiersSign in
Multi-Sig and Thresholds (High-Level)Sign in

Part 9

Key Management, Wallets, and Identity Models

Key Management, Wallets, and Identity ModelsSign in
Seeds and Hierarchical KeysSign in
Custody ModelsSign in
Identity and PseudonymitySign in

Part 10

Replication and Consistency

Replication and ConsistencySign in
Replication Styles and Failure BoundariesSign in
Strong vs Eventual Consistency Under DelaySign in
CAP as a Constraint Lens for LedgersSign in

Part 11

Fault Models and Adversaries

Fault Models and AdversariesSign in
Crash vs Byzantine FailuresSign in
Honest Majority AssumptionsSign in
Adversary CapabilitiesSign in

Part 12

Consensus as Log Agreement

Consensus as Log AgreementSign in
Classical Consensus IntuitionSign in
Logs, Epochs, LeadersSign in
Why Public Blockchains DifferSign in

Part 13

Overlay Networks and Node Discovery

Overlay Networks and Node DiscoverySign in
Peer Tables and DiscoverySign in
Bootstrapping and LivenessSign in
Churn and Peer ManagementSign in

Part 14

Gossip, Propagation, and Flooding Control

Gossip, Propagation, and Flooding ControlSign in
Gossip for Blocks and TransactionsSign in
Controlling DuplicationSign in
Modeling Propagation DelaySign in

Part 15

Network-Level Security and Abuse Resistance

Network-Level Security and Abuse ResistanceSign in
Sybil Attacks at the Network LayerSign in
Eclipse, Partition, CensorshipSign in
MitigationsSign in

Part 16

Transaction Models

Transaction ModelsSign in
UTXO Model: Inputs/Outputs and Parallel ValidationSign in
Account Model: Balances, Nonces, Ordering, and ReplaySign in
Trade-offs: Privacy, Complexity, and Future ScalabilitySign in

Part 17

Transaction Validation and Lifecycles

Transaction Validation and LifecyclesSign in
Validity Rules: Signatures, Balances, Replay Protection, and Local Acceptance vs Global FinalitySign in
Fees and Mempools: Gas/Fees, Prioritization, and What Mempool Policy Really ControlsSign in
Double-Spend Handling: Local Detection, Conflicts, and Why Forks Make Valid Time-DependentSign in

Part 18

Block Structure and Merkle Trees

Block Structure and Merkle TreesSign in
Block Headers and Metadata: Parent Links, Timestamps, Roots, and What They Commit ToSign in
Merkle Proofs and SPV: Inclusion Proofs and What Light Clients Can Safely ConcludeSign in
Multiple Roots and Extensions: Separating Transactions, Receipts, and State Commitments ConceptuallySign in

Part 19

Chains, Forks, and Reorganizations

Chains, Forks, and ReorganizationsSign in
Chain as a Tree: Competing Branches and Why "the Tip" Is an Opinion Until FinalizedSign in
Temporary Forks and Orphans: Propagation Races as a Normal ConditionSign in
Confirmation Depth: Probabilistic Finality and What You Can Promise at Different DepthsSign in

Part 20

Basic Chain Selection Rules

Basic Chain Selection RulesSign in
Longest/Heaviest Chain: Selection Rules as Incentive and Security MechanismsSign in
Difficulty and Target Times: Adjusting Work/Weight and the Stability of Issuance and ThroughputSign in
Attack Implications: How Selection Rules Interact With Selfish Behavior and Network DelaySign in

Part 21

Proof-of-Work (PoW)

Proof-of-Work (PoW)Sign in
Puzzle Design and Difficulty: Adjustable Work and Why Verification Must Be CheapSign in
Mining Economics: Rewards, Fees, and Energy as Part of the Security BudgetSign in
Security and Attacks (High-Level): Majority Power, Selfish Mining Intuition, and Reorg RealitiesSign in

Part 22

Proof-of-Stake (PoS)

Proof-of-Stake (PoS)Sign in
Validators and Selection: Stake as Weight and the Implications for MembershipSign in
Slashing and Penalties: Aligning Incentives and Defining Punishable BehaviorsSign in
Finality and Checkpoints: Confirmations, Finality Gadgets, and What "Reorg Resistance" MeansSign in

Part 23

BFT-Style Consensus

BFT-Style ConsensusSign in
PBFT-Like Rounds: Proposals, Votes, Commits and Quorum ThresholdsSign in
Committees and Thresholds: Byzantine Limits and Why Committee Selection Is Security-CriticalSign in
Partial Synchrony: Liveness Conditions and the Timing Assumptions Hiding Inside ProtocolsSign in

Part 24

Hybrid and Novel Consensus Designs

Hybrid and Novel Consensus DesignsSign in
Layering PoS and BFT: Separating Block Production from FinalizationSign in
DAG-Style Protocol Intuition: Non-Linear Histories and Why They Complicate ReasoningSign in
Randomness and VRFs: Leader Election, Unpredictability, and Grinding Risks at a High LevelSign in

Part 25

Security, Finality, and Fault Tolerance

Security, Finality, and Fault ToleranceSign in
Safety, Liveness, Finality: Defining the Guarantees Precisely Before Arguing About ThemSign in
Economic Security: When Incentives Substitute for (or Weaken) Mathematical GuaranteesSign in
Long-Range and "Nothing-at-Stake": Attack Classes and Why Governance and Social Recovery MatterSign in

Part 26

Execution Models and Virtual Machines

Execution Models and Virtual MachinesSign in
Deterministic Execution: Why "Same Input, Same Output" Must Hold Across All NodesSign in
VM Design Choices: Stack vs Register Models and What They Imply for Tooling and PerformanceSign in
Gas and Halting Guarantees: Metering as Denial-of-Service Prevention and Economic ControlSign in

Part 27

On-Chain State and Storage

On-Chain State and StorageSign in
State Commitment Structures: Trie-like State Trees and the Difference Between "State" and "History"Sign in
Account Types: Contract Accounts vs Externally Owned Accounts as Security BoundariesSign in
Logs/Events vs Persistent State: Indexing, Off-Chain Consumption, and AuditabilitySign in

Part 28

Contract Design Patterns

Contract Design PatternsSign in
Ownership and Access Control: Authorization as the Most Common Failure SurfaceSign in
Pausing and Configuration: Operational Control Planes for On-Chain SystemsSign in
Modularity and Composition: Call Graphs, Dependency Risks, and Upgrade PressureSign in

Part 29

Oracles and Off-Chain Integration

Oracles and Off-Chain IntegrationSign in
The Oracle Problem: Why External Truth Is Adversarial by DefaultSign in
Push vs Pull and Aggregation: Verification Strategies and Failure ContainmentSign in
Incentives and Trust: Designing Oracle Systems as Economic Protocols, Not APIsSign in

Part 30

Contract Security and Common Pitfalls

Contract Security and Common PitfallsSign in
Canonical Bugs: Reentrancy, Arithmetic Issues, and Authorization Mistakes as PatternsSign in
MEV at Contract Level: Front-Running Dynamics and How Contract Structure Invites ExtractionSign in
Audit-Friendly Design: Defense-in-Depth, Invariants, and Making Behaviors ReviewableSign in

Part 31

Scaling On-Chain: Throughput and Data

Scaling On-Chain: Throughput and DataSign in
Throughput Knobs: Block Size, Gas Limits, and What They Trade AgainstSign in
State Growth: Pruning, Archival Models, and Why Storage Is GovernanceSign in
Data Availability and Light Clients: What Must Be Available for Verification to Remain MeaningfulSign in

Part 32

Layer-2 Protocols: Channels and Rollups

Layer-2 Protocols: Channels and RollupsSign in
Channels: Lock-In, Update, Settle, and What Users Must AssumeSign in
Optimistic vs ZK Rollups (Conceptual): Challenges vs Proofs and What Each Shifts to OperatorsSign in
Security Assumptions: Trust Models and How Failures Surface to End UsersSign in

Part 33

Sharding and Parallel Execution

Sharding and Parallel ExecutionSign in
Sharding Choices: State Sharding vs Transaction Sharding and the Coordination CostsSign in
Cross-Shard Communication: Message Passing, Receipts, and Consistency ExpectationsSign in
Parallelism and Conflicts: Contention Detection and Why Independent Transactions Are Rare at ScaleSign in

Part 34

Bridges and Cross-Chain Protocols

Bridges and Cross-Chain ProtocolsSign in
Bridge Mechanisms: Lock-and-Mint, Burn-and-Release, and Light-Client ApproachesSign in
Custodial vs Non-Custodial Bridges: Where Trust Lives and How It FailsSign in
Bridge Risk Surfaces: Contract Risk, Replay, Centralization Pressure, and Operational MonitoringSign in

Part 35

Privacy in Blockchain Systems

Privacy in Blockchain SystemsSign in
Transparency Limits: Why Naive Ledgers Leak Structure Even Without NamesSign in
Privacy Techniques: Mixers, Stealth Addresses, Confidential Transactions, and What They HideSign in
Zero-Knowledge at a High Level: Shielded Pools, Proof Costs, and Integration Trade-OffsSign in

Part 36

MEV, Ordering, and Fairness

MEV, Ordering, and FairnessSign in
Ordering as Power: How Transaction Ordering Becomes Extractable ValueSign in
MEV Patterns: Front-Running, Sandwiching, Back-Running, and Why They PersistSign in
Mitigations (Conceptual): Auctions, Commit-Reveal, Encrypted Mempools, and What They Shift ElsewhereSign in

Part 37

Native Currencies and Monetary Policy

Native Currencies and Monetary PolicySign in
Native Coin vs Tokens: Base Asset Roles and What Must Be Special in the ProtocolSign in
Issuance Schedules: Inflation, Deflation, Halvings, and Long-Term Security BudgetsSign in
Economic Roles: Medium of Exchange, Store of Value, Gas Unit, and How Role Conflicts AppearSign in

Part 38

Tokens, Assets, and Representation Models

Tokens, Assets, and Representation ModelsSign in
Fungible and Non-Fungible Assets - Representation Choices and Their Implied InvariantsSign in
Token Standards (Conceptual) - Balance Tracking, Metadata, and Interoperability ExpectationsSign in
Asset Semantics - Transfer Restrictions, Ownership Meaning, and Edge CasesSign in

Part 39

Incentive Design for Validators and Users

Incentive Design for Validators and UsersSign in
Rewards and Fees - Block Rewards, Fee Markets, Tips, and User Behavior ShapingSign in
Slashing and Incentive Compatibility - Punishments, False Positives, and Participation RiskSign in
Modeling Rational Behavior - Assumptions You Must State to Claim "Secure"Sign in

Part 40

Governance, Upgrades, and DAOs

Governance, Upgrades, and DAOsSign in
Governance Models: Off-Chain Coordination vs On-Chain Voting and Their Failure ModesSign in
Upgrades: Forks, Versioning, and What Continuity Means for Users and ContractsSign in
DAO Mechanics: Treasuries, Voting, Incentives and How Governance Becomes an Attack SurfaceSign in

Part 41

Designing End-to-End Blockchain Systems

Designing End-to-End Blockchain SystemsSign in
Reference Architectures: Simple Coin, General Smart-Contract Chain, and App-Specific ChainSign in
Decentralize vs Centralize: Choosing What Must Be Trustless and What Can Be Operationally ManagedSign in
End-to-End Threat and Incentive Review: Ensuring Ledger, Consensus, Networking, Contracts, and Economics AlignSign in

Part 42

Application Domains and Use-Cases

Application Domains and Use-CasesSign in
Payments and Remittances: Constraints, UX Realities, and Trust BoundariesSign in
DeFi, Supply Chain, Identity (High-Level): What the Ledger Adds and What It Does Not SolveSign in
When Not to Use a Blockchain: Negative Criteria, Opportunity Cost, and Simpler AlternativesSign in

Part 43

Security Patterns and Threat Modeling

Security Patterns and Threat ModelingSign in
Attacker Models: Protocol-Level, Network-Level, Economic-Level and How They ComposeSign in
Defense-in-Depth: Cryptographic, Protocol, Economic, Operational Layers and What Each Can Realistically PreventSign in
Threat Modeling Templates: Turning Assumptions into Explicit Test Plans for New DesignsSign in

Part 44

Observability, Monitoring, and Operations

Observability, Monitoring, and OperationsSign in
Node and Network Health: Peers, Performance, Forks, and Chain Liveness IndicatorsSign in
Indexing and Querying: Turning Append-Only Data into Operational Visibility and Product FeaturesSign in
Incident Response: Handling Protocol Incidents, Economic Attacks, and Coordinated RemediationSign in

Part 45

Testing, Simulation, and Formal Methods

Testing, Simulation, and Formal MethodsSign in
Testing Layers: Unit Tests, Integration Tests, Testnets and What Each CatchesSign in
Adversarial Simulation: Network Conditions, Byzantine Behavior, and Economic Stress TestingSign in
Formal Methods (High-Level): What Can Be Proven About Contracts and Protocols, and Where Proofs StopSign in

Part 46

Design Checklists for New Blockchain Systems

Design Checklists for New Blockchain SystemsSign in
Cryptography, Consensus, and the Network Model: Choices, Assumptions, and Explicit Trade-offsSign in
Tokenomics and Governance: Incentives, Upgrade Paths, and Attacker Profit ModelsSign in
Interoperability and Regulatory Constraints: Upgradeability, Bridge Risk, and Operating in Real JurisdictionsSign in

Course overview