A nostr relay in C with sqlite on the back end.

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### [NIPs](https://github.com/nostr-protocol/nips)

- [x] NIP-01: Basic protocol flow implementation
- [x] NIP-09: Event deletion
- [x] NIP-11: Relay information document
- [x] NIP-13: Proof of Work
- [x] NIP-15: End of Stored Events Notice
- [x] NIP-20: Command Results
- [ ] NIP-22: Event `created_at` Limits
- [ ] NIP-25: Reactions
- [ ] NIP-26: Delegated Event Signing
- [ ] NIP-28: Public Chat
- [ ] NIP-33: Parameterized Replaceable Events
- [ ] NIP-40: Expiration Timestamp
- [ ] NIP-42: Authentication of clients to relays
- [ ] NIP-45: Counting results. [experimental](#count)
- [ ] NIP-50: Keywords filter. [experimental](#search)
- [ ] NIP-70: Protected Events

## NIP-13: Proof of Work Configuration

The relay supports NIP-13 Proof of Work validation with configurable settings. PoW validation helps prevent spam and ensures computational commitment from event publishers.

### Environment Variables

Configure PoW validation using these environment variables:

- `RELAY_POW_ENABLED` - Enable/disable PoW validation (default: `1`)
  - `1`, `true`, or `yes` to enable
  - `0`, `false`, or `no` to disable

- `RELAY_MIN_POW_DIFFICULTY` - Minimum required difficulty (default: `0`)
  - Range: `0-64` (reasonable bounds)
  - `0` = no minimum requirement (events without PoW are accepted)
  - Higher values require more computational work

- `RELAY_POW_MODE` - Validation mode (default: `basic`)
  - `basic` - Basic PoW validation
  - `full` - Full validation with nonce tag requirements
  - `strict` - Strict anti-spam mode with committed target validation
  - `disabled` - Disable PoW validation entirely

### Examples

```bash
# Basic setup - accept events with or without PoW
export RELAY_POW_ENABLED=1
export RELAY_MIN_POW_DIFFICULTY=0
export RELAY_POW_MODE=basic

# Anti-spam setup - require minimum difficulty 16
export RELAY_POW_ENABLED=1
export RELAY_MIN_POW_DIFFICULTY=16
export RELAY_POW_MODE=strict

# Disable PoW validation completely
export RELAY_POW_ENABLED=0
```

### Behavior

- **min_difficulty=0**: Events without PoW are accepted; events with PoW are validated
- **min_difficulty>0**: All events must have valid PoW meeting minimum difficulty
- **strict mode**: Additional validation prevents difficulty commitment gaming
- **NIP-11 integration**: PoW configuration is advertised via relay information document

### Testing

Run the comprehensive PoW test suite:

```bash
./tests/13_nip_test.sh
```

The test suite validates:
- NIP-11 PoW support advertisement
- Event acceptance without PoW (when min_difficulty=0)
- Event validation with valid PoW
- Configuration via environment variables
- NIP-13 reference event validation