1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
# Nostr HTTP Authentication (NIP-98)
This package implements [NIP-98](https://github.com/nostr-protocol/nips/blob/master/98.md) authentication for gRPC using the standard `credentials.PerRPCCredentials` interface.
## Overview
NIP-98 provides HTTP authentication using Nostr event signatures instead of bearer tokens or OAuth2. It uses cryptographic signatures to prove the request came from a specific public key, without requiring passwords or centralized identity providers.
## How It Works
### Authentication Flow
1. **Client** creates a special kind 27235 event with:
- `u` tag: Full request URI
- `method` tag: HTTP method (GET, POST, etc.) or gRPC method name
- `payload` tag (optional): SHA256 hash of the request body
- `created_at`: Current Unix timestamp
2. **Client** signs the event with their private key
3. **Client** base64-encodes the event JSON and sends it in the `Authorization` header:
```
Authorization: Nostr <base64-encoded-event>
```
4. **Server** validates the event:
- Verifies the signature matches the pubkey
- Checks the timestamp is recent (prevents replay attacks)
- Verifies the `u` and `method` tags match the actual request
- Optionally validates the payload hash
5. **Server** adds the validated pubkey to the request context for use by handlers
### Example Event
```json
{
"id": "9e1b6471f...",
"pubkey": "79be667ef9dc...",
"created_at": 1682327852,
"kind": 27235,
"tags": [
["u", "https://api.example.com/nostr.v1.NostrRelay/PublishEvent"],
["method", "POST"],
["payload", "5c9e3a4d..."]
],
"content": "",
"sig": "d2d6e9f0..."
}
```
## Usage
### Client Side
Use the `NostrCredentials` type with standard gRPC dial options:
```go
import (
"google.golang.org/grpc"
"northwest.io/muxstr/internal/auth"
"northwest.io/muxstr/internal/nostr"
)
// Generate or load your private key
key, _ := nostr.GenerateKey()
// Create credentials
creds := auth.NewNostrCredentials(key)
// Use with gRPC client
conn, err := grpc.NewClient(
"localhost:50051",
grpc.WithPerRPCCredentials(creds),
grpc.WithTransportCredentials(insecure.NewCredentials()),
)
```
The credentials automatically sign each request with a fresh NIP-98 event.
### Server Side
Use the interceptors to validate incoming requests:
```go
import (
"google.golang.org/grpc"
"northwest.io/muxstr/internal/auth"
)
// Create auth options
authOpts := &auth.InterceptorOptions{
TimestampWindow: 60, // Accept events within 60 seconds
Required: true, // Reject unauthenticated requests
}
// Create gRPC server with interceptors
server := grpc.NewServer(
grpc.UnaryInterceptor(auth.NostrUnaryInterceptor(authOpts)),
grpc.StreamInterceptor(auth.NostrStreamInterceptor(authOpts)),
)
```
### Accessing the Authenticated Pubkey
In your handlers, retrieve the authenticated pubkey from the context:
```go
func (s *Server) PublishEvent(ctx context.Context, req *pb.PublishEventRequest) (*pb.PublishEventResponse, error) {
pubkey, ok := auth.PubkeyFromContext(ctx)
if !ok {
return nil, status.Error(codes.Unauthenticated, "no authentication")
}
// Verify the event was signed by the authenticated user
if req.Event.Pubkey != pubkey {
return nil, status.Error(codes.PermissionDenied, "event pubkey doesn't match auth")
}
// Process the event...
}
```
## Security Considerations
### Replay Protection
Events include a `created_at` timestamp. The server validates that events are recent (within the configured `TimestampWindow`). This prevents replay attacks where an attacker intercepts and re-sends a valid auth event.
### Transport Security
While NIP-98 provides authentication (proving who you are), it doesn't provide encryption. Use TLS/SSL to encrypt the connection and prevent eavesdropping.
```go
// Client with TLS
creds := credentials.NewClientTLSFromCert(nil, "")
conn, err := grpc.NewClient(addr,
grpc.WithTransportCredentials(creds),
grpc.WithPerRPCCredentials(nostrCreds),
)
```
### Payload Validation
The `payload` tag is optional but recommended for POST/PUT requests. When present, the server can verify the request body hasn't been tampered with:
```go
authOpts := &auth.InterceptorOptions{
ValidatePayload: true, // Verify payload hash if present
}
```
## Configuration Options
### InterceptorOptions
- **`TimestampWindow`**: Maximum age of events in seconds (default: 60)
- **`Required`**: Whether to reject unauthenticated requests (default: false)
- **`ValidatePayload`**: Whether to verify payload hash when present (default: false)
- **`AllowedPubkeys`**: Optional whitelist of allowed pubkeys (nil = allow all)
### NostrCredentials Options
- **`IncludePayload`**: Whether to include payload hash in auth events (default: false)
## Benefits Over Traditional Auth
1. **No passwords**: Uses public key cryptography
2. **Decentralized**: No central identity provider
3. **Per-request auth**: Each request is independently authenticated
4. **Nostr compatible**: Works with existing Nostr identities and tools
5. **Standard pattern**: Uses industry-standard gRPC credentials interface
6. **Key rotation**: Easy to rotate keys without server-side updates
## Compatibility
This implementation follows the gRPC `credentials.PerRPCCredentials` interface, making it a drop-in replacement for OAuth2, JWT, or other auth mechanisms. It works with:
- Standard gRPC clients (Go, Python, JS, etc.)
- gRPC-Web and Connect protocol
- All gRPC features (unary, streaming, metadata, etc.)
|
