Migration from Stratum V1 to Stratum V2

This guide helps pool operators and mining software developers migrate from Zcash’s existing Stratum V1 protocol (ZIP 301) to Stratum V2.

Current Zcash Mining Landscape

Existing Stratum V1 Implementations

Based on research, the current Zcash mining ecosystem uses:

Mining Software:

• lolMiner - GPU miner with Equihash support
• miniZ - Optimized Equihash miner
• GMiner - Multi-algorithm GPU miner
• Legacy: EWBF, nheqminer, Genoil ZECMiner

Major Pools:

• Flypool - Europe, Asia, US servers
• F2Pool - Global, PPS payout
• 2miners - PPLNS/solo options
• ViaBTC - PPS+ payout

ASIC Miners:

• Bitmain Antminer Z15 Pro (840 KSol/s)
• Innosilicon A9++ (140 KSol/s)

Protocol Comparison

ZIP 301 (Stratum V1) vs Stratum V2

Message Mapping

V1 Protocol Details (ZIP 301)

Current Message Format

{"id": 1, "method": "mining.subscribe", "params": ["user-agent/1.0", null, "pool.example.com", 3333]}
{"id": 2, "method": "mining.authorize", "params": ["wallet.worker", "password"]}
{"id": null, "method": "mining.notify", "params": ["job_id", "version", "prev_hash", "merkle_root", "reserved", "time", "bits", true]}
{"id": 4, "method": "mining.submit", "params": ["wallet.worker", "job_id", "time", "nonce_2", "solution"]}

V1 Nonce Handling

ZIP 301 specifies:

• NONCE_1: Server-assigned prefix (less than 32 bytes)
• NONCE_2: Miner iterates (32 - len(NONCE_1) bytes)
• Combined as little-endian 32-byte nonce

// V1 nonce construction
nonce = NONCE_1 || NONCE_2  // concatenation
// Incrementing: miner adds (1 << (len(NONCE_1) * 8)) to preserve NONCE_1

V1 Solution Format

Equihash solution with compactSize prefix:

// 1344 bytes for Equihash 200,9
solution_with_size = compactSize(1344) || solution_bytes

V2 Protocol Details

Binary Message Format

+----------------+----------------+------------------+
|  Message Type  |  Payload Len   |     Payload      |
|    (1 byte)    |   (2 bytes LE) |   (variable)     |
+----------------+----------------+------------------+

V2 Nonce Handling

Same conceptual split, but binary encoded:

// V2 nonce construction
let mut nonce = [0u8; 32];
nonce[..extranonce.len()].copy_from_slice(&extranonce);
nonce[extranonce.len()..].copy_from_slice(&nonce2_bytes);

V2 Solution Format

Raw 1344 bytes, no compactSize prefix:

struct SubmitSharesStandard {
    channel_id: u32,
    sequence_number: u32,
    job_id: u32,
    nonce: [u8; 32],
    ntime: u32,
    solution: [u8; 1344],  // Raw solution, no length prefix
}

Migration Steps

For Pool Operators

Phase 1: Dual-Stack Support

Run both V1 and V2 endpoints:

Pool Server
├── Port 3333: Stratum V1 (existing)
└── Port 3335: Stratum V2 (new)

Share validation and payout tracking remain unified.

Phase 2: V2 Feature Enablement

1. Enable Noise encryption on V2 endpoint
2. Enable Job Declaration support
3. Optionally enable Full-Template mode

Phase 3: V1 Deprecation

After sufficient V2 adoption:

1. Announce V1 deprecation timeline
2. Redirect V1 connections to V2 (with proxy if needed)
3. Retire V1 endpoint

For Mining Software Developers

Step 1: Add Binary Codec

Replace JSON-RPC parsing with binary message handling:

// V1: JSON parsing
let msg: Value = serde_json::from_str(&line)?;

// V2: Binary parsing
let msg_type = reader.read_u8()?;
let payload_len = reader.read_u16::<LittleEndian>()?;
let payload = reader.read_exact(payload_len)?;

Step 2: Implement New Handshake

// V1
mining.subscribe() -> session_id, nonce_1
mining.authorize() -> success

// V2
SetupConnection -> SetupConnection.Success
OpenStandardMiningChannel -> OpenStandardMiningChannel.Success (includes extranonce)

Step 3: Handle Binary Jobs

// V1: Parse JSON fields
let job_id = params[0].as_str()?;
let prev_hash = hex::decode(params[2].as_str()?)?;

// V2: Parse binary struct
let job = NewMiningJob {
    channel_id: reader.read_u32::<LittleEndian>()?,
    job_id: reader.read_u32::<LittleEndian>()?,
    prev_hash: reader.read_exact(32)?,
    // ...
};

Step 4: Update Solution Submission

// V1: JSON with hex-encoded solution
{"method": "mining.submit", "params": ["worker", "job_id", "time", "nonce2_hex", "solution_hex"]}

// V2: Binary submission
writer.write_u8(0x1C)?;  // SubmitSharesStandard
writer.write_u16::<LittleEndian>(payload.len())?;
writer.write_all(&channel_id.to_le_bytes())?;
writer.write_all(&nonce)?;
writer.write_all(&solution)?;  // Raw bytes, no hex

Step 5: Add Noise Support (Optional but Recommended)

use bedrock_noise::{NoiseInitiator, PublicKey};

// Before: plain TCP
let stream = TcpStream::connect(pool_addr)?;

// After: Noise-encrypted
let server_key = PublicKey::from_hex(pool_pubkey)?;
let initiator = NoiseInitiator::new(server_key);
let stream = initiator.connect(TcpStream::connect(pool_addr)?)?;

Configuration Migration

lolMiner Example

V1 Configuration:

lolMiner --algo EQUI200_9 
  --pool stratum+tcp://zec.f2pool.com:3357 
  --user wallet.worker 
  --pass x

V2 Configuration:

lolMiner --algo EQUI200_9 
  --pool stratum2+tcp://pool.example.com:3335 
  --user wallet.worker 
  --sv2-pubkey a1b2c3d4...

miniZ Example

V1:

miniZ --url wallet.worker@pool:3357 --par 200,9

V2:

miniZ --url-sv2 wallet.worker@pool:3335 --par 200,9 --sv2-key <pubkey>

Compatibility Considerations

ASIC Miners

Most Zcash ASICs (Antminer Z15, Innosilicon A9) have firmware-level Stratum V1 support. Options:

1. Firmware update: Manufacturers release SV2 firmware
2. Translation proxy: Run proxy that accepts V1 from ASIC, speaks V2 to pool
3. Hybrid mode: Pool supports both V1 and V2

Translation Proxy

For miners that can’t upgrade:

ASIC (V1) ──▶ Translation Proxy ──▶ Pool (V2)

// Proxy pseudocode
fn handle_v1_submit(v1_msg: V1Submit) -> V2Submit {
    V2Submit {
        channel_id: channel_map[&v1_msg.worker],
        job_id: job_map[&v1_msg.job_id],
        nonce: decode_nonce(&v1_msg.nonce2),
        solution: hex::decode(&v1_msg.solution)?,
    }
}

Feature Comparison Matrix

Testing Your Migration

Compatibility Test

# Start test pool with both endpoints
cargo run --example dual_stack_pool

# Test V1 connection
nheqminer -l 127.0.0.1:3333 -u test.worker

# Test V2 connection
cargo run --example sv2_test_miner -- --pool 127.0.0.1:3335

Performance Benchmark

Compare bandwidth and latency:

# V1 bandwidth (JSON)
tcpdump -i eth0 port 3333 -w v1.pcap
# Analyze: typically 200-500 bytes per job notification

# V2 bandwidth (binary)
tcpdump -i eth0 port 3335 -w v2.pcap
# Analyze: typically 100-200 bytes per job notification

Timeline Recommendations

Resources

• ZIP 301: Zcash Stratum Protocol - Current V1 specification
• Stratum V2 Specification - V2 protocol reference