Technical Overview

Bitmark is built on a Bitcoin-derived codebase with significant modifications for multi-algorithm proof-of-work and the Marking system.

Architecture

Core Specifications

Network Parameters

Parameter	Mainnet	Testnet
Default Port	9265	19265
RPC Port	9266	19266
Address Prefix	85 (b)	130 (u)
Message Magic	0xf9beb4d9	0x0b110907
Genesis Timestamp	July 13, 2014	-

Block Parameters

Parameter	Value
Target Block Time	120 seconds (2 minutes)
Per-Algorithm Target	960 seconds (16 minutes)
Difficulty Window	25 blocks (per algorithm)
Block Size Limit	1 MB
Block Version	4+ (post-fork)

Monetary Policy

Parameter	Value
Maximum Supply	~27,579,894 MARKS
Initial Block Reward	20 MARKS
Per-Algorithm Reward	2.5 MARKS (20/8)
Smallest Unit	1 satoshi (10⁻⁸ MARKS)

Consensus Rules

Block Validity

A block is valid if:

1. Header valid: Correct hash, meets difficulty target
2. Algorithm valid: Hash matches declared algorithm
3. Timestamp valid: Within 2 hours of network time
4. Transactions valid: All transactions pass validation
5. Merkle root valid: Matches computed root
6. Size valid: Under block size limit
7. Subsidy valid: Coinbase claims correct reward

Transaction Validity

A transaction is valid if:

1. Inputs exist: All referenced UTXOs exist
2. Not double-spend: UTXOs not already spent
3. Scripts valid: All input scripts execute successfully
4. Amount valid: Inputs ≥ Outputs
5. Size valid: Under transaction size limit

Key Components

Block Header

Standard (non-Equihash):

┌────────────────────────────────────────────────────────────┐
│ nVersion (4)│hashPrevBlock(32)│hashMerkle(32)│nTime(4)    │
├────────────────────────────────────────────────────────────┤
│ nBits (4)   │ nNonce (4)                                   │
└────────────────────────────────────────────────────────────┘
Total: 80 bytes

Equihash:

┌────────────────────────────────────────────────────────────┐
│ nVersion(4)│hashPrevBlock(32)│hashMerkle(32)│hashReserved(32)
├────────────────────────────────────────────────────────────┤
│ nTime(4)   │ nBits(4)       │ nNonce256(32) │ nSolution(var)
└────────────────────────────────────────────────────────────┘

Version Field Encoding

Bits 0-7:   Standard version number (≥4 for fork)
Bit 8:      AUXPOW flag (merged mining)
Bits 9-11:  Algorithm selector (0-7)
Bit 12:     UPDATE_SSF flag (scaling factor)
Bits 16+:   Chain ID (for AuxPow)

Transaction Structure

┌─────────────────────────────────────────────────────────────┐
│ Version (4 bytes)                                           │
├─────────────────────────────────────────────────────────────┤
│ Input Count (varint)                                        │
├─────────────────────────────────────────────────────────────┤
│ Inputs:                                                     │
│   - Previous Tx Hash (32 bytes)                             │
│   - Previous Output Index (4 bytes)                         │
│   - Script Length (varint)                                  │
│   - Script Sig (variable)                                   │
│   - Sequence (4 bytes)                                      │
├─────────────────────────────────────────────────────────────┤
│ Output Count (varint)                                       │
├─────────────────────────────────────────────────────────────┤
│ Outputs:                                                    │
│   - Value (8 bytes)                                         │
│   - Script Length (varint)                                  │
│   - Script PubKey (variable)                                │
├─────────────────────────────────────────────────────────────┤
│ Lock Time (4 bytes)                                         │
└─────────────────────────────────────────────────────────────┘

Source Code Organization

bitmark/
├── src/
│   ├── ar2/           # Argon2 implementation
│   ├── consensus/     # Consensus rules
│   ├── crypto/        # Cryptographic functions
│   ├── cryptonight/   # CryptoNight implementation
│   ├── Lyra2RE/       # Lyra2REv2 implementation
│   ├── net/           # P2P networking
│   ├── policy/        # Policy defaults
│   ├── primitives/    # Block, transaction structures
│   ├── qt/            # GUI wallet
│   ├── rpc/           # RPC interface
│   ├── script/        # Script interpreter
│   ├── wallet/        # Wallet functionality
│   ├── yescrypt/      # Yescrypt implementation
│   ├── chainparams.cpp  # Network parameters
│   ├── core.cpp       # Core functions
│   ├── main.cpp       # Main logic, consensus
│   ├── pureheader.h   # Algorithm definitions
│   └── scrypt.cpp     # Scrypt implementation
├── doc/               # Documentation
├── share/             # Build resources
└── contrib/           # Utilities

Key Files Reference

File	Purpose
src/chainparams.cpp	Network and genesis parameters
src/main.cpp	Consensus rules, block validation
src/pureheader.h	Algorithm definitions, version flags
src/core.cpp	Block/transaction helpers
src/rpcmining.cpp	Mining RPC commands
src/scrypt.cpp	Scrypt PoW function

Differences from Bitcoin

Feature	Bitcoin	Bitmark
Block Time	10 minutes	2 minutes
Algorithms	SHA256D only	8 algorithms
Difficulty	Every 2016 blocks	Every block (DGWv3)
Max Supply	21 million	~27.58 million
Emission	Halving only	Halving + Quartering
Merge Mining	No	Yes (all algorithms)
Special Tx	None	MRK marks

See Also

• Multi-Algorithm PoW - Deep dive into the 8 algorithms
• Difficulty Adjustment - DGWv3 details
• Emission Model - Monetary policy details
• Network Parameters - Complete parameter reference