Blockchain Layer: Multi-Chain Support

Blockchain Selection Criteria and Supported Chains

BlockGram’s blockchain layer is architected for flexibility and broad compatibility, supporting multiple blockchain protocols to maximize accessibility and performance:

• Supported Chains:

  • Ethereum Virtual Machine (EVM) Compatible Chains: Ethereum, Binance Smart Chain, Polygon, Avalanche, etc., selected for their mature smart contract ecosystems and wide adoption.

  • Cosmos SDK-based Chains: Employed for their modular architecture and fast finality, enabling efficient payment processing.

  • Layer-2 Solutions: Optimistic Rollups (e.g., Optimism), zk-Rollups (e.g., zkSync), and sidechains reduce gas costs and latency while preserving security.

• Selection Criteria:

  • Security: Chain decentralization and robust consensus mechanisms.

  • Throughput & Latency: Support for real-time transaction finality aligned with chat UX.

  • Interoperability: Availability of bridges or interoperability protocols.

  • Cost Efficiency: Low transaction fees critical for microtransactions and bill splitting.

  • Developer Ecosystem: Rich tooling and smart contract standards (e.g., ERC-20, ERC-721).

Wallet Architecture: HD Wallets, Key Derivation, and Secure Storage

• Hierarchical Deterministic (HD) Wallets: BlockGram employs HD wallets compliant with BIP-32/BIP-44 standards, allowing deterministic generation of multiple addresses and keys from a single seed phrase. This facilitates:

  • Multi-currency support: Generating addresses for different chains and token standards from one seed.

  • Scalable wallet management: Efficiently handling many user accounts and tokens.

• Key Derivation Paths: Standardized paths per chain and token type enable consistent address generation, enhancing interoperability and ease of recovery.

• Secure Storage:

  • Private keys are encrypted at rest using strong AES-256 encryption with hardware security modules (HSMs) employed in backend infrastructure.

  • For user devices, keys are stored securely using platform-native secure enclaves or keystores.

  • Non-custodial design ensures BlockGram does not hold user keys directly, minimizing centralized risk.

Smart Contract Design Patterns

• Payments and Escrow:

  • Use of multi-signature and time-locked contracts to increase transaction security and enable conditional fund releases.

  • Escrow contracts facilitate dispute resolution and trustless transactions in peer-to-peer payments.

• Bill Splitting Contracts:

  • Employ modular, upgradable smart contracts following proxy patterns to manage group payments.

  • Algorithms embedded within contracts enforce fair shares, handle late payments, and trigger automatic settlements.

• Gift Cards and NFTs:

  • Smart contracts issue NFT-backed gift cards, embedding metadata that represents value, merchant information, and redemption conditions.

  • Cross-chain token wrapping techniques enable gift card redemption across supported blockchains.

• Upgradeable Contracts:

  • Use of transparent proxies or beacon proxies enables contract upgrades without disrupting existing state or user balances, ensuring long-term maintainability.

Cross-Chain Interoperability

• Bridges: BlockGram integrates with trusted decentralized bridges to enable seamless token transfers and communication between chains. Examples include Wormhole and Hop Protocol.

• Atomic Swaps: For trustless cross-chain exchanges, BlockGram employs hashed time-lock contracts (HTLCs) to facilitate atomic swaps, ensuring either both sides complete or both revert, eliminating counterparty risk.

• Inter-Chain Messaging: Leveraging protocols like Cosmos IBC (Inter-Blockchain Communication) for state synchronization and asset transfer across Cosmos-based chains and compatible networks.

Transaction Batching and Gas Optimization

• Batching Strategies:

  • Aggregates multiple user transactions into single on-chain operations to reduce gas consumption and improve throughput.

  • Uses meta-transactions allowing a relayer to submit batched requests on behalf of users.

• Gas Optimization Techniques:

  • Smart contract code is optimized for minimal opcode usage, utilizing libraries like OpenZeppelin’s Gas Optimized Contracts.

  • Employs Layer-2 solutions where gas is substantially cheaper.

  • Implements transaction fee estimation and dynamic gas pricing algorithms to optimize cost and confirmation time.

• Fee Abstraction: BlockGram abstracts transaction fees, optionally subsidizing gas or allowing payment in multiple tokens, improving user experience.