Product Security Engineer - Hashgraph

## About Hashgraph: Hashgraph is a fast-growing software company committed to supporting, developing and servicing Hedera, an open source, proof-of-stake platform. Hedera is EVM-compatible and has been specifically built to meet the needs of enterprise and web3 applications, which require speed, security, stability and sustainability. Hedera’s public network is governed by industry-leading organizations, spanning 11 sectors and 14 regions who oversee the development and direction of the decentralized platform.

### In this role, you will: - Conduct end-to-end security assessments of blockchain-based systems, from cryptographic primitive design and protocol architecture through smart contract implementation and deployed infrastructure. - Find real vulnerabilities through hands-on review, adversarial testing, and proof-of-concept exploit development, not just automated scanning. - Design adversarial test cases and proof-of-concept exploits for Hedera-native services, EVM-compatible contracts, cross-chain bridges, and consensus-layer components. - Own threat modeling and security architecture reviews across product phases. - Define and enforce security gates before new components reach production. - Partner directly with engineering teams to translate cryptographic and protocol-level risks into concrete, prioritized remediation work. - Build and improve security tooling, fuzzing infrastructure, and CI/CD security automation to scale security coverage without scaling headcount. - Track emerging blockchain and web3 attack patterns, map them to the internal codebase, and drive proactive mitigation before threats materialize.

### What you bring: Core capabilities: - Hands-on vulnerability discovery and security testing across blockchain protocols, smart contracts, nodes, and APIs. - A track record of catching real bugs, not just running automated scans. - Strong threat modeling and security architecture review experience applied to distributed cryptographic systems. - Experience assessing cross-chain protocols, threshold signature schemes, or other cryptographic systems with complex trust assumptions. - Deep working knowledge of applied cryptography, including BLS signatures, pairing-based schemes, polynomial commitments, and Fiat-Shamir constructions. - Ability to reason about cryptographic failure modes and how they show up in production systems. - Direct experience auditing or breaking a cross-chain bridge. - Ability to reason through trust model tradeoffs, including state proof, multisig, and oracle attestation models, and what each means for the attack surface. ### Functional expertise: - Blockchain security and secure coding practices across EVM-compatible and non-EVM chains. - Security testing tooling, including static analysis, dynamic analysis, and fuzzing. - Experience developing custom fuzzing harnesses or security test infrastructure. - Ability to read and audit Rust and/or Java cryptographic code. - Understanding of memory safety, constant-time correctness, secret handling, and security risks at JNI boundaries. ### Nice to haves: - Experience designing and operating grammar-aware fuzzing campaigns against gRPC, JSON-RPC, or protocol-level endpoints. - Experience building classifier pipelines to distinguish security signal from noise. - Prior work on Ethereum consensus client security. - Prior work on production threshold signature systems. - Experience building security automation tooling. - Experience integrating AI-assisted workflows into security review and triage processes.

Hashgraph is a software company that provides technical and product development, marketing support, and open-source tools for the Hedera network, including services like Hedera Consensus Service, Token Service, and Smart Contract Service. It develops community tools such as HashScan and enterprise products for loyalty tokens, NFTs, payments, and offers HashSphere, a private permissioned network powered by Hedera technology. Founded by Hedera co-founders Mance Harmon and Dr. Leemon Baird, it focuses on accelerating builders in the digital economy.