• Failed a technical interview for a Blockchain Security Engineer role — need help with cryptography prep

    Sayali Bhandari

    Sayali Bhandari

    @SayaliB
    Updated: Oct 9, 2025
    Views: 75

    I recently gave a technical interview for a Blockchain Security Engineer position and didn’t make it through. Most of the questions were around cryptography, and I realized that’s where my understanding isn’t strong enough.

    They asked about hash functions, digital signatures, elliptic curve cryptography, and key management — but the depth of the questions were out of my knowledge to answer confidently.

    For those who’ve cleared similar interviews, what are the key cryptography and security concepts I should focus on while preparing?
    Any good learning path or resource list you’d recommend for improving technical preparation in this area?

    3
    Replies
Howdy guest!
Dear guest, you must be logged-in to participate on ArtOfBlockChain. We would love to have you as a member of our community. Consider creating an account or login.
Replies
  • Abdil Hamid

    @ForensicBlockSmith2w

    I’ve been on both sides of the table for blockchain security interviews, and what often filters candidates isn’t the math. It’s the connection between cryptography and system design.

    If you’re aiming for a security engineer role, here’s the mental model I suggest:

    1️⃣ Hashing isn’t just SHA or Keccak — it’s about trust boundaries. Understand why blockchains rely on one-way functions. Be able to explain collision resistance and preimage resistance in the context of Merkle proofs, state roots, and light clients. If you can explain how a corrupted Merkle root can invalidate an entire chain state — that’s depth.

    2️⃣ Digital signatures = identity layer of Web3. Go beyond “ECDSA = private-public key pair.” Learn nonce reuse attacks, deterministic signatures (RFC 6979), and why Ethereum moved to EIP-2098 for gas-efficient signatures. Interviewers often ask, “What if the RNG fails while generating a signature?”

    3️⃣ Key management separates hobbyists from professionals. Discuss cold/hot wallet segregation, threshold signatures (TSS), and MPC. Most projects today care more about secure custody than about perfect math.

    4️⃣ Zero-Knowledge Proofs (ZKPs) & commitments. Even if not your daily work, you must know Pedersen commitments, zk-SNARK verification flow, and the difference between trusted vs trustless setup.

    💡 Pro tip: Instead of reading random blogs, review real audit reports — OpenZeppelin, Trail of Bits, ConsenSys Diligence. They expose cryptographic misuse patterns (e.g., insecure randomness, weak entropy sources, signature malleability). That’s what interviewers mean by practical cryptography.

Home Channels Search Login Register