Audit and construction of a secure infrastructure for sending BTC transactions

Budget: 27000 UAH Deadline: 14 days

Realistically, this task should be divided into two stages. I would allocate the budget of 27,000 UAH only for a short initial analysis, not for an audit plus building a new secure infrastructure. For the first working stage, I set the budget at 96,000 UAH and 14 days - an audit of the current scheme, threat model, risk map for seed phrases and private keys, recommendations for hot/cold storage, multisig 2-of-3, PSBT, and implementation plan.

!!I would start with the audit and architectural documentation!!, not with implementation on live keys. Then, if the audit findings confirm that the system should be rebuilt, we will separately assess the implementation - Bitcoin Core RPC, watch-only via xpub, offline signing, broadcasting, UTXO and fee management, address whitelisting, limits, access segregation, logs, monitoring, and handover. Here, we cannot play the hero - one weak process can cost more than the entire development =/

> What is the amount and frequency of transactions - one-time withdrawals, daily payouts, or an operational wallet?
> Is there already a Bitcoin Core node, hardware wallets, multisig, and a description of the current address generation?

For similar tasks, I show not a crypto showcase, but projects close in architectural responsibility:
> https://business.ingello.com/platforma - corporate system with roles, processes, and action control
> https://business.ingello.com/forma-bpm - process, status, and access management
> indirectly close in terms of accuracy level - https://business.ingello.com/lita - sensitive data and strict project logic
> https://systems-fl.ingello.com - main page of Ingello Systems on FLH Expand

Budget: 27000 UAH Deadline: 10 days

I have experience in Bitcoin security: BIP32/39/44, PSBT, multisig, Bitcoin Core RPC, bitcoinjs-lib.

Part 1 (audit): threat modeling of the key generation process, analysis of seed/private key leak vectors, environment assessment (browser, proxy, workstations, backups). Report with findings and prioritized recommendations.

Part 2 (infrastructure): air-gapped key generation (Coldcard/HSM), hot/cold architecture, multisig 2-of-3 with offline signing via PSBT, watch-only by xpub, control of address whitelists and limits, management of UTXO and fees.

Ready for details.

Budget: 27000 UAH Deadline: 7 days

Hello! The task has been read completely — both stages are clear.

Regarding the audit (Part 1):
I will conduct threat modeling of the current system: analysis of the key generation process, assessment of private key and seed phrase leakage vectors, evaluation of the environment (browser, proxy, workstations, backups). The result will be a report with findings, CVSS risk assessment, and prioritized recommendations.

Regarding the infrastructure (Part 2):
I will design the architecture from scratch:

- Air-gapped key generation (Coldcard or similar), hot/cold fund separation
- Multisig 2-of-3 via Sparrow/Caravan, offline signing through PSBT
- Sending pipeline: watch-only xpub → PSBT formation → signing on air-gapped device → broadcast
- UTXO management, fee control, address whitelisting, least privilege access
- Monitoring, logging, documentation, and handover to the team
- Stack: Bitcoin Core RPC, bitcoinjs-lib / BDK, PSBT, BIP32/44/84/86, SegWit/Taproot.

I am ready to discuss the details of the current system under NDA. Please write. Expand

Budget: 27000 UAH Deadline: 14 days

Hello! I have experience working as a DevOps in setting up infrastructure for secure key storage, and I also work as a smart contract developer. I work with Solana, EVM networks, and Bitcoin. I would be happy to discuss the details!

Budget: 26990 UAH Deadline: 29 days

Good day! My name is Valentin, and I represent Arctic Web Agency. We are a team that specializes in creating modern and effective solutions for businesses. I can provide examples of our similar work in personal messages. We are ready to take your project to work!

Sincerely,
Arctic Web Team
Freelancehunt

Budget: 27000 UAH Deadline: 14 days

Hello!

I understand that you need a Bitcoin security engineer for auditing and building a secure infrastructure for sending BTC transactions.

What I will do:
— Conduct an audit of the current wallet generation system and private key management to identify vulnerabilities.
— Create a detailed report with recommendations for improving security.
— Design and build a secure infrastructure for key storage using air-gapped and multisig approaches.
— Organize monitoring, logging, and documentation for system resilience.

I work quickly and efficiently, and I am available at all stages. I am ready to offer a turnkey solution.

Please clarify if you already have a description of the current system or if it needs to be created from scratch?

Let’s discuss the details and get started! Expand

Budget: 27000 UAH Deadline: 1 day

The project looks quite serious, why not use ready-made solutions that have passed an audit for your tasks?

Budget: 27000 UAH Deadline: 5 days

Before submitting a proposal, I would like to clarify one point. For part 2, are you looking for your own backend (integration of BDK/bitcoinjs-lib directly into your own systems with an API for operational use), or an architecture built on open-source coordinator/signing tools? (for example, Sparrow, Specter, Caravan). They differ significantly in timelines and risk profiles, and the right choice usually depends on whether you need software-controlled sending APIs or a signing workflow involving a human. I can provide a specific recommendation within the audit of part 1.

Budget: 27000 UAH Deadline: 1 day

I can conduct an audit of the infrastructure and security processes: servers, access, workstations, network, backups, privilege control, and potential compromise vectors. I can also design and implement a secure infrastructure with access segregation, monitoring, and logging. To assess the second part regarding Bitcoin keys and transactions, it is necessary to clarify the current architecture and the tools being used.