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Bucharest advisory deskOne adviser, since 2019

Most blockchain work goes wrong on the boring parts.

Sperfy is one person. I am M A Naeli Abdelkarim, an independent adviser working from Andronache in Bucharest. Companies bring me a plan, a half built network or a question their auditor asked, and I work through it with their engineers until the thing runs the way it should.

30 min first call, no fee 4 lines of work EN / RO spoken at the desk
Route diagram of a Sperfy engagement Four coloured lines run from an opening call through architecture review, operations and handover, meeting at three interchange points labelled scope, build and run. ARCHITECTURE NETWORK OPS KEYS AND SIGNING RULES AND RECORDS SCOPE BUILD RUN HANDOVER
Fig. 01 · how the four lines of work meet during an engagement
S.01 Ground we cover

Four subjects, explained the way we explain them on a call

Clients arrive with very different starting points. Some have run nodes for years, some read one article and want to know whether any of it applies to them. These four notes are the same ground I walk through in a first session.

How linked blocks work Three blocks in a row. Each block holds a header, a reference to the block before it, and a list of entries. Copies of the same chain sit on four separate machines below. BLOCK 812BLOCK 813BLOCK 814 prev 9af1…prev 41c7…prev b038… 14 entries9 entries21 entries time 09:41time 09:51time 10:02 COPY 1COPY 2COPY 3COPY 4
Fig. 02 · one chain, kept in full by every machine on the network

Blockchain technology

A blockchain is a shared record that many machines keep at once. Each batch of entries carries a fingerprint of the batch before it, so rewriting old history means redoing everything after it and then persuading the rest of the network to accept your version instead. That is the whole trick, and everything else is engineering around it.

It earns its cost when several organisations need one record and none of them wants to host it for the others. When a single company owns the data and everyone already trusts that company, an ordinary database is cheaper and easier to run. I say so when I think it, and a fair number of first calls end there.

network choicedata modelpermissioned vs public
Path of a Bitcoin transaction A signed transaction moves from a wallet into the waiting pool, is picked up by a mining pool, lands in a block and then gathers confirmations across the node network. WALLETsigns tx MEMPOOLwaiting BLOCKassembled 6 CONFsettled RELAYED BY ~18 000 LISTENING NODES EVERY NODE CHECKS THE SAME RULES BEFORE PASSING ANYTHING ON
Fig. 03 · a signed instruction from wallet to settled block

The bitcoin ecosystem

Bitcoin still runs on close to the design it launched with in 2009, which makes it a useful teaching network. A signed instruction goes to the waiting pool, a mining pool picks it up, and the block that carries it gets buried under later blocks until everyone treats it as settled. Fees rise when the pool is crowded and fall when it is not.

Companies usually come to us for the plumbing around it: running a full node so they check the chain themselves rather than trusting an API, reading confirmations correctly, handling fee spikes, and keeping signing keys somewhere a departing employee cannot reach.

full nodesfee handlingkey handling
Validator setup with one active signer An active validator and a standby machine sit behind a beacon node. Only the active machine holds the signing key. A monitor watches both, and the withdrawal key is kept offline. ACTIVE SIGNERsigning key: yesslot duty: live STANDBY BOXsigning key: nocold spare BEACON NODEchain viewMONITORalerts on miss WITHDRAWAL KEYoffline, sealed ONE KEY, ONE MACHINE
Fig. 04 · the layout that keeps a standby box from double signing

Staking and validators

On a proof of stake network, validators are the machines that propose and attest to blocks. An operator bonds tokens against good behaviour, and the protocol can take part of that bond back if the machine signs two conflicting messages or stays offline long enough to matter. The technical risk is rarely exotic. It is a helpful sysadmin bringing the standby box up while the primary is still running.

We look at client software choice, redundancy that cannot double sign, separation between signing and withdrawal keys, monitoring that pages a human, and the exit procedure written down before anyone needs it.

slashing conditionsclient diversityexit plans
What a token record actually contains A record card lists issuer, supply rule, transfer rule and the address that controls upgrades, alongside three questions that decide which rulebook applies. LEDGER RECORD issuer 0x7c2…9ab supply rule fixed, 21 000 000 transfer open, no allowlist upgrade key multisig 3 of 5 metadata off chain, pinned audit 2 firms, 2025 WHO CAN CHANGE THE RULES?answer decides governance work WHAT DOES THE HOLDER GET?answer decides the rulebook WHERE DOES THE DATA LIVE?answer decides the hosting bill
Fig. 05 · the record card I fill in before anyone writes a contract

Digital assets, in plain terms

A digital asset is a record on a ledger plus a rule about who may change it. Everything that matters follows from those two things: who controls the upgrade key, what the holder is actually entitled to, and where the data behind the record is stored. Get those written down and most arguments in a project meeting stop.

Since the EU rulebook for crypto-asset markets came into full effect at the end of 2024, Romanian companies also have to say clearly which category a token falls into. I map the technical facts and the questions your lawyer will ask. I am not a lawyer, so the legal opinion comes from your counsel and I work alongside them.

token design reviewdocumentationcounsel handover
S.02 Operations panel

What an operator watches, week by week

Every engagement that touches validator machines ends with a monitoring view like this one. The question it answers is dull and important: did your machines meet the duties the network handed them?

Illustrative sample. Fictional nodes, made up figures.

node-alba, node-bravo and node-ceahlau are invented names used for the demo. The figures are not measurements of any real network or operator.

Reading the dip in week 36

The dashed green line loses about five percent of its slots in one week. In a review session that is the first thing I point at, and the questions that follow are always the same. Was it a client upgrade run without a canary machine? Did the alert reach anyone at 03:00? Was the standby box brought up while the primary still held the key?

# the check I leave behind on every handover
$ sperfy-check duties --window 7d
  node-alba     met 1 611 / 1 613  ok
  node-bravo    met 1 598 / 1 613  ok
  node-ceahlau  met 1 532 / 1 613  review
  double-sign guard: armed on all hosts

Your team owns the machines and the keys throughout. I read the same screens as your engineers, ask uncomfortable questions and write down the answers.

Open line for other advisors

Advising in this field yourself? Let us compare notes.

I work with other independent specialists in Bucharest, Cluj and further out: infrastructure people, security reviewers, accountants who already know the sector. If a client of yours needs a second pair of eyes, or you want mine on your bench, call the number below. The first conversation costs nothing and I am happy for it to stay collegial.

+40 746 162 748 · Monday to Friday, 09:00 to 18:00 EET

S.03 How it runs

Four stops from first call to handover

The order matters here, so we number it. Nothing starts before you have a written scope with a price on it, and nothing ends without a document your team can use when we are gone.

STOP 01 · 30 MINUTES · NO FEE

The first call

You describe the situation, I ask questions and say whether I am the right person for it. Some calls end with a suggestion to use a normal database and no invoice from me.

STOP 02 · 2 TO 4 DAYS

Written scope

A short document: what we will look at, who from your side needs to be in the room, how many days it takes, what it costs. You sign it or you do not.

STOP 03 · 1 TO 8 WEEKS

Working sessions

Screen sharing with your engineers, architecture review, runbook drafting, sometimes a week on site. I work on your systems with your people, never around them.

STOP 04 · ONGOING

Handover and check back

Diagrams, runbooks and the open questions in one document. A follow up call at 30 and 90 days is included, because that is when the real problems appear.

Who I take on

Companies and project teams: engineering groups inside larger firms, startups with a working prototype, and specialists who need a second reviewer. Contracts are signed with my registered practice, invoiced from Bucharest with Romanian VAT handling.

Private individuals asking about their own holdings are outside my scope, and that is deliberate. It keeps the desk focused on system design and operations, where my answers are worth what they cost.

Recognition, not rewards with a price tag

Long standing clients get a place in the quarterly technical roundtable, first pick of workshop dates and a direct number rather than a form. That is the whole loyalty scheme.

None of it carries a cash value. It cannot be purchased, transferred to anyone else or exchanged for money or anything else. It is access and priority, and it exists because repeat clients ask better questions.

S.04 Voices

What engineers said afterwards

Collected from the people who actually sat in the sessions. Quoted with permission, surnames used as given.

We had two validators signing on a testnet and no idea which one was doing what. Sperfy sat with our infra lead for an afternoon and found the standby image still carried a copy of the keystore. Fixed the same day, and the runbook he wrote is the one we still follow.
Jake SmithBackend engineer, logistics platform, Rotterdam
The useful part was being told what not to build. We arrived with a plan for a permissioned chain across four partners. Two sessions later we had a signed off design with a boring shared database and one anchoring job. Cheaper to run, and our auditor stopped asking questions.
Mara IonescuPlatform engineer, Cluj-Napoca
Our fee logic broke every time the mempool filled up. Sperfy went through the estimator line by line with me, and the thing that fixed it was replacing a hardcoded number with a percentile read from our own node. Not glamorous. It just worked.
Tomás FerreiraInfrastructure engineer, Lisbon
I have sat through a lot of consultancy decks. This was one man in a room with a whiteboard asking where the withdrawal key lives. Nobody on our side could answer for about a minute. That minute paid for the engagement.
Anneke de VriesStaff engineer, payments team, Utrecht
He wrote the on-call procedure with our SREs rather than for them, so it survived contact with a real 04:00 alert in November. The escalation path in it is the only document from that project nobody has rewritten.
Rareș DobreSite reliability engineer, Bucharest
English throughout, no jargon we had to look up afterwards, and a summary the same evening. My only complaint is that he was honest about how much of our roadmap was unnecessary, which made the following sprint planning quite awkward.
Priya NairSenior software engineer, Berlin

S.05 Contact

Tell us what you are building

Two or three sentences is plenty for a first note. I answer within one working day, and the first call is 30 minutes with no fee and no obligation.

Or call +40 746 162 748

The office

M A Naeli Abdelkarim
84 Strada Ropotului
Andronache, Bucharest 022521
Romania

Direct lines

Phone +40 746 162 748
hello@sperfy.com

Registration

M A Naeli Abdelkarim, PFA
Registrul Comerțului F40/1187/2019
CUI 41276358, Bucharest, Romania

Sperfy

Sperfy is the advisory practice of M A Naeli Abdelkarim, working with companies on blockchain systems from Bucharest since 2019.

Sperfy is a one person consulting practice run by M A Naeli Abdelkarim, an independent adviser registered in Romania. The work is technical and operational guidance, training and documentation. Fees cover advisory time only, clients keep control of their own systems, keys and business decisions, and nothing on this site is legal or tax advice.

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M A Naeli Abdelkarim
84 Strada Ropotului
Andronache, Bucharest 022521
Romania
+40 746 162 748
hello@sperfy.com

PFA, Registrul Comerțului F40/1187/2019 · CUI 41276358
Mon to Fri, 09:00 to 18:00 EET

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