The stamp that loses its evidentiary value.
A Pix payment receipt is digitally signed. The signature works like a notary’s stamp: years later, in a dispute or a lawsuit, it proves that the transfer happened, that way, at that time.
Once a quantum computer exists, that stamp faces two risks. Backwards: whoever recovers the private key from the public one can fabricate "old" receipts that look legitimate, and then no old receipt proves anything on its own. Forwards: every new signature must be made with the new lock from day one.
The second risk is solved by switching the signature algorithm (ML-DSA, the NIST standard). The first is harder: it requires re-signing or time-stamping the old archive before the key falls. None of this is quick, and none of it starts without a list of what exists.
Where the requirement should land first.
Open banking: the country’s largest surface
Statements, balances, investments and credit data travel between institutions with today’s connection padlock (TLS with elliptic curves). Whoever records those connections now can open them when the computer arrives: harvest now, decrypt later.
Example: a 12-month statement shared today with a fintech, with consent, becomes readable to whoever recorded the connection.
Pix and DICT: signatures that must hold for years
Institutions authenticate to the Pix key directory with ICP-Brasil certificates (elliptic curve or RSA), and queries and receipts are signed. Their evidentiary value must last for years.
Example: a receipt disputed in 2031 must still prove that the 2026 transfer happened.
Privacy law: "suitable technical measures"
Article 46 of Brazil’s data protection law (LGPD) requires suitable technical measures to protect personal data. With NIST standards published in 2024 and experts warning publicly, keeping long-lived data under the old lock alone becomes hard to defend later.
Example: the question in a 2030 class action will be "you knew in 2026, what did you do?".
Drex: sophisticated but classical cryptography
Brazil’s digital real uses zero-knowledge proofs for confidentiality between participants, on elliptic curves. There is no ready post-quantum drop-in: migrating Drex means rethinking the project’s cryptography, and that drags the whole supplier chain along.
Example: a custody supplier to a participating bank must be ready before the announcement, not after.
Other central banks have moved
According to our April 2026 survey, the BIS, the ECB, the Fed, Singapore’s authority and the Bank of Canada had published studies, pilots or guidance on the subject. BACEN had no specific public document yet.
Example: a regulator known as technically strong is unlikely to be last in the G20.
Who has already moved.
| Authority | What it did | Status |
|---|---|---|
| BIS (the central banks’ bank) | Study on post-quantum cryptography for central banks | published in 2024 |
| ECB (euro area) | Pilot with the Bundesbank and Banque de France | active in 2024–2025 |
| Federal Reserve (US) | Task force and guidance for banks | in development |
| MAS (Singapore) | Guidance on quantum readiness for financial institutions | published in 2024 |
| Bank of Canada | Technical study on migration in settlement | published in 2023 |
| BACEN (Brazil) | No specific public document | pending as of Apr 2026 |
Survey from the original version of this analysis (April 2026). Check each item against each regulator’s primary source before citing it.
When the rule should arrive.
BACEN tends to adopt international recommendations with an 18-to-24-month lag, and open banking took about 18 months from consultation to resolution. At that pace, and with the BIS study in 2024, the projection below is our reading.
It could come 6 to 12 months earlier after a major cryptographic leak, a quantum breakthrough announcement or a rushed rule from another G20 regulator. It could also slip, but every year of delay shortens the window for whoever has not started.
| When | What we expect |
|---|---|
| Q2–Q3 2026 | BACEN technical notice on emerging risks in cryptography, no obligation. |
| Q4 2026 | Public consultation on cryptographic inventory at institutions. |
| Q1–Q2 2027 | Resolution with a mandatory inventory schedule and migration plan. |
| H2 2027 | New certificates with hybrid support. |
| 2028 | Mandatory switch on critical open-banking and DICT channels. |
| 2029 | End of old locks in new services; the quantum computer enters the window of possibility. |
Four things before the first notice.
Cryptographic inventory
Where RSA, elliptic curves and Diffie-Hellman appear: certificates, SSH keys, signed tokens, ICP-Brasil certificates, API keys, key vaults (HSMs), payment modules. Automated, not a spreadsheet.
Exposure score
For each system, how long the data must stay secret: 7 years of transactions, 20 of medical records, contracts valid in 2040. What must stay secret beyond 2029 is already exposed today.
Hybrid exchange
Agree on keys with the old lock and the new one (ML-KEM) at the same time, as Google, Cloudflare and iMessage already do. It protects against the quantum computer and against a flaw in the new lock.
Key governance
Which keys exist, where they live, who has access, when they were rotated, with which algorithm and validity. Most institutions do not know, and that is the first debt to pay.
The inventory and exposure score in 24 hours.
The free assessment delivers the critical inventory, a 90-day roadmap and an investment estimate, as a PDF.
The list of where cryptography is used and of which kind. Nothing gets switched without it, and it is what the regulator should ask for first.
An old signature’s ability to keep proving something. It disappears once its key can be recovered.
Two locks on the same door: the old one and the new one. Opening one is not enough.
Where this could be wrong.
It is a projection
None of the dates on this page was announced by BACEN. It is our reading of precedents, and it could be wrong either way.
The 18-to-24-month pace is our observation
We took it from earlier cases (Basel, open banking, privacy law in the financial sector). It is not a written rule.
The international survey needs checking
The table of other regulators comes from the April 2026 version of this analysis. Check the primary sources before using it in an official document.
24 to 36 months is for a sizeable institution
A small institution with fewer systems may switch faster. A large one, with legacy systems and suppliers, may take longer.
← Post-quantum · stickybit.com.br
- Original version of this analysis: Andrey Andrade, Stickybit, 6 April 2026; revised September 2026.
- Filippo Valsorda, "CRQC timeline", 2026.
- NIST: FIPS 203 (ML-KEM) and FIPS 204 (ML-DSA), August 2024.
- LGPD, Law 13,709/2018, art. 46.
- BIS, ECB, Federal Reserve, MAS and Bank of Canada documents cited as in the April 2026 survey (check the primary source).