Lasting ideas on signature, identity and evidence.
Articles for those who decide how an organization signs: principles, practices and criteria that hold up as rules and technologies change.
What a signature proves, and what it doesn't.
A signature answers four questions: who, what, when and with what intent. Cryptography settles only some of them.
Read the article · 7 min readFoundations of proof
What a signature demonstrates, how it holds up over time and who decides whether it is valid.
What a signature proves, and what it doesn't.
A signature answers four questions: who, what, when and with what intent. Cryptography settles only some of them.
Read the article · 7 min read1.2Time is evidence too.
Why every signature needs a clock that does not belong to the signer.
Read the article · 6 min read1.3Signatures that outlive their algorithms.
How proof stays alive when the cryptography that created it ages.
Read the article · 7 min read1.4Who says a signature is valid.
Validation as a process: trusted lists, revocation and policy.
Read the article · 7 min readIdentity and consent
Knowing who is signing and showing that this person meant to.
Knowing who signs: levels of assurance.
Proofing, credential and authentication: three distinct moments, and a level that risk should decide.
Read the article · 7 min read2.2Impersonation: the patterns that keep coming back.
Techniques change; the shapes of identity fraud repeat.
Read the article · 7 min read2.3Signing on behalf of someone else.
Powers of attorney, representation and systems acting for people.
Read the article · 7 min read2.4Designing consent.
What the screen shows is part of the proof as well.
Read the article · 6 min readFlows and organizations
How to sign well at scale: processes, roles, retention and selection criteria.
From paper to flow: five mistakes when going digital.
The habits of paper that carry over into digital, and how to avoid them.
Read the article · 6 min read3.2Order matters.
Sequences, parallel signing, roles and approvals.
Read the article · 6 min read3.3Keeping without losing.
Archiving, retention periods and disposal of signed documents.
Read the article · 7 min read3.4How to evaluate a signing service.
The questions that never fail, whatever the provider.
Read the article · 7 min readThe institutional map
Who sets the rules for electronic signatures and how they fit together.
eIDAS explained: Europe's architecture of trust.
Identification, trust services, tiers and supervision: how the European model fits together.
Read the article · 7 min read4.2UNCITRAL: the model laws that brought order to the world.
Three United Nations principles behind almost every signature law.
Read the article · 7 min read4.3Mercosur: signing across the border.
Mutual recognition of documents and signatures among the bloc's countries.
Read the article · 6 min read4.4Digital public infrastructure.
Identity, payments and data as public rails: what the World Bank, the IDB, the OECD and CDPI propose, and where signatures fit.
Read the article · 7 min read4.5Who writes the standards.
ISO, ETSI, CEN, IETF, W3C and industry forums: a map of standardization.
Read the article · 7 min readSignatures around the world
How each region answers the same question: when an electronic signature is valid.
Two traditions: the open model and the tiered model.
Technology neutrality or graded presumptions: two paths and their consequences.
Read the article · 6 min read5.2Latin America: from state certificates to tiers.
How signature laws evolved across the region.
Read the article · 7 min read5.3How to read any country's signature law.
Seven questions to understand a legal framework in an afternoon.
Read the article · 5 min read5.4Uruguay: trust at national scale.
A public infrastructure for signature, identity and certification.
Read the article · 7 min readSignatures by sector
What changes, and what does not, when signatures enter a bank, a hospital or a public office.
Banking and finance.
Knowing the customer, preventing fraud and proving every transaction.
Read the article · 7 min read6.2Health: signing where lives are at stake.
Informed consent, medical records and prescriptions.
Read the article · 6 min read6.3The State and its citizens.
Signatures in public service models: identity, single window and a State that both signs and relies.
Read the article · 7 min read6.4Electronic procedures and case files.
How a paperless case file is built, signed and kept.
Read the article · 6 min read6.5People and employment.
Contracts, payslips and policies across working life.
Read the article · 6 min read6.6Flows across departments.
When a document travels through the organization: handoffs, reviews, deadlines and owners.
Read the article · 6 min readThe cryptography of signatures
The mathematics and mechanisms that make signing possible: asymmetric keys, RSA, elliptic curves, hash functions and chains of trust. With labs to try.
The idea that changed cryptography.
One way functions, trapdoors and discrete logarithms: the foundations of public key cryptography, from Diffie and Hellman onward.
Read the article · 9 min read7.2RSA from the inside.
Modular arithmetic, Euler's theorem and why an RSA signature without padding is not a signature.
Read the article · 10 min read7.3Elliptic curves without fear.
Adding points, multiplying by a number and understanding why 256 bits are enough where RSA needs 3072.
Read the article · 10 min read7.4The fingerprint of everything.
How a hash function works on the inside, what it must withstand and how MD5 and SHA 1 fell.
Read the article · 11 min read7.5How a signature is made.
RSA PSS, ECDSA and EdDSA step by step: what is computed, what is verified and where the risk lies.
Read the article · 11 min read7.6The chain of trust.
X.509 certificates, authorities, path validation and revocation: how a public key comes to have a name.
Read the article · 10 min read7.7What exactly gets signed.
CMS, signed attributes and the byte range of a PDF: the anatomy of a signature inside a document.
Read the article · 9 min read7.8When the mathematics is not enough.
Real failures, from Debian to ROCA, that did not break the algorithms but the way they were used.
Read the article · 10 min read7.9After RSA: post quantum signatures.
Shor's algorithm, lattices and hash based signatures: how signatures are getting ready for the next change.
Read the article · 10 min readScale and adoption
Who sustains trust, how signing devices changed and what it takes for a whole country to sign.
The role of trust service providers.
What a trust service provider does and why its supervision underpins everything else.
Read the article · 5 min read8.2From smart card to cloud.
How signing devices evolved: tokens, cards, chip IDs, server modules and remote signing.
Read the article · 5 min read8.3Trends by region.
What repeats and what sets Europe, the Americas, Asia and Africa apart in signature adoption.
Read the article · 5 min read8.4How to bring signatures to everyone.
The real barriers to adoption and the levers that remove them.
Read the article · 5 min read8.5A perspective for governments.
Public policy choices that decide whether a country's digital signature takes off.
Read the article · 6 min readOrchestration architecture
How to design signing platforms that integrate, compose and grow. Design principles and vision; here Signing Flows appears as an example.
Keys to interoperability.
Formats, protocols and interface contracts that let a signature travel between systems.
Read the article · 4 min read9.2Designing composable systems.
Interchangeable parts for identity, signing, time and evidence.
Read the article · 4 min read9.3Orchestration and choreography.
Two ways to coordinate services, and when each one suits a signing process.
Read the article · 4 min read9.4Gateways, connectors and open source.
How to connect providers, trusted lists and open components without lock in.
Read the article · 4 min read9.5Signing inside the workflow.
Integrating signatures with external workflow engines.
Read the article · 4 min read9.6Ready for post quantum.
Crypto agility as an architectural principle, not an emergency migration.
Read the article · 4 min read9.7A vision: signing as a trust layer.
Why we think of Signing Flows as a platform that orchestrates, and where it can grow.
Read the article · 4 min read