Awarded once after a correct answer.
Minimize personal data before choosing the ledger
Useful first : Hashes, keys and signatures · Tokenization and real-world asset rights
Reading path · 10 / 18 · Advanced
A public address can be personal data when it relates to an identifiable individual.
The essentials
A public address can be personal data when it relates to an identifiable individual. Pseudonymity is not the same as anonymisation. Hashing personal information does not automatically remove it from data-protection scope, especially when it can be linked back or tested against likely inputs.
How it works
Public replication and durable records can complicate correction, erasure, retention and accountability. Decide whether personal data needs to be on-chain at all. Off-chain storage with carefully designed references may reduce exposure, but the reference itself still needs analysis. Identify roles and lawful processing grounds before implementation.
What to watch
For example, publishing a customer’s identity documents on-chain would expose them far beyond ordinary verification needs. A design review should examine purpose limitation, access, retention, data-subject rights and cross-border implications. Technical immutability should not be assumed to override legal requirements or make every blockchain use impermissible.
Understand the details
A public address or hash can still relate to an identifiable person depending on context and available information. Pseudonymization is not automatically anonymization. Start by asking which data is necessary, who determines its use, who receives it and how long it must remain available. Technical permanence does not remove data-protection responsibilities.
Boundaries and common mistakes
Keeping sensitive records off-chain can reduce exposure, but an on-chain pointer or commitment still needs assessment. Encryption and key deletion do not automatically settle every legal question about erasure. Roles, lawful basis, rights handling and any required impact assessment must be considered for the actual design.
The mechanism at a glance
- 01Purpose and minimum data
- 02Off-chain access controls
- 03Assess public commitment
- 04Rights and retention process
Read these as connected concepts, not necessarily consecutive steps.
Read the explanation
A public address or hash can still relate to an identifiable person depending on context and available information. Pseudonymization is not automatically anonymization. Start by asking which data is necessary, who determines its use, who receives it and how long it must remain available. Technical permanence does not remove data-protection responsibilities.
Put the mechanism into context
A diploma service proposes publishing names and grades on a public chain. Redesign the information flow with the minimum necessary proof and controlled off-chain records. Identify what a public observer could still link or infer.
Apply it in the workshop →What this mechanism does not guarantee
Keeping sensitive records off-chain can reduce exposure, but an on-chain pointer or commitment still needs assessment. Encryption and key deletion do not automatically settle every legal question about erasure. Roles, lawful basis, rights handling and any required impact assessment must be considered for the actual design.
The distinction that changes the analysis
Replacing a name with an address does not necessarily stop someone linking the record back to a person. Draw the auxiliary data that could make that link possible. Consider whether the information needs to be public before selecting a storage mechanism.
Explain it yourself
Revisit the case above. Name what is established, what remains to be checked and the evidence needed to conclude. A strong answer addresses both sides of the diagram.
Apply the lesson to a case
A diploma service proposes publishing names and grades on a public chain. Redesign the information flow with the minimum necessary proof and controlled off-chain records. Identify what a public observer could still link or infer.
Someone can hash likely names or combine other information to test a match. Assess identifiability and linkage in context rather than assuming the hash is anonymous. Document the data flow and remaining risks before selecting a permanent public record.
Terms in this lesson
- Hash
- A fixed-length fingerprint computed from data by a hash function. It checks consistency, not truth.
Prepare a correction note
Describe the passage and the proposed correction. This creates a local note for you to share; it sends nothing. Do not include personal or confidential information.