How to Create a Secure Re-Identification Key (Storage + Access Rules)

A secure re-identification key (also called a “linking file” or “code key”) is a separate record that connects anonymized transcripts to real identities when you truly need to re-contact someone or verify data. To keep people safe and reduce legal and ethical risk, store the key separately from transcripts, encrypt it, and limit access to a small number of named roles. This guide walks you through practical storage and access rules, plus a simple SOP for creating, updating, emergency-accessing, and disposing of the key at study close.

• Primary keyword: secure re-identification key

Key takeaways

• Keep the re-identification key physically and logically separate from anonymized transcripts.
• Use strong encryption and restricted, role-based access with a clear owner.
• Plan for updates and emergencies (break-glass access) before you need them.
• Log every access and change, and dispose securely at study close based on your retention rules.

What a re-identification key is (and what it is not)

A re-identification key is a mapping that links an internal study ID (like P0123) to direct identifiers (like a participant’s name and contact details). You use it to re-contact participants, correct records, handle withdrawals, or follow up on safety issues.

It is not the transcript itself, and it is not a “nice to have” spreadsheet sitting next to your files. If someone gets both the anonymized transcripts and the key, anonymization no longer protects participants.

What to include in the key (keep it minimal)

Include only what you need to perform approved study tasks. A smaller key is easier to protect.

• Required: Study ID ↔ participant identity (name or unique participant record ID).
• Often needed: Contact method (email/phone) and recruitment source code.
• Sometimes needed: Consent version/date, withdrawal status, notes for re-contact rules.
• Avoid if possible: Full addresses, dates of birth, government IDs, and anything not essential.

What to put in anonymized transcripts instead

Anonymized transcripts should contain the study ID and de-identified context, not direct identifiers. Replace names and unique details with consistent labels.

• Use participant labels: [P0123] and interviewer labels: [INT01].
• Generalize unique facts: “a small town in Ohio” instead of the town name.
• Redact direct identifiers: emails, phone numbers, account numbers, and exact street addresses.

Separate storage: the most important rule

Store the mapping key separately from anonymized transcripts in both location and access path. “Separate” means that a person (or attacker) cannot easily get both sets of files with one login or one folder permission.

What “separate” looks like in practice

• Different systems: transcripts in your research drive; key in a secure vault or restricted database.
• Different permission groups: most staff can access transcripts; only key custodians can access the key.
• Different encryption keys: transcripts and key encrypted under different keys or vault policies.

Common separation mistakes

• Saving the key in the same project folder “but with a different filename.”
• Keeping the key in a personal laptop “temporarily,” then forgetting it.
• Putting the key in an email thread or chat message for convenience.
• Storing the key in a shared spreadsheet without strong access controls.

Encryption and access rules that hold up under pressure

You want controls that still work when deadlines hit, staff change, or an incident happens. Think in layers: encryption, access control, and auditing.

1) Encrypt the key at rest and in transit

Use encryption for stored files (“at rest”) and when you send or sync data (“in transit”). If your organization provides an approved encrypted storage or vault, use it instead of building your own.

• At rest: store the key inside an encrypted vault, encrypted database, or encrypted file container.
• In transit: use secure transfer methods (HTTPS/TLS) and avoid emailing the key as an attachment.
• Password handling: never store vault passwords in the same place as the key.

If you work in health research or handle protected health information, align your controls with relevant rules and internal policies. In the U.S., HIPAA Security Rule safeguards provide a baseline for administrative, physical, and technical protections (see the HHS HIPAA Security Rule overview).

2) Restrict access using role ownership and least privilege

Assign clear role ownership for the key, then grant access only to roles that must perform re-identification. “Least privilege” means people get the minimum access needed for their job.

• Key Custodian (Owner): accountable for storage, access approvals, updates, and disposal.
• Backup Custodian: limited backup access in case the owner is unavailable.
• Study Lead/PI: approves re-identification requests based on protocol and consent.
• Analysts/Transcribers: access to anonymized transcripts only, not the key.

3) Add strong authentication and session controls

• Require multi-factor authentication (MFA) for key access.
• Use time-bound access when possible (temporary permissions that expire).
• Disable access quickly during offboarding or role changes.

4) Audit and log every access

Logging is your safety net and your proof of good controls. Record who accessed the key, when, what they did, and why.

• Access log: date/time, user, action (view/edit/export), ticket or approval reference.
• Change log: what changed (new ID added, contact updated), who approved, and version number.
• Review cadence: monthly or per study milestone, depending on sensitivity.

Choosing a storage method: decision criteria

The “best” storage depends on your environment, but the decision criteria stay the same. Pick the simplest option that meets security, audit, and availability needs.

Option A: Secure vault (preferred for many teams)

• Pros: strong encryption, access policies, MFA support, logging, and easier key rotation.
• Cons: requires setup and admin support; some teams need training.

Option B: Restricted database table

• Pros: structured data, controlled queries, strong audit trails, easy role-based access.
• Cons: requires database management and careful query permissions.

Option C: Encrypted file container with strict permissions

• Pros: simple; works offline; can be stored in an approved secure drive.
• Cons: version control and logging can be weaker if you don’t add process controls.

Quick checklist for any storage option

• Can you enforce MFA and least-privilege access?
• Can you log access and changes?
• Can you rotate credentials and recover from staff turnover?
• Can you keep the key separate from transcripts and raw audio?
• Can you dispose of it securely at study close?

Simple SOP: key creation, updates, emergency access, and disposal

Use this SOP as a starting point, then align it with your IRB, privacy office, and IT policies. Keep the SOP short, assign owners, and make it easy to follow under stress.

Scope and roles

• Scope: re-identification key for study transcripts and related qualitative data.
• Key Custodian: maintains the key and grants access.
• Backup Custodian: supports emergency continuity.
• Approver (PI/Study Lead): authorizes re-identification events.

1) Key creation SOP (Day 0–Day 7 of study start)

• Create a unique Study ID format: e.g., P0001, P0002 (no embedded meaning like site initials if not needed).
• Set up secure storage: vault or restricted database, with MFA and logging enabled.
• Create the key structure: columns for Study ID, participant identity reference, contact method, consent date, withdrawal flag.
• Assign ownership: name the Key Custodian and Backup Custodian in writing.
• Set permissions: only custodians can access; approver can request re-identification but not necessarily access the full key.
• Document location: record the storage system name and path in a controlled study admin record (not in a shared project folder).

2) Key update SOP (ongoing maintenance)

• Trigger events: new participant added, contact info changed, withdrawal requested, data correction needed.
• Update process: Key Custodian edits the key in the secure system, then saves a new version or commits the change with a note.
• Double-check: verify the Study ID matches the correct participant record before saving.
• Log the change: include date/time, editor, reason, and approver reference when required.
• Notify only as needed: do not email the updated key; share updates through controlled workflows.

3) Routine access SOP (standard re-identification request)

• Request: analyst or coordinator submits a request with Study ID, reason, and required fields (minimum necessary).
• Approval: PI/Study Lead approves based on protocol, consent, and participant preferences.
• Access grant: Key Custodian provides the needed info, preferably as a time-limited view or single-use extract.
• Recordkeeping: log the request ID, what was shared, who received it, and when.
• Clean-up: delete temporary extracts from local devices and shared folders immediately after use.

4) Emergency (“break-glass”) access SOP

Emergency access is for rare cases like urgent safety follow-up or legal obligations. Define it now so nobody improvises later.

• Define emergencies: specify examples and thresholds in the study governance plan.
• Two-person rule: require at least two authorized roles (Approver + Custodian, or Custodian + Backup Custodian) to proceed.
• Time limit: grant access for the shortest window possible, then remove it.
• Document fast: log what happened within 24 hours, including why emergency access was needed.
• Post-incident review: review whether controls worked and whether SOP needs updates.

5) Credential rotation and staff changes SOP

• Rotation cadence: rotate vault credentials, API keys, or database passwords on a set schedule or after any suspected exposure.
• Offboarding: remove access the same day someone leaves the project.
• Role change: re-approve access when someone changes responsibilities, even if they stay on the team.

6) Secure disposal SOP (study close)

At study close, you either securely dispose of the key or archive it under strict retention rules. Decide which applies based on your protocol, consent language, contracts, and applicable law.

• Confirm retention requirements: check IRB/protocol, sponsor contract, and organizational policy.
• Freeze final version: export a final, encrypted archive only if retention is required, then lock permissions.
• Dispose securely: if disposal is approved, delete using your organization’s secure deletion process and confirm backups and exports are handled.
• Revoke access: remove all user and service accounts tied to the key.
• Close out documentation: record date of disposal/archival, who approved, and where proof is stored.

If you handle personal data under privacy regimes like GDPR, align disposal and minimization practices with those requirements (see the GDPR principles in Article 5 for purpose limitation and storage limitation concepts).

Pitfalls to avoid (and safer alternatives)

Most failures happen because teams choose convenience over separation and process. Use these safer defaults to prevent common mistakes.

• Pitfall: one person holds the only copy of the key. Safer: assign a backup custodian and documented emergency access.
• Pitfall: re-identification done “informally” in chat. Safer: require a request + approval + log entry.
• Pitfall: exporting the full key for a small task. Safer: share only the single record or field needed.
• Pitfall: storing the key with raw audio files. Safer: keep raw audio restricted and separate as well.
• Pitfall: unclear ownership. Safer: name a key custodian role and keep it current.

Common questions

Is a re-identification key the same as anonymization?

No. Anonymization removes or masks identifiers in the transcript, while the key preserves a controlled link back to identity for approved reasons.

Who should have access to the re-identification key?

Only named roles that must re-identify participants, usually a Key Custodian and a Backup Custodian, with approvals handled by the Study Lead or PI.

Can I store the key in a spreadsheet?

You can, but it needs strong controls: encryption, restricted access, MFA where possible, and reliable logging. A secure vault or restricted database often makes those controls easier to enforce.

How often should we rotate passwords or credentials?

Follow your organization’s policy, and rotate immediately after staff turnover or suspected exposure. If you do not have a policy, set a reasonable schedule and document it in the SOP.

What should we do if the key is exposed?

Treat it as a security incident: revoke access, preserve logs, notify internal security/privacy teams, and follow your incident response process. You may also need to notify an IRB, sponsor, or affected individuals depending on rules and contracts.

Do we need an emergency access process if we rarely re-identify?

Yes, because rare events often happen under pressure. A simple two-person, time-limited “break-glass” rule prevents rushed decisions.

When should we destroy the key?

At study close, destroy it if you no longer need re-identification and retention rules allow disposal. If you must retain it, archive it encrypted, lock down access, and document the retention basis.

Where transcripts and captions fit into a secure workflow

Security works best when the re-identification key lives in its own lane and everything else stays de-identified. That includes transcripts shared with analysts, stakeholders, or vendors.

• Use anonymized transcripts for review and analysis.
• Keep the key out of transcription and captioning workflows unless re-identification is explicitly required.
• Consider adding a final check step before distribution to confirm identifiers are removed.

If you need help preparing accurate text from audio while keeping your privacy workflow clean, GoTranscript offers transcription proofreading services and closed caption services that can support teams working with structured review processes.

Helpful next step

If you are setting up a study workflow and want a clean separation between anonymized transcripts and your re-identification key, it helps to start with consistent, high-quality transcripts and a clear handling process. GoTranscript provides the right solutions for teams that need dependable text output as part of a privacy-aware workflow, including professional transcription services.