SSH-sleutelbeheer: hoe u alle geprivilegieerde referenties in kaart brengt vóór uw volgende toegangscontrole.

Published: June 2026. Updated: August 2026. Reviewed by Encryption Consulting’s SSH Key Management team.

Every access review rests on a quiet assumption: for each credential granting access to a sensitive system, someone can answer three questions. Who owns this? Why does it exist? Should it still be here? For human accounts tied to a directory and a Human Resources (HR) record, those questions are usually answerable. For the privileged keys that machines, services, and automation use to talk to one another, above all SSH key ownership, they frequently are not, and that gap is what this article closes.

Een SSH-sleutel is een inloggegeven waarmee een computer of gebruiker via een SSH-verbinding verbinding kan maken met een andere computer of gebruiker. Secure Shell (SSH) protocol, very often with administrative or root-level access. Unlike a password, an SSH key does not expire on its own, carries no built-in record of who created it, and is rarely tied to any directory or HR system. That combination, high privilege, long life, and no inherent owner, makes SSH keys the hardest credential to govern.

This is the uncomfortable reality behind many clean-looking attestation campaigns. Reviewers certify the human accounts they can see, while a far larger population of SSH keys, API tokens, and service-account credentials sits outside the review entirely, often with privileged or even root-level access. This article explains why ownership of SSH keys is so hard to establish, how to build a lifecycle ownership model, the exact mapping process to run before your next review, and the audit evidence a SOC 2 or PCI DSS assessor will actually ask for. This piece is the practical how-to for that mapping and review work; for the broader lifecycle program it sits inside, see our Uitgebreide handleiding voor het beheer van de levenscyclus van SSH-sleutels, and for the risk case behind unowned keys, see why unmanaged SSH keys are your biggest privileged access gap.

Why Is SSH Key Ownership So Hard to Track?

Three shifts have turned privileged-key ownership from a housekeeping detail into a governance priority: machine identities now vastly outnumber human ones, a large share of them have no owner at all, and regulators and insurers have begun asking who is accountable for them.

Machine identities now outnumber human ones

Access governance was built for a world where humans were the majority of identities. That world is gone. Non-human identities, including SSH keys, API tokens, and service accounts, now outnumber human ones by a wide and growing margin. If an access review only covers human accounts, it is reviewing a small and shrinking fraction of everything that can actually reach production.

Het echte probleem is het niet-beheerde volume.

The problem is not merely volume; it is unowned volume. A meaningful share of enterprise credentials have no owner in HR or identity systems because the creator left while the account and its access remained, and many non-human identities go a year or more with no rotation. An access review without ownership data cannot make a revoke-or-retain decision; it can only rubber-stamp what is already there.

Why SSH keys specifically resist ownership

An SSH public key on a server is a standing, unsupervised access decision. The operating system simply asserts that whoever holds the matching private key can authenticate as that account. To the SSH daemon, a legitimate administrative key and an orphaned key look identical: no embedded user, no expiry, no link to a directory. NISTIR 7966, NIST’s guidance on SSH access management, specifically calls out the need for strict provisioning, termination, and monitoring controls precisely because the protocol itself provides none (NIST, “Security of Interactive and Automated Access Management Using Secure Shell (SSH),” NISTIR 7966). A typical Linux estate accumulates user keys, root keys, service keys, deployment keys, break-glass keys, vendor keys, and leftovers from decommissioned scripts, and nothing in the protocol tells them apart.

Ownership is further complicated by trust relationships between systems. SSH keys establish automated connections across systems and even between organizations, and an unmapped one can quietly bridge a development system into production. These webs of trust are exactly what let an attacker who compromises one host pivot across many, and they are invisible to a review that looks only at individual accounts.

What Is the SSH Key Ownership Lifecycle Model?

Ownership is not a field you fill in once. It is a role that has to be assigned, confirmed, and reassigned at specific points in a key’s life, or it decays back into the anonymous state that makes access reviews unreliable. A usable lifecycle model attaches an accountable owner to five stages, and defines what changes hands at each one.

The five stages of ownership accountability

• Creation and provisioning: The requester names a business justification, a target system, and an owner at the moment the key is generated, not after the fact. A key created without an owner of record should not be authorized on any server.
• Actief gebruik: The owner is the point of contact for that key for as long as it remains authorized. Usage telemetry (last-authenticated timestamp, source host, target host) is attributed to the owner, not just to the key fingerprint.
• Rotation: Ownership does not reset at rotation; it is the trigger that confirms the owner still needs the key. A rotation event with no response from the owner of record is itself a finding.
• Role change or transfer: When a person changes teams or a service is re-platformed, ownership must transfer explicitly, with a new named owner and a documented handoff. An unacknowledged transfer is functionally the same as an orphaned key.
• Decommission and revocation: The owner of record is responsible for confirming removal from every authorized_keys file where the key was trusted, not just the primary system, and for closing out the record rather than leaving it dormant.

Three ownership models, and when to use each

Not every key fits the same ownership pattern. Matching the model to the key type is what keeps the ownership record accurate instead of becoming another field nobody updates.

• Individueel eigendom: Best for personal administrative keys. One named person, tied directly to their directory identity, is accountable. This is the easiest model to audit and the default for any key tied to a human’s interactive access.
• Team or role-based ownership: Best for shared operational access, such as an on-call rotation’s break-glass key. A named team owns the key, with a designated lead as the point of accountability so the ownership record never resolves to “the team,” which an auditor will reject.
• Service or pipeline ownership: Best for CI/CD and automation keys. The owner is the engineering team or platform group responsible for the pipeline, with the key’s business justification tied to that pipeline’s function rather than to any individual who happened to generate it.

Whichever model applies, a usable ownership record must capture the same core fields: the responsible owner, where the private key lives, what it can access, when it was last used, its age and rotation status, and the business justification for its existence. For SSH specifically, that includes mapping the relationship between a private key on a user machine or in a pipeline and every authorized_keys entry it can satisfy.

How Do You Map Every Privileged SSH Key? A Four-Step Process

Stripped to its core, mapping ownership is four steps. Everything else in an SSH governance program supports one of these.

1. Inventaris: Discover every SSH key across servers, cloud instances, containers, and user machines using both agent-based and agentless methods. Aim for completeness first; a partial inventory produces partial assurance, and any host you did not scan is a host you cannot attest to.
2. Correlate to identity: Match each private key to the human account, service account, or pipeline that actually holds it, using directory data, HR records, and last-used telemetry to separate active keys from dormant ones. A key that correlates to no identity at all is a finding, not a gap to skip over.
3. Eigenaar toewijzen: Attach a named, accountable owner using the model that fits the key (individual, team, or service), and record the business justification for why the key exists. Ownership assignment is not complete until the owner has acknowledged it.
4. Valideren: Check the resulting access against policy: privilege level, environment (does a non-production key reach production?), rotation age, and continued business need. Where validation fails, the outcome is documented remediation, not silent tolerance.

Where no owner can be found in step 3, that absence is itself the finding to escalate to security leadership, not a record to leave blank and move past.

How Should Access Policy Tie to Key Ownership?

Ownership data is only useful if it is enforced through policy, not just recorded for reference. An SSH access policy that is actually tied to ownership should specify who can request a key, what approval is required before it is provisioned, how long it may remain valid before mandatory rotation or re-justification, and which environments carry stricter controls.

In practice, that means production access is governed differently from development access, service accounts follow different rules than human users, and a key that bridges environments, for example a key valid in both staging and production, requires explicit, documented approval rather than being permitted by default. Policy should also define what happens when no owner claims a key during validation: automatic quarantine (blocking further authentication while the finding is investigated) is a safer default than either automatic deletion, which risks breaking an unrecognized but legitimate dependency, or silent retention, which is how orphaned keys accumulate in the first place.

Tying policy to ownership also means the policy has an owner: someone accountable for keeping the rotation schedule, approval workflow, and environment restrictions current as the infrastructure changes, rather than a document written once and never revisited.

What Rotation Triggers Should Be Tied to Ownership Changes?

Calendar-based rotation alone misses the events that actually change risk. Ownership data lets rotation respond to what happened to the owner, not just how much time has passed. The triggers that matter most:

• Uitdiensttreding: When the owner of record leaves the organization or their role is terminated, every key attributed to them must be revoked immediately, not queued for the next scheduled rotation cycle. Disabling a directory account does not revoke the SSH keys that person distributed across servers; each one has to be located and removed individually unless discovery and revocation are automated.
• Role or team transfer: A role change should force re-justification of every key the person owns. If the new role no longer needs the access, the key is revoked rather than silently carried forward.
• Suspected compromise: Any signal of compromise, endpoint infection, a leaked repository, an anomalous authentication pattern, triggers immediate rotation of every key attributable to that owner or host, not just the specific key implicated.
• Vendor or third-party engagement ending: Contractor and vendor keys are reviewed against the ownership record as soon as an engagement closes, since these keys are disproportionately likely to be forgotten.
• Age and policy expiry: Keys exceeding the organization’s maximum cryptoperiod are rotated on schedule, with shorter intervals for high-privilege and service-account keys than for standard user keys, consistent with NIST SP 800-57’s general key-management guidance on cryptoperiods (NIST SP 800-57 Part 1 Rev. 5).

Every trigger above depends on ownership data existing in the first place. Without it, offboarding and role-change rotation cannot happen at all, because there is no record connecting the departing person to the keys they hold.

What Audit Evidence Do You Need for a Formal Access Review?

This is the section that determines whether your review passes. Both major frameworks are explicit that privileged and service accounts, not just human logins, fall in scope, and both expect documented, periodic review rather than a one-time cleanup.

What PCI DSS 4.0.1 requires

PCI DSS 4.0.1 Requirement 7.2.4 requires that all user accounts and access privileges, including third-party and vendor accounts, be reviewed at least once every six months to confirm access is still appropriate and to remove what is not. Requirement 7.2.5 extends least-privilege assignment specifically to application and system accounts, limiting them to only the systems, applications, or processes that require them, and Requirement 7.2.5.1 requires that these accounts undergo periodic review at a frequency the organization defines through a targeted risk assessment, with management sign-off on the result. On the service-account side, Requirement 8.6.1 requires that any system or application account capable of interactive login be managed with the same controls as human accounts, 8.6.2 prohibits hard-coding those credentials in scripts or configuration files, and 8.6.3 requires credential rotation on a schedule set by risk analysis (PCI DSS v4.0 Requirement 7 account review guidance; PCI DSS service account requirements, Schellman; full standard at the PCI Security Standards Council document library). An SSH key with no named owner cannot satisfy any of these, because there is no one to review it against.

What SOC 2 requires

Under the AICPA’s Trust Services Criteria, SOC 2’s CC6.2 and CC6.3 both call for periodic review of access credentials and access roles to confirm they remain appropriate and to remove access that is no longer needed, alongside prompt removal of access when a person no longer requires it (SOC 2 CC6 logical and physical access controls). Auditors treat access control as one of the most evidence-heavy areas of a SOC 2 examination, and they expect that evidence to come from a system of record, not a reconstruction assembled right before fieldwork.

Five artifacts auditors actually ask for

Across both frameworks, the specific evidence an assessor requests reduces to five artifacts:

• A complete key inventory with fingerprint, host, and discovery date, timestamped to the review period.
• An owner-of-record for every key, mapped to a named individual, team, or pipeline, not to a generic account.
• A policy exception log documenting every key that deviates from standard policy, such as a cross-environment key, with the approver and business justification recorded.
• Rotation and revocation history showing when each key was last rotated, and confirming that keys tied to departed staff were revoked at offboarding rather than at the next scheduled cycle.
• A signed review attestation in which the accountable owner or manager confirms, for the review period, that access was checked and is still appropriate.

Beyond the two frameworks above, NIST SP 800-192 defines verification and test methods for confirming that an access control policy is actually enforced as designed, a useful reference when building the validation step of the mapping process into something an assessor can independently check rather than take on faith (NIST SP 800-192, Verification and Test Methods for Access Control Policies/Models).

Wat gaat er mis als het eigenaarschap ontbreekt?

Wanneer een toegangscontrole wordt uitgevoerd zonder eigendomsgegevens voor geprivilegieerde sleutels, zijn de gevolgen concreet.

Faal modus	Wat gaat er mis?	Zakelijke impact
Toegang voor weeskinderen blijft bestaan	Sleutels van vertrokken medewerkers worden nooit gemarkeerd omdat er geen eigenaar is die de verwijdering activeert.	Permanente, niet-traceerbare achterdeuren naar geprivilegieerde systemen.
Recensenten geven toe aan angst.	Teams vermijden het verwijderen van sleutels die ze niet begrijpen.	Verouderde, te brede toegang blijft oneindig lang bestaan.
Trage incidentrespons	Gecompromitteerde sleutels kunnen niet snel worden opgespoord of ingetrokken.	Grotere explosieradius en langere verblijftijd van de aanvaller.
Audit- en compliance-lacunes	Geen gedocumenteerde eigenaar of rechtvaardiging voor bevoorrechte toegang.	Bevindingen en sancties onder PCI DSS, HIPAA, GDPRen soortgelijke regimes.
Valse geruststelling	De verklaring heeft uitsluitend betrekking op personen en is ondertekend als zijnde volledig.	Leidinggevenden zijn van mening dat toegang wordt gereguleerd, terwijl dat niet het geval is.

Manual Spreadsheet Tracking vs. Automated Discovery and Mapping: Which Should You Use?

Studies indicate that 60 to 90 percent of organizations lack a complete inventory of their active SSH keys, and a large share still rely on manual processes such as spreadsheets to track them. That approach breaks down well before the volume most enterprises operate at.

Afmeting	Manual spreadsheet tracking	Automated discovery and mapping
Dekking	Relies on self-reported keys; unscanned hosts are invisible.	Agent-based and agentless scanning finds keys regardless of whether anyone reported them.
Ownership accuracy	Goes stale within weeks as staff and pipelines change.	Refreshed continuously against directory and usage telemetry.
Time to review	Days to weeks of manual reconciliation per cycle.	Review-ready reports generated on demand.
Offboarding response	Depends on someone remembering to check the spreadsheet.	Automated revocation triggered directly by an HR or directory offboarding event.
Controlebewijs	Assembled manually before fieldwork; hard to prove it reflects the actual review period.	Timestamped inventory, rotation, and attestation records generated as a byproduct of normal operation.
Scales to thousands of keys	No; breaks down well under enterprise volume.	Yes; this is the primary reason enterprises adopt it.

Spreadsheets are not a governance failure by themselves; they are a scale failure. A team can track fifty keys in a spreadsheet reasonably well. No team can keep an accurate, continuously updated ownership record for tens of thousands of keys across a distributed estate by hand, which is why automated discovery and mapping is what actually makes ownership data trustworthy at review time.

How Do You Respond When an Orphaned Key Surfaces During a Review?

Finding an unowned, privileged key mid-review is common, and how you respond matters as much as the discovery itself. Treat it as a contained incident, not routine cleanup: first, do not delete it. Removing the wrong key can break backups, deployments, or an emergency access path nobody documented. Instead, quarantine it (block further authentication while leaving it in place) and check its last-used telemetry to determine whether it is actively in use.

Second, trace every host where the key is trusted, not just the one where it was found; a key discovered on one server is frequently authorized on several others through the same trust relationship. Third, stage the eventual removal through configuration management during a maintenance window, and monitor application and pipeline behavior immediately afterward. Fourth, document the finding, the investigation, and the resolution in the same evidence trail used for the broader review, since an auditor will ask how an orphaned key discovered mid-cycle was handled, not just whether one existed. Finally, feed the root cause back into the ownership process: if the key surfaced because a departing employee’s access was never revoked, that is a gap in the offboarding trigger, not a one-off exception.

What Does This Mean for Each Security Stakeholder?

Establishing ownership is not one team’s job. Each function depends on it differently.

• CISO's Een verdedigbare verklaring is nodig. Het goedkeuren van een toegangsbeoordeling waarbij de meeste geprivilegieerde inloggegevens worden uitgesloten, vormt een risico voor de governance en aansprakelijkheid dat direct kan worden beperkt door middel van eigendomsgegevens.
• IAM-teams Het beheer moet verder reiken dan alleen menselijke accounts. Dezelfde levenscycluscontroles die van toepassing zijn op nieuwe medewerkers, medewerkers die overstappen naar een andere organisatie en medewerkers die vertrekken, moeten ook gelden voor serviceaccounts, tokens en sleutels, die zich anders gedragen en vaak een langere levensduur hebben.
• Beveiligingsarchitecten Eigendoms- en blootstellingsgegevens kunnen worden gebruikt om de impact te bepalen, waardoor de reikwijdte van een enkele authenticatie-sleutel wordt beperkt en de tijd dat deze ongewijzigd blijft, wordt afgemeten.
• PKI- en cryptografieteams zijn de natuurlijke eigenaren van de sleutelvoorraad en kunnen SSH-sleutels integreren in hetzelfde beheersysteem dat van toepassing is op certificaten.
• DevSecOps- en platformteams Ze bevatten de context voor pipeline- en servicegegevens en zijn essentieel voor het koppelen van sleutels aan de automatisering die ze gebruikt.
• Audit- en compliance-teams Verkrijg de gedocumenteerde eigenaar en de onderbouwing die een beoordeling verandert van een formaliteit in bewijs van zeggenschap.

What Is the Practical Implementation Workflow?

Closing the ownership gap is a sequenced program, and most of it can be completed before the next review cycle if started deliberately. This builds directly on the four-step mapping process above and turns it into a standing operation.

1. Ontdek alles over sleutels en hosts: Use both agent-based and agentless discovery to find every SSH key on servers and user machines, and extend the same discipline to API tokens and service-account credentials.
2. Koppel sleutels aan eigenaren met behulp van meerdere signalen: Map private keys to the accounts and pipelines that use them, correlate against directory and HR data, and use last-used telemetry to distinguish active keys from dormant ones.
3. Classificeer op basis van privileges en blootstelling, niet alleen op leeftijd: Prioritize keys with root or administrative reach, keys that bridge trust boundaries such as non-production into production, and keys that have not rotated within policy.
4. Scheid ontdekking van sanering: Never begin cleanup by deleting keys you do not recognize. Stage removals through configuration management during a maintenance window and monitor application behavior immediately afterward.
5. Vervang in rapportages de activiteitsstatistieken door blootstellingsstatistieken: Rather than reporting how many items were reviewed, track identities without owners, credentials older than policy, and privileged keys that reach sensitive systems outside normal patterns.
6. Verminder de bestaande populatie zodat toekomstige evaluaties kleiner worden: Wherever possible, move from long-lived keys toward short-lived, automatically rotated credentials so there is simply less standing access to attribute.
7. Zorg voor doorlopend eigendom, niet jaarlijks: Feed discovery and ownership into an ongoing inventory so new keys acquire an owner at creation and orphaned keys are flagged as they appear, rather than waiting for the next campaign.

Beperkingen

Ownership mapping closes a specific gap; it does not solve every SSH governance problem on its own, and it is worth being direct about what it leaves unaddressed.

• It does not replace privileged access management (PAM). Ownership tells you who is accountable for a standing key; it does not by itself broker just-in-time access or eliminate standing credentials the way session-based PAM controls can.
• It requires organizational buy-in to stay accurate. An ownership record that owners do not acknowledge, or that new keys bypass at creation, decays back into the same anonymous state the program was built to fix.
• It does not eliminate risk from legitimate, correctly owned keys. A properly attributed root key is still a high-value target; ownership makes it accountable and revocable, not invulnerable.
• Discovery coverage depends on what you can scan. Air-gapped systems, unmanaged personal devices, and shadow infrastructure outside IT’s visibility will not appear in an inventory built only from known hosts.
• It is one part of a larger credential governance program. API tokens, OAuth secrets, and cloud workload credentials need the same ownership discipline, and treating SSH keys in isolation leaves those other privileged credentials exactly as ungoverned as before.

Wat zou Encryption Consulting aanbevelen?

Het handmatig uitvoeren van dit programma is lastig op bedrijfsniveau, en dat is waar speciaal ontwikkelde tools uitkomst bieden. Bij Encryption Consulting begrijpen we de uitdagingen waar bedrijven voor staan ​​bij het beheren van SSH-sleutels op grote schaal. Onze oplossing, SSH beveiligd, is built to deliver end-to-end key lifecycle security, centralized visibility, and HSM-backed protection, so organizations can manage keys confidently without added complexity.

Enkele belangrijke kenmerken van SSH Secure zijn:

• Gecentraliseerde zichtbaarheids- en eigendomsmapping: Door een combinatie van agentgebaseerde en agentloze detectie vindt SSH Secure elke SSH-sleutel Dit geldt voor alle servers en gebruikerscomputers. Alle sleutels worden opgeslagen in een uniforme inventaris met eigendoms- en gebruiksgegevens, waardoor er geen ongebruikte sleutels meer overblijven en volledige verantwoording binnen de omgeving wordt gewaarborgd.
• Geautomatiseerde sleutellevenscyclusorkestratie: SSH Secure automates the complete key lifecycle, covering secure generation, policy-driven rotation, and revocation. Keys can be rotated or revoked on demand or in accordance with organizational policies. For sensitive operations, SSH Secure can issue ephemeral session-bound keys that expire automatically, so an offboarding or role-change trigger closes the access immediately instead of waiting for the next scheduled cycle.
• HSM-geïntegreerde beveiliging: Alle privésleutels worden gegenereerd en opgeslagen in HSM's. De sleutels worden gegenereerd met behulp van sterke cryptografische algoritmen zoals RSA-4096. ECDSAen Ed25519, die sterke cryptografische bescherming, weerstand tegen cryptanalytische aanvallen en efficiënte prestaties bieden.
• Beleidsgestuurde controle voor cruciale operationele processen: All key operations, such as generation, approval workflows, rotation, and revocation, are enforced through policy-based controls. This ensures consistency across the environment, reduces manual errors, and maintains organization-wide security standards.
• Continue monitoring, auditing en paraatheid voor naleving: SSH Secure provides real-time monitoring of key activities with detailed event logging and built-in anomaly detection. Logs can be integrated with Splunk or Grafana Loki dashboards for advanced visualization, correlation, and alerting, and downloadable audit reports map directly to the evidence artifacts a SOC 2 or PCI DSS assessor will request.

Implementing HSM-backed SSH key management at enterprise scale involves more than choosing the right hardware. It requires discovery, lifecycle orchestration, policy enforcement, and ongoing visibility across a complex environment, which is exactly what SSH Secure is built to deliver.

Conclusie

Een toegangscontrole waarbij niet voor elke bevoorrechte sleutel een eigenaar kan worden aangewezen, is in feite geen controle; het is een gedeeltelijke inventarisatie met een handtekening eraan vast. De referenties die het meest waarschijnlijk schade veroorzaken, de verweesde, overbevoorrechte en onverklaarde sleutels, zijn precies de sleutels die door een controle door een mens glippen en die een voorzichtige controleur waarschijnlijk ongemoeid zal laten. De oplossing is niet een zorgvuldigere ondertekening; het is betere data die aan de ondertekening ten grondslag ligt.

To uncover who owns every privileged key before your next access review, discover comprehensively, correlate keys to owners using directory, pipeline, and usage signals, assign a named owner using the model that fits the key, and validate the result against policy before the auditor does it for you. Tie rotation to the moments ownership actually changes, above all offboarding, and keep the evidence, inventory, owner-of-record, exception log, rotation history, and attestation, current as a byproduct of normal operation rather than a scramble before fieldwork. Do that, and the next access review stops being an exercise in hoping nothing privileged was missed and becomes a confident statement about exactly who can reach what and why. For the fuller lifecycle program this mapping work supports, see our Uitgebreide handleiding voor het beheer van de levenscyclus van SSH-sleutels, and for what happens when this mapping never gets done, see why unmanaged SSH keys are your biggest privileged access gap.

Veelgestelde Vragen / FAQ

How is SSH key ownership different from SSH key inventory?
An inventory tells you a key exists and where. Ownership tells you who is accountable for it, why it exists, and who confirms whether it should stay. A review needs both; an inventory without ownership only tells you what to be worried about, not what to do next.

How often should SSH keys be reviewed for a compliance audit?
PCI DSS 4.0.1 Requirement 7.2.4 sets a minimum of once every six months for general user and privileged accounts, with system and service accounts reviewed at a frequency the organization sets through risk assessment under Requirement 7.2.5.1. SOC 2 does not fix a specific interval, but auditors expect a documented, repeatable cadence, not an ad hoc one-time check.

What should we do with a key we cannot attribute to any owner?
Quarantine it rather than deleting it immediately, trace every host where it is trusted, and escalate it as a finding. Document the investigation and outcome, since an unowned key discovered and resolved during a review is stronger audit evidence than a review that never surfaced it at all.

Does rotating SSH keys on a schedule remove the need for ownership mapping?
No. Rotation replaces the key material; it does not tell you who is accountable for the new key or whether the access is still needed. Without ownership, rotation just produces a fresh key with the same unanswered questions attached.

Can a spreadsheet work for SSH key ownership in a small environment?
For a handful of servers and a small, stable team, a well-maintained spreadsheet can work temporarily. It breaks down as key counts grow into the hundreds or thousands, as ownership changes with staff turnover, and at the exact moment an auditor asks for evidence that reflects the actual review period rather than a reconstruction assembled just before fieldwork.

Referenties

• NIST, “Security of Interactive and Automated Access Management Using Secure Shell (SSH),” NISTIR 7966 (2015)
• NIST SP 800-192, Verification and Test Methods for Access Control Policies/Models
• NIST SP 800-57 Part 1 Rev. 5, Recommendation for Key Management
• PCI Security Standards Council, PCI DSS v4.0.1 Document Library
• PCI DSS v4.0 Requirement 7: Accounts and Access Reviews
• PCI DSS Service Account Requirements, Schellman
• SOC 2 CC6: Logical and Physical Access Controls