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A Turkish e-signature expiry monitor should read the token’s public X.509 certificate, track its notAfter date, and alert the holder and operational owner ahead of expiry. It must check revocation separately: a certificate can be unexpired but revoked, and an expiry countdown alone does not establish that the certificate is usable.
What the monitor needs to establish
A qualified electronic certificate identifies its holder and provider and includes a serial number and validity period. The Information and Communication Technologies Authority of Türkiye (BTK) says every electronic certificate has a clearly specified start and end time for use; it also says validity generally varies from one to three years. That range is general guidance, not a term to assume for an individual token: use the dates in the certificate itself. See BTK’s e-signature FAQ.
In X.509, notBefore and notAfter define the validity interval. RFC 5280 treats the interval as inclusive and requires applications to process both UTCTime and GeneralizedTime encodings. Calculate remaining time against a UTC clock, and do not treat a certificate as currently valid before notBefore or after notAfter. See RFC 5280.
Expiry and revocation answer different questions. BTK advises third parties to check qualification, revocation, validity, and restrictions on certificate use. An expiry monitor can report the date and a separate status check, but should not label an unexpired certificate simply “valid” unless the system has performed the relevant checks.
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Identify certificates reliably
Do not key the inventory on a display name alone. Names can be ambiguous or change; use stable certificate metadata to distinguish certificates and associate them with the provider and responsible people.
- Issuer and provider: record the issuing provider and issuer information from the certificate.
- Serial number: retain the certificate serial number as a distinct identifier.
- Subject or holder reference: use an appropriate holder identifier while limiting access to personal data.
- Validity: store the parsed
notBeforeandnotAftervalues, including the source certificate and the time it was read.
BTK’s electronic certificate service provider list is a starting point for provider identification, but provider status and documentation can change. Confirm the current provider and supported certificate profile when configuring each integration.
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Read and parse the public certificate
Design the monitor around public certificate metadata. It does not need, and should never request or export, the private signing key. The certificate may be read from a software export or from a physical token, depending on the provider’s supported workflow and the deployment’s hardware.
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- Choose the supported input: determine whether the deployment imports a certificate file or reads the certificate through the provider’s token software and a compatible reader.
- Parse the X.509 certificate: extract issuer, serial number, subject or holder reference,
notBefore, andnotAfter. - Handle both time encodings: support UTCTime and GeneralizedTime as required by RFC 5280 rather than assuming a single representation.
- Normalize time: compare parsed dates with a UTC clock; calculate the remaining interval without silently changing the certificate’s encoded instant.
- Validate the record: flag unreadable, malformed, or mismatched certificates for attention instead of creating a misleading expiry date.
A Turkish ESHS certificate profile is provider-specific evidence, not proof that every provider uses the same token interface. The TURKTRUST profile is one provider-specific example. Test the actual provider, certificate, token, reader, and operating system combination before claiming support or planning unattended monitoring.
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Keep expiry and revocation as separate states
Store at least two independent results: the certificate’s time validity and the most recent revocation-status result. A failure to reach a status service is not evidence that the certificate is good. Show unavailable, stale, unknown, and revoked as distinct states, and record when the last successful status check occurred.
OCSP
Online Certificate Status Protocol (OCSP) supports querying the status of an individual certificate, either without downloading a certificate revocation list (CRL) or as a supplement to one. The responder can return good, revoked, or unknown; these results must remain distinct. In particular, good does not replace checking that the certificate is within its notBefore/notAfter interval. Validate the response and its freshness, and surface responder failures rather than converting them to a positive status. See RFC 6960.
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CRLs
A CRL is a provider-issued list of revoked certificates. The monitor should check its update timing, including thisUpdate and nextUpdate, and treat an out-of-date list as stale rather than as a current all-clear. CRLs are periodically issued, so the interval between publications affects how quickly revocation information can be reflected. RFC 5280 describes CRL processing and timing considerations at RFC 5280.
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Use the OCSP responder or CRL location advertised for the certificate or provider when available and permitted in the deployment. Turkish ESHS providers maintain certificate status information and prepare CRLs; BTK’s Turkish e-signature FAQ describes provider responsibilities. Record the source used for each check so operators can distinguish a provider-side outage from a certificate result.
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Configure useful expiry alerts
Set lead times to suit the organization’s renewal process and the consequences of interruption; the sources do not prescribe a universal alert schedule. Base every reminder on the actual notAfter value, not on BTK’s general one-to-three-year validity range.
- Make alert thresholds configurable by the operator rather than hard-coding one schedule.
- Send reminders to both the certificate holder and an operational owner, with enough identifying metadata to locate the right certificate.
- Include the expiry date, remaining time, last successful revocation check, and any stale or unavailable status warning in the alert.
- Escalate when a certificate cannot be read or a status check repeatedly fails; do not suppress operational problems behind a countdown.
- Keep an auditable history of certificate changes, alerts, and status-check outcomes.
Validate provider and token support before deployment
There is no established universal Turkish token-reading interface in the cited material. Provider, token, reader, operating-system support, and status-service behavior must be confirmed for each supported setup. BTK’s provider list and legislation index provide starting points; consult current provider documentation and test the deployed hardware and software rather than inferring compatibility from another ESHS’s profile.
Law No. 5070 on Electronic Signature entered into force on July 23, 2004, according to BTK’s general information page. That date supplies Turkish legal context; it does not establish a particular token’s interface or compatibility.
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Operational checks before relying on alerts
- Verify that the monitor reads the intended certificate and associates it with the right holder and provider.
- Test certificates using both UTCTime and GeneralizedTime encodings.
- Confirm that the displayed validity result changes correctly at the certificate’s start and end boundaries.
- Exercise OCSP outcomes, including
good,revoked, andunknown, plus timeout and stale-response handling. - Test CRL freshness handling where CRLs are used.
- Confirm that reminders reach both the holder and operational owner, and that failed certificate reads and status checks are visible.
- Recheck provider endpoints and documentation when they change; the provider registry and services are not static.
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