94 lines
7.1 KiB
Markdown
94 lines
7.1 KiB
Markdown
# checker-email-keys
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DANE-Email posture checker for happyDomain.
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Runs a comprehensive testsuite on a domain's DNS-published OpenPGP key
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(`OPENPGPKEY`, [RFC 7929][rfc7929]) or S/MIME certificate (`SMIMEA`,
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[RFC 8162][rfc8162]) and renders an actionable HTML report whose top
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block nudges the user toward the fix for the most common failure
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scenarios.
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This checker binds to the happyDomain services:
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- `abstract.OpenPGP`: individual user's PGP key, owner-hashed below
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`._openpgpkey.<zone>`.
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- `abstract.SMimeCert`: user's S/MIME certificate, owner-hashed below
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`._smimecert.<zone>`.
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[rfc7929]: https://www.rfc-editor.org/rfc/rfc7929
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[rfc8162]: https://www.rfc-editor.org/rfc/rfc8162
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## Security scope
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This checker validates DNS publication and the structure/metadata of the
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keys it finds. It does **not** cryptographically verify them:
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- OpenPGP signatures (self-signatures, third-party certifications,
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revocations beyond the presence of a revocation packet) are **not**
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verified.
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- S/MIME certificate chains are **not** built or validated against any
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trust anchor; revocation (CRL/OCSP) is **not** checked.
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- Authenticity of the records themselves is delegated to the
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validating resolver via the DNSSEC `AD` flag (see
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`dnssec_not_validated`). Run the checker against a resolver you
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trust to perform DNSSEC validation.
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Treat a green report as "the record is well-formed and DNSSEC-signed",
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not as "the key is trustworthy".
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## Rules
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| Code | Description | Severity |
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|-----------------------------------|---------------------------------------------------------------------------------------------------|---------------------|
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| `dns_query_failed` | Verifies that the DNS lookup for the OPENPGPKEY/SMIMEA record succeeds. | CRITICAL |
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| `dns_no_record` | Verifies that an OPENPGPKEY/SMIMEA record is published at the expected owner name. | CRITICAL |
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| `dns_record_mismatch` | Verifies that the record returned by DNS matches the service-declared record. | WARNING |
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| `dnssec_not_validated` | Verifies that the record is authenticated by DNSSEC (AD flag set). | CRITICAL |
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| `owner_hash_mismatch` | Verifies that the owner-name first label equals hex(sha256(username))[:28]. | CRITICAL |
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| `pgp_parse_error` | Verifies that the OPENPGPKEY record decodes as a valid OpenPGP key. | CRITICAL |
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| `pgp_primary_revoked` | Verifies that the OpenPGP primary key carries no revocation signature. | CRITICAL |
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| `pgp_primary_expired` | Verifies that the OpenPGP primary key has not passed its self-signature expiry. | CRITICAL |
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| `pgp_primary_expiring_soon` | Warns when the OpenPGP primary key expires within the configured window. | WARNING |
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| `pgp_weak_algorithm` | Verifies that OpenPGP keys do not use legacy algorithms (DSA/ElGamal). | WARNING |
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| `pgp_weak_key_size` | Verifies that OpenPGP RSA keys meet the minimum 2048-bit size (3072+ preferred). | CRITICAL |
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| `pgp_no_encryption_subkey` | Verifies that at least one active OpenPGP key advertises encryption capability. | CRITICAL |
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| `pgp_no_identity` | Verifies that the OpenPGP key carries at least one self-signed User ID. | WARNING |
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| `pgp_uid_mismatch` | Checks that at least one OpenPGP UID references <username@...>. | INFO |
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| `pgp_multiple_entities` | Verifies that the record carries a single OpenPGP entity (RFC 7929). | WARNING |
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| `pgp_record_too_large` | Verifies that the OPENPGPKEY record stays below 4 KiB to fit typical UDP answers. | WARNING |
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| `smimea_bad_usage` | Verifies that the SMIMEA usage field is 0, 1, 2, or 3. | CRITICAL |
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| `smimea_bad_selector` | Verifies that the SMIMEA selector field is 0 (Cert) or 1 (SPKI). | CRITICAL |
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| `smimea_bad_match_type` | Verifies that the SMIMEA matching type is 0 (Full), 1 (SHA-256), or 2 (SHA-512). | CRITICAL |
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| `smimea_cert_parse_error` | Verifies that the SMIMEA record decodes as a valid X.509 certificate or SPKI. | CRITICAL |
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| `smimea_cert_not_yet_valid` | Verifies that the S/MIME certificate's NotBefore is in the past. | CRITICAL |
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| `smimea_cert_expired` | Verifies that the S/MIME certificate's NotAfter is in the future. | CRITICAL |
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| `smimea_cert_expiring_soon` | Warns when the S/MIME certificate expires within the configured window. | WARNING |
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| `smimea_no_email_protection_eku` | Verifies that the S/MIME certificate advertises the emailProtection EKU. | CRITICAL |
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| `smimea_missing_key_usage` | Verifies that the certificate carries digitalSignature and/or keyEncipherment key usage. | WARNING |
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| `smimea_weak_signature_algorithm` | Verifies that the certificate is not signed with a deprecated algorithm (MD2/MD5/SHA-1). | CRITICAL |
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| `smimea_weak_key_size` | Verifies that SMIMEA RSA keys meet the minimum 2048-bit size (3072+ preferred). | CRITICAL |
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| `smimea_self_signed` | Flags self-signed certificates paired with PKIX-EE (usage 1). | INFO |
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| `smimea_email_mismatch` | Checks that at least one email SAN on the certificate begins with <username>@. | INFO |
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| `smimea_hash_only` | Notes that SMIMEA matching types 1/2 transport only a digest, preventing certificate inspection. | INFO |
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## Options
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| Id | Type | Default | Description |
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| --- | --- | --- | --- |
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| `resolver` | string | *(system)* | Validating resolver to query; comma-separated list accepted. |
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| `certExpiryWarnDays` | number | 30 | Raise an `expiring_soon` warning within this window. |
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| `requireDNSSEC` | bool | true | When false, missing AD is a warn instead of crit. |
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| `requireEmailProtection` | bool | true | When false, missing `emailProtection` EKU is a warn instead of crit. |
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Auto-filled by the host: `domain_name`, `subdomain`, `service`,
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`service_type`.
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## Running
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```bash
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# Plugin (loaded by happyDomain at startup)
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make plugin
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# Standalone HTTP server
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make && ./checker-email-keys -listen :8080
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```
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