Skip to main content

X.509 Certificates

Status: Scaffold — content in progress

X.509 is the ITU-T standard for public key certificates, used in TLS, code signing, email (S/MIME), and identity authentication.

Encoding Formats

FormatExtensionDescription
DER.der, .cerBinary ASN.1 encoding
PEM.pem, .crt, .keyBase64-encoded DER with headers
PKCS#12 / PFX.pfx, .p12Bundle: cert + private key (password-protected)
PKCS#7 / P7B.p7bCertificate chain, no private key

Certificate Validation

  1. Signature validation (chain to trusted root)
  2. Validity period check
  3. Revocation check (CRL or OCSP)
  4. Key usage / EKU check (is this cert allowed for this purpose?)
  5. Name check (does the SAN match the expected identity?)

Certificate Theft Targets

LocationToolMethod
Windows Certificate Storecertutil, Mimikatz crypto::certificatesExport with private key
Current user storePowerShell Get-ChildItem Cert:\CurrentUser\MyExport if non-exportable flag bypassed
PKCS#12 filesFile system search*.pfx, *.p12
MemoryMimikatzCAPI/CNG key extraction
TopicLink
PKI Overviewpki-overview
Certificate Theftcertificate-theft