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Verify a certificate chain

Source: R/x509.R
cert_chain_verify.Rd

Builds the path from a leaf certificate to a trust anchor you supply, verifying each signature, each validity window, and the constraints that stop a certificate being used for something it was not issued for.

Usage

cert_chain_verify(
  leaf,
  trust,
  intermediates = list(),
  at_time = Sys.time(),
  purpose = NULL,
  crls = list(),
  policies = NULL,
  revocation = c("supplied", "fetch", "none")
)

Arguments

leaf

The certificate to validate, from cert_parse() or anything cert_parse() accepts.

trust

A list of trust anchors – the certificates you have decided to believe. A chain that does not reach one of these fails.

intermediates

Optional further certificates to build the path through. They are not trusted by being supplied; they still have to verify.

at_time

The time to check validity windows at. Defaults to now.

purpose

Optional extended key usage the leaf must carry, as a name ( "timeStamping", "codeSigning", ...) or an OID.

crls

Optional list of CRLs, as raw or paths, to check the chain against.

policies

Acceptable certificate policy OIDs. Supplied, the path must yield at least one of them after policy mapping and the constraints in RFC 5280 section 6.1; omitted, policies are processed but only reported as a failure when a certificate in the path requires an explicit policy.

revocation

"supplied" (the default) checks only the CRLs given in crls. "fetch" additionally retrieves CRLs from the distribution points in the certificates and queries OCSP responders – which makes verification depend on the network and discloses to the responder which certificates are being checked, so it is never the default. "none" skips revocation entirely.

Value

A list of class bricklayer_certpath_check: ok, the path that was built, and a checks data frame.

Details

at_time is the point the validity windows are checked against, and it matters which one you pass. For a timestamp token the right answer is the time the token asserts: a token signed in 2020 by a certificate that expired in 2021 was validly signed, and checking it against today would reject it for no good reason. For a signature you are being asked to rely on now, pass now.

See also

cert_parse(), timestamp_verify().

Examples

if (FALSE) { # \dontrun{
res <- cert_chain_verify("tsa.crt", trust = "ca.crt",
                         purpose = "timeStamping")
res$ok
res$checks
} # }