R2r Root Certificate __top__ ★ Editor's Choice

An R2R certificate is not a cross-signature, nor a subordinate CA, nor a bridge. It is a cryptographic handshake between two ultimate authorities—a treaty signed at the summit of two distinct mountains of trust. In practical terms, it occurs when Root CA A issues a certificate directly to Root CA B , making B a subordinate of A in one direction, while B simultaneously (or previously) considers itself a peer. The result is a cyclic dependency of absolute power. To understand the R2R, we must first recall the root’s defining feature: self-signature . A root certifies itself. Its validity is an axiom, not a proof. When you install a root certificate, you are performing an act of faith, encoded in a hash.

Thus, the R2R certificate is a masterpiece of engineering irony: a structure designed to be invisible, operating only in the shadow of the root’s self-signed solitude. It is the cryptographic equivalent of two mirrors facing each other — infinite regression masked as redundancy. r2r root certificate

More troubling is the . If two roots cross-certify each other directly, an attacker compromising one root can now impersonate the other. Because the compromised root can issue a certificate that chains to the honest root (via the R2R), the honest root’s name and key material are now effectively co-signed by the adversary. The two roots’ security postures merge. Trust becomes the weakest link multiplied. The R2R in the Wild: Case Study of an Ageing Internet The most famous example is the VeriSign Class 1 – Thawte Roots cross-certification from the early 2000s, though those were typically CA-to-CA, not pure root-to-root. A purer example exists in the Federal Bridge Certificate Authority (U.S. government), where multiple agency roots cross-certify with the Bridge, creating a mesh. At the extreme, two agency roots could directly cross-certify — a true R2R. An R2R certificate is not a cross-signature, nor