All, This email launches a new discussion related to sunsetting the future use of SHA1 in the Mozilla Root Store Policy (MRSP) <https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/policy/>.
It is related to GitHub Issue #178 <https://github.com/mozilla/pkipolicy/issues/178> (as well as Issue #201 <https://github.com/mozilla/pkipolicy/issues/201>). SHA1 is still allowed to be used in signing SMIME certificates, Authority Revocation Lists (ARLs), and CRLs, and OCSP responses (but see CABF Ballot <https://lists.cabforum.org/pipermail/servercert-wg/2022-January/003090.html> SC53: Sunset for SHA-1 OCSP Signing <https://lists.cabforum.org/pipermail/servercert-wg/2022-January/003090.html> ). Can the future use of SHA1 signing be eliminated from the MRSP altogether, and if so, on what timeframes? Currently, SHA1 is mentioned in the MRSP as follows: ----------- *Section 5.1.1 RSA* <https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/policy/#511-rsa> When a root or intermediate certificate's RSA key is used to produce a signature, only the following algorithms may be used, and with the following encoding requirements: - RSASSA-PKCS1-v1_5 with SHA-1. The encoded AlgorithmIdentifier MUST match the following hex-encoded bytes: 300d06092a864886f70d0101050500. See section 5.1.3 for further restrictions on the use of SHA-1. Section 5.1.3 SHA-1 <https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/policy/#513-sha-1> CAs MAY sign SHA-1 hashes over end-entity certificates which chain up to roots in Mozilla's program only if all the following are true: 1. The end-entity certificate: - is not within the scope of the Baseline Requirements; - contains an EKU extension which does not contain either of the id-kp-serverAuth or anyExtendedKeyUsage key purposes; - has at least 64 bits of entropy from a CSPRNG in the serial number. 2. The issuing certificate: - contains an EKU extension which does not contain either of the id-kp-serverAuth or anyExtendedKeyUsage key purposes; - has a pathlen:0 constraint. Point 2 does not apply if the certificate is an OCSP signing certificate manually issued directly from a root. CAs MAY sign SHA-1 hashes over intermediate certificates which chain up to roots in Mozilla's program only if the certificate to be signed is a duplicate of an existing SHA-1 intermediate certificate with the only changes being all of: - a new key (of the same size); - a new serial number (of the same length); - the addition of an EKU and/or a pathlen constraint to meet the requirements outlined above. CAs MAY sign SHA-1 hashes over OCSP responses only if the signing certificate contains an EKU extension which contains only the id-kp-ocspSigning EKU. CAs MAY sign SHA-1 hashes over CRLs for roots and intermediates only if they have issued SHA-1 certificates. CAs MUST NOT sign SHA-1 hashes over other data, including CT pre-certificates. ----------- I am thinking that we could amend MSRP sections 5.1.1 and 5.1.3 to have sunset dates and to also say something to the effect that: "CAs MUST NOT sign SHA-1 hashes over any data." Thoughts? Thanks, Ben -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/a/mozilla.org/d/msgid/dev-security-policy/CA%2B1gtaZ69aUkmG9m978YTjeiDsRtznTmL0-%2B_6eP%2BfmiDgpSGQ%40mail.gmail.com.
