Mozilla 1024-Bit Cert Deprecation Leaves 107,000 Sites Untrusted

msm1267 writes: Mozilla has deprecated 1024-bit RSA certificate authority certificates in Firefox 32 and Thunderbird. While there are pluses to the move such as a requirement for longer, stronger keys, at least 107,000 websites will no longer be trusted by Mozilla. Data from HD Moore's Project Sonar, which indexes more than 20 million websites, found 107,535 sites using a cert signed by what will soon be an untrusted CA certificate. Grouping those 107,000-plus sites by certificate expiration date, the results show that 76,185 certificates had expired as of Aug. 25; of the 65 million certificates in the total scan, 845,599 had expired but were still in use as of Aug. 25, Moore said.

Comments

Re:So 1024 Bits Not Enough Now?

[heypete]

Symmetric and asymmetric keys are different things and have different key lengths. One cannot directly compare key sizes between two wholly different classes of ciphers. There are numerous reasons, mostly involving arcane mathematics, why asymmetric ciphers require longer key lengths than symmetric ciphers to offer similar levels of protection.

For example, a 1024-bit RSA key (RSA is an asymmetric cipher) is essentially equivalent to an 80-bit symmetric key (AES, 3DES, etc. are symmetric ciphers). SHA1, a hashing algorithm, provides less than 80 bits of security; those wishing stronger signatures are switching to SHA-256 (which offers 128 bits of security) and SHA-512 (which offers 256 bits).

A 2048-bit RSA key, such as those used by most CAs and web servers these days, has the same strength as a 112-bit symmetric key. NIST says they should be good enough until around 2030.

3072-bit RSA keys offer the same strength as a 128-bit symmetric key. A whopping 15,360-bit RSA key would be needed for 256-bit security; the same level of security could be achieved with a 512-bit elliptic curve key, which would be much, much faster than such a large RSA key.