Talk:Extension Manager:Addon Update Security:Signature: Difference between revisions

Below, Dave explains that there is a [http://developer.mozilla.org/en/docs/Extension_Versioning%2C_Update_and_Compatibility#Update_RDF_Format developer page] with more examples, which may work, but it's still not a specification.

Here are some comments on the page [[User:Mossop:Fx-Docs:AddonUpdateSignature]]

A2. According to the example, it is the raw binary RSA signature, base64 encoded. It is not encoded as an ASN.1 bit string, and so is not the same signature format as that used in certificates in RFC 3280.  Neither is it encoded as an ASN.1 "encryptedDigest" (an octet string) as defined in RFC 2315 (PKCS#7), nor as a "SignatureValue" (also an octet string) as defined in RFC 3852.  Whether leading zero octets are to be suppressed or not is not specified.   

<b>Q3. What is the required/expected syntax of a DSA signature?</b>

which is exactly 20 bytes.  Perhaps they are to be concatenated into a single 40-byte binary block, as done by SSL 3.0, or perhaps they are to be ASN.1 encoded as a sequence of two integers, as in the Dss-Sig-Value in RFC 2246 (TLS 1.0).   

1. The page gives an example of an RDF/XML construct that contains a key.  I am not sure, but I think that construct is called an "install-manifest".  This install-manifest appears to have many of the properties of a public key certificate.  It appears to be a binding of a contributor name, and one or more product identifiers, to a public key.  However, the manifest itself is not cryptographically protected.  It is not signed.  I imagine this is because it is intended to be downloaded via https, and the copy downloaded is presumed to be valid at the source server.  That's not unreasonable.  However, if it was signed, it would also offer detection of alteration after downloading.  Also, IINM, there is another proposed standard that defines a certificate entirely encoded in XML.  One wonders if that standard should be used rather than inventing yet another.

So I think we now know the expected and required signature format for these manifests, including DSA signature format.  Unfortunately, this particular ASN.1 sequence doesn't match any standard signature syntax known to me.  So, I think a custom signature generating tool will be necessary, to produce signatures in this unusual encoding.