SHA-1 Authenticode signature and legacy timestamp

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Jeremy Barton

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Feb 27, 2019, 3:24:19 PM2/27/19
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This is more of a product distribution question than a security question, but it seems similar enough that it felt like a reasonable start.

Firefox.exe is Authenticode-signed using only a SHA-1-based digest. The Timestamp Authority that it uses in this signature (http://timestamp.verisign.com/scripts/timstamp.dll) is so old that its RSA signatures are not PKCS#1 conforming (they utilize the raw digest value instead of the DigestInfo version of the digest), and also based on SHA-1.

Since all of the versions of Windows that Microsoft supports support SHA-2 based Authenticode and SHA-2 based RFC3161-compliant timestamping, it seems like there shouldn't really be a reason to hang on to SHA-1 signing for the product distribution.

(If nothing else, please move to a newer TSA, since the inability to validate the signature with certain platforms is what prompted this inquiry)

-Jeremy Barton
Cryptography and Security, .NET Platform

dve...@mozilla.com

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Feb 27, 2019, 5:55:34 PM2/27/19
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I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1531165 to get this fixed.

-Dan Veditz
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