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-----BEGIN PGP SIGNED MESSAGE----- |
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Hash: SHA512 |
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On 08/14/2015 04:54 PM, Rich Freeman wrote: |
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> On Fri, Aug 14, 2015 at 8:45 AM, Kristian Fiskerstrand |
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> <k_f@g.o> wrote: |
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>> |
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>>> |
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>>> 2. The question is why manifests are modified for rsync. In |
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>>> git manifests are thin (only distfiles are there), in rsync |
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>>> they also contain checksums for ebuilds and files dir content. |
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>>> Do we really need this? These manifests are not signed now, so |
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>>> of little use. |
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>> |
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>> They will be OpenPGP signed by a releng key during thickening |
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>> and portage will auto-verify it using gkeys once things are in |
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>> place. As such checksum for ebuilds and other files certainly |
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>> needs to be part of the manifest, otherwise it can open up for |
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>> malicious alterations of these files. |
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>> |
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> |
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> As much as I'd love to see it all folded into git, the reality is |
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> also that git signatures are only bound to files by a series of |
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> sha1 hashes, and sha1 is not a strong hash function. Git really |
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> ought to move to sha256 at some point, preferably in a manner that |
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> makes it expandable in the future to other hash functions. But, |
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> this isn't a high-priority for upstream. |
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|
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I'm not really too worried about second preimage attacks on sha1 at |
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the present time, so can understand that priority. |
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|
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> |
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> The same limitation is true of any git gpg signature, including |
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> tag signatures. It is all held together by sha1. The manifest |
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> system is much stronger. |
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> |
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|
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Well, it is only as good as the input it gets, so if the git |
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infrastructure (if sha1 truly turns out to be an issue, presuming that |
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it is verified at point of staging) or the staging area for rsync |
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mirror is compromised (since the Manifests are signed when thickened, |
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a compromise here can override everything else) it will replicate to |
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users, so these points needs to be properly protected. |
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|
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- -- |
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Kristian Fiskerstrand |
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Public PGP key 0xE3EDFAE3 at hkp://pool.sks-keyservers.net |
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fpr:94CB AFDD 3034 5109 5618 35AA 0B7F 8B60 E3ED FAE3 |
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