[R-SIG-Mac] SHA-1 Hash for R-3.5.0.pkg Incorrect

[Marc Schwartz]

Hi Simon,

Understood, as the digital signature is superior to the stand alone hash value, since like the hash value, it provides a check against file modifications/corruption since being signed, and unlike the stand alone hash value, it provides source validation and non-repudiation.

In either case, I see that you have now changed the labeling of the SHA hash on CRAN, to indicate that it is SHA-1 specifically, and that hash value now checks locally. Thank you for making that change.

I wonder if it might make sense, given that the signature is superior to the stand alone hash values, to begin to drop the latter for signed PKG files intended for ongoing (non-legacy) binary versions of R for macOS, for the reasons below.

If so, it might make sense to also move in the same direction for the signed PKG files in the macOS tools folder on CRAN, which now just have the MD5 hash values.

Thanks again Simon.

Marc


> On Apr 26, 2018, at 1:35 PM, Simon Urbanek <simon.urbanek at r-project.org> wrote:
> 
> Marc,
> 
> no, the hashes merely a legacy to check that you don't have a corrupted download. They are neither intended nor used for validation. To verify the validity you should use the signature check.
> 
> Cheers,
> Simon
> 
> 
> 
>> On Apr 25, 2018, at 4:37 PM, Marc Schwartz <marc_schwartz at me.com> wrote:
>> 
>> Hi Simon,
>> 
>> Thanks for the explanation.
>> 
>> It did not occur to me that SHA-0 was being used, since it was withdrawn as a standard circa early 90's, after significant flaws were identified.
>> 
>> Apple (and others) either have or are moving away from SHA-1 to SHA-2, at least for TLS/PKI security:
>> 
>>  https://support.apple.com/en-us/HT207459
>> 
>> recognizing the differences between session specific TLS/PKI trust uses and longer term file integrity checking. I know Linus is more "relaxed" regarding SHA-1 and the implications for Git, or at least was last year, albeit indicating a path away from it in time.
>> 
>> I guess the question boils down to, if we are going to provide hashes of the files under the premise that it should offer a high level of comfort to useRs that the file has not been modified/replaced since generation, presuming that the published hash value itself was not altered, I would put forth for further discussion, moving to SHA-2 and away from both MD5 and SHA-1 (certainly moving away from SHA-0), depending upon a more broad assessment of the implications of doing so.
>> 
>> Thanks!
>> 
>> Marc
>> 
>> 
>>> On Apr 25, 2018, at 2:54 PM, Simon Urbanek <simon.urbanek at R-project.org> wrote:
>>> 
>>> Marc,
>>> 
>>> thanks, the issue is:
>>> 
>>> hagal:R-3.5.0$ openssl sha R-3.5.0-el-capitan-signed.pkg
>>> SHA(R-3.5.0-el-capitan-signed.pkg)= 9f5f3365afee54d3fe3148a60c1405955916f076
>>> 
>>> hagal:R-3.5.0$ openssl sha1 R-3.5.0-el-capitan-signed.pkg
>>> SHA1(R-3.5.0-el-capitan-signed.pkg)= 6e90d38892bb366630ae30c223a898e8af84dff7
>>> 
>>> so either we change the label to SHA (or SHA-0?) or change the checksum. In the root we actually provide both, even if that may or may not be relevant. For now I did the latter in the index.html.
>>> 
>>> Cheers,
>>> Simon
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> On Apr 25, 2018, at 7:57 AM, Marc Schwartz <marc_schwartz at me.com> wrote:
>>>> 
>>>> Hi All,
>>>> 
>>>> Last month:
>>>> 
>>>> https://stat.ethz.ch/pipermail/r-sig-mac/2018-March/012691.html
>>>> 
>>>> there was a report that the SHA-1 hash of the R-3.4.4.pkg, as listed on CRAN, was not correct, even though the MD5 hash and the digital signature appeared to be correct.
>>>> 
>>>> The same phenomenon is the case with R-3.5.0.pkg.
>>>> 
>>>> The MD5 hash on CRAN is:
>>>> 
>>>> MD5-hash: 414029c9c9f706d3d04baa887ccffbc4 
>>>> 
>>>> and I get:
>>>> 
>>>> md5 R-3.5.0.pkg
>>>> MD5 (R-3.5.0.pkg) = 414029c9c9f706d3d04baa887ccffbc4
>>>> 
>>>> from the CLI on my Mac.
>>>> 
>>>> However, the SHA-1 hash on CRAN is:
>>>> 
>>>> SHA-hash: 9f5f3365afee54d3fe3148a60c1405955916f076 
>>>> 
>>>> and I get:
>>>> 
>>>> shasum R-3.5.0.pkg
>>>> 6e90d38892bb366630ae30c223a898e8af84dff7  R-3.5.0.pkg
>>>> 
>>>> from the CLI on my Mac.
>>>> 
>>>> It would seem that there is a lingering issue with the generation of the SHA-1 hash value on CRAN.
>>>> 
>>>> Thanks,
>>>> 
>>>> Marc Schwartz
>>>> 
>>>> _______________________________________________
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>>>> R-SIG-Mac at r-project.org
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>> 
>> 
>