[tor-bugs] #5894 [EFF-HTTPS Everywhere]: Replace sha256.js and base64_encode() with Mozilla's internal equivalents

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#5894: Replace sha256.js and base64_encode() with Mozilla's internal equivalents
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 Reporter:  gk                    |          Owner:  pde
     Type:  enhancement           |         Status:  new
 Priority:  normal                |      Milestone:     
Component:  EFF-HTTPS Everywhere  |        Version:     
 Keywords:                        |         Parent:     
   Points:                        |   Actualpoints:     
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 To reduce code bloat and avoid JavaScript's bit shifting inefficiencies it
 would be good to replace sha256.js and base64_encode() in ssl-
 observatory.js with functionality provided by Mozilla itself. The former
 is quite easy using nsICryptoHash (see the the example "Computing the Hash
 of a String" on
 https://developer.mozilla.org/en/XPCOM_Interface_Reference/nsICryptoHash).
 The latter is not working directly using btoa(). The reason is that
 |derData| is an array but btoa() needs a string as argument. But one can
 construct a string out of the array and use that in turn as input. The
 relevant code snipped would be something like

 {{{
   let result = "";
   for (let j = 0, dataLength = derData.length; j < dataLength; ++j) {
     result += String.fromCharCode(derData[j]);
   }
   base64Certs.push(btoa(result));
 }}}

 I have implemented both approaches in JonDoFox and they work as expected.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5894>
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