Pad rev 4 encryption keys to be >= 16 bytes (issue 19484)

[rossj]

This PR fixes issue #19484 by extending too-short keys to 16 bytes (padded with 0s) for revision 4 encryption. This key-extension behavior seems undocumented, but is necessary to properly decrypt string & stream data of problematic files found in the wild (supposedly generated by InDesign).

[Snuffleupagus]

• Does this patch pass all existing, i.e. npx gulp test, tests locally?

• Since I believe that you created those PDFs yourself, could we perhaps commit them to repository instead of relying on links (since that's always preferable where possible)?

• Can you please add more context to the commit message, i.e. what you included in Pad rev 4 encryption keys to be >= 16 bytes (issue 19484) #19555 (comment), to make the patch understandable on e.g. the git command line as well?

[rossj]

• Does this patch pass all existing, i.e. npx gulp test, tests locally?

Mostly, except for:

• issue5939.pdf - cannot download as link is 404
• Repeated failure for caches image resources at the document/page level, with main-thread copying of complex images (issue 11518) | in chrome | Expected 1160 to be less than 1064.5. - seems like a timing / perf check, so may be a flaky test
• I have a number of pages that don't match ref in Chrome, even if I generate fresh refs. Looks like minor single-pixel color differences in the diff viewer. Firefox refs all match.

• Since I believe that you created those PDFs yourself, could we perhaps commit them to repository instead of relying on links (since that's always preferable where possible)?

Updated

• Can you please add more context to the commit message, i.e. what you included in Pad rev 4 encryption keys to be >= 16 bytes (issue 19484) #19555 (comment), to make the patch understandable on e.g. the git command line as well?

Updated

[Snuffleupagus]

• issue5939.pdf - cannot download as link is 404

That one should have been fixed by a PR earlier today.

• Repeated failure for caches image resources at the document/page level, with main-thread copying of complex images (issue 11518) | in chrome | Expected 1160 to be less than 1064.5. - seems like a timing / perf check, so may be a flaky test

We've seen that occasionally failing on the bots, but as long as Firefox works that's fine.

• I have a number of pages that don't match ref in Chrome, even if I generate fresh refs. Looks like minor single-pixel color differences in the diff viewer. Firefox refs all match.

We actually had so much trouble with unstable reference tests in Chrome that we nowadays only test in Firefox for that reason.

[Snuffleupagus]

/botio unittest

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Received

Command cmd_unittest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/b675d134bbf2b40/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

---

Received

Command cmd_unittest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/4c0dec0495c1e79/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Success

Full output at http://54.241.84.105:8877/b675d134bbf2b40/output.txt

Total script time: 2.35 mins

• Unit Tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Success

Full output at http://54.193.163.58:8877/4c0dec0495c1e79/output.txt

Total script time: 7.63 mins

• Unit Tests: Passed

[Snuffleupagus]

/botio browsertest

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Received

Command cmd_browsertest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/2fd0ab3b5122714/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

---

Received

Command cmd_browsertest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/7ed13e22fbb43d1/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Success

Full output at http://54.241.84.105:8877/2fd0ab3b5122714/output.txt

Total script time: 16.86 mins

• Regression tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.193.163.58:8877/7ed13e22fbb43d1/output.txt

Total script time: 30.49 mins

• Regression tests: FAILED

  different ref/snapshot: 1

Image differences available at: http://54.193.163.58:8877/7ed13e22fbb43d1/reftest-analyzer.html#web=eq.log

[Snuffleupagus]

Hopefully we have enough test-coverage for this part of the code-base, since we're trying to match unspecified Adobe Reader behaviour here (rather than fixing an "actual" bug).
However, I suppose that we have to land this to actually find out if there's any breakage :-)

r=me, thank you.

[Snuffleupagus]

/botio makeref

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Received

Command cmd_makeref from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/a652726527fb822/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

---

Received

Command cmd_makeref from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/4855bcef8426829/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Success

Full output at http://54.241.84.105:8877/a652726527fb822/output.txt

Total script time: 16.81 mins

• Make references: Passed
• Check references: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Success

Full output at http://54.193.163.58:8877/4855bcef8426829/output.txt

Total script time: 30.33 mins

• Make references: Passed
• Check references: Passed