[webcrypto] JWK: Reject keys with non-minimal bigintegers.

[webcrypto] JWK: Reject keys with non-minimal bigintegers.

RSA properties such as n, e, d, p, q, dp, dq, qi are big integers encoded as base64 url-safe, big-endian octet strings.

 * Reject big integers that contain leading zeros, since by the JWA rules they must be minimal.
 * Reject big integers that are the empty octet string (since 0 is the minimal representation of the big-endian number 0, not empty string).

This also changes the exception message and type when one of the optional parameters p, q, dp, dq, qi are missing. Before it would give an OperationError, because NSS was unable to infer the missing parameters. Now it gives a DataError explaining that the parameter is required.

BUG=374927, 383998
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285798

[Ryan Sleevi, 2014-07-26 00:52:34]

lgtm

https://codereview.chromium.org/416993009/diff/20001/content/child/webcrypto/...
File content/child/webcrypto/shared_crypto_unittest.cc (right):

https://codereview.chromium.org/416993009/diff/20001/content/child/webcrypto/...
content/child/webcrypto/shared_crypto_unittest.cc:2406: // implementation does
not allow them. See http://crbug/com/374927
You can actually put a stronger message here if you want.

// According to JWA, such keys are valid, but applications SHOULD
// include all the parameters when sending, and recipients MAY
// accept them, but are not required to. Chromium's WebCrypto does
// not allow such degenerate keys.

[eroman, 2014-07-26 00:57:12]

https://codereview.chromium.org/416993009/diff/20001/content/child/webcrypto/...
File content/child/webcrypto/shared_crypto_unittest.cc (right):

https://codereview.chromium.org/416993009/diff/20001/content/child/webcrypto/...
content/child/webcrypto/shared_crypto_unittest.cc:2406: // implementation does
not allow them. See http://crbug/com/374927
On 2014/07/26 00:52:33, Ryan Sleevi wrote:
> You can actually put a stronger message here if you want.
> 
> // According to JWA, such keys are valid, but applications SHOULD
> // include all the parameters when sending, and recipients MAY
> // accept them, but are not required to. Chromium's WebCrypto does
> // not allow such degenerate keys.

Done.

[eroman, 2014-07-26 00:59:08]

The CQ bit was checked by eroman@chromium.org

[commit-bot: I haz the power, 2014-07-26 05:00:30]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/eroman@chromium.org/416993009/40001

[commit-bot: I haz the power, 2014-07-26 11:40:13]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_x64_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-07-26 19:59:27]

Change committed as 285798