Add COSE structure extensions that allow use of predefined cryptographic backends + an OpenSSL based backend.

[pulsastrix]

This PR will add cipher implementations based on the openssl crate, which binds to the native openssl library.¹

Currently, only one algorithm per "type" is currently supported (ECDSA for signing, AES-GCM for encrypting, AES-Key-Wrap for key distribution, HMAC for message authentication codes).

In order to not inflate this PR further, other algorithms and a potential RustCrypto based backend are probably better added in separate, smaller PRs.

Footnotes

1. Better Nate than lever! ↩

[coveralls]

Pull Request Test Coverage Report for Build 9601666399

Details

• 280 of 363 (77.13%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-1.8%) to 88.397%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/error/mod.rs	0	1	0.0%
src/token/crypto_impl/openssl.rs	274	356	76.97%

Files with Coverage Reduction	New Missed Lines	%
src/common/scope/mod.rs	2	93.06%

Totals
Change from base Build 4532502856:	-1.8%
Covered Lines:	1897
Relevant Lines:	2146

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9727733938

Details

• 703 of 939 (74.87%) changed or added relevant lines in 9 files are covered.
• 14 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-6.4%) to 83.78%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/token/cose/encrypt/mod.rs	6	7	85.71%
src/token/cose/sign/sign1.rs	121	127	95.28%
src/token/cose/sign/sign.rs	151	158	95.57%
src/error/mod.rs	3	14	21.43%
src/token/cose/crypto_impl/openssl.rs	94	108	87.04%
src/token/cose/sign/mod.rs	42	58	72.41%
src/token/cose/encrypt/encrypt0.rs	185	210	88.1%
src/token/cose/header_util.rs	22	65	33.85%
src/token/cose/key.rs	79	192	41.15%

Files with Coverage Reduction	New Missed Lines	%
src/token/mod.rs	1	84.62%
src/common/scope/mod.rs	2	93.06%
src/endpoints/token_req/mod.rs	11	77.48%

Totals
Change from base Build 4532502856:	-6.4%
Covered Lines:	1906
Relevant Lines:	2275

---

💛 - Coveralls

[falko17]

Thank you for the PR! It's nice to finally get an actual cipher implementation. As always, here's my list of pedantic comments.

[coveralls]

Pull Request Test Coverage Report for Build 9767273749

Details

• 715 of 929 (76.96%) changed or added relevant lines in 9 files are covered.
• 14 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-5.5%) to 84.68%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/token/cose/encrypt/mod.rs	6	7	85.71%
src/token/cose/sign/sign1.rs	121	127	95.28%
src/token/cose/sign/sign.rs	151	158	95.57%
src/error/mod.rs	3	13	23.08%
src/token/cose/crypto_impl/openssl.rs	94	108	87.04%
src/token/cose/sign/mod.rs	46	62	74.19%
src/token/cose/header_util.rs	23	47	48.94%
src/token/cose/encrypt/encrypt0.rs	192	217	88.48%
src/token/cose/key.rs	79	190	41.58%

Files with Coverage Reduction	New Missed Lines	%
src/token/mod.rs	1	84.62%
src/common/scope/mod.rs	2	93.06%
src/endpoints/token_req/mod.rs	11	77.48%

Totals
Change from base Build 4532502856:	-5.5%
Covered Lines:	1918
Relevant Lines:	2265

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 10239234233

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 1365 of 1705 (80.06%) changed or added relevant lines in 29 files are covered.
• 12 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-5.3%) to 84.966%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/common/cbor_map/mod.rs	1	2	50.0%
src/common/scope/mod.rs	0	1	0.0%
src/token/cose/encrypted/encrypt/tests.rs	78	79	98.73%
src/token/cose/encrypted/encrypt0/tests.rs	57	58	98.28%
src/token/cose/signed/sign/tests.rs	72	73	98.63%
src/token/cose/aad.rs	34	36	94.44%
src/token/cose/maced/mac0/tests.rs	58	60	96.67%
src/token/cose/maced/mod.rs	23	27	85.19%
src/token/cose/signed/mod.rs	24	28	85.71%
src/token/tests.rs	106	112	94.64%

Files with Coverage Reduction	New Missed Lines	%
src/token/mod.rs	1	83.0%
src/common/scope/mod.rs	2	93.06%
src/error/mod.rs	4	48.37%
src/token/tests.rs	5	93.66%

Totals
Change from base Build 4532502856:	-5.3%
Covered Lines:	2724
Relevant Lines:	3206

---

💛 - Coveralls

[falko17]

Oh, before I forget: When you're working on the documentation, could you also update the README, specifically the section about the COSE cipher? To do so, you can change the crate-level documentation in lib.rs, and then run cargo-rdme to update the README.md file (it already contains the appropriate tags for it).

[pulsastrix]

Aside from fixing the links in the documentation and running cargo rdme again, this should now finally be the end of it.

[falko17]

Some¹ final suggestions, but most of these are automatically applicable formatting fixes, the rest are just a few open questions.

Footnotes

1. Okay, a lot, but to be fair this was also a huge PR ↩