chore: Solution-wide code cleanup

[DennisDyallo]

Solution wide code cleanup using Rider and our common settings

[github-actions]

Test Results: Windows

    2 files      2 suites   9s ⏱️
3 972 tests 3 972 ✅ 0 💤 0 ❌
3 974 runs  3 974 ✅ 0 💤 0 ❌

Results for commit a3f3ed6.

[github-actions]

Test Results: Ubuntu

    2 files      2 suites   17s ⏱️
3 964 tests 3 964 ✅ 0 💤 0 ❌
3 966 runs  3 966 ✅ 0 💤 0 ❌

Results for commit a3f3ed6.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Yubico.Core	40%	31%	4362	❌
Yubico.YubiKey	51%	47%	21090	➖
Summary	49% (36711 / 74796)	44% (8876 / 20097)	25452	➖

Minimum allowed line rate is 40%

[github-actions]

Test Results: MacOS

    2 files      2 suites   9s ⏱️
3 964 tests 3 964 ✅ 0 💤 0 ❌
3 966 runs  3 966 ✅ 0 💤 0 ❌

Results for commit a3f3ed6.

To fix the problem, we need to avoid the use of ECB mode and instead use a secure cipher mode such as CBC. Specifically, change the line tDesObject.Mode = CipherMode.ECB; to use CBC: tDesObject.Mode = CipherMode.CBC;. When using CBC mode, an initialization vector (IV) is required. Since the test currently passes null for the IV in CreateEncryptor, this must be changed to an actual IV value. The IV should be 8 bytes for TripleDES and, for deterministic/reproducible test results, can be set to a fixed value such as all zero bytes. Update all calls to CreateEncryptor to use the IV argument instead of null. Only lines relevant to cipher mode and IV usage are to be changed; all other logic remains the same.

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To fix the issue, update the encryption mode from ECB to CBC, which is standard and far more secure. CBC (Cipher Block Chaining) requires an initialization vector (IV) which should be unique and random for each encryption operation, but for unit tests, a fixed IV (e.g., all zeros) can be used to produce deterministic results. The changes should be focused on the region where the mode is set (line 183), and all invocations of .CreateEncryptor() need the IV argument to be non-null. Add an IV definition to the method, and pass it to the encryptor. No additional imports are needed, but add the IV definition and update calls as required in the affected method (lines ~157-199).

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To fix this issue, replace ECB mode with CBC mode for both the TripleDES and DES objects. The CBC mode is more secure as it uses an IV (Initialization Vector) to ensure identical plaintext blocks encrypt differently. For unit testing with deterministic results, set the IV to a fixed value (e.g., all zeros), which will not impact security in the context of a unit test but avoids the use of ECB.

Specifically:

• Replace tDesObject.Mode = CipherMode.ECB; with tDesObject.Mode = CipherMode.CBC; and set tDesObject.IV = new byte[8];
• Replace desObject.Mode = CipherMode.ECB; with desObject.Mode = CipherMode.CBC; and set desObject.IV = new byte[8];
• When creating encryptors or decryptors, replace the null IV parameters with the explicitly provided IV.

These changes will preserve the test's functionality while using a more secure cipher mode. No additional imports are required.

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To remediate this issue, change the cipher mode from ECB to a secure alternative, typically CBC (Cipher Block Chaining) mode, which is standard for both DES/TripleDES and avoids pattern leakage vulnerabilities. CBC requires an initialization vector (IV) to provide semantic security. In test code, the IV can be set to a zeroed byte array of the appropriate length if deterministic results are desired (as commonly done in tests), or a random IV otherwise.

The required changes are:

• Replace tDesObject.Mode = CipherMode.ECB; with tDesObject.Mode = CipherMode.CBC;
• Replace desObject.Mode = CipherMode.ECB; with desObject.Mode = CipherMode.CBC;
• When creating encryptors or decryptors, replace the null IV with an explicit zero IV, e.g. new byte[8].
• Ensure the test logic remains consistent with this mode switch.

All changes are to be made in the shown regions of Yubico.YubiKey/tests/unit/Yubico/YubiKey/Piv/KeyTests.cs.

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To address this issue, replace the insecure use of CipherMode.ECB with a secure cipher mode—most commonly CipherMode.CBC. CBC mode requires an Initialization Vector (IV) to ensure the same plaintext encrypts to different ciphertexts each time. In the context of this code, which appears to encrypt 8 bytes from a buffer, you can generate a random IV or use a fixed IV if deterministic outputs are needed for testing only. You must modify both the cipher mode and supply a suitable IV (instead of null) when creating the encryptor.

Edit only within the supplied lines (lines 111–114) in Yubico.YubiKey/tests/utilities/Yubico/YubiKey/TestUtilities/HollowConnection.cs:

• Change CipherMode.ECB to CipherMode.CBC.
• Generate and provide an appropriate IV (8 bytes for TripleDES) for use with CBC mode, replacing the null IV argument in the CreateEncryptor call.
• If you need deterministic output for tests, you can use a fixed IV (e.g., all zeros or any test vector); otherwise, generate a random value.

No extra dependencies are necessary; .NET standard libraries are sufficient.

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