Improve and Expand Documentation for SymmetricEncryptionManager

[MayMeow]

Description

The SymmetricEncryptionManager is a core component of our encryption library, but its documentation is currently incomplete and lacks clarity. This makes it difficult for new developers to use the class correctly and safely, increasing the risk of improper implementation.

The goal of this task is to thoroughly review and update the XML documentation comments (\<summary\>, \<param\>, \<returns\>, etc.) for the class and its public members.

Areas for Improvement

The updated documentation should address the following points:

1. Class-Level Summary (\<summary\>):
   • Clearly state the purpose of the SymmetricEncryptionManager.
   • Mention the underlying algorithm being used (e.g., AES).
   • Provide a brief, high-level example of its usage.
2. Constructor Documentation:
   • Explain the role of each parameter (e.g., key, iv).
   • Specify the expected size and format for keys and IVs.
   • Add security notes about key and IV management (e.g., "The IV should be unique per encryption operation").
3. Method Documentation (Encrypt, Decrypt):
   • Parameters (\<param\>): Clearly describe the input (e.g., "The plaintext string to encrypt").
   • Return Values (\<returns\>): Describe the output (e.g., "The Base64-encoded ciphertext").
   • Exceptions (\<exception\>): Document all possible exceptions that can be thrown (e.g., ArgumentNullException if input is null, CryptographicException on padding errors).
   • Remarks (<remarks>): Add any important implementation details or usage notes.
4. Code Examples (<example>):
   • Provide a complete, copy-paste-friendly code example demonstrating the full lifecycle:
     1. Instantiating the manager.
     2. Encrypting a piece of data.
     3. Decrypting the resulting ciphertext.
     4. Properly disposing of the manager instance (e.g., within a using block).

Acceptance Criteria

• Every public class, method, and property in SymmetricEncryptionManager has comprehensive XML documentation.
• The documentation includes clear explanations for all parameters, return values, and potential exceptions.
• At least one complete code example is included in the class-level documentation.
• Security best practices regarding key and IV handling are mentioned where appropriate.
• The generated documentation is clear, professional, and easy for other developers to understand.