Remove comment about zero padding HMAC{256,384,512} keys.

[vcsjones]

Summary

The zero padding is not observed in the Key property. It's an implementation detail of how HMAC works. To avoid any confusion, let's just remove this comment. We don't have it for HMACSHA1 or HMACMD5.

I initially tried to re-word this to something like If it is less than 64 bytes long, the key is internally zero padded to 64 bytes. However, I'm not sure it makes sense to document the internals of how HMAC works in the key parameter documentation. I left the documentation for if the key is too large because we do have observable changes to the Key property in that case.

See dotnet/runtime#80180 for background on why I am suggesting this change.

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Issue Details

---

Summary

The zero padding is not observed in the Key property. It's an implementation detail of how HMAC works. To avoid any confusion, let's just remove this comment. We don't have it for HMACSHA1 or HMACMD5.

I initially tried to re-word this to something like If it is less than 64 bytes long, the key is internally zero padded to 64 bytes. However, I'm not sure it makes sense to document the internals of how HMAC works in the key parameter documentation. I left the documentation for if the key is too large because we do have observable changes to the Key property in that case.

See dotnet/runtime#80180 for background on why I am suggesting this change.

Author:	vcsjones
Assignees:	vcsjones
Labels:	area-System.Security
Milestone:	-

[learn-build-service-prod]

Learn Build status updates of commit a6c99f5:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System.Security.Cryptography/HMACSHA256.xml	✅Succeeded	View
xml/System.Security.Cryptography/HMACSHA384.xml	✅Succeeded	View
xml/System.Security.Cryptography/HMACSHA512.xml	✅Succeeded	View

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