I know that Azure Service Bus is secure while in transit because of SSL, but I'm unable to find any information about if it's encrypted while at rest.
If the content of the message is sensitive in nature, can Azure be relied on to keep messages private while within the Azure infrastructure - or should we implement message security?
As of 4/25/2018, the page that @tyler-pollack referenced, has been updated to specify that encryption at rest is provided at all tiers. https://docs.microsoft.com/en-us/azure/security/azure-security-encryption-atrest
You can see the update in this github commit: https://github.com/MicrosoftDocs/azure-docs/commit/66214db8a21eefcece6441ae566041b90b2615fa#diff-f55bddd3fba462832c4a2d0e7918f750
Service Bus Premium currently supports encryption at rest - https://docs.microsoft.com/en-us/azure/security/azure-security-encryption-atrest#azure-resource-providers-encryption-model-support
