@Marcia Varotto As I understand you do you need to encrypt the documents and upload the data to Blob Storage, am I correct, If not please correct me?
Data in Azure Storage is encrypted and decrypted transparently using 256-bit AES encryption, one of the strongest block ciphers available, and is FIPS 140-2 compliant. Azure Storage encryption is similar to BitLocker encryption on Windows.
Azure Storage encryption is enabled for all storage accounts, Azure Storage encryption cannot be disabled. Because your data is secured by default, you don't need to modify your code or applications to take advantage of Azure Storage encryption.
This article will will help you how to encrypt and upload: https://learn.microsoft.com/en-us/azure/storage/blobs/storage-encrypt-decrypt-blobs-key-vault#encrypt-blob-and-upload
This is how to decrypt and download: https://learn.microsoft.com/en-us/azure/storage/blobs/storage-encrypt-decrypt-blobs-key-vault#decrypt-blob-and-download
You can also perform Doubly encrypt data with infrastructure encryption
Hope this helps!
Kindly let us know if the above helps or you need further assistance on this issue.
-----------------------------------------------------------------------------------------------------------
Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.