Azure Key Vault Encrypt with AES returns 413 Request Entity Too Large

Question

Azure Key Vault Encrypt with AES returns 413 Request Entity Too Large

Bobby Bridges 0

I'm using a 256 bit AES key that's stored in Azure Managed HSM and I'm trying to encrypt data using the Azure SDK. When I try to encrypt the data using the AES key, the SDK returns a 413 Request Entity Too Large error. The data is likely in JSON format and I'm using Encoding.UTF8.GetBytes prior to making the Encrypt call with the SDK. Do you have any suggestions to avoid this error?

Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-14T18:15:39.6833333+00:00

Hi @Bobby Bridges
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-17T17:52:03.5333333+00:00

Hi @Bobby Bridges
we haven't heard back from you about the last issue. Just checking in to see if you've found a solution. If you have, please share it with the community it could really help others. If not, let us know more details, and we'll do our best to assist you."

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Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-14T18:15:39.6833333+00:00

Hi @Bobby Bridges
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-17T17:52:03.5333333+00:00

Hi @Bobby Bridges
we haven't heard back from you about the last issue. Just checking in to see if you've found a solution. If you have, please share it with the community it could really help others. If not, let us know more details, and we'll do our best to assist you."

Answer 1

Akhilesh Vallamkonda 15,355 Moderator

Hi @Bobby Bridges

Thank you for posting Microsoft Q&A Forum!

The 413 Request Entity Too Large error typically occurs when the size of the data being sent exceeds the maximum allowed limit.

Sign and verify operations algorithms must match the key type, otherwise service will return key size is incorrect error. could you please verify Key types, algorithms, and operations and Azure Key Vault service limits is compatible.

Bobby Bridges 0 Reputation points

2025-02-05T12:07:30.5+00:00

@Akhilesh Vallamkonda does this mean the data to be encrypted has to be less than 4KB in size?
Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-05T20:35:35.1133333+00:00

Hi @Bobby Bridges
May I know the size of the JSON data you are using, could you please send us the JSON data file to azcommunity [at] microsoft [dot] com referencing this issue with a subject line "ATTN:akhilesh"
Bobby Bridges 0 Reputation points

2025-02-06T12:41:38.3666667+00:00

@Akhilesh Vallamkonda the sizes of the data that is failing ranges from 24KB to 82KB. I sent an email reply with a sample of the JSON data that is failing.
Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-06T22:51:09.9233333+00:00

Hi @Bobby Bridges
I am checking this and will get back to you with further inputs.
Akhilesh Vallamkonda 15,355 Reputation points Moderator

2025-02-13T14:05:46.1733333+00:00

Hi @Bobby Bridges,

Apologies for the delayed response as we were discussing with our team internally on this.

The 413 Request Entity Too Large error typically indicates that the data being sent exceeds the maximum allowed size for the operation.

As per the Azure Key Vault documentation provides information on service limits, including the maximum size for encrypt and decrypt for AES key operations.

AES key operations (number of operations per second per HSM instance)

Can you confirm what is the end goal?
Bobby Bridges 0 Reputation points

2025-02-18T12:09:23.8233333+00:00

@Akhilesh Vallamkonda we had to change our approach with using azure hsm to send smaller data in order to get around the 413 error.
Raja Pothuraju 47,080 Reputation points Microsoft External Staff Moderator

2025-02-24T14:31:33.6366667+00:00

Hello @Bobby Bridges,

Thank you for posting your solution over the thread.

The 413 Request Entity Too Large error typically occurs when the data being sent exceeds the maximum allowed size for the operation.

According to the Azure Key Vault documentation, there are service limits for encryption and decryption operations using AES keys, with a maximum packet size of 4KB.

I'm glad to hear that you were able to resolve the issue by adjusting your approach and using Azure HSM to process smaller data chunks, thereby avoiding the 413 error.

Thank you again for your time and patience throughout this process. Let us know if you need any further assistance.

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Azure Key Vault Encrypt with AES returns 413 Request Entity Too Large

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