# Limitations when using SCRAM secrets
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Note the following limitations when using SCRAM secrets:
+ Amazon MSK only supports SCRAM-SHA-512 authentication.
+ An Amazon MSK cluster can have up to 1000 users.
+ You must use an AWS KMS key with your Secret. You cannot use a Secret that uses the default Secrets Manager encryption key with Amazon MSK. For information about creating a KMS key, see [Creating symmetric encryption KMS keys](https://docs.aws.amazon.com/kms/latest/developerguide/create-keys.html#create-symmetric-cmk).
+ You can't use an asymmetric KMS key with Secrets Manager.
+ You can associate up to 10 secrets with a cluster at a time using the [ BatchAssociateScramSecret](https://docs.aws.amazon.com/msk/1.0/apireference/clusters-clusterarn-scram-secrets.html#BatchAssociateScramSecret) operation.
+ The name of secrets associated with an Amazon MSK cluster must have the prefix **AmazonMSK\$1**.
+ Secrets associated with an Amazon MSK cluster must be in the same Amazon Web Services account and AWS region as the cluster.