Right now we're using our own built-in solution based on SSS, and we want to switch to KMS.

How far can we go? Can we use AWS' KMS for both the KEK and the DEK?


There's nothing within the PCI DSS which would prevent you from using AWS KMS for both the KEK and the DEK.

You should ensure you're generating strong keys, the KEK is equivalent strength to the DEK (e.g. both AES 256-bit), the DEK is encrypted by the KEK and you have separate key custodians for key components.

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  • Got it, thank you! One quick question. It does make a bit more sense to generate a DEK, encrypt it using a KMS KEK, store the encrypted DEK on a file on the servers. And at server boot up it decrypts the stored encrypted DEK using KMS. Or is there a better way? – MB. Jun 25 '19 at 23:39
  • Depends on requirements whether you want to decrypt data in KMS or on your server instance. The key could potentially be leaked from memory in the server instance whereas this isn't generally such a threat within a KMS HSM. It's worth looking at crypto operation speed requirements in terms of whether it's best to do in server memory or in the KMS and associated costs. It's most secure to never have the clear text keys outside the HSM. – AndyMac Jul 11 '19 at 14:49

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