KMS Sign digest message format

[paullallier]

Hi,

I'm not sure if this is a misunderstanding on my part, an issue with the documentation, or a bug.

I'm trying to use KSM:Sign with ECDSA_SHA_256 and a pre-hashed digest message. The documentation suggests the message should be in base64 encoding. I believe an SHA_256 hash digest is 32bytes, which is 44 characters in base64, but when I gets a request with a 44 character base64 string, I get:

ValidationException (client): Digest is invalid length for algorithm ECDSA_SHA_256.

I've tried stripping the final '=' off the hash to make a 43 character string, but I get the same error.

Has anyone manages to use this with a digest message from the SDK? It works fine with RAW message types.