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Please provide as much information as possible. At least, this should include a description of your issue and steps to reproduce the problem. If possible please provide a summary of what steps or workarounds you have already tried, and any docs or articles you found (un)helpful.

Problem you have encountered:
- I am using widevine DRM, so according to the documentation, I had to put in my key in the secret manager (secretManagerKeySource.secretVersion). But according to https://cloud.google.com/transcoder/docs/reference/drm#encryptionkey  , it requires a 128 bit key, but I only have 256 bit key from widevine. I've tried truncating the first and last 32 characters of the key, the transcoding was successful and content seems to be encrypted, but the content can't seem to be decrypted. That leads me to thinking that the encryption key is incorrect. I'm not sure if widevine drm should be the one responsible for generating me another 128 bit key to be used or there is more detailed instruction for this. I would also like to see a sample of the keyId and keyUri, at the moment I'm putting my IV as keyID and keyUri is https://license.staging.widevine.com/cenc/getcontentkey/{provider}, please correct me if i'm wrong.

What you expected to happen:
- Able to decrypt and play the content successfully.

Steps to reproduce:
- Use the following object in secret manager
{
  "encryptionKeys": [
    {
      "keyId": "this_is_my_iv",
      "key": "my_256_bit_key_doesnt_work_here_getting_error_length_should_be_128bit",
      "iv": "this_is_my_iv_as_well",
      "keyUri": "https://license.staging.widevine.com/cenc/getcontentkey/{provider}",
      "matchers": [
        {
          "muxStreams": ["360p", "720p", "1080p", "audio"]
        }
      ]
    }
  ]
}



Other information (workarounds you have tried, documentation consulted, etc):