cc/examples/mac/mac_test_keyset.json

{
    "primaryKeyId": 691856985,
    "key": [
      {
        "keyData": {
          "typeUrl": "type.googleapis.com/google.crypto.tink.HmacKey",
          "keyMaterialType": "SYMMETRIC",
          "value": "EgQIAxAgGiDZsmkTufMG/XlKlk9m7bqxustjUPT2YULEVm8mOp2mSA=="
        },
        "outputPrefixType": "TINK",
        "keyId": 691856985,
        "status": "ENABLED"
      }
    ]
  }