PutObjectRequest request = new PutObjectRequest(bucket, key, srcPath);
request.SetCosServerSideEncryption();

// 存储桶名称，此处填入格式必须为 bucketname-APPID, 其中 APPID 获取参考 https://console.tencentcloud.com/developer
string bucket = "examplebucket-1250000000";
string key = "exampleobject"; //对象键
string srcPath = @"temp-source-file";//本地文件绝对路径
//.cssg-snippet-body-start:[put-object-sse-c]   
PutObjectRequest request = new PutObjectRequest(bucket, key, srcPath);
request.SetCosServerSideEncryptionWithKMS("KMS Custem Key ID", "Context Json");

PutObjectRequest request = new PutObjectRequest(bucket, key, srcPath);
request.SetCosServerSideEncryptionWithCustomerKey("Your Secret Key");