A secure bytecode instrumentation facility, wherein a new code fragment is registered in an encrypted registry by first extracting a digital certificate from a specified code fragment location. A certification authority (CA) in the digital certificate is compared against a list of registered trusted certification authorities in the registry. If the CA is in the registry list, the code fragment origin in the digital certificate is compared against a list of registered trusted origins in the registry. If the code fragment origin is in the registry list, a determination is made as to whether the code fragment is authentic. If so, the information of the code fragment is recorded into the registry. The injection of code fragments may begin upon the initialization of the instrumentation facility if the encrypted registry has not been corrupted since last accessed, and if the code fragment content matches code fragment information in the registry.