Method for operating a technical device that is a trackside or vehicle-side component of a railway technical facility, wherein the technical device is equipped with a certificate store, characterised in that the certificate store is a root certificate store in which root certificates regarded as valid are stored, with which the technical device can check whether newly transmitted or newly installed software or newly received files are to be classified as trustworthy and may be used or executed, wherein the procedure for modifying the content of the root certificate store is such that - a data container is generated on the operator side and contains at least the following: - a command for modifying the content of the root certificate store and, in the event of a new root certificate being added to the root certificate store, the respective root certificate, - an operator-side signature certificate containing a public key, - a chain-of-trust data record that refers to a base root certificate and allows a verification of the operator-side signature certificate, and - a signature (SIG(PS) generated with a private key (PS) of the operator-side signature certificate, - the trustworthiness of the signature (SIG(PS) is checked on the device side, namely on the basis of the public key in the operator-side signature certificate, the chain-of-trust data record and at least one base root certificate stored on the device side and regarded as valid on the device side, and - in the event of a signature check confirming the trustworthiness, the command for modifying the content of the root certificate store contained in the data container is executed on the device side. the certificate store is a root certificate store in which root certificates regarded as valid are stored, with which the technical device can check whether newly transmitted or newly installed software or newly received files are to be classified as trustworthy and may be used or executed, wherein the procedure for modifying the content of the root certificate store is such that - a data container is generated on the operator side and contains at least the following: - a command for modifying the content of the root certificate store and, in the event of a new root certificate being added to the root certificate store, the respective root certificate, - an operator-side signature certificate containing a public key, - a chain-of-trust data record that refers to a base root certificate and allows a verification of the operator-side signature certificate, and - a signature (SIG(PS) generated with a private key (PS) of the operator-side signature certificate, - the trustworthiness of the signature (SIG(PS) is checked on the device side, namely on the basis of the public key in the operator-side signature certificate, the chain-of-trust data record and at least one base root certificate stored on the device side and regarded as valid on the device side, and - in the event of a signature check confirming the trustworthiness, the command for modifying the content of the root certificate store contained in the data container is executed on the device side. - a data container is generated on the operator side and contains at least the following: - a command for modifying the content of the root certificate store and, in the event of a new root certificate being added to the root certificate store, the respective root certificate, - an operator-side signature certificate containing a public key, - a chain-of-trust data record that refers to a base root certificate and allows a verification of the operator-side signature certificate, and - a signature (SIG(PS) generated with a private key (PS) of the operator-side signature certificate, - a command for modifying the content of the root certificate store and, in the event of a new root certificate being added to the root certificate store, the respective root certificate, - an operator-side signature certificate containing a public key, - a chain-of-trust data record that refers to a base root certificate and allows a verification of the operator-side signature certificate, and - a signature (SIG(PS) generated with a private key (PS) of the operator-side signature certificate, - the trustworthiness of the signature (SIG(PS) is checked on the device side, namely on the basis of the public key in the operator-side signature certificate, the chain-of-trust data record and at least one base root certificate stored on the device side and regarded as valid on the device side, and - in the event of a signature check confirming the trustworthiness, the command for modifying the content of the root certificate store contained in the data container is executed on the device side.