A method for digitally signing an electronic file, characterised by the following steps carried out by a server: - generating a challenge value comprising a projection parameter, - transferring the challenge value to a client device through a communications channel, - receiving, through a communications channel, an evidence record, the electronic file to be signed, and a user's biometric data from the client device, the evidence record being generated by the client device by associating - the challenge value, - a hash of reduced biometric data, the reduced biometric data being generated from the biometric data applying a projection utilising the projection parameter, and - a hash of the electronic file, - generating reduced biometric verification data from the biometric data applying the projection utilising the projection parameter, - generating the hash of the reduced biometric verification data, - generating a hash of the electronic file, - generating a verification evidence record by associating the challenge value, the hash of the reduced biometric verification data, and the hash of the electronic file, and comparing it against the evidence record sent by the client device and only continuing the digital signature process if the verification evidence record is identical with the evidence record sent by the client device, - identifying the user of the client device and defining at least one user data item, - generating a server certificate by associating at least the hash of the electronic file, the at least one user data item, and signature data relating at least to the time of the signature, - signing the server certificate applying the server's private signing key, thereby generating a signed server certificate, - generating a digital signature by associating at least the signed server certificate and the hash of the electronic file, and - associating the digital signature with the electronic file, thereby generating a digitally signed electronic file. - generating a challenge value comprising a projection parameter, - transferring the challenge value to a client device through a communications channel, - receiving, through a communications channel, an evidence record, the electronic file to be signed, and a user's biometric data from the client device, the evidence record being generated by the client device by associating - the challenge value, - a hash of reduced biometric data, the reduced biometric data being generated from the biometric data applying a projection utilising the projection parameter, and - a hash of the electronic file, - the challenge value, - a hash of reduced biometric data, the reduced biometric data being generated from the biometric data applying a projection utilising the projection parameter, and - a hash of the electronic file, - generating reduced biometric verification data from the biometric data applying the projection utilising the projection parameter, - generating the hash of the reduced biometric verification data, - generating a hash of the electronic file, - generating a verification evidence record by associating the challenge value, the hash of the reduced biometric verification data, and the hash of the electronic file, and comparing it against the evidence record sent by the client device and only continuing the digital signature process if the verification evidence record is identical with the evidence record sent by the client device, - identifying the user of the client device and defining at least one user data item, - generating a server certificate by associating at least the hash of the electronic file, the at least one user data item, and signature data relating at least to the time of the signature, - signing the server certificate applying the server's private signing key, thereby generating a signed server certificate, - generating a digital signature by associating at least the signed server certificate and the hash of the electronic file, and - associating the digital signature with the electronic file, thereby generating a digitally signed electronic file.