Computer device for the time-based management of digital documents, of the type comprising: - a memory capable of storing at least one digital document and a respective date stamp, said date stamp defining a correspondence between one or more first signatures and at least one time value, the first signatures being established from the digital document according to a first signature method, - a signature generator capable, when presented with a document content, of establishing one or more respective second signatures according to a second signature method, - a time stamper, including a time election function, capable of establishing a correspondence between one or more signatures and a value-result of the time election function, - a signature verifier capable, when presented with a digital document content and a date stamp, of verifying that they match according to one or more predetermined rules, - a supervisor capable, when presented with the digital document and its date stamp, of carrying out the following operations: - effecting operation of the signature generator on the digital document in order to obtain one or more second signatures, - effecting operation of the signature verifier on the digital document and the date stamp, and - in the case where the digital document matches the date stamp, effecting operation of the time stamper with at least the time value of the digital document and at least some of the second signatures in order to form a new date stamp including second signatures. - a memory capable of storing at least one digital document and a respective date stamp, said date stamp defining a correspondence between one or more first signatures and at least one time value, the first signatures being established from the digital document according to a first signature method, - a signature generator capable, when presented with a document content, of establishing one or more respective second signatures according to a second signature method, - a time stamper, including a time election function, capable of establishing a correspondence between one or more signatures and a value-result of the time election function, - a signature verifier capable, when presented with a digital document content and a date stamp, of verifying that they match according to one or more predetermined rules, - a supervisor capable, when presented with the digital document and its date stamp, of carrying out the following operations: - effecting operation of the signature generator on the digital document in order to obtain one or more second signatures, - effecting operation of the signature verifier on the digital document and the date stamp, and - in the case where the digital document matches the date stamp, effecting operation of the time stamper with at least the time value of the digital document and at least some of the second signatures in order to form a new date stamp including second signatures. - effecting operation of the signature generator on the digital document in order to obtain one or more second signatures, - effecting operation of the signature verifier on the digital document and the date stamp, and - in the case where the digital document matches the date stamp, effecting operation of the time stamper with at least the time value of the digital document and at least some of the second signatures in order to form a new date stamp including second signatures.