A method for decrypting data sent by a first user having at least a first role in a first entity, the first entity comprising at least the first user and a first instance, to a second user having at least a second role in a second entity, the second entity comprising at least the second user and a second instance, the data being encrypted using a symmetric encryption key comprising one or more partial symmetric encryption keys, the one or more partial symmetric encryption keys of the symmetric encryption key being encrypted using a public key of an asymmetric key pair comprising a private key and a public key, wherein the asymmetric key pair is associated with the second role of the second user, and the encrypted data is associated with a transmission ID, the method comprising the following steps: a) the second user receives the encrypted data in his second role, b) the second user provides an element of identification and authentication identifying the second user in its second role and being unique to the user in its second role and the asymmetric key pair associated with this role or user, c) the second user sends a first request to the second instance requesting access to the encrypted transmission, the first request comprising the transmission ID and the element for electronic or digital identification and authentification identifying the second user in its second role and being unique to the user in its second role, and if the transmission ID is a new transmission ID for the second instance, an information request is sent by the second instance to the first instance for information about the transmission, d) in response to the first request the second instance sends an identification token to the second user, the identification token will be used for identifying and authenticating the user and its role in the second entity, e) the second user sends a second request to the first instance for access to the one or more partial symmetric encryption keys held by the first instance, the second request comprising the identification token, information identifying the second role of the second user and the transmission ID, f) the first instance in reaction to the second request sends a third request to the second instance to obtain authentication and verification of the identity of the second user, the third request comprising the identification token and the information identifying the second role of the second user, g) if the second instance recognizes the identification token and the information identifying the second role of the second user, the second instance responds to the third request by transmitting the name and other relevant data regarding the second user to the first instance, h) the first instance in reaction to the authentication of the role and name and other relevant data regarding the second user received in step g) transmits the held one or more partial symmetric encryption keys to the second user, after which the second user if appropriate combines the one or more partial symmetric encryption keys to create the symmetric key that is then used to decrypt the encrypted data. a) the second user receives the encrypted data in his second role, b) the second user provides an element of identification and authentication identifying the second user in its second role and being unique to the user in its second role and the asymmetric key pair associated with this role or user, c) the second user sends a first request to the second instance requesting access to the encrypted transmission, the first request comprising the transmission ID and the element for electronic or digital identification and authentification identifying the second user in its second role and being unique to the user in its second role, and if the transmission ID is a new transmission ID for the second instance, an information request is sent by the second instance to the first instance for information about the transmission, d) in response to the first request the second instance sends an identification token to the second user, the identification token will be used for identifying and authenticating the user and its role in the second entity, e) the second user sends a second request to the first instance for access to the one or more partial symmetric encryption keys held by the first instance, the second request comprising the identification token, information identifying the second role of the second user and the transmission ID, f) the first instance in reaction to the second request sends a third request to the second instance to obtain authentication and verification of the identity of the second user, the third request comprising the identification token and the information identifying the second role of the second user, g) if the second instance recognizes the identification token and the information identifying the second role of the second user, the second instance responds to the third request by transmitting the name and other relevant data regarding the second user to the first instance, h) the first instance in reaction to the authentication of the role and name and other relevant data regarding the second user received in step g) transmits the held one or more partial symmetric encryption keys to the second user, after which the second user if appropriate combines the one or more partial symmetric encryption keys to create the symmetric key that is then used to decrypt the encrypted data.