A method for offline authenticity testing of a virtual document by means of a first and a second electronic device (102, 152), wherein the first electronic device comprises a first memory, in which the virtual document and a memory ID of the virtual document are stored, and wherein the memory ID is encrypted together with the virtual document by the first device using a cryptographic key of the second device, wherein the second electronic device comprises a second memory in which there is stored a cryptographically secured database, which comprises hash values of a plurality of virtual documents as authentically stored hash values, wherein the memory ID of the virtual document identifies an entry of the database with the hash value of the virtual document, wherein the cryptographically secured database is a blockchain and the hash value of the virtual document is stored as a transaction in a block of the blockchain, and wherein the second electronic device does not require an online connection to a remote central server system to test the authenticity of the virtual document, wherein the method comprises: • transmitting the virtual document together with the memory ID from the first electronic device to the second electronic device, • calculating a hash value of the virtual document by the second electronic device, • identifying the database entry with the hash value of the virtual document by the second electronic device with use of the memory ID of the virtual document, • comparing the calculated hash value with the hash value of the virtual document stored in the identified database entry, wherein the authenticity of the virtual document is confirmed if both hash values match. wherein the first electronic device comprises a first memory, in which the virtual document and a memory ID of the virtual document are stored, and wherein the memory ID is encrypted together with the virtual document by the first device using a cryptographic key of the second device, wherein the second electronic device comprises a second memory in which there is stored a cryptographically secured database, which comprises hash values of a plurality of virtual documents as authentically stored hash values, wherein the memory ID of the virtual document identifies an entry of the database with the hash value of the virtual document, wherein the cryptographically secured database is a blockchain and the hash value of the virtual document is stored as a transaction in a block of the blockchain, and wherein the second electronic device does not require an online connection to a remote central server system to test the authenticity of the virtual document, wherein the method comprises: • transmitting the virtual document together with the memory ID from the first electronic device to the second electronic device, • calculating a hash value of the virtual document by the second electronic device, • identifying the database entry with the hash value of the virtual document by the second electronic device with use of the memory ID of the virtual document, • comparing the calculated hash value with the hash value of the virtual document stored in the identified database entry, wherein the authenticity of the virtual document is confirmed if both hash values match. • transmitting the virtual document together with the memory ID from the first electronic device to the second electronic device, • calculating a hash value of the virtual document by the second electronic device, • identifying the database entry with the hash value of the virtual document by the second electronic device with use of the memory ID of the virtual document, • comparing the calculated hash value with the hash value of the virtual document stored in the identified database entry, wherein the authenticity of the virtual document is confirmed if both hash values match.