METHOD, FIRST DEVICE, FIRST SERVER, SECOND SERVER AND SYSTEM FOR ACCESSING A PRIVATE KEY

The invention relates to a method 20 for accessing a private key.The method comprises:- storing, by a first device 12, the private key and an associated public key;- generating 22 an access token;- sending 24 to a second device 14, the access token;- sending 28, to a first server 16, an address relating to a decentralized identifier and the access token;- sending 29, by the first server, to a ledger 112, a request for getting a decentralized identifier along with the decentralized identifier address;- sending 212, to the first server, the decentralized identifier including the public key;- generating 214 a challenge;- encrypting 216 the challenge;- sending 218, through a second server 18, to the first device, the encrypted challenge and the access token, an address relating to the second server being identified by using the decentralized identifier;- verifying 224 whether the received access token is or is not the generated access token;- decrypting 226, only in the affirmative, by using the private key, the encrypted challenge;- sending 228, to the first server, the challenge;- verifying 230, whether the received challenge is or is not the generated challenge; and- attesting 232, only in the affirmative, that the decentralized identifier includes data that belongs to a user.The invention also relates to corresponding first device, first and second server and system.