Method for checking the identity of a user (U), comprising the following steps implemented by an identity-checking device : • reading if there, from a public blockchain , confidentiality-protected data generated beforehand, by an identity-attesting device , from an identity element of a user (U) and from at least one random datum specific to the user (U), • obtaining proof data, the proof data having been generated beforehand, by a client device belonging to the user (U), from the identity element of the user (U) and from the random datum specific to the user (U), and the proof data being obtained by reading proof data from the public blockchain , • implementing predetermined processing for the user (U) only if the following conditions are met: - the confidentiality-protected data generated by the identity-attesting device are associated in the public blockchain with first transaction data indicating that the identity-attesting device has transferred a predetermined amount of a digital currency to a recipient, - the read proof data are associated, in the public blockchain , with confidentiality-protected data generated beforehand by the identity-attesting device , - the found confidentiality-protected data and the proof data associated with the found confidentiality-protected data are related by a predetermined mathematical relationship. • reading if there, from a public blockchain , confidentiality-protected data generated beforehand, by an identity-attesting device , from an identity element of a user (U) and from at least one random datum specific to the user (U), • obtaining proof data, the proof data having been generated beforehand, by a client device belonging to the user (U), from the identity element of the user (U) and from the random datum specific to the user (U), and the proof data being obtained by reading proof data from the public blockchain , • implementing predetermined processing for the user (U) only if the following conditions are met: - the confidentiality-protected data generated by the identity-attesting device are associated in the public blockchain with first transaction data indicating that the identity-attesting device has transferred a predetermined amount of a digital currency to a recipient, - the read proof data are associated, in the public blockchain , with confidentiality-protected data generated beforehand by the identity-attesting device , - the found confidentiality-protected data and the proof data associated with the found confidentiality-protected data are related by a predetermined mathematical relationship. - the confidentiality-protected data generated by the identity-attesting device are associated in the public blockchain with first transaction data indicating that the identity-attesting device has transferred a predetermined amount of a digital currency to a recipient, - the read proof data are associated, in the public blockchain , with confidentiality-protected data generated beforehand by the identity-attesting device , - the found confidentiality-protected data and the proof data associated with the found confidentiality-protected data are related by a predetermined mathematical relationship. <EOS>