A method for producing a security device able to store confidential data associated with the holder of said security device, characterized in that it comprises the following phases: - a preparation phase comprising the following steps: - a step of first acquisition of a first recording representative of a biometric information from the holder (7, 71) of the security device, - collection of the confidential data (2, 20), - transformation of the confidential data (2, 20) into encrypted data (2, 21), by means of an encryption using the first recording representative of a biometric information to determine an encryption key, such that the inverse transformation can only be carried out by means of said biometric information, - a production phase comprising the following steps: - manufacture of a blank security device (1, 10), - storage of said encrypted data (2, 21) in said security device, then - delivery of the security device (1, 11), then - a post-production activation phase comprising the following steps: ∘ - a step of second acquisition of a second recording representative of the same biometric information from the holder (7, 72), ∘ - transformation of the encrypted data (2, 21) to find the confidential data (2, 22), by means of a decryption, so that the security device contains said decrypted data, the decryption using the second recording representative of the biometric information to determine a decryption key, then - storage of the confidential data in the security device. - a preparation phase comprising the following steps: - a step of first acquisition of a first recording representative of a biometric information from the holder (7, 71) of the security device, - collection of the confidential data (2, 20), - transformation of the confidential data (2, 20) into encrypted data (2, 21), by means of an encryption using the first recording representative of a biometric information to determine an encryption key, such that the inverse transformation can only be carried out by means of said biometric information, - a step of first acquisition of a first recording representative of a biometric information from the holder (7, 71) of the security device, - collection of the confidential data (2, 20), - transformation of the confidential data (2, 20) into encrypted data (2, 21), by means of an encryption using the first recording representative of a biometric information to determine an encryption key, such that the inverse transformation can only be carried out by means of said biometric information, - a production phase comprising the following steps: - manufacture of a blank security device (1, 10), - storage of said encrypted data (2, 21) in said security device, then - delivery of the security device (1, 11), then - manufacture of a blank security device (1, 10), - storage of said encrypted data (2, 21) in said security device, then - delivery of the security device (1, 11), then - a post-production activation phase comprising the following steps: ∘ - a step of second acquisition of a second recording representative of the same biometric information from the holder (7, 72), ∘ - transformation of the encrypted data (2, 21) to find the confidential data (2, 22), by means of a decryption, so that the security device contains said decrypted data, the decryption using the second recording representative of the biometric information to determine a decryption key, then - storage of the confidential data in the security device. ∘ - a step of second acquisition of a second recording representative of the same biometric information from the holder (7, 72), ∘ - transformation of the encrypted data (2, 21) to find the confidential data (2, 22), by means of a decryption, so that the security device contains said decrypted data, the decryption using the second recording representative of the biometric information to determine a decryption key, then - storage of the confidential data in the security device. - storage of the confidential data in the security device.