The present invention relates to a method to build a non-alterable structure and to such a non-alterable structure including data relative to a set of cryptographic material generated randomly or derived from a secret key linked to a business use, the non-alterable structure being intended to be transferred from a first entity to a second entity, the entities sharing at least an encryption/decryption key and a signature key, the structure comprising at least business data relative to the intended use of cryptographic material, an encrypted protection key encrypted with the encryption key, an encrypted set of cryptographic material encrypted with the protection key, a signature of the set of cryptographic material, the protection key and the data relative to the intended use of cryptographic material signed with the signature key.