Strong authentication of a user of a communication terminal

A communication terminal comprising a processor configured to implement the following upon establishing an audio communication with a server:

• sending via said audio communication, to said server, a request to access said server, said request comprising a first identifier associated with the communication terminal and a second identifier associated with a service requested in said server,
• receiving via said audio communication, from an authentication device, an authentication request asking the user to speak at least one word,
• communicating via said audio communication at least one word spoken by the user to the authentication device, and
• in response to said communication of said at least one spoken word, said at least one spoken word corresponding to a voiceprint of the user speaking at least one first word, said voiceprint being recorded beforehand in association with the identifier of said communication terminal receiving, from the authentication device, an additional authentication request for additional authentication of the user.

An authentication device comprising a processor configured to implement the following, upon establishing an audio communication with a server:

• receiving via said audio communication, from said server, a first identifier associated with a communication terminal and a second identifier associated with a service requested in said server,
• sending via said audio communication, to the communication terminal associated with the first identifier, an authentication request asking a user of said communication terminal to speak at least one word,
• receiving via said audio communication the at least one spoken word from the terminal, said at least one spoken word corresponding to a voiceprint of the user recorded beforehand in association with the first identifier, and
• in response to said reception of said at least one spoken word, said at least one spoken word corresponding to a voiceprint of the user speaking at least one first word, said voiceprint being recorded beforehand in association with the identifier of said communication terminal, sending, to the communication terminal, an additional authentication request for additional authentication of the user.