A method of authentication of collaborative mobile devices , the method comprising: receiving, by a first mobile device of a user, a challenge message wherein the challenge message is signed by a private key of an authenticator device ; maintaining, by the first mobile device , a public key for the authenticator device; validating, by the first mobile device , the signature of the authenticator device using the public key for the authenticator device; in response to validating the signature of the authenticator device , deriving a challenge response message based on the challenge message wherein the method further comprises: signing, by the first mobile device and using a first mobile device private key, the challenge response message to produce a signed challenge response message; and conveying, by the first mobile device to a second mobile device of the user, a first short-range wireless signal comprising the challenge message ; receiving, from the second mobile device , a second short-range wireless signal comprising a second mobile device authentication result, wherein the second mobile device authentication result is based on the challenge message ; and conveying, by the first mobile device to an authenticator device , the first mobile device authentication result and the second mobile device authentication result ; wherein conveying, by the first mobile device to the authenticator device, the first mobile device authentication result comprises conveying the signed challenge response message; authenticating , by the authenticator device, one or more of the first mobile device, the second mobile device, and the user. receiving, by a first mobile device of a user, a challenge message wherein the challenge message is signed by a private key of an authenticator device ; maintaining, by the first mobile device , a public key for the authenticator device; validating, by the first mobile device , the signature of the authenticator device using the public key for the authenticator device; in response to validating the signature of the authenticator device , deriving a challenge response message based on the challenge message wherein the method further comprises: signing, by the first mobile device and using a first mobile device private key, the challenge response message to produce a signed challenge response message; and conveying, by the first mobile device to a second mobile device of the user, a first short-range wireless signal comprising the challenge message ; receiving, from the second mobile device , a second short-range wireless signal comprising a second mobile device authentication result, wherein the second mobile device authentication result is based on the challenge message ; and conveying, by the first mobile device to an authenticator device , the first mobile device authentication result and the second mobile device authentication result ; signing, by the first mobile device and using a first mobile device private key, the challenge response message to produce a signed challenge response message; and conveying, by the first mobile device to a second mobile device of the user, a first short-range wireless signal comprising the challenge message ; receiving, from the second mobile device , a second short-range wireless signal comprising a second mobile device authentication result, wherein the second mobile device authentication result is based on the challenge message ; and conveying, by the first mobile device to an authenticator device , the first mobile device authentication result and the second mobile device authentication result ; wherein conveying, by the first mobile device to the authenticator device, the first mobile device authentication result comprises conveying the signed challenge response message; authenticating , by the authenticator device, one or more of the first mobile device, the second mobile device, and the user. <EOS>