A trusted display (18) of a trusted authorization device (TAD) (10) displays on a trusted display (18) first information about a transaction to be authorized by a user (14) using a trusted keypad (20). The TAD (10) generates (208) a random number (R); generates (1210) second information from the first information, the random number (R) and a first identification code (TADID-A) of the TAD (10); generates (212) a signature of the second information using a first encryption process; egnerates (216) a set of session keys (Ks1, Ks2, Ks3) by a second encryption process responsive to the random number (R) and a set of stored working keys (K_w1, K_w2, K_w3); and generates (218) third information by encrypting the second information and the signature using a third encryption process responsive to the set of session keys (Ks1, Ks2, Ks3). A dat structure (42) is formed comprising the random numer (R), the first identification code (TADID-A), and the third information; and communicated (220) from the TAD (10) to the client (12) to a host server (28) for verification by a verification decryption server (32).