A receiver of digitally encoded voice signals that may be encrypted according to a plurality of keep subjects a received signal to decryption according to each of the keys. Decrypted signals are tested for the presence of modulation, and the signal, if any, that is decrypted is recovered for use. If it is desired, a visual indication may tell a user which key is being used to decrypt the signal.
A wireless mobile unit includes a voice encoder circuit that receives an analog voice signal and creates digital voice data representing a user's voice. The mobile unit receives an encryption key entered by the user, typically on the keypad or through a voice recognition circuit, and stores the encryption key in a storage device. An encryption circuit encrypts the digital voice data using the encryption key. A transmitter then modulates the encrypted voice data onto an RF signal and transmits the RF signal to a base station in a wireless network. The base station uses the same encryption key to decrypt the signal before transmitting it to another base station or mobile unit. Signals transmitted from the base station to the mobile unit are encrypted and decrypted using a user-selected encryption key in a similar manner.
A transmission apparatus 100 includes a secret key storage unit 103 that stores three secret keys K1, K2 and K3, a secret key selection unit 104 that selects one secret key Ks from the secret keys, a message generation unit 106 for generating a message M used as a carrier for indicating a secret key, an encryption module 105 for generating a cryptogram Ca by encrypting the generated message M using the secret key Ks, an encryption module 107 for generating a cryptogram Cm by encrypting the message M using the message M itself as the secret key, and two transmission units 111 and 112 for transmitting the cryptograms Ca and Cm to the reception apparatus 200 to indicate the selected secret key Ks. The reception apparatus 200 includes a decryption module, such as 221, for generating decrypted data Mi by decrypting the cryptogram Ca using a secret key Ki out of the three secret keys, and a decryption module, such as 222, for generating decrypted data Mii by decrypting the cryptogram Cm using the decrypted data Mi, and authorizes that the secret key Ki has been selected when the decrypted data Mi matches the decrypted data Mii.
In a receiver (100), an encrypted communication (104) is decrypted using a decryptor (101) and a key (107) to produce a decrypted communication (105). A comparator (103) compares decrypted symbol patterns in the decrypted communication against a set of predetermined symbol patterns (108). When the decrypted symbol patterns are distributed non-uniformly relative to the set of predetermined symbol patterns, the receiver is identified as a target of the encrypted communication.
An improved method for password validation comprising the steps of identifying bad passwords having one or more characters; computing a frequency of occurrence of bad password characters; computing a probability of occurrence T of the bad password characters within the bad passwords based upon the computed frequency of occurrence; identifying a proposed password having one or more characters; and comparing the proposed password characters with the probability of occurrence T of the bad password characters. The method further comprises the steps of establishing a validation threshold and validating the proposed password based upon the correspondence between (i) a value, BAp, reflecting the relationship between the probability of occurrence T of bad password characters within bad passwords and the proposed password characters and (ii) an established validation threshold. A Markov model is use to compute the probability of occurrence. The present invention also includes an improved password validation system.
A transmission apparatus 100 includes a secret key storage unit 103 that stores three secret keys K1, K2 and K3, a secret key selection unit 104 that selects one secret key Ks from the secret keys, a message generation unit 106 for generating a message M used as a carrier for indicating a secret key, an encryption module 105 for generating a cryptogram Ca by encrypting the generated message M using the secret key Ks, an encryption module 107 for generating a cryptogram Cm by encrypting the message M using the message M itself as the secret key, and two transmission units 111 and 112 for transmitting the cryptograms Ca and Cm to the reception apparatus 200 to indicate the selected secret key Ks. The reception apparatus 200 includes a decryption module, such as 221, for generating decrypted data Mi by decrypting the cryptogram Ca using a secret key Ki out of the three secret keys, and a decryption module, such as 222, for generating decrypted data Mii by decrypting the cryptogram Cm using the decrypted data Mi, and authorizes that the secret key Ki has been selected when the decrypted data Mi matches the decrypted data Mii.
