Importance

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Abstract

A system is employed for providing two different levels of protection for cryptographic devices transmitting digital information. The system is independent of the cryptographic algorithm used and works with any keyed cryptographic algorithm. High grade encryption is used for data transmitted from the transmitter device and employs an encryption key of 'Y' bits. This information is decrypted at the receiver by a decryption circuit also having a 'Y' key size. At the receiver, return information is encrypted by an encryption key having 'X' bits, where X=Y-Z, with Z being a variable. The low grade information encrypted at the receiver is supplied back to the transmitter, which incorporates a decryption circuit having an 'X' key size for decrypting the lower grade information.

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First Claim