Patent ID: 7773753
Filing Date: 2010-08-10
Classification: H04L

Abstract:
1. A method for encryption of plaintext data on a host, the plaintext data having an arbitrary data size, the encryption based on a secret key stored in a hardware token separate from the host and connected to the host without revealing the secret key to the host, the method comprising: in the host, dividing the plaintext data into a first plaintext section and a second plaintext section, wherein said first plaintext section has a predetermined size, and wherein said second plaintext section has a size larger than said predetermined size of the first plaintext section; in the host, computing a value based on said first plaintext section; sending said value from the host to the hardware token; in the hardware token, encrypting said value according to the secret key to obtain a derivative key; in the hardware token, encrypting said derivative key according to the secret key, to obtain a first ciphertext section; sending said derivative key and said first ciphertext section to the host; in the host, encrypting said second plaintext section according to said derivative key, to obtain a second ciphertext section, wherein said second ciphertext section has a size identical to that of said second plaintext section; and in the host, combining said first ciphertext section and said second ciphertext section to obtain ciphertext data having a size identical to the arbitrary data size of said plaintext data, and wherein said ciphertext data is the encryption of the plaintext data.