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Deriving a symmetric key from an asymmetric key for file encryption or decryption

  • US 7,181,016 B2
  • Filed: 01/27/2003
  • Issued: 02/20/2007
  • Est. Priority Date: 01/27/2003
  • Status: Expired due to Fees
First Claim
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1. A method comprising:

  • accessing a private key of an asymmetric key pair in a key device;

    deriving a symmetric master key from the private key of the asymmetric key pair using a single sign-on process, the single sign-on process allowing a user to encrypt or decrypt files in response to a file encryption key, the file encryption key being encrypted or decrypted using the symmetric master key;

    storing the symmetric master key in a computer memory location, wherein the files can be encrypted or decrypted in response to the symmetric master key even if the user deactivates the key device;

    deactivating the key device; and

    following the deactivation of the key device, accessing a process that encrypts or decrypts the file encryption key using the previously stored symmetric master key, wherein accessing the process uses the single sign-on process on a remote computer that is remote from a computer that is used to derive the symmetric master key from the private key of the asymmetric key pair.

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