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Format-preserving cryptographic systems

  • US 8,208,627 B2
  • Filed: 04/29/2009
  • Issued: 06/26/2012
  • Est. Priority Date: 05/02/2008
  • Status: Active Grant
First Claim
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1. A method for performing encryption at computing equipment, comprising:

  • with an encryption engine on computing equipment, obtaining an encoded binary value representing an unencrypted string in a given format, wherein obtaining the encoded binary value comprises;

    obtaining the unencrypted string in the given format; and

    encoding the unencrypted string to produce the encoded binary value;

    with the encryption engine on the computing equipment, applying a block cipher to the encoded binary value to produce a block cipher output;

    after each application of the block cipher, with the encryption engine on the computing equipment, determining whether the block cipher output is representative of a string in the given format;

    whenever it is determined that the block cipher output is not representative of a string in the given format, with the encryption engine on the computing equipment, applying the block cipher an additional time to update the block cipher output; and

    when it is determined that the block cipher output is representative of a string in the given format, with the encryption engine on the computing equipment, processing the block cipher output to produce an encrypted version of the unencrypted string.

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