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Verifiable, Leak-Resistant Encryption and Decryption

  • US 20110138192A1
  • Filed: 12/02/2010
  • Published: 06/09/2011
  • Est. Priority Date: 12/04/2009
  • Status: Active Grant
First Claim
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1. A method for encrypting plaintext data by a device with an internal secret state, while limiting the re-use of cryptographic keys, comprising:

  • (a) deriving a message key from said internal secret state and a message to identifier by computing a plurality of successive intermediate keys, starting with at least a portion of said internal secret state and leading to said message key, where each successive key is derived based on at least a portion of said message identifier and a prior key;

    (b) using said one or more cryptographic keys based on at least said message key to encrypt one or more segments of said plaintext data to produce one or more encrypted data segments;

    (c) computing a cryptographic hash from at least one said encrypted data segment;

    (d) deriving a validator from at least a secret value and said cryptographic hash, where said deriving includes computing a plurality of successive intermediate values, starting with said secret value, where each successive value is at least based on a prior one of said values and a portion of said cryptographic hash;

    (e) outputting said one or more encrypted data segments and said validator.

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