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Protection system for intelligent cards

  • US 4,453,074 A
  • Filed: 10/19/1981
  • Issued: 06/05/1984
  • Est. Priority Date: 10/19/1981
  • Status: Expired due to Term
First Claim
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1. A system for allowing authorized users of portable intelligent cards to effect transactions via at least one transaction terminal comprising a plurality of user intelligent cards each having stored therein a code which is the encryption of a combination of a password associated with the respective user and a reference text which is common to all users, the codes stored in all of said cards having been encrypted with the same private key which is associated with the public key of a public-key cryptosystem pair;

  • and at least one transaction terminal having means for allowing a card user to inut a password, and means for controlling (1) the retrieval of the code stored in an inserted card, (2) the decryption of the retrieved code with the use of said public key to derive a password part and a text part, (3) the comparisons of the derived password part with the inputted password, and the text part with said common reference text, and (4) the effecting of a transaction only if both of said comparisons are successful.

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