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Memory EM4056 and its security

Memory EM4056 and its security. J.-D. Chatelain. 1 0 1 0 1 0. Laser ROM. 0 1. 1 0. 1 1. LSB. MSB. OTP Write protection of one word. The memory is made up of 128 words, each of 18 bits.

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Memory EM4056 and its security

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  1. Memory EM4056 and its security J.-D. Chatelain

  2. 1 0 1 0 1 0 Laser ROM 0 1 1 0 1 1 LSB MSB OTP Write protection of one word The memory is made up of 128 words, each of 18 bits The word at address 126 permits configuration of the soft protection activated by the password, which is found at address 127 The last two bits of each word (LSB: Least Significant Bits) are dedicated to its protection The first three words (laser ROM) contain the transponder’s unique identification number The following three words are reserved for CONTRINEX There remain 16 usable bits per word for data OTP (One Time Programmable) Read protection of one word OTP Read and Write protection of one word 000 001 002 003 004 005 006 007 008 009 010 011 100% 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 75% 50% 25% 122 123 124 125 126 127

  3. Mask protected region Read protection Write protection Reading a protected word without login Setting the « Mask protected region » bit TAG not logged in Its equivalent in HEX Result of a reading A memory word in binary

  4. Reading a protected word with login When words are protected with a « Password », they can be accessed only with a login. When a word is protected by a « Read protection » bit, it may onlybe compared with a known word. Mask protected region TAG logged in Read protection Write protection Result of a reading

  5. Comparison Result of reading transponder addresses 20 through to 24 Result of reading the same addresses after having protected addresses 21 and 22

  6. The acknowledgment (error) code "4" after the second phase indicates that the entered data is not identical to the data stored in the memory. Complete words are to be compared The acknowledgment (error) code "0“, after the second phase, indicates that the entered data is identical to the data stored in the memory Content of the memory of the transponder

  7. Memory EM4056 and its security End of this chapter J.-D. Chatelain

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