Forum › MIFARE SDK › [MIFARE DESFIRE EV1] How to update IV in AES(read/write). › Reply To: [MIFARE DESFIRE EV1] How to update IV in AES(read/write).
Hi,
the example explains an AES authentication in detail. The IV vector is used in block ciphers to chain blocks together. The first block uses usually a random or a “well known” value. In the case of the DESFire authentication the IV is for the first block 00…00. But for the second block you do not use 00..00 again! You use the output of the previous block for the IV vector of the next block. In this way all blocks are “chained”.
Please visit:
https://en.wikipedia.org/wiki/Initialization_vector
and:
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation
Kind regards,
The MIFARE Team
the example explains an AES authentication in detail. The IV vector is used in block ciphers to chain blocks together. The first block uses usually a random or a “well known” value. In the case of the DESFire authentication the IV is for the first block 00…00. But for the second block you do not use 00..00 again! You use the output of the previous block for the IV vector of the next block. In this way all blocks are “chained”.
Please visit:
https://en.wikipedia.org/wiki/Initialization_vector
and:
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation
Kind regards,
The MIFARE Team
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