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Decryption of ReadData Response does not output the expected result for NTAG 424

Question asked by Ibrahim Atli on May 11, 2020
Latest reply on Jun 3, 2020 by Jonathan Iglesias

I am trying to decrypt the response data from ReadData (FileNo 03) Command using AN12196.

I have successfully authenticated myself and also successfully send the read data (SW1 91 SW2 00)

 

But I cannot encrypt the data as expected.

 

What I send via APDU

INSCLA: 90 -- INSCODE: ad -- p1: 00 -- p2: 00 -- data: 030000000000002c959ad85afdebb2 -- le: 256

SW1: 91, SW2 00

What I get:

b4173043af196e3140a67efb0bf051d84264fd86b439688302c0648bb46196044ce2329e0bb0880df3948f7ab315e9acbcfe36caf02ff499a5ed61b86c625012da89b18d0c4975d2e18f765c254c14d1216779d43f94f871a516497879bc9550e37ae4357abca8e8f63c5e0d8f2e97e9a8120cec73f5fa6c309e40fbd7f1bf4df3c95960b8a852bfa7f8a87c63b0653a05ec9ad9afcbef32

Relevant data to decrypt it:

SESAUTHENC: 5de37b95b1e54b312883e2302ee659d4

SESAUTHMAC: ff831facdfea267567eabb827b266b1f

TI: 1595b419

CMD: AD

CMDCTR: 0100

 

What the result should be (plain data in FileNo3) in hex:

68656C6C6F776F726C6430303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030

 

But I get:

fce6560788d457e8b732928c7a6752f2b9b3a445e71a778874cc057fbd93e529c15c29115568c60d847a7d86a6c56c3550bd15b887479e279462c567af4dd14a1ae560c839efc52a96813af882ab610ec96d3227ec17f10cc8c89014fbe28604aad975b13355f3bf7ae2c544e1525190ab360488213cd156e3414c26393a72197dba828e8a544260fd3cd91fe0ae20ad

 

I would really appreciate a calculation on how to get the expected result. Thank you very much in advance.

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