libs/RFID.MFRC522
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Authenticate devices with long uids

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It seems that the last four uid bytes should be used for
auth instead of first ones.

This patch allows to work with Mifare plus cards in SL1 mode,
that have 7 byte uids (e.g. Troyka transport cards.)

See also "3.2.5 MIFARE Classic Authentication" of AN10927 document.
http://cache.nxp.com/documents/application_note/AN10927.pdf
This commit is contained in:
Alexander Inyukhin
2016-09-10 11:01:34 +03:00
parent bec50c194e
commit 76adf6e383
1 changed files with 6 additions and 2 deletions
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8
MFRC522.cpp
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@@ -843,8 +843,12 @@ MFRC522::StatusCode MFRC522::PCD_Authenticate(byte command, ///< PICC_CMD_MF_AU
for (byte i = 0; i < MF_KEY_SIZE; i++) { // 6 key bytes for (byte i = 0; i < MF_KEY_SIZE; i++) { // 6 key bytes
sendData[2+i] = key->keyByte[i]; sendData[2+i] = key->keyByte[i];
} }
for (byte i = 0; i < 4; i++) { // The first 4 bytes of the UID // Use the last uid bytes as specified in http://cache.nxp.com/documents/application_note/AN10927.pdf
sendData[8+i] = uid->uidByte[i]; // section 3.2.5 "MIFARE Classic Authentication".
// The only missed case is the MF1Sxxxx shortcut activation,
// but it requires cascade tag (CT) byte, that is not part of uid.
for (byte i = 0; i < 4; i++) { // The last 4 bytes of the UID
sendData[8+i] = uid->uidByte[i+uid->size-4];
} }
// Start the authentication. // Start the authentication.