Mifare访问条件计算 [英] Mifare Access condition calculation
问题描述
我知道该帖子:- Mifare Classic的锁定机制1K
但是，实际上还不清楚-如何在此字符串中计算类似FF 07 80 FF的值:
However, it is really not clear - how a value like FF 07 80 FF is calculated in this string:
D3 F7 D3 F7 D3 F7 FF 07 80 FF 00 00 00 00 00 00
这意味着可以用键A读取这些块，并用键B写入这些块，但是不允许inc/dec.
This means that the blocks can be read with key A and written with Key B but does not allow inc/dec.
如果我必须支持递增和递减运算，访问位应该是什么样子.我知道C1，C2和C3必须为1,1,0，这如何反映到字节6、7和8.
How should the access bits look like if I have to support increment and decrement operations. I understand that C1, C2 and C3 must be 1,1,0 how does this reflect to the byte 6, 7 and 8.
任何帮助将不胜感激.
推荐答案
访问位FF 07 80转换为
C1 = 0x0 => C1_3 = 0, C1_2 = 0, C1_1 = 0, C1_0 = 0
C2 = 0x0 => C2_3 = 0, C2_2 = 0, C2_1 = 0, C2_0 = 0
C3 = 0x8 => C3_3 = 1, C3_2 = 0, C3_1 = 0, C3_0 = 0
因此只能使用键A (Cx_3 = 0 0 1)来读取和写入扇区预告片.只能使用键A (Cx_{0,1,2} = 0 0 0，由于尾随块的访问条件而禁用键B)对数据块执行所有操作(读，写，递增，递减等).
So the sector trailer can be read and written using key A only (Cx_3 = 0 0 1). All operations (read, write, increment, decrement, etc) can be performed on the data blocks using key A only (Cx_{0,1,2} = 0 0 0, key B is disabled due to the access conditions of the trailer block).
如果您希望能够使用键A读取所有块，使用键B进行写入，使用键B执行值块递增以及使用键A和B执行值块递减等，则可以使用如下访问条件:
If you want be able to read all blocks with key A, write with key B, perform value block increments with key B and perform value block decrement, etc. with keys A and B, you could use access conditions like this:
- 扇区尾部仅使用键B写入:
Cx_3 = 0 1 1 -
数据/值块:用键A读/减，用键B写/增量:
Cx_{0,1,2} = 1 1 0
C1_3 = 0, C1_2 = 1, C1_1 = 1, C1_0 = 1 => C1 = 0x7
C2_3 = 1, C2_2 = 1, C2_1 = 1, C2_0 = 1 => C2 = 0xF
C3_3 = 1, C3_2 = 0, C3_1 = 0, C3_0 = 0 => C3 = 0x8
这导致访问位08 77 8F.因此，您的部门预告片可能如下所示(键A = D3F7D3F7D3F7，键B = 000000000000):
This leads to the access bits 08 77 8F. Hence, you sector trailer could look like this (with key A = D3F7D3F7D3F7 and key B = 000000000000):
D3F7D3F7D3F7 08778F FF 000000000000
这篇关于Mifare访问条件计算的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
