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

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

3. Reading a protected word without login
LF - EN
Memory EM4056
Reading a protected word without login
Mask protected region
Setting the « Mask protected region » bit
Write protection
Read protection
TAG not logged in
Its equivalent in HEX
Result of a reading
A memory word in binary

4. Reading a protected word with login
LF - EN
Memory EM4056
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 only be compared with a known word.
TAG logged in
Mask protected region
Write protection
Read protection
Result of a reading

5. Comparison Result of reading transponder addresses 20 through to 24
LF - EN
Memory EM4056
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
LF - EN
Memory EM4056
Memory EM4056
and its security
End of this chapter
J.-D. Chatelain