How to use 32-digit php to encrypt and decrypt IDs (code attached)

I recently encountered a problem in the project. The current user shares an invitation code with a friend. After the friend registers as a new user based on the invitation code, he becomes the current user's subordinate. Under certain conditions, the subordinate user's information can be obtained. A range of rebates. What is implemented here is to generate an encrypted string based on the current user's id, which can be reversely decrypted. After constant testing and adjustments, the final result was finally obtained. For example:

id = 12 code = 85U43DM

First implementation

First enter the code, as follows:

Introduction to the idea:

Set a salt value, $salt, and concatenate it with the id to form a new string. The salt value can be used to securely calibrate the invitation code later. test. Perform md4 encryption on the string (considering that md4 is faster and less secure than md5), get $encodestr, split the string into two parts, the first part $startLen , 13 strings; the second part $endLen, 8 strings. Mix $string, here the passed in id, and $uidlen into the previous part of the string. Therefore, it currently only supports a maximum length of id of 9, so the length of $uidlen is 1, so in the end we get a string of length 22.

During the encryption process, we actually mix the value of the id and the length of the id into the encrypted string. During encryption, we find the corresponding position based on the stored information to get the id.

Here, we do not have high requirements for security. In order to make the program run faster, there is no verification during decryption.

Test, encrypt the id:

Output result:

23471DC2352712F34D6780

Test, decrypt the invitation code

Output result :

12

The results obtained do not seem to have any problems, but in the actual test, such a problem was found. This may exist for ordinary users. A friend sent a message to his WeChat mobile phone. Invitation code, and then he wants to use a computer to register, but he doesn’t know how to transfer the invitation code from the mobile phone to the computer or finds it troublesome. At this time, he has to enter the invitation code manually on the computer. Oh my God, It's 22 digits, and it's still a mix of capital letters and numbers. He probably has to give up on registration.

Therefore, we have made adjustments and changed to a 7-digit invitation code.

Explore again

Is the method encapsulated before writing the article, or is it better to directly add the code first

Introduction to ideas

This method was adopted under the guidance of a master who has worked for many years. Convert the id into a fixed-length 32-digit string and add your own algorithm. Why is base 32 used here instead of other bases? The 32-digit system can contain enough English characters, and the generated encrypted string will look more standardized. On the other hand, some English characters that are not easily recognized (ILOU is excluded here) are excluded, so the 32-digit system is used instead of 36 base.

Encryption process, method idToString(), considering that when the id is relatively small at the beginning, there will be more 0s when converting to 32 hexadecimal, which seems very irregular, so an initial value INIT_NUM is set. , this can be customized. According to the passed id, after adding the initial value, a value with a length of 10 digits is obtained. The interval bit of this value is split into $num1 with a length of 4 digits and $num2 with a length of 6 digits. The two values ​​are converted separately. It is hexadecimal. After conversion, $num1 will get a string with a length of 3. Use U to make up for the shortage. $num2 will get a string with a length of 4. Use L to make up for the shortage.

Decryption is a reverse operation, just reverse the operation.

Test: Generate

Result:

85U43DM

Decryption:

Result:

12

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