What does DRM licensing on your phone mean?

DRM, the full name of digital rights management in English, is generally translated as digital rights protection or digital rights management. DRM is divided into two categories, one is multi-protection, such as encrypting movies, audio, and streaming files. The other type is encrypted documents, such as Word, Excel, PDF, etc.

DRM mainly uses technical means to protect documents, movies, and ** from piracy. This technology protects digital content by encrypting it and attaching usage rules that determine whether a user is compliant.

System principle: The system will write the key identifier and license authority address to the header of the packaged encrypted content, and use another pair of keys to sign the header information through the elliptic curve encryption algorithm to prevent the header information from being illegally modified. The encryption process for the content part can be simply described as first processing the 56-bit key using the SHA-1 hash algorithm to obtain a 160-bit, or 20-byte key hash. The first 12 bytes of this key hash will be used as the key used in the generation encryption process.

These 12 bytes will be used as a key, and an all-zero 64-byte string is encrypted by the RC4 algorithm to obtain a 64-byte encryption result, in which the first 48 bytes, that is, 12 32-bit words are used as the key to generate the encrypted content, and the first 6 32-bit words and the last 6 32-bit words are operated respectively. For the encrypted content, the encrypted content is first divided into 8-byte data blocks. For each 8-byte block, the first 32 bits of data will be computed with the first 6 32-bit words of the key, and the last 32 bits will be computed with the last 6 bytes of the key.

The specific operation process is that the 32-bit data is multiplied by the first byte of the key of 6 32-bit words, then divided by the 4294967296 to get the remainder, and the upper 16 bits and the lower 16 bits of the result are exchanged, and then multiplied by the second byte of the key of the 6 32-bit words, and then divided by the 4294967296 to take the rest of the number, and the upper 16 bits and the lower 16 bits of the result are exchanged, and then multiplied by the third byte of the key of the 6 32-bit words. Then divide by 4294967296 to get the remainder and exchange the upper 16 bits and 16 bits lower of the result, then multiply it by the fourth byte of the 6-byte key, then divide by the 4294967296 to get the remainder, and exchange the upper 16 bits and 16 bits lower of the result, then multiply it by the first byte of the key of the 6 32-bit words, then divide by the 4294967296 to get the remainder, and exchange the upper 16 bits and the lower 16 bits of the result, and then add 6 keys of the 32-bit word, The process is then divided by 4294967296 to take the remainder, and the above process is defined as the function f(x), with a 64-bit state value and an initial value of zero.

It's just a permission, copyright.

DRM, the full name of digital rights management in English, is generally translated as digital rights protection or digital rights management. DRM is divided into two categories, one is multi-bend protection, such as encrypting movie, audio, and streaming files. The other type is encrypted documents, such as Word, Excel, PDF, etc.

DRM mainly uses technical means to protect documents, movies, and Peiyinqiao** from piracy.

DRM Permissions:

It is an option displayed under the storage status menu of some domestic mobile phones, which our users can't open, and this is the key permission used by professional devices to read mobile phone resources.

DRM permission is manifested in the fact that no one has claimed to have cracked it, when you install some programs or other files on your mobile phone (especially those that have been installed before leaving the factory), these programs and files are subject to copyright protection, and the DRM permission table is to record the information of these programs and files, and you can use those programs and files normally with these records, so you can't view and modify the things in this permission table.

In addition, this permission table also has some functions similar to the Windows registry.