Research On Digital Audio Encryption Algorithm Based On Content-associated Key

With the development of mobile technology,VoIP technology has gradually matured,anti-eavesdropping awareness,audio copyright protection awareness has also gradually increased,a large amount of audio data is transmitted on mobile devices,information security has become a topic of increasing concern,and currently on digital audio the research on encryption algorithms is still far from deep.The traditional encryption algorithm mode is fixed,and one key corresponds to multiple files.It has security risks when dealing with massive data.The content-associated key technology does not depend entirely on computational complexity,and is suitable for processing massive data,but the encryption effect depends on the file formats,such as poor performance when processing PCM data.By combining the AES encryption algorithm and the content-associated key idea,a new idea of digital audio encryption on the Android platform is proposed for two typical audio data formats,PCM and AAC.The PCM data is unencoded,does not contain the file header,and the signal is recorded to the buffer in real time through AudioRecord.AES encryption is performed on each 2048-byte buffer data in 128-bit key and ECB unfilled mode,which confuses the data.The content-associated encryption algorithms are performed according to the random number generated by the linear congruential pseudo-random function,so that the data is defective.The defect data can hardly be restored to plaintext by AES decryption,thus achieving encryption.After encoding,AAC contains the file header,records the signal into AAC_ADTS file format through MediaRecorder,parses the flag bit of the audio frame header,acquires the start and end points of the data part,groups it and performs block encryption according to the above operation mode.In the experiment,the two plaintext data are encrypted under different conditions.After many tests and comparative analysis,the encryption method of AES combined with the content-associated key idea is excellent for PCM data,and the security of the data is greatly improved.For AAC data,even if AES encryption is not used,a good encryption effect can be achieved while ensuring a certain extraction ratio.