CN1243325C - Quick enciphering method and device for wavelet image - Google Patents

Abstract

The present invention relates to a quick encryption method and quick encryption device of wavelet images, which is a method and a device used for the safe transmission of information. The encryption device is composed of a DSP module 1, a FLASH module 2, a power supply management module 3 and a clock module 4. The encryption method of the present invention comprises the following steps: step 1), a preliminarily coded cipher key is input to the encryption device through a serial port; step 2), an image data flow enters the encryption device through a duplex channel composed of a serial port of DSP; step 3), an images is disassembled into a low frequency component and a high frequency detail component; step 4), wavelet coefficients of the low frequency component are converted into fixed point numbers from floating point numbers; step 5), the wavelet coefficients of the low frequency component are divided into a plurality of groups by using 128 bit as a unit; step 6), the groups are orderly encrypted with an AES algorithm; step 7), the wavelet coefficients of the low frequency component after being encrypted are converted into floating point numbers from fixed point numbers; step 8), the wavelet coefficients of the low frequency component and the wavelet coefficients of the high frequency component are combined for generating a compressed image file; step 9), the image data flow processed through compression and encryption are output from the encryption device through the serial port of the DSP.

Description

The fast encrypt method of Wavelet image and fast encrypt device

Technical field

The present invention is encryption method and the fast encrypt device in a kind of method and apparatus, especially image information safe transmission that is used for information security transmission.

Background technology

Because computer computation ability constantly improves and based on the development of the Distributed Calculation of Internet; have only the DES algorithm of 56bit to constitute huge threat to key length; therefore; the activity of U.S.'s National Institute of Standards and Tech on April 15 (NIST) initiation collection Advanced Encryption Standard (AES) algorithm in 1997; and, be intended to protect the sensitivity of government and hetero-organization thereof, the transmission of non-confidential information in the data encryption standards of announcement on October 2nd, 2000 Rijndael as U.S. a new generation.

Ri jndael algorithm is that a kind of data block length is 128bits, the iteration block cipher that key length is variable, and key block length can be respectively 128,192 or 256bits.Because Ri jndael algorithm is derived from the Square algorithm, its structure has very strong dirigibility, is easy to expansion.

The multimedia especially processing and the transmission of video information has become an important directions of Information Technology Development from now on, and multimedia communication becomes the important means of information interchange between the people gradually.People carry out internet trade etc. by the various information of internet exchange.Therefore, the safety of information seems more and more important with secret, and the development of technology is also had higher requirement to information protection.The algorithm of general universality is encrypted code stream, and algorithm is only required the input binary bit stream, and and be indifferent to the meaning of bit stream; The advantage of this cryptographic algorithm is any data are used greatly, and the encryption of each bit must make the implementation efficiency of algorithm reduce.

But for multimedia messages, image information especially, traditional encryption technology is encrypted it as common data stream, and does not consider certain limitation is arranged the characteristics of multi-medium data.

Based on the special image compress-encrypt device of DSP (Digital Signal Processing, digital signal processor), also on the market not occur, at home and abroad also be a kind of blank.

Summary of the invention

Technical matters

The purpose of this invention is to provide a kind of fast encrypt method and fast encrypt device with Wavelet image of characteristics such as anti-attack ability is strong, calculated amount is little, processing speed is fast.

Technical scheme

The fast encrypt device of Wavelet image of the present invention, by the digital signal processor module, flash memory module, power management module, clock module is formed, wherein " D0～D15; A0～A15 " of digital signal processor module end connects " D0～D15; A0～A15 " end of flash memory module respectively, " CE# " end of " DS# " termination flash memory module of digital signal processor module, " RW#; MSTRB# " end of digital signal processor module is held by " WE# " that " logic gates M " connects flash memory module, and " MSTRB#; XF " end of digital signal processor module connects " OE# " end of flash memory module by " amplifier F; logic gates M "; " CVdd, DVdd, RST# " end of clock module connects " 1OUT, 2OUT, 1RESET# " end of power management module respectively; " RST# " end of " 1RESET# " termination flash memory module of power management module; " McBSP0BDR0 " end of digital signal processor module is the input end of 128bit key, " McBSP1 BDR1 " end of digital signal processor module is the input end of image to be encrypted, and " BDX1 " of digital signal processor module holds the output terminal for the image of having encrypted.

Performing step of the present invention is:

1. the key of the 128bit that will finish is in advance imported encryption equipment;

2. the image data stream of encryption to be compressed is imported encryption equipment;

3. image being carried out two-dimensional discrete wavelet conversion and handle (2-D Discrete Wavelet Transform), is low frequency component and high frequency details component with picture breakdown;

4. the wavelet coefficient with low frequency component is converted into fixed-point number by floating number;

5. the wavelet coefficient with low frequency component is the unit by 128bit, is divided into some groupings;

6. utilize AES (Advanced Encryption Standard, superencipherment algorithm) algorithm successively these groupings to be encrypted;

7. the low frequency component wavelet coefficient after will encrypting is converted into floating number by fixed-point number;

8. compressed image file is returned in the wavelet coefficient conversion of low frequency component and high frequency details component;

9. export encryption equipment through the image data stream of overcompression and encryption by the DSP serial port.

After one 256 * 256 pixel image carried out wavelet decomposition, wavelet coefficient had 65536, and only need encrypt the effect that 256 coefficients (8192bit) of low frequency component wherein can reach encryption.

Beneficial effect

Adopt this programme that multiple image is tested, after one 256 * 256 pixel image carried out wavelet decomposition, wavelet coefficient had 65536, and only need encrypt the effect that 256 coefficients (8192bit) of low frequency component wherein can reach encryption.Synthetic again image after encrypt has greatly destroyed original image to the encryption of low frequency component coefficient, thereby has reached the image encryption effect.If do not know just to be decrypted key to image yet.

The present invention adopts the conduct of Rijndael algorithm that the low frequency wavelet coefficient of the image of compression is encrypted with the dedicated encrypted device of DSP as compression of images and encryption, has characteristics such as attacking ability is strong, calculated amount is little, processing speed is fast, has obtained result preferably.This algorithm is transplanted to (this platform is core with TMS320VC5402 on the common DSP hardware platform, comprise peripheral basic data IO channel), and in conjunction with the storer characteristics of DSPs, and the code optimization device that uses corresponding support software to provide, algorithm is carried out complex optimum, and the speed of compression of images and encryption and decryption is greatly improved.

The present invention is a kind of fast encrypt device that operates in the Wavelet image on the common DSP hardware platform, realizes wavelet compression and encryption to image, has characteristics such as anti-attack ability is strong, calculated amount is little, processing speed is fast.

We have realized Wavelet image compression and the algorithm of encrypting on the TMS320VC5402 hardware platform, and to the optimization of carrying out different levels of algorithm, make having arrived significantly of arithmetic speed of encryption equipment improve.

Description of drawings

Fig. 1 is that encryption equipment is formed module map.Digital signal processor module 1, flash memory module 2, power management module 3 and clock module 4 are wherein arranged.

Fig. 2 is the fast encrypt device encryption flow block diagram of Wavelet image.

Fig. 3 is the circuit theory diagrams of the fast encrypt device left-half of Wavelet image.Fig. 4 is the circuit theory diagrams of the fast encrypt device right half part of Wavelet image.

Embodiment

The fast encrypt device of Wavelet image of the present invention is by digital signal processor module 1, FLASH module 2, power management module 3, clock module 4 is formed, wherein " DO～D15; A0～A15 " of digital signal processor module 1 end connects " D0～D15; A0～A15 " end of flash memory module 2 respectively, " CE# " end of " DS# " termination flash memory module 2 of digital signal processor module 1, " RW#; MSTRB# " end of digital signal processor module 1 is held by " WE# " that " logic gates M " connects flash memory module 2, and " MSTRB#; XF " end of digital signal processor module 1 connects " OE# " end of flash memory module 2 by " amplifier F; logic gates M "; " CVdd, DVdd, RST# " end of clock module 4 connects " 1OUT, 2OUT, 1RESET# " end of power management module 3 respectively; " RST# " end of " 1RESET# " termination flash memory module 2 of power management module 3; " McBSP0 BDR0 " end of digital signal processor module 1 is the input end of 128bit key, " McBSP1 BDR1 " end of digital signal processor module 1 is the input end of image to be encrypted, and " BDX1 " of digital signal processor module 1 holds the output terminal for the image of having encrypted.

The device list of forming this encryption equipment is as follows:

Device name	Model
		DSP power storage device 64K * 16SRAM CONNECTOR crystal oscillator 10MHz JTAG	TMS320VC5402 TPS73HD318 AM29LV400A CY7C-1021 ST-3120-5B (two)

The optimization of the realization of enciphering and deciphering algorithm and code on TMS320VC5402

Two kinds of on-chip memories are arranged: two addressable memories (DARAM) and single addressable memory among the TMS320VC5402.The characteristics of two addressable memories are to allow CPU in the single cycle it to be visited twice.Single addressable memory has two kinds of forms: (1) single addressing read/writable memory device (SARAM), and (2) single addressing ROM (read-only memory) (ROM or DROM), CPU can be in the single cycle to each memory unit access once.These two kinds of storeies all can be mapped to the program space and data space.In addition, TMS320VC5402 can plug-in chip external memory, but CPU to sheet external memory unit access once, wants two cycles at least.Compare with chip external memory, on-chip memory has does not need to insert waiting status, cost and advantage such as low in energy consumption.

Match with it, TI company provides corresponding code development the integration environment---and Code ComposerStudio (CCS), it integrates code Core Generator and debugging acid, and processor information and supervisory programme performance can be provided.CCS can use all instruments in a control window.

CCS carries code optimization device Optimizer, it can carry out the optimization of 4 different levels to all source codes that are included in CCS Project the inside: register (Register) level is optimized, local variable (Local) level is optimized, global variable (Global) level is optimized, file (FILE) level is optimized, and the optimization range of these 4 levels and degree are progressively to expand and deepen.

We have realized Wavelet image compression and the algorithm of encrypting on the TMS320VC5402 hardware platform, and to the optimization of carrying out different levels of algorithm, make encryption equipment arithmetic speed arrived certain raising.The fast encrypt device of Wavelet image, can produce key or the key that will finish in advance by serial port McBSP pours into encryption equipment by random generator, then, data stream (view data) enters encryption equipment by the duplex channel of the serial ports formation of DSP, realizes wavelet compression and the encryption or the decrypt operation of image on the TMS320C5402DSP of TIX chip.

Performing step of the present invention is:

1). the key that will finish in advance by serial port pours into encryption equipment;

2). image data stream enters encryption equipment by the duplex channel of the serial ports formation of DSP;

3). image being carried out two-dimensional discrete wavelet conversion handle, is low frequency component and high frequency details component with picture breakdown;

4). the wavelet coefficient of low frequency component is converted into fixed-point number by floating number;

5). is that dividing elements is some groupings with the wavelet coefficient of low frequency component by 128bit;

6). utilize aes algorithm successively these groupings to be encrypted;

7). the low frequency component wavelet coefficient after will encrypting is converted into floating number by fixed-point number;

8). the set of wavelet coefficients symphysis of low frequency component and high fdrequency component is become compressed image file;

9). the image data stream through overcompression and encryption is exported encryption equipment by the serial ports of DSP.

After one 256 * 256 pixel image carried out wavelet decomposition, wavelet coefficient had 65536, and only need encrypt the effect that 256 coefficients (8192bit) of low frequency component wherein can reach encryption.

Adopt method of the present invention that multiple image is tested, image with one 256 * 256 pixel is that example is done above-mentioned processing, be low frequency component and high frequency details component with two-dimensional discrete wavelet conversion with picture breakdown earlier, then with the wavelet coefficient of low frequency component (owing to be that floating number can't be carried out bit manipulation, be translated into fixed-point number earlier) be that dividing elements is some groupings by 128bit, utilize aes algorithm successively these groupings to be encrypted at last.

Synthetic again image after encrypt has greatly destroyed original image to the encryption of low frequency component coefficient, thereby has reached the image encryption effect.If do not know just to be decrypted key to image yet.Simultaneously as can be seen, the progression of wavelet decomposition is high more, and the effect of encrypting low frequency component is poor more, this is because kept more detail of the high frequency on other components of unencrypted, increase the encrypted packets number, can strengthen the effect of encryption, but also strengthened the operand of encrypting.

The performance evaluation of Wavelet image cryptographic algorithm

The objective evaluation standard that is usually used in Image Data Compression is to use Y-PSNR PSNR, is that the image of N * N is defined as to pixel count

$\mathrm{PSNR}=10\log \left[\frac{255\×255}{\frac{1}{N\×N}\underset{m=0}{\overset{N-1}{\∑}}\underset{n=0}{\overset{N-1}{\∑}}{(x_{\mathrm{mn}}-\widehat{x_{\mathrm{mn}}})}^2}\right]$

X wherein _Mn^, x _MnBe respectively (m, n) gray-scale value behind the gray-scale value of individual pixel and the compressed decompress(ion) of N * N image.We encode to the LENNA image of one 512 * 512 pixel, obtain following result:

Ratio of compression	Total speed	Total distortion	The RMS error	PSNR (unencryption)	PSNR (encryption)	Subjective assessment
							1∶1	232643	4534.21	0.131517	65.7512	65.6631	Undistorted
8∶1	32765.8	1.86574e+06	2.66782	39.6077	39.6075	Fabulous
							16∶1	16379	3.87079e+06	3.84264	36.4382	36.4381	Fine
32∶1	8161.11	7.50844e+06	5.35186	33.5607	33.5607	Good, do not see distortion substantially
							64∶1	4094.35	1.36965e+07	7.22828	30.9501	30.9501	Some blurs a little in edge
80∶1	3263.11	1.66627e+07	7.97266	30.0987	30.0987	Edge is fuzzy bigger
							128∶1	2039.83	2.45897e+07	9.68515	28.4087	28.4087	Big distortion is arranged

The image of unencrypted image and encryption is compared, the conversion distortion when its faint PSNR decline derives from encryption between wavelet coefficient floating number and the fixed-point number, and enciphering and deciphering algorithm itself can't harm information.

Claims (2)

1, a kind of fast encrypt device of Wavelet image, it is characterized in that this encryption equipment is by digital signal processor module (1), flash memory module (2), power management module (3), clock module (4) is formed, wherein " D0～D15; A0～A15 " of digital signal processor module (1) end connects " D0～D15; A0～A15 " end of flash memory module (2) respectively, " CE# " end of " DS# " termination flash memory module (2) of digital signal processor module (1), " RW#; MSTRB# " end of digital signal processor module (1) is held by " WE# " that " logic gates M " connects flash memory module (2), and " MSTRB#; XF " end of digital signal processor module (1) connects " OE# " end of flash memory module (2) by " amplifier F; logic gates M "; " CVdd, DVdd, RST# " end of clock module (4) connects " 1OUT, 2OUT, 1RESET# " end of power management module (3) respectively; " RST# " end of " 1RESET# " termination flash memory module (2) of power management module (3); " McBSP0 BDR0 " end of digital signal processor module (1) is the input end of 128bit key, " McBSP1 BDR1 " end of digital signal processor module (1) is the input end of image to be encrypted, and " BDX1 " of digital signal processor module (1) holds the output terminal for the image of having encrypted.

2, a kind of encryption method that is applied to the fast encrypt device of the described Wavelet image of claim 1 is characterized in that the steps include:

1) key that will finish in advance by serial port pours into encryption equipment;

2) image data stream enters encryption equipment by the duplex channel of the serial ports formation of digital signal processor;

3) image being carried out two-dimensional discrete wavelet conversion and handle, is low frequency component and high frequency details component with picture breakdown;

4) wavelet coefficient with low frequency component is converted into fixed-point number by floating number;

5) wavelet coefficient with low frequency component is that dividing elements is some groupings by 128bit;

6) utilize Advanced Encryption Standardalgorithm successively these groupings to be encrypted;

7) the low frequency component wavelet coefficient after will encrypting is converted into floating number by fixed-point number;

8) the set of wavelet coefficients symphysis with low frequency component and high frequency details component becomes compressed image file;

9) export encryption equipment through the image data stream of overcompression and encryption by the serial ports of digital signal processor.

Images