128 lines
3.5 KiB
Python
128 lines
3.5 KiB
Python
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# -*- coding: utf-8 -*-
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"""
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Created on Mon Jun 10 15:26:43 2019
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@author: Administrator
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"""
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import math
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class Jsteg:
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def __init__(self):
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self.sequence_after_dct=None
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def set_sequence_after_dct(self,sequence_after_dct):
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self.sequence_after_dct=sequence_after_dct
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self.available_info_len=len([i for i in self.sequence_after_dct if i not in (-1,1,0)]) # 不是绝对可靠的
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print ("Load>> 可嵌入",self.available_info_len,'bits')
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def get_sequence_after_dct(self):
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return self.sequence_after_dct
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def write(self,info):
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"""先嵌入信息的长度，然后嵌入信息"""
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info=self._set_info_len(info)
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info_len=len(info)
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info_index=0
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im_index=0
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while True:
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if info_index>=info_len:
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break
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data=info[info_index]
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if self._write(im_index,data):
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info_index+=1
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im_index+=1
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def read(self):
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"""先读出信息的长度，然后读出信息"""
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_len,sequence_index=self._get_info_len()
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info=[]
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info_index=0
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while True:
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if info_index>=_len:
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break
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data=self._read(sequence_index)
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if data!=None:
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info.append(data)
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info_index+=1
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sequence_index+=1
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return info
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#===============================================================#
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def _set_info_len(self,info):
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l=int(math.log(self.available_info_len,2))+1
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info_len=[0]*l
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_len=len(info)
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info_len[-len(bin(_len))+2:]=[int(i) for i in bin(_len)[2:]]
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return info_len+info
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def _get_info_len(self):
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l=int(math.log(self.available_info_len,2))+1
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len_list=[]
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_l_index=0
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_seq_index=0
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while True:
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if _l_index>=l:
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break
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_d=self._read(_seq_index)
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if _d!=None:
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len_list.append(str(_d))
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_l_index+=1
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_seq_index+=1
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_len=''.join(len_list)
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_len=int(_len,2)
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return _len,_seq_index
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# 注意经过DCT会有负值，此处最低有效位的嵌入方式与空域LSB略有不同
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def _write(self,index,data):
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origin=self.sequence_after_dct[index]
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if origin in (-1,1,0):
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return False
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lower_bit=origin%2
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if lower_bit==data:
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pass
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elif origin>0:
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if (lower_bit,data) == (0,1):
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self.sequence_after_dct[index]=origin+1
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elif (lower_bit,data) == (1,0):
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self.sequence_after_dct[index]=origin-1
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elif origin<0:
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if (lower_bit,data) == (0,1):
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self.sequence_after_dct[index]=origin-1
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elif (lower_bit,data) == (1,0):
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self.sequence_after_dct[index]=origin+1
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return True
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def _read(self,index):
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if self.sequence_after_dct[index] not in (-1,1,0):
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return self.sequence_after_dct[index]%2
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else:
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return None
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'''
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import cv2
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import numpy as np
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def dct(m):
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m = np.float32(m)/255.0
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return cv2.dct(m)*255
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'''
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if __name__=="__main__":
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jsteg=Jsteg()
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# 写
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sequence_after_dct=[-1,0,1]*100+[i for i in range(-7,500)]
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#print(sequence_after_dct)
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jsteg.set_sequence_after_dct(sequence_after_dct)
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info1=[0,1,0,1,1,0,1,0]
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jsteg.write(info1)
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sequence_after_dct2=jsteg.get_sequence_after_dct()
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# 读
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jsteg.set_sequence_after_dct(sequence_after_dct2)
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info2=jsteg.read()
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print (info2)
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