getDigital Osterrätsel 2020 Lösungsansätze, Diskussionen etc.

$ ent q1yRm.txt 
Entropy = 4.168739 bits per byte.

Optimum compression would reduce the size
of this 79 byte file by 47 percent.

[...]
$ ent 01NUV.txt  # oder jede andere Datei
Entropy = 5.493654 bits per byte.

Optimum compression would reduce the size
of this 79 byte file by 31 percent.

[...]

q1yRm.txt	4.168739
(andere)	5.493654
bhsyj.txt	5.811719
CpeNP.txt	5.811719

$ sed -e 's/\x00//g' < 01NUV.txt | ent
Entropy = 5.977280 bits per byte.
[...]
$ sed -e 's/\x00//g' < CpeNP.txt | ent
Entropy = 5.977280 bits per byte.
[...]
$ sed -e 's/\x00//g' < bhsyj.txt | ent
Entropy = 5.977280 bits per byte.

In [5]: log(26+26+10+1)/log(2)                                                                                                                                                                   
Out[5]: 5.977279923499917

$ pngchunks Hort\ der\ prophezeihungen-02.png 
Chunk: Data Length 13 (max 2147483647), Type 1380206665 [IHDR]
  Critical, public, PNG 1.2 compliant, unsafe to copy
  IHDR Width: 1886
  IHDR Height: 233
  IHDR Bitdepth: 8
  IHDR Colortype: 2
  IHDR Compression: 0
  IHDR Filter: 0
  IHDR Interlace: 0
  IHDR Compression algorithm is Deflate
  IHDR Filter method is type zero (None, Sub, Up, Average, Paeth)
  IHDR Interlacing is disabled
  Chunk CRC: 189006455
Chunk: Data Length 9 (max 2147483647), Type 1935231088 [pHYs]
  Ancillary, public, PNG 1.2 compliant, safe to copy
  ... Unknown chunk type
  Chunk CRC: 2024095606
Chunk: Data Length 7771 (max 2147483647), Type 1413563465 [IDAT]
  Critical, public, PNG 1.2 compliant, unsafe to copy
  IDAT contains image data
  Chunk CRC: 96258982
Chunk: Data Length 0 (max 2147483647), Type 1145980233 [IEND]
  Critical, public, PNG 1.2 compliant, unsafe to copy
  IEND contains no data
  Chunk CRC: -1371381630

$ identify -verbose Hort\ der\ prophezeihungen-02.png 
Image: Hort der prophezeihungen-02.png
  Format: PNG (Portable Network Graphics)
  Mime type: image/png
  Class: DirectClass
  Geometry: 1886x233+0+0
  Resolution: 118.11x118.11
  Print size: 15.9682x1.97274
  Units: PixelsPerCentimeter
  Type: Grayscale
  Endianess: Undefined
  Colorspace: sRGB
  Depth: 8-bit
  Channel depth:
    gray: 8-bit
  Channel statistics:
    Pixels: 439438
    Gray:
      min: 0 (0)
      max: 255 (1)
      mean: 217.152 (0.851578)
      standard deviation: 88.4011 (0.346671)
      kurtosis: 1.98911
      skewness: -1.97637
      entropy: 0.20846
  Colors: 17
  Histogram:
     58160: (  0,  0,  0) #000000 gray(0)
       472: ( 16, 16, 16) #101010 gray(16)
       463: ( 32, 32, 32) #202020 gray(32)
       205: ( 48, 48, 48) #303030 gray(48)
      3572: ( 64, 64, 64) #404040 gray(64)
        16: ( 80, 80, 80) #505050 gray(80)
       625: ( 96, 96, 96) #606060 gray(96)
        13: (112,112,112) #707070 gray(112)
      3353: (128,128,128) #808080 gray(128)
        16: (143,143,143) #8F8F8F gray(143)
       570: (159,159,159) #9F9F9F gray(159)
         7: (175,175,175) #AFAFAF gray(175)
      3828: (191,191,191) #BFBFBF gray(191)
        79: (207,207,207) #CFCFCF gray(207)
       476: (223,223,223) #DFDFDF gray(223)
       571: (239,239,239) #EFEFEF gray(239)
    367012: (255,255,255) #FFFFFF gray(255)
...