digital signatures, font files, and recursion illustrated examples
Post on 21-Dec-2015
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TRANSCRIPT
![Page 1: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/1.jpg)
Digital Signatures, Font Files, and Recursion
Illustrated Examples
![Page 2: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/2.jpg)
Original signed file
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red nodes indicate hash values in the signed file
![Page 3: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/3.jpg)
Subsetted signed file
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subsetted file contains glyphs 0, 1, and 2
![Page 4: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/4.jpg)
Further subsetted file
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further subsetted file contains just glyph 1
![Page 5: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/5.jpg)
Illustration of subsetting glyphs 0, 1, and 2
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black highlightednodes indicate thecurrent recursive call
return h(0, 0).do not emit.
red: smallest glyph in file not processed yetblue: smallest glyph in output file not processed yet
![Page 6: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/6.jpg)
Illustration (slide 2)
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return h(1, 1).do not emit.
![Page 7: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/7.jpg)
Illustration (slide 3)
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return h(0, 1).do not emit.
![Page 8: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/8.jpg)
Illustration (slide 4)
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return h(2, 2).do not emit.
![Page 9: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/9.jpg)
Illustration (slide 5)
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return h(3, 3).emit h(3, 3).
![Page 10: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/10.jpg)
Illustration (slide 6)
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return h(2, 3).do not emit.
![Page 11: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/11.jpg)
Illustration (slide 7)
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return h(0, 3).do not emit.
![Page 12: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/12.jpg)
Illustration (slide 8)
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return h(4, 4).do not emit.
![Page 13: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/13.jpg)
Illustration (slide 9)
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return h(5, 5).do not emit.
![Page 14: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/14.jpg)
Illustration (slide 10)
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return h(4, 5).do not emit.
![Page 15: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/15.jpg)
Illustration (slide 11)
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return h(6, 6).do not emit.
![Page 16: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/16.jpg)
Illustration (slide 12)
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return h(7, 7).do not emit.
![Page 17: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/17.jpg)
Illustration (slide 13)
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return h(6, 7).do not emit.
![Page 18: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/18.jpg)
Illustration (slide 14)
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return h(4, 7).emit h(4, 7).
![Page 19: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/19.jpg)
Illustration (slide 15)
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copy h(0, 7) from original file to output file.
![Page 20: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/20.jpg)
Subsetting
• Important: Note that the decisions to emit a hash value to the output file and whether to make recursive calls depend on the position of the red and blue arrows at the time the recursive call is made.
![Page 21: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/21.jpg)
Illustration of further subsetting to just glyph 1
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return h(0, 0).emit h(0, 0).
Input file has glyphs 0, 1, 2,and hash values h(3, 3) andh(4, 7).Output file has just glyph 1.
![Page 22: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/22.jpg)
Illustration (slide 2)
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return h(1, 1).do not emit.
![Page 23: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/23.jpg)
Illustration (slide 3)
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return h(0, 1).do not emit.
![Page 24: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/24.jpg)
Illustration (slide 4)
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return h(2, 2).do not emit.
![Page 25: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/25.jpg)
Illustration (slide 5)
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return h(3, 3).do not emit.
![Page 26: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/26.jpg)
Illustration (slide 6)
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return h(2, 3).emit h(2, 3).
![Page 27: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/27.jpg)
Illustration (slide 7)
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return h(0, 3).do not emit.
![Page 28: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/28.jpg)
Illustration (slide 8)
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return h(4, 7), which is in the original file.emit h(4, 7).
![Page 29: Digital Signatures, Font Files, and Recursion Illustrated Examples](https://reader035.vdocuments.net/reader035/viewer/2022062516/56649d585503460f94a36db7/html5/thumbnails/29.jpg)
Illustration (slide 9)
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copy h(0, 7) from original file to output file.