February 2023
Intermediate
256 pages
5h 50m
Japanese
Content preview from アルゴリズム図鑑 増補改訂版 絵で見てわかる33のアルゴリズム
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
公開鍵暗号方式は、暗号化にも復号にも時間がかかる傾向にあります。計算時間を短縮する
ため、実際はメッセージを直接暗号化するのではなく、まずはメッセージのハッシュ値を求
め、そのハッシュ値を暗号化して署名に用います（下図参照）。
5-3
p.144
internet
S
P
7f05
7f05
7f05
A B
abc abc
=
「認証」、「改ざんの検出」、「否認防止」の機能を備えるデジタル署名ですが、
1
つ問題があ
ります。
B
さんはデジタル署名を用いたやりとりを通して、メッセージの送信者が
A
さんだと信じ
ていますが、実際には、
A
さんを騙る悪意のある
X
さんとやりとりをしていた可能性はゼロと
はいえません。
その根本的な原因は、公開鍵暗号方式において、公開鍵が誰のものであるのかがわからない
ことにあります。受け取った公開鍵には、作成者を示す情報が一切含まれていません。そのた
め、
A
さんを騙る他の誰かが作成した公開鍵である可能性もあり、はっきりとしません。
この問題は、次節で解説する「デジタル証明書」の仕組みで解決することができます。
5-10
p.186
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.