$ irb irb(main):001:0> require 'securerandom' => true irb(main):002:0> SecureRandom.hex(64) => "string------------------------" SecureRandomの使い方 base64(n=nil) nはbase64文字列の長さのバイト数 ** 実際に出力される文字列の長さはnの4/3程度 生成される文字列に含まれる文字: A-Z, a-z, 0-9, “+”, “/” and “=”
![[Ruby 2.x] SecureRandom を利用した乱数の生成方法 - Qiita](https://cdn-ak-scissors.b.st-hatena.com/image/square/9c8b8cdc1a3b49c681b20c53c8d9648c61ece9cf/height=288;version=1;width=512/https%3A%2F%2Fqiita-user-contents.imgix.net%2Fhttps%253A%252F%252Fcdn.qiita.com%252Fassets%252Fpublic%252Farticle-ogp-background-412672c5f0600ab9a64263b751f1bc81.png%3Fixlib%3Drb-4.0.0%26w%3D1200%26mark64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZ3PTk3MiZoPTM3OCZ0eHQ9JTVCUnVieSUyMDIueCU1RCUyMFNlY3VyZVJhbmRvbSUyMCVFMyU4MiU5MiVFNSU4OCVBOSVFNyU5NCVBOCVFMyU4MSU5NyVFMyU4MSU5RiVFNCVCOSVCMSVFNiU5NSVCMCVFMyU4MSVBRSVFNyU5NCU5RiVFNiU4OCU5MCVFNiU5NiVCOSVFNiVCMyU5NSZ0eHQtYWxpZ249bGVmdCUyQ3RvcCZ0eHQtY29sb3I9JTIzMjEyMTIxJnR4dC1mb250PUhpcmFnaW5vJTIwU2FucyUyMFc2JnR4dC1zaXplPTU2JnM9YTRmOWMzN2VlZDFmMDlhNzk5ZTQwYjgyZDRkMzlkZTE%26mark-x%3D142%26mark-y%3D57%26blend64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZoPTc2Jnc9NzcwJnR4dD0lNDBjb2xvcnJhYmJpdCZ0eHQtY29sb3I9JTIzMjEyMTIxJnR4dC1mb250PUhpcmFnaW5vJTIwU2FucyUyMFc2JnR4dC1zaXplPTM2JnR4dC1hbGlnbj1sZWZ0JTJDdG9wJnM9NzVkYWE3NzRhZDk0NGI5OWZhN2I0OThhNWQwNWUxNDI%26blend-x%3D142%26blend-y%3D486%26blend-mode%3Dnormal%26s%3Da0a65a4927c29b3621a221605749ccfc)