🔐 密码强度检测Password Strength

「熵（Entropy）」衡量口令的不可预测性，单位是 bit：每多 1 bit，暴力破解尝试次数翻一倍。本工具按「字符集大小 × 长度」估算熵值——例如 8 位纯小写（26 个字符）约 37.6 bit，而 12 位含大小写数字符号（95 个字符）约 78.9 bit，后者破解难度约为前者的 2^41 倍。Entropy measures how unpredictable a password is, in bits: each extra bit doubles the number of guesses needed. This tool estimates entropy as charset size × length — e.g. 8 lowercase chars (26) ≈ 37.6 bits, while 12 chars mixing upper/lower/digits/symbols (95) ≈ 78.9 bits, ~2^41× harder to brute-force.

实际破解往往不走穷举，而是先查「已泄露口令库」与常见模式。因此本工具除熵值外还检查：是否命中 100+ 常见弱口令（含中文站常见值）、连续序列（123456/abcdef）、键盘行（qwerty/asdf）、常见日期与重复模式。建议使用密码管理器生成 16 位以上随机口令，并为每个网站单独设置。Real-world attacks usually check breached-password lists and common patterns first, not brute force. So this tool also flags 100+ common weak passwords (incl. common Chinese values), sequential runs, keyboard rows, dates and repeated patterns. Prefer a password manager generating 16+ random chars, unique per site.