具有四个条件的密码正则表达式

Question

我正在尝试在 PHP 中编写一个正则表达式，以确保密码符合以下条件：

• 至少应包含 8 个字符
• 应至少包含一个特殊字符
• 应至少包含一个大写字母。

我写了如下表达式：

$pattern=([a-zA-Z\W+0-9]{8,})

但是，它似乎无法按照列出的标准工作。请问我可以再找一双眼睛来帮助我吗？

Answer 1

您的正则表达式 - ([a-zA-Z\W+0-9]{8,}) - 实际上在至少 8 个字符长的较大文本中搜索子字符串，但也允许任何英文字母、非单词字符（[a-zA-Z0-9_] 除外）和数字，所以它不强制执行您的 2 个要求。可以使用look-aheads 进行设置。

这是一个固定的正则表达式：

^(?=.*\W.*)(?=.*[A-Z].*).{8,}$

实际上，如果您还想匹配/允许非英文字母，您可以将[A-Z] 替换为\p{Lu}。您还可以考虑使用\p{S} 而不是\W，或者通过添加符号或字符类来进一步精确您的special character 标准，例如[\p{P}\p{S}]（这也将包括所有 Unicode 标点符号）。

增强的正则表达式版本：

^(?=.*[\p{S}\p{P}].*)(?=.*\p{Lu}.*).{8,}$

人类可读的解释：

• ^ - 字符串的开头
• (?=.*\W.*) - 要求至少有 1 个非单词字符
  OR (?=.*[\p{S}\p{P}].*) - 至少 1 个 Unicode 特殊符号或标点符号
• (?=.*[A-Z].*) - 要求至少有 1 个大写英文字母
  或 (?=.*\p{Lu}.*) - 至少 1 个 Unicode 字母
• .{8,} - 要求至少 8 个符号
• $ - 字符串结束

见Demo 1和Demo 2 (Enhanced regex)

示例代码：

if (preg_match('/^(?=.*\W.*)(?=.*[A-Z].*).{8,}$/u', $header)) {
 // PASS
} 
else {
    # FAIL
}

Answer 2

使用正数 lookahead ?= 我们确保满足所有密码要求。

---

强密码要求：

至少 8 个字符长
至少 1 个大写字母
至少 1 个特殊字符

---

正则表达式：

^((?=[\S]{8})(?:.*)(?=[A-Z]{1})(?:.*)(?=[\p{S}])(?:.*))$

---

PHP 实现：

if (preg_match('/^((?=[\S]{8})(?:.*)(?=[A-Z]{1})(?:.*)(?=[\p{S}])(?:.*))$/u', $password)) {
    # Strong Password
} else {
    # Weak Password
}

---

示例：

12345678 - WEAK
1234%fff - WEAK
1234_44A - WEAK
133333A$ - STRONG

---

正则表达式解释：

^ assert position at start of the string
1st Capturing group ((?=[\S]{8})(?:.*)(?=[A-Z]{1})(?:.*)(?=[\p{S}])(?:.*))
    (?=[\S]{8}) Positive Lookahead - Assert that the regex below can be matched
        [\S]{8} match a single character present in the list below
            Quantifier: {8} Exactly 8 times
            \S match any kind of visible character [\P{Z}\H\V]
    (?:.*) Non-capturing group
        .* matches any character (except newline) [unicode]
            Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
    (?=[A-Z]{1}) Positive Lookahead - Assert that the regex below can be matched
        [A-Z]{1} match a single character present in the list below
            Quantifier: {1} Exactly 1 time (meaningless quantifier)
            A-Z a single character in the range between A and Z (case sensitive)
    (?:.*) Non-capturing group
        .* matches any character (except newline) [unicode]
            Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
    (?=[\p{S}]) Positive Lookahead - Assert that the regex below can be matched
        [\p{S}] match a single character present in the list below
            \p{S} matches math symbols, currency signs, dingbats, box-drawing characters, etc
    (?:.*) Non-capturing group
        .* matches any character (except newline) [unicode]
            Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
$ assert position at end of the string
u modifier: unicode: Pattern strings are treated as UTF-16. Also causes escape sequences to match unicode characters

---

演示：

https://regex101.com/r/hE2dD2/1