从证书PEM字符串开始和结束的正则表达式

Question

证书PEM文件包含开头和结尾，如：

-----BEGIN CERTIFICATE----- [Base64 of certificate] -----END CERTIFICATE

我只需要提取[Base64 of certificate]部分，即去掉"-----BEGIN CERTIFICATE----- "和" -----END CERTIFICATE-----"字符串，我想知道这是否可以用正则表达式来完成，如果可以，正则表达式会是什么样子？

我试过：

-----BEGIN CERTIFICATE----- (.*) -----END CERTIFICATE-----

但是，它并没有给我证书的Base64，而是返回了所有内容。

谢谢，Jim

Answer 1

由于我不知道你使用的语言，我给你一个相对可移植的模式（必须支持先行和后向）：

(?<=-----BEGIN CERTIFICATE----- )(?:S+|s(?!-----END CERTIFICATE-----))+(?=s-----END CERTIFICATE-----)

结果是整个模式，因为环视只是检查。

Answer 2

在perl:中

my base64_cert_data;
if ($certbuf=~/(-+BEGIN CERTIFICATE-+)(.*?)(-+END CERTIFICATE-+)/s) {
    base64_cert_data = $2;
}

Regex解释：

/(-+BEGIN CERTIFICATE-+)(.*?)(-+END CERTIFICATE-+)/s
1st Capturing group (-+BEGIN CERTIFICATE-+)
    -+ matches the character - literally
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
    BEGIN CERTIFICATE matches the characters BEGIN CERTIFICATE literally (case sensitive)
    -+ matches the character - literally
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
2nd Capturing group (.*?)
    .*? matches any character
        Quantifier: *? Between zero and unlimited times, as few times as possible, expanding as needed [lazy]
3rd Capturing group (-+END CERTIFICATE-+)
    -+ matches the character - literally
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
    END CERTIFICATE matches the characters END CERTIFICATE literally (case sensitive)
    -+ matches the character - literally
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
s modifier: single line. Dot matches newline characters

Answer 3

Hi下面是一个示例perl代码来支持您的需求。

my $Str = "-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----";
if($Str =~ /^W+w+s+w+W+s(.*)s+W+.*$/s) {
    print "$1" . "nn";
} else {
    print "Non" . "nn";
}

输出：
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Answer 4

base64字符集为：

[A-Za-z0-9+/rn]+={0,2}-这是对PEM文件（base64证书）通常使用的内容的准确描述。=用于填充（在末尾），rn是换行符。

综合起来我们得到：

"-+BEGIN\s+.*CERTIFICATE[^-]*-+(?:\s|\r|\n)+" // Header
 + "([A-Za-z0-9+/rn]+={0,2})"                   // Base64 text
 + "-+END\s+.*CERTIFICATE[^-]*-+"                // Footer

如果你想成为语言不可知论者，你可以期望页眉/页脚是一个或多个-字符，后面跟着大写字母，再后面跟着一个或更多个-字符。

Answer 5

这里是正则表达式：

(?<=-----BEGIN CERTIFICATE-----)[sS]*?(?=-----END CERTIFICATE-----)

Java示例：

        final String text = Files.readString("file.txt") // file with certs ;
        final List<String> results = new ArrayList<>();
        final Matcher matcher = Pattern.compile("(?<=-----BEGIN CERTIFICATE-----)[\s\S]*?(?=-----END CERTIFICATE-----)")
                .matcher(text);
        while (matcher.find()) {
            final String m = matcher.group()
                    .replaceAll("\n", "")
                    .replaceAll("\r", "");
            results.add(m);
        }