如何在原生 Go 中将 PEM 证书链转换为 PKCS7？

Question

我正在寻找将 PEM 编码的 x509 证书链转换为 Go 语言中的 PKCS7 格式的实用方法。

这个 openssl 命令行说明了我试图在本机 Go 中实现的目标。

openssl crl2pkcs7 -nocrl -certfile certificate-chain.pem > pkcs7.pem

我可以使用 exec 包从 Go 程序中运行 openssl 命令行，但我正在寻找 Go 中的有效解决方案。

输入文件包含一系列 PEM 格式的证书，以 -----BEGIN CERTIFICATE-----\n 和 base64 编码数据开头。所需的输出需要采用 PKCS7 格式，以 -----BEGIN PKCS7----- 开头。

我正在寻找一个有效的解决方案，因为我实际上并不是在读写文件，而是在内存中将大量证书作为字符串处理。

感谢任何建议。

Answer 1

首先，需要说明的是，您请求的输入和输出都是 PEM 格式。输入是一系列 PEM 编码的 X509 证书，您请求的输出是 PEM 编码的 PKCS#7 退化 "certs only" 结构。如果给它 -outform DER 选项，OpenSSL 可以输出 PKCS#7 结构的原始 ASN.1 DER，但默认情况下它会对其输出进行 PEM 编码。

有许多 Go 包可以构建这种 PKCS#7 结构。以下示例使用 this one.

如果您的输入是 PEM 编码的字符串，并且您希望输出是 PEM 编码的字符串，那么基本步骤是：

从您的输入中提取每个 PEM 块，对其进行解码，并收集其原始字节。
从这些字节创建 PKCS7 结构。
PEM 将该结构编码为字节数组。
将该字节数组转换为字符串。

这是一个简单的例子：

package main

import (
    "encoding/pem"
    "fmt"
    "log"

    "github.com/fullsailor/pkcs7"
)

var certChain = `-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`

func main() {

    // Decode each PEM block in the input and append the ASN.1
    // DER bytes for each certificate therein to the data slice.

    input := []byte(certChain)
    data := []byte{}

    for len(input) > 0 {
        var block *pem.Block
        block, input = pem.Decode(input)
        data = append(data, block.Bytes...)
    }

    // Build a PKCS#7 degenerate "certs only" structure from
    // that ASN.1 certificates data.

    var err error
    data, err = pkcs7.DegenerateCertificate(data)
    if err != nil {
        log.Fatalf("couldn't create degenerate PKCS7 object: %v", err)
    }

    // Convert the PKCS#7 structure to a PEM-encoded string.

    pemString := string(pem.EncodeToMemory(&pem.Block{
        Type:  "PKCS7",
        Bytes: data,
    }))

    // Print the string, or do whatever you want with it.

    fmt.Printf("%s", pemString)
}

并显示它给出与您的 OpenSSL 命令相同的输出：

paul@mac:certstop7$ cat certs.pem
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
paul@mac:certstop7$ openssl crl2pkcs7 -nocrl -certfile certs.pem > openssl_p7.pem
paul@mac:certstop7$ ./certstop7 > generated_p7.pem
paul@mac:certstop7$ diff generated_p7.pem openssl_p7.pem
paul@mac:certstop7$

如何在原生 Go 中将 PEM 证书链转换为 PKCS7？

How to convert PEM certificate chain to PKCS7 in native Go?

ssl

go

pem

pkcs#7