(Erlang)以pem格式从证书中提取公钥

问题描述 投票:4回答:2

我有pem格式的证书,我想提取公钥(RSA)。我已经这么远了:

{ok, PemBin} = file:read_file("/path/to/certificate.pem").
[Certificate] = public_key:pem_decode(PemBin).

现在,我可以做到以下几点:

public_key:pem_entry_decode(Certificate).

这给了我一个包含证书上各种细节的元组,但我看不到任何公钥的条目。如何从此证书中获取公钥?应该是直截了当但我在public_key模块中找不到任何功能。

erlang certificate rsa public-key pem
2个回答
5
投票

好的,这是模块中的完整功能:

-module(crypto_helper).
-include_lib("public_key/include/public_key.hrl").
-export([get_public_key_from_cert/1]).

get_public_key_from_cert(PathToCert) ->
   {ok, PemBin} = file:read_file(PathToCert),
   PemEntries = public_key:pem_decode(PemBin),
   {value, CertEntry} = lists:keysearch(‘Certificate’, 1, PemEntries)
   {_, DerCert, _} = CertEntry,
   Decoded = public_key:pkix_decode_cert(DerCert, otp),
   PublicKey = Decoded#'OTPCertificate'.tbsCertificate#'OTPTBSCertificate'.subjectPublicKeyInfo#'OTPSubjectPublicKeyInfo'.subjectPublicKey,
   PublicKey.

现在您可以按如下方式使用它:

PublicKey = crypto_helper:get_public_key_from_cert("/usr/admin/myServer/priv/certificate.pem"),
EncryptedMsg = public_key:encrypt_public(<<"Hallo">>, PublicKey),

3
投票

public_key:pem_entry_decode(Certificate)返回Certificate记录。要从中提取公钥,您需要加载记录定义。在Erlang shell中,键入以下内容:

rr(public_key).

将记录定义加载到shell后,返回值将包含字段名称和字段值,这应该使事情更清晰一些。

在Erlang模块中,加载头文件,如下所示:

-include_lib("public_key/include/public_key.hrl").

然后你可以像这样提取公钥信息:

DecodedCertificate = public_key:pem_entry_decode(Certificate).
DecodedCertificate#'Certificate'.tbsCertificate#'TBSCertificate'.subjectPublicKeyInfo.

返回:

#'SubjectPublicKeyInfo'{
    algorithm = 
        #'AlgorithmIdentifier'{
            algorithm = {1,2,840,113549,1,1,1},
            parameters = <<5,0>>},
    subjectPublicKey = 
        <<48,130,2,10,2,130,2,1,0,195,76,200,181,90,146,51,183,
          39,91,176,28,95,117,241,28,140,...>>}

或者进一步挖掘一个级别以获得密钥本身:

DecodedCertificate#'Certificate'.tbsCertificate
    #'TBSCertificate'.subjectPublicKeyInfo
    #'SubjectPublicKeyInfo'.subjectPublicKey.
<<48,130,2,10,2,130,2,1,0,195,76,200,181,90,146,51,183,39,
  91,176,28,95,117,241,28,140,212,223,132,...>>
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