【技术】PEM格式RSA密钥解析（一）——Base64转16进制格式

后缀是.PEM的数字证书是BASE64编码的，以ASCII码来表示。常见的证书如下所示(以RSA1024为例)：

私钥：

----BEGIN RSA PRIVATE KEY----

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

-----END RSAPRIVATE KEY-----

公钥：

----BEGIN PUBLIC KEY----

MIGeMA0GCSqGSIb3DQEBAQUAA4GMADCBAKBgHU4CF6yvqb5WBhwcYfvh/o3NpwcSJlcfjOnIZeKHLYvJOlgzkV6elTLobl1bXcd7WwSzAfRXHoszOgYU7Uh93YKrqd09Mrmx3eGOyeY2GtXUWOuNMFIAUscwzE5sJoJT6QwRa0/7/AqlQBZhlsBDSs/w71qtao8Lg6/wxOsehAgMBAAF=

----END PUBLIC KEY----

需要将公私钥进行解析后，以16进制数据按要求写入LKT芯片。在此需要借助一些转换工具，解析步骤如下：

BASE64编码转换16进制，如要找出相应的RSA的密钥值需要先将BASE64编码转换成16进制格式数据。

打开rsa_V3.4软件(公司内部软件，用户可使用)，如图一所示。在“RSA”页面下选择“Tool”，进入图二界面。在上面的文本输入框中拷贝私钥的Base64编码，然后点击“Base64—>HEX”按钮，下面的文本框中会显示转换后的HEX数据。下图中为私钥的转换，公钥转换类似。

转换后的私钥：

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

转换后的公钥：

30819E300D06092A864886F70D010101050003818C003081880281807538085EB2BEA6F95818707187EF87FA37369C1C48995C7E3D2721978A1CB62F24E220CE457A7884CBA1B9756D771DED6BEF4B301F4571E8B333AA614ED487DDD82ABA9D3BD32B9B1DDE1B4C9E6361AD5D45B4B8D30594052C730CC4E6C268253E90C116B4FFBFCOAA540166122C0424ACFF0FF55EAB5AA3C2F0EBFC313AC7A10203010001