Kerberos令牌反序列化及令牌信息解析方法咨询

Hi Jochen, great question! Let's walk through how you can decode and parse that Kerberos token to find the expiration time and other details you're looking for.

First off, that long string in <GetKerberosTokenResult> is Base64-encoded Kerberos ticket data (either a Ticket-Granting Ticket or a service ticket). The line breaks are just formatting, so you'll want to strip those out first to get a continuous Base64 string before decoding.

Here are the practical steps and tools you can use to unpack it:

• Step 1: Clean up the Base64 string
  Remove all line breaks, spaces, and extra whitespace from the token string to create a single, uninterrupted Base64 sequence.

• Step 2: Decode the Base64 to binary
  You can use built-in command-line tools for this:

  • On Linux/macOS:

    echo "your-cleaned-base64-string" | base64 -d > kerberos_token.bin
    

  • On Windows (PowerShell):

    [Convert]::FromBase64String("your-cleaned-base64-string") | Set-Content -Path kerberos_token.bin -Encoding Byte
    

• Step 3: Parse the binary Kerberos ticket
  Kerberos tickets use ASN.1 DER encoding under the hood, so you'll need tools that understand this structure:

  • MIT Kerberos tools (recommended): If you have the krb5-user package installed (common on Linux), use krb5-print-ticket to get a human-readable breakdown:

    krb5-print-ticket kerberos_token.bin
    

    This will output all key details: client principal, service principal, start time, end time (expiration), renewable until time, session key info, and more.
  • OpenSSL ASN.1 parser: If you don't have Kerberos-specific tools, use OpenSSL to inspect the ASN.1 structure:

    openssl asn1parse -inform der -in kerberos_token.bin
    

    This will show you the nested ASN.1 nodes. Look for fields labeled GeneralizedTime — these correspond to the ticket's start, end, and renewal times (formatted as UTC timestamps).
  • Windows-specific tools: On Windows, you can use the built-in Klist.exe if you import the ticket into your Kerberos cache, or use third-party tools like the Kerberos PowerShell module to parse the binary ticket directly.

A quick note: Unlike JWT (which is JSON-based and easy to read after Base64 decoding), Kerberos tickets are designed for secure authentication, so their structure is more opaque. But rest assured, all the time-related fields you're looking for are absolutely present in the token — you just need the right tools to unpack them.

备注：内容来源于stack exchange，提问作者JochenW