从Python中的公钥派生SSH指纹

Question

我正在尝试理解获取OpenSSH公钥的步骤，如下所示：

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAqmEmDTNBC6O8HGCdu0MZ9zLCivDsYSttrrmlq87/YsEBpvwUTiF3UEQuFLaq5Gm+dtgxJewg/UwsZrDFxzpQhCHB6VmqrbKN2hEIkk/HJvCnAmR1ehXv8n2BWw3Jlw7Z+VgWwXAH50f2HWYqTaE4qP4Dxc4RlElxgNmlDPGXw/dYBvChYBG/RvIiTz1L+pYzPD4JR54IMmTOwjcGIJl7nk1VjKvl3D8Wgp6qejv4MfZ7Htdc99SUKcKWAeHYsjPXosSk3GlwKiS/sZi51Yca394GE7T4hZu6HTaXeZoD8+IZ7AijYn89H7EPjuu0iCAa/cjVzBsFHGszQYG+U5KfIw==

然后将其转换为标准指纹，如下所示：

2048 49:d3:cb:f6:00:d2:93:43:a6:27:07:ca:12:fd:5d:98 id_rsa.pub (RSA)

我试图深入到OpenSSH源代码中去理解这一点，但我对此一无所知。我的第一个猜测是对键文本做一个简单的MD5，但是结果与上面的输出不匹配。

Answer 1

它是base64编码密钥的MD5和：

import base64
import hashlib

def lineToFingerprint(line):
    key = base64.b64decode(line.strip().split()[1].encode('ascii'))
    fp_plain = hashlib.md5(key).hexdigest()
    return ':'.join(a+b for a,b in zip(fp_plain[::2], fp_plain[1::2]))

Answer 2

https://github.com/ojarva/sshpubkeys

pip install sshpubkeys

用法：

import sshpubkeys
key = sshpubkeys.SSHKey("ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAqmEmDTNBC6O8H" +
    "GCdu0MZ9zLCivDsYSttrrmlq87/YsEBpvwUTiF3UEQuFLaq5Gm+dtgxJewg/UwsZrDFxz" +
    "pQhCHB6VmqrbKN2hEIkk/HJvCnAmR1ehXv8n2BWw3Jlw7Z+VgWwXAH50f2HWYqTaE4qP4" +
    "Dxc4RlElxgNmlDPGXw/dYBvChYBG/RvIiTz1L+pYzPD4JR54IMmTOwjcGIJl7nk1VjKvl" +
    "3D8Wgp6qejv4MfZ7Htdc99SUKcKWAeHYsjPXosSk3GlwKiS/sZi51Yca394GE7T4hZu6H" +
    "TaXeZoD8+IZ7AijYn89H7EPjuu0iCAa/cjVzBsFHGszQYG+U5KfIw== user@host")
print(key.bits)   # 2048
print(key.hash()) # '49:d3:cb:f6:00:d2:93:43:a6:27:07:ca:12:fd:5d:98'