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erlangrsagnupgpublic-key

Erlang - Importing GPG Public Key


I'm trying to do some public-key-related things in Erlang, and they require me to track public keys. According to this page, I should be able to import PEM format keys by using file:read_file/1 and public_key:decode_pem/1. The thing is, when I try to import a GPG public key, I don't get a result.

I've got a file called inaimathi.pubkeywith the following content:

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.4.11 (GNU/Linux)
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q0aATJsUO4fsNe+4/9cBXCSP+4P6irX1EfliqaySt0LEr0WYhIgNgYq8PB7yx4Cv
0mOMv8lXBMYZs8NTrMJl2XHfi3egu8Ti14VChCklnWe95sZvKrk9/3BYxwARAQAB
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BBMBAgAiBQJPTQSEAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRDlo9AP
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dj38smSNAMqOeQQwZlmKFVwmIu4ozqszgZ2oqWS7q2NJgg64dnQlA60VMebQ0e8d
MMqy41VJ1FF8PCT1GGMsL+H4vdoZ+/wF2bhMQISWqFSVa5EAEQEAAYkCHwQYAQIA
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aeryKzy3TWikj3cq8Mdj2mKqNwkn1uu89j3xvxbq6gxX7lGX8pCLS2W6a7PYDaXf
no1/C31//Shn26LD9YfzRhcA/B/uXtEST3eShM5uS2sm+oOpxpiRaBv477K2TLpn
zh82VgwRTDkelpYJG8R8eBXwbBik+WSeIprZ8IrMfzZNs7xwn+z9isB0P3+VObWj
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5NsttvIOclBY5A==
=Zqph
-----END PGP PUBLIC KEY BLOCK-----

which seems to be in the correct format, but the result I get is

1> {ok, GpgBin} = file:read("inaimathi.pubkey").
{ok,<<"-----BEGIN PGP PUBLIC KEY BLOCK-----\nVersion: GnuPG v1.4.11 (GNU/Linux)\n\nmQINBE9NBIQBEADMSzN6b0FaPP0rGiLDWKf"...>>}
2> public_key:pem_decode(GpgBin).
[]

Based on the documentation, I'd expect this to return an RSAEntry which I could then decode into a public key. Is there something special I need to do to import public keys through this mechanism? Are GPG keys actually valid PEM files? Am I missing something else?


Solution

  • ASCII-armored and PEM are very similar. You just need to change the BEGIN/END markers, strip the PGP headers and checksums (the checksum is the last line =Zqph), and add the PEM header. So, you have to change the inaimathi.pubkey to this file:

    -----BEGIN RSA PUBLIC KEY-----
    mQINBE9NBIQBEADMSzN6b0FaPP0rGiLDWKfH4ehN66Z0SAIynXm6lBHjmO69pNsm
    iIe4p1X9aXhr7EgEZKdbqevfXW7NuA/oL7Rbt+tzBT5nS2cYSHoZhUC/onVhJxUb
    drCR9NsBDZc1wZs+b95K3vWW91wMPYs4tn71DeeNgUVCcZOGofWltI7+etTVVIyG
    zMEW4lOiEwBgLee+5u3XyGsBbyhtWnbp8ZMewiXjo14w0UCMEQxvf55NjggAO/vR
    C+Czz5FQ7m9AnZwqIZJfaAw+aM81lmcXRZenGZ/H25H6WLq2DrVXnRjEyUvK+juj
    K6rTHcot6K4Cgvo3P47uZcze92c4KaI22jTePRB1qov8ygAQw8BPsaZ+cA3AQ2Zv
    4hjIyx2Qovs+vb1xWhk9Mgqyt0ToMZ6HNn386ICxaeYR8XY/rhf9ej0PJOS5c9Nx
    reeTdrYXeco27kp/x+nDSWzqy0MrSAAD19xCK1w8Eiwc9MmjAAX1yarQzUy/ICey
    eY6SaBfdK7x7A1ecUSu7mS7LmGFWB49Tx5u3ENXw9rU2hKbmGbbQsc+xCx5s7ZM1
    q0aATJsUO4fsNe+4/9cBXCSP+4P6irX1EfliqaySt0LEr0WYhIgNgYq8PB7yx4Cv
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    5NsttvIOclBY5A==
    -----END RSA PUBLIC KEY-----