[erlang-questions] public_key:pem_decode/1 and public_key:verify/4

Niclas Axelsson <>
Tue Feb 15 11:33:12 CET 2011


On 01/31/2011 07:27 PM, Seth Falcon wrote:
> Hi Ingela,
>
> I've updated my patch:
>
>      https://github.com/seth/otp/tree/sf/rsa_pub_key
>
> it now includes basic tests for decoding and encoding both RSA and DSA
> public keys in the SubjectPublicKeyInfo format.  After moving all
> lib/FOO/test directories with references to wx, I was able to run the
> tests for public_key on my OS X laptop :-)
>
> Here's the summary of where I ended up:
>
>      {ok, RSAPubPem} = file:read_file(filename:join(Datadir, "rsa_pub.pem")),
>      [{'SubjectPublicKeyInfo', _, _} = PubEntry1] =
>          public_key:pem_decode(RSAPubPem),
>      RSAPubKey = public_key:pem_entry_decode(PubEntry1),
>      true = check_entry_type(RSAPubKey, 'RSAPublicKey'),
>      PubEntry1 = public_key:pem_entry_encode('RSAPublicKey', RSAPubKey),
>
> Notes:
>
> - I haven't merged in the trivial patch from Joakim to allow reading
>    RSA public keys in "unwrapped" form where the PEM header has "RSA
>    Public Key".
>
> - RSA public key records get encoded into the SubjectPublicKeyInfo
>    wrapper form.  So to create the form that Joakim is dealing with,
>    one would have to use der_encode directly I believe.
>
> - When encoding RSAPublic keys, there is a parameter spot where it
>    seems the right thing to put is<<5, 0>>, but I wanted to mention
>    this in case I'm wrong about this being the right value for all RSA
>    public keys in SPKI form.
>
> Let me know what else I can do to help get this patch into the
> public_key module :-)
>
> Best,
>
> + seth
>
>    
Thanks Seth.

I merged your branch to 'pu' yesterday but forgot to send a mail about it.

Regards
Niclas Axelsson, Erlang/OTP


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