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Erlang - Decoding RSA public Key

Follow-up to this one.

I got the reading/decoding working

1> {ok, F} = file:read_file("inaimathi.rsapub").
{ok,<<"-----BEGIN RSA PUBLIC KEY-----\nmQINBE9NBIQBEADMSzN6b0FaPP0rGiLDWKfH4ehN66Z0SAIynXm6lBHjmO69pNsm\niIe4p1X9aXhr"...>>}
2> [Entry] = public_key:pem_decode(F).
[{'RSAPublicKey',<<153,2,13,4,79,77,4,132,1,16,0,204,75,
                   51,122,111,65,90,60,253,43,26,34,195,
                   88,167,...>>,
                 not_encrypted}]

According to the docs, the last thing I have to do in order to get a working public key out of this is run public_key:pem_entry_decode/1 on that Entry. However, when I try to do that, I get an eror.

3> public_key:pem_entry_decode(Entry).
** exception error: no match of right hand side value 
                    {error,
                        {asn1,
                            {{badmatch,{error,{asn1,{wrong_tag,{131097,16}}}}},
                             [{'OTP-PUB-KEY',dec_RSAPublicKey,2,
                                  [{file,"OTP-PUB-KEY.erl"},{line,5956}]},
                              {'OTP-PUB-KEY',decode,2,
                                  [{file,"OTP-PUB-KEY.erl"},{line,493}]},
                              {public_key,der_decode,2,
                                  [{file,"public_key.erl"},{line,166}]},
                              {erl_eval,do_apply,6,
                                  [{file,"erl_eval.erl"},{line,576}]},
                              {shell,exprs,7,[{file,"shell.erl"},{line,668}]},
                              {shell,eval_exprs,7,
                                  [{file,"shell.erl"},{line,623}]},
                              {shell,eval_loop,3,
                                  [{file,"shell.erl"},{line,608}]}]}}}
     in function  public_key:der_decode/2 (public_key.erl, line 170)

What am I doing wrong here?

EDIT: Didn't think it would matter, but someone asked, so.

I'm running Debian Wheezy on a Core i3 with Erlang installed from a ~2 day old checkout of this.

erl --version says

Erlang R15B02 (erts-5.9.2) [source] [64-bit] [smp:4:4] [async-threads:0] [hipe] [kernel-poll:false]
Solution

  • Your code works fine here:

    decode() ->
    [application:start(X) || X <- [crypto, public_key, ssl]],
    RawData = ["-----BEGIN PUBLIC KEY-----\n",
               "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDBm8yuHmd0P6scl48DEi+xp47w\n",
               "XVZaKWRygGKtA2XkdRuCU99f0Tq07Llcgf8XuR+Wnk+z2CdMMFMzOGhCePblVIAn\n",
               "33dcBVlDokpBF7AnTClsaLcixxZw1LIUiaPaBdN7oG8vt3G2caLHRrrkoEnccY+6\n",
               "GadfH7iuHdcVsz1mowIDAQAB\n",
               "-----END PUBLIC KEY-----"],
    D = iolist_to_binary(RawData),
    [Entry] = public_key:pem_decode(D),
    public_key:pem_entry_decode(Entry).

    Generates output (shortened):

     {'RSAPublicKey',135956...,65537}