Tried to parse a DER key from a minecraft server auth protocol.openssl asn1parse -inform DER correctly parses the key, but when I try to use d2i_X509 function from within C to parse this data, I receive null, and the error stack looks like this:

140508081342272:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:crypto/asn1/tasn_dec.c:1149:
140508081342272:error:0D06C03A:asn1 encoding routines:asn1_d2i_ex_primitive:nested asn1 error:crypto/asn1/tasn_dec.c:713:
140508081342272:error:0D08303A:asn1 encoding routines:asn1_template_noexp_d2i:nested asn1 error:crypto/asn1/tasn_dec.c:646:Field=serialNumber, Type=X509_CINF
140508081342272:error:0D08303A:asn1 encoding routines:asn1_template_noexp_d2i:nested asn1 error:crypto/asn1/tasn_dec.c:646:Field=cert_info, Type=X509

This is how I call d2i_X509:

X509 *key_struct = d2i_X509(NULL, byte_data, byte_data_length);
if(key_struct == NULL) { ERR_print_errors_fp(stderr);
}

OpenSSL returns this:

openssl asn1parse -inform DER < out.bin 0:d=0 hl=3 l= 159 cons: SEQUENCE 3:d=1 hl=2 l= 13 cons: SEQUENCE 5:d=2 hl=2 l= 9 prim: OBJECT :rsaEncryption 16:d=2 hl=2 l= 0 prim: NULL 18:d=1 hl=3 l= 141 prim: BIT STRING

1 Answer

What you have there isn't an X.509 structure (certificate) it's a SubjectPublicKeyInfo that is just defined in X.509 RFC that seems like an RSA public key. I'd suggest using another openssl function that is made to parse this structure d2i_PUBKEY() documented here:

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