Hi All: I am reading cer file into X509 object, http://SVRSecure-G3-aia.verisign.com/SVRSecureG3.cer cert = d2i_X509_fp(fp, NULL); it will return fail, as below Error: error:0D07207B:asn1 encoding routines:ASN1_get_object:header too long Lib: asn1 encoding routines Func: ASN1_get_object Reason: header too long I use openssl to convert cer from DER format to PEM format it works fine, So I think it is a DER format file, but why d2i_X509_fp() read it failed. Thanks! -- Rejoice,I Desire!