目的を調べるフラグ

X509_PURPOSE_SSL_CLIENT (integer)

X509_PURPOSE_SSL_SERVER (integer)

X509_PURPOSE_NS_SSL_SERVER (integer)

X509_PURPOSE_SMIME_SIGN (integer)

X509_PURPOSE_SMIME_ENCRYPT (integer)

X509_PURPOSE_CRL_SIGN (integer)

X509_PURPOSE_ANY (integer)