itox = function(i) {
        var h = i.toString(16);
        if (h.length == 1) h = '0' + h;
        return h;
    }
get hexadecimal value of object identifier from dot noted oid value
@name oidIntToHex
@memberOf KJUR.asn1.ASN1Util
@function
@param {String} oidString dot noted string of object identifier
@return {String} hexadecimal value of object identifier
@since jsrsasign 4.8.3 asn1 1.0.7
@description
This static method converts from object identifier value string.
to hexadecimal string representation of it.
@example
KJUR.asn1.ASN1Util.oidIntToHex("2.5.4.6") &rarr; "550406"