reworked zero-padding machinery and added one more instance of zero-padding

3 files changed, 20 insertions, 14 deletions

diff --git a/lib/consumer.cc b/lib/consumer.cc
index 12866f0..282f0cc 100644
--- a/lib/consumer.cc
+++ b/lib/consumer.cc
@@ -1,344 +1,345 @@
 #include <algorithm>
 #include <cassert>
 #include <opkele/util.h>
 #include <opkele/exception.h>
 #include <opkele/data.h>
 #include <opkele/consumer.h>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <curl/curl.h>
 #include <pcre++.h>
 
 #include <iostream>
 
 #include "config.h"
 
 namespace opkele {
     using namespace std;
 
     class curl_t {
 	public:
 	    CURL *_c;
 
 	    curl_t() : _c(0) { }
 	    curl_t(CURL *c) : _c(c) { }
 	    ~curl_t() throw() { if(_c) curl_easy_cleanup(_c); }
 
 	    curl_t& operator=(CURL *c) { if(_c) curl_easy_cleanup(_c); _c=c; return *this; }
 
 	    operator const CURL*(void) const { return _c; }
 	    operator CURL*(void) { return _c; }
     };
 
     static CURLcode curl_misc_sets(CURL* c) {
 	CURLcode r;
 	(r=curl_easy_setopt(c,CURLOPT_FOLLOWLOCATION,1))
 	|| (r=curl_easy_setopt(c,CURLOPT_MAXREDIRS,5))
 	|| (r=curl_easy_setopt(c,CURLOPT_DNS_CACHE_TIMEOUT,120))
 	|| (r=curl_easy_setopt(c,CURLOPT_DNS_USE_GLOBAL_CACHE,1))
 	|| (r=curl_easy_setopt(c,CURLOPT_USERAGENT,PACKAGE_NAME"/"PACKAGE_VERSION))
 	|| (r=curl_easy_setopt(c,CURLOPT_TIMEOUT,20))
 #ifdef	DISABLE_CURL_SSL_VERIFYHOST
 	|| (r=curl_easy_setopt(c,CURLOPT_SSL_VERIFYHOST,0))
 #endif
 #ifdef	DISABLE_CURL_SSL_VERIFYPEER
 	|| (r=curl_easy_setopt(c,CURLOPT_SSL_VERIFYPEER,0))
 #endif
 	;
 	return r;
     }
 
     static size_t _curl_tostring(void *ptr,size_t size,size_t nmemb,void *stream) {
 	string *str = (string*)stream;
 	size_t bytes = size*nmemb;
 	size_t get = min(16384-str->length(),bytes);
 	str->append((const char*)ptr,get);
 	return get;
     }
 
     assoc_t consumer_t::associate(const string& server) {
 	util::dh_t dh = DH_new();
 	if(!dh)
 	    throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
 	dh->p = util::dec_to_bignum(data::_default_p);
 	dh->g = util::dec_to_bignum(data::_default_g);
 	if(!DH_generate_key(dh))
 	    throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
 	string request = 
 	    "openid.mode=associate"
 	    "&openid.assoc_type=HMAC-SHA1"
 	    "&openid.session_type=DH-SHA1"
 	    "&openid.dh_consumer_public=";
 	request += util::url_encode(util::bignum_to_base64(dh->pub_key));
 	curl_t curl = curl_easy_init();
 	if(!curl)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
 	string response;
 	CURLcode r;
 	(r=curl_misc_sets(curl))
 	|| (r=curl_easy_setopt(curl,CURLOPT_URL,server.c_str()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POST,1))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDS,request.data()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDSIZE,request.length()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&response))
 	;
 	if(r)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
 	if(r=curl_easy_perform(curl))
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
 	params_t p; p.parse_keyvalues(response);
 	if(p.has_param("assoc_type") && p.get_param("assoc_type")!="HMAC-SHA1")
 	    throw bad_input(OPKELE_CP_ "unsupported assoc_type");
 	string st;
 	if(p.has_param("session_type")) st = p.get_param("session_type");
 	if((!st.empty()) && st!="DH-SHA1")
 	    throw bad_input(OPKELE_CP_ "unsupported session_type");
 	secret_t secret;
 	if(st.empty()) {
 	    secret.from_base64(p.get_param("mac_key"));
 	}else{
 	    util::bignum_t s_pub = util::base64_to_bignum(p.get_param("dh_server_public"));
-	    vector<unsigned char> ck(DH_size(dh));
-	    int cklen = DH_compute_key(&(ck.front()),s_pub,dh);
+	    vector<unsigned char> ck(DH_size(dh)+1);
+	    unsigned char *ckptr = &(ck.front())+1;
+	    int cklen = DH_compute_key(ckptr,s_pub,dh);
 	    if(cklen<0)
 		throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
-	    ck.resize(cklen);
-	    // OpenID algorithm requires extra zero in case of set bit here
-	    if(ck[0]&0x80) ck.insert(ck.begin(),1,0);
+	    if(cklen && (*ckptr)&0x80) {
+		(*(--ckptr)) = 0; ++cklen;
+	    }
 	    unsigned char key_sha1[SHA_DIGEST_LENGTH];
-	    SHA1(&(ck.front()),ck.size(),key_sha1);
+	    SHA1(ckptr,cklen,key_sha1);
 	    secret.enxor_from_base64(key_sha1,p.get_param("enc_mac_key"));
 	}
 	int expires_in = 0;
 	if(p.has_param("expires_in")) {
 	    expires_in = util::string_to_long(p.get_param("expires_in"));
 	}else if(p.has_param("issued") && p.has_param("expiry")) {
 	    expires_in = util::w3c_to_time(p.get_param("expiry"))-util::w3c_to_time(p.get_param("issued"));
 	}else
 	    throw bad_input(OPKELE_CP_ "no expiration information");
 	return store_assoc(server,p.get_param("assoc_handle"),secret,expires_in);
     }
 
     string consumer_t::checkid_immediate(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
 	return checkid_(mode_checkid_immediate,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_setup(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
 	return checkid_(mode_checkid_setup,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_(mode_t mode,const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
 	params_t p;
 	if(mode==mode_checkid_immediate)
 	    p["mode"]="checkid_immediate";
 	else if(mode==mode_checkid_setup)
 	    p["mode"]="checkid_setup";
 	else
 	    throw bad_input(OPKELE_CP_ "unknown checkid_* mode");
 	string iurl = canonicalize(identity);
 	string server, delegate;
 	retrieve_links(iurl,server,delegate);
 	p["identity"] = delegate.empty()?iurl:delegate;
 	if(!trust_root.empty())
 	    p["trust_root"] = trust_root;
 	p["return_to"] = return_to;
 	try {
 	    string ah = find_assoc(server)->handle();
 	    p["assoc_handle"] = ah;
 	}catch(failed_lookup& fl) {
 	    string ah = associate(server)->handle();
 	    p["assoc_handle"] = ah;
 	}
 	if(ext) ext->checkid_hook(p,identity);
 	return p.append_query(server);
     }
 
     void consumer_t::id_res(const params_t& pin,const string& identity,extension_t *ext) {
 	if(pin.has_param("openid.user_setup_url"))
 	    throw id_res_setup(OPKELE_CP_ "assertion failed, setup url provided",pin.get_param("openid.user_setup_url"));
 	string server,delegate;
 	retrieve_links(identity.empty()?pin.get_param("openid.identity"):canonicalize(identity),server,delegate);
 	params_t ps;
 	try {
 	    assoc_t assoc = retrieve_assoc(server,pin.get_param("openid.assoc_handle"));
 	    const string& sigenc = pin.get_param("openid.sig");
 	    vector<unsigned char> sig;
 	    util::decode_base64(sigenc,sig);
 	    const string& slist = pin.get_param("openid.signed");
 	    string kv;
 	    string::size_type p = 0;
 	    while(true) {
 		string::size_type co = slist.find(',',p);
 		string f = (co==string::npos)?slist.substr(p):slist.substr(p,co-p);
 		kv += f;
 		kv += ':';
 		f.insert(0,"openid.");
 		kv += pin.get_param(f);
 		kv += '\n';
 		if(ext) ps[f.substr(sizeof("openid.")-1)] = pin.get_param(f);
 		if(co==string::npos)
 		    break;
 		p = co+1;
 	    }
 	    secret_t secret = assoc->secret();
 	    unsigned int md_len = 0;
 	    unsigned char *md = HMAC(
 		    EVP_sha1(),
 		    &(secret.front()),secret.size(),
 		    (const unsigned char *)kv.data(),kv.length(),
 		    0,&md_len);
 	    if(sig.size()!=md_len || memcmp(&(sig.front()),md,md_len))
 		throw id_res_mismatch(OPKELE_CP_ "signature mismatch");
 	}catch(failed_lookup& e) { /* XXX: more specific? */
 	    const string& slist = pin.get_param("openid.signed");
 	    string::size_type pp = 0;
 	    params_t p;
 	    while(true) {
 		string::size_type co = slist.find(',',pp);
 		string f = "openid.";
 		f += (co==string::npos)?slist.substr(pp):slist.substr(pp,co-pp);
 		p[f] = pin.get_param(f);
 		if(co==string::npos)
 		    break;
 		pp = co+1;
 	    }
 	    p["openid.assoc_handle"] = pin.get_param("openid.assoc_handle");
 	    p["openid.sig"] = pin.get_param("openid.sig");
 	    p["openid.signed"] = pin.get_param("openid.signed");
 	    try {
 		string ih = pin.get_param("openid.invalidate_handle");
 		p["openid.invalidate_handle"] = ih;
 	    }catch(failed_lookup& fl) { }
 	    try {
 		check_authentication(server,p);
 	    }catch(failed_check_authentication& fca) {
 		throw id_res_failed(OPKELE_CP_ "failed to check_authentication()");
 	    }
 	}
 	if(ext) ext->id_res_hook(pin,ps,identity);
     }
 
     void consumer_t::check_authentication(const string& server,const params_t& p) {
 	string request = "openid.mode=check_authentication";
 	for(params_t::const_iterator i=p.begin();i!=p.end();++i) {
 	    if(i->first!="openid.mode") {
 		request += '&';
 		request += i->first;
 		request += '=';
 		request += util::url_encode(i->second);
 	    }
 	}
 	curl_t curl = curl_easy_init();
 	if(!curl)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
 	string response;
 	CURLcode r;
 	(r=curl_misc_sets(curl))
 	|| (r=curl_easy_setopt(curl,CURLOPT_URL,server.c_str()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POST,1))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDS,request.data()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDSIZE,request.length()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&response))
 	;
 	if(r)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
 	if(r=curl_easy_perform(curl))
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
 	params_t pp; pp.parse_keyvalues(response);
 	if(pp.has_param("invalidate_handle"))
 	    invalidate_assoc(server,pp.get_param("invalidate_handle"));
 	if(pp.has_param("is_valid")) {
 	    if(pp.get_param("is_valid")=="true")
 		return;
 	}else if(pp.has_param("lifetime")) {
 	    if(util::string_to_long(pp.get_param("lifetime")))
 		return;
 	}
 	throw failed_check_authentication(OPKELE_CP_ "failed to verify response");
     }
 
     void consumer_t::retrieve_links(const string& url,string& server,string& delegate) {
 	server.erase();
 	delegate.erase();
 	curl_t curl = curl_easy_init();
 	if(!curl)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
 	string html;
 	CURLcode r;
 	(r=curl_misc_sets(curl))
 	|| (r=curl_easy_setopt(curl,CURLOPT_URL,url.c_str()))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
 	|| (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&html))
 	;
 	if(r)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
 	r = curl_easy_perform(curl);
 	if(r && r!=CURLE_WRITE_ERROR)
 	    throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
 	pcrepp::Pcre bre("<body\\b",PCRE_CASELESS);
 	// strip out everything past body
 	if(bre.search(html))
 	    html.erase(bre.get_match_start());
 	pcrepp::Pcre hdre("<head[^>]*>",PCRE_CASELESS);
 	if(!hdre.search(html))
 	    throw bad_input(OPKELE_CP_ "failed to find head");
 	html.erase(0,hdre.get_match_end()+1);
 	pcrepp::Pcre lre("<link\\b([^>]+)>",PCRE_CASELESS),
 	    rre("\\brel=['\"]([^'\"]+)['\"]",PCRE_CASELESS),
 	    hre("\\bhref=['\"]([^'\"]+)['\"]",PCRE_CASELESS);
 	while(lre.search(html)) {
 	    string attrs = lre[0];
 	    html.erase(0,lre.get_match_end()+1);
 	    if(!(rre.search(attrs)&&hre.search(attrs)))
 		continue;
 	    if(rre[0]=="openid.server") {
 		server = hre[0];
 		if(!delegate.empty())
 		    break;
 	    }else if(rre[0]=="openid.delegate") {
 		delegate = hre[0];
 		if(!server.empty())
 		    break;
 	    }
 	}
 	if(server.empty())
 	    throw failed_assertion(OPKELE_CP_ "The location has no openid.server declaration");
     }
 
     assoc_t consumer_t::find_assoc(const string& server) {
 	throw failed_lookup(OPKELE_CP_ "no find_assoc() provided");
     }
 
     string consumer_t::canonicalize(const string& url) {
 	string rv = url;
 	// strip leading and trailing spaces
 	string::size_type i = rv.find_first_not_of(" \t\r\n");
 	if(i==string::npos)
 	    throw bad_input(OPKELE_CP_ "empty URL");
 	if(i)
 	    rv.erase(0,i);
 	i = rv.find_last_not_of(" \t\r\n");
 	assert(i!=string::npos);
 	if(i<(rv.length()-1))
 	    rv.erase(i+1);
 	// add missing http://
 	i = rv.find("://");
 	if(i==string::npos) { // primitive. but do we need more?
 	    rv.insert(0,"http://");
 	    i = sizeof("http://")-1;
 	}else{
 	    i += sizeof("://")-1;
 	}
 	string::size_type qm = rv.find('?',i);
 	string::size_type sl = rv.find('/',i);
 	if(qm!=string::npos) {
 	    if(sl==string::npos || sl>qm)
 		rv.insert(qm,1,'/');
 	}else{
 	    if(sl==string::npos)
 		rv += '/';
 	}
 	return rv;
     }
 
 }
diff --git a/lib/server.cc b/lib/server.cc
index e81d4b6..8db97be 100644
--- a/lib/server.cc
+++ b/lib/server.cc
@@ -1,169 +1,170 @@
 #include <vector>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <opkele/util.h>
 #include <opkele/exception.h>
 #include <opkele/server.h>
 #include <opkele/data.h>
 
 namespace opkele {
     using namespace std;
 
     void server_t::associate(const params_t& pin,params_t& pout) {
 	util::dh_t dh;
 	util::bignum_t c_pub;
 	unsigned char key_sha1[SHA_DIGEST_LENGTH];
 	enum {
 	    sess_cleartext,
 	    sess_dh_sha1
 	} st = sess_cleartext;
 	if(
 		pin.has_param("openid.session_type")
 		&& pin.get_param("openid.session_type")=="DH-SHA1" ) {
 	    /* TODO: fallback to cleartext in case of exceptions here? */
 	    if(!(dh = DH_new()))
 		throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
 	    c_pub = util::base64_to_bignum(pin.get_param("openid.dh_consumer_public"));
 	    if(pin.has_param("openid.dh_modulus"))
 		dh->p = util::base64_to_bignum(pin.get_param("openid.dh_modulus"));
 	    else
 		dh->p = util::dec_to_bignum(data::_default_p);
 	    if(pin.has_param("openid.dh_gen"))
 		dh->g = util::base64_to_bignum(pin.get_param("openid.dh_gen"));
 	    else
 		dh->g = util::dec_to_bignum(data::_default_g);
 	    if(!DH_generate_key(dh))
 		throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
-	    vector<unsigned char> ck(DH_size(dh));
+	    vector<unsigned char> ck(DH_size(dh)+1);
+	    unsigned char *ckptr = &(ck.front())+1;
 	    int cklen = DH_compute_key(&(ck.front()),c_pub,dh);
 	    if(cklen<0)
 		throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
-	    ck.resize(cklen);
-	    // OpenID algorithm requires extra zero in case of set bit here
-	    if(ck[0]&0x80) ck.insert(ck.begin(),1,0);
-	    SHA1(&(ck.front()),ck.size(),key_sha1);
+	    if(cklen && (*ckptr)&0x80) {
+		(*(--ckptr)) = 0; ++cklen;
+	    }
+	    SHA1(ckptr,cklen,key_sha1);
 	    st = sess_dh_sha1;
 	}
 	assoc_t assoc = alloc_assoc(mode_associate);
 	time_t now = time(0);
 	pout.clear();
 	pout["assoc_type"] = assoc->assoc_type();
 	pout["assoc_handle"] = assoc->handle();
 	/* TODO: eventually remove deprecated stuff */
 	pout["issued"] = util::time_to_w3c(now);
 	pout["expiry"] = util::time_to_w3c(now+assoc->expires_in());
 	pout["expires_in"] = util::long_to_string(assoc->expires_in());
 	secret_t secret = assoc->secret();
 	switch(st) {
 	    case sess_dh_sha1:
 		pout["session_type"] = "DH-SHA1";
 		pout["dh_server_public"] = util::bignum_to_base64(dh->pub_key);
 		secret.enxor_to_base64(key_sha1,pout["enc_mac_key"]);
 		break;
 	    default:
 		secret.to_base64(pout["mac_key"]);
 		break;
 	}
     }
 
     void server_t::checkid_immediate(const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
 	checkid_(mode_checkid_immediate,pin,return_to,pout,ext);
     }
 
     void server_t::checkid_setup(const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
 	checkid_(mode_checkid_setup,pin,return_to,pout,ext);
     }
 
     void server_t::checkid_(mode_t mode,const params_t& pin,string& return_to,params_t& pout,extension_t *ext) {
 	if(mode!=mode_checkid_immediate && mode!=mode_checkid_setup)
 	    throw bad_input(OPKELE_CP_ "invalid checkid_* mode");
 	pout.clear();
 	assoc_t assoc;
 	try {
 	    assoc = retrieve_assoc(pin.get_param("openid.assoc_handle"));
 	}catch(failed_lookup& fl) {
 	    // no handle specified or no valid handle found, going dumb
 	    assoc = alloc_assoc(mode_checkid_setup);
 	    if(pin.has_param("openid.assoc_handle"))
 		pout["invalidate_handle"]=pin.get_param("openid.assoc_handle");
 	}
 	string trust_root;
 	try {
 	    trust_root = pin.get_param("openid.trust_root");
 	}catch(failed_lookup& fl) { }
 	string identity = pin.get_param("openid.identity");
 	return_to = pin.get_param("openid.return_to");
 	validate(*assoc,pin,identity,trust_root);
 	pout["mode"] = "id_res";
 	pout["assoc_handle"] = assoc->handle();
 	if(pin.has_param("openid.assoc_handle") && assoc->stateless())
 	    pout["invalidate_handle"] = pin.get_param("openid.assoc_handle");
 	pout["identity"] = identity;
 	pout["return_to"] = return_to;
 	/* TODO: eventually remove deprecated stuff */
 	time_t now = time(0);
 	pout["issued"] = util::time_to_w3c(now);
 	pout["valid_to"] = util::time_to_w3c(now+120);
 	pout["exipres_in"] = "120";
 	pout["signed"]="mode,identity,return_to";
 	if(ext) ext->checkid_hook(pin,pout);
 	pout.sign(assoc->secret(),pout["sig"],pout["signed"]);
     }
 
     void server_t::check_authentication(const params_t& pin,params_t& pout) {
 	vector<unsigned char>  sig;
 	const string& sigenc = pin.get_param("openid.sig");
 	util::decode_base64(sigenc,sig);
 	assoc_t assoc;
 	try {
 	    assoc = retrieve_assoc(pin.get_param("openid.assoc_handle"));
 	}catch(failed_lookup& fl) {
 	    throw failed_assertion(OPKELE_CP_ "invalid handle or handle not specified");
 	}
 	if(!assoc->stateless())
 	    throw stateful_handle(OPKELE_CP_ "will not do check_authentication on a stateful handle");
 	const string& slist = pin.get_param("openid.signed");
 	string kv;
 	string::size_type p =0;
 	while(true) {
 	    string::size_type co = slist.find(',',p);
 	    string f = (co==string::npos)?slist.substr(p):slist.substr(p,co-p);
 	    kv += f;
 	    kv += ':';
 	    if(f=="mode")
 		kv += "id_res";
 	    else {
 		f.insert(0,"openid.");
 		kv += pin.get_param(f);
 	    }
 	    kv += '\n';
 	    if(co==string::npos)
 		break;
 	    p = co+1;
 	}
 	secret_t secret = assoc->secret();
 	unsigned int md_len = 0;
 	unsigned char *md = HMAC(
 		EVP_sha1(),
 		&(secret.front()),secret.size(),
 		(const unsigned char *)kv.data(),kv.length(),
 		0,&md_len);
 	pout.clear();
 	if(sig.size()==md_len && !memcmp(&(sig.front()),md,md_len)) {
 	    pout["is_valid"]="true";
 	    pout["lifetime"]="60"; /* TODO: eventually remove deprecated stuff */
 	}else{
 	    pout["is_valid"]="false";
 	    pout["lifetime"]="0"; /* TODO: eventually remove deprecated stuff */
 	}
 	if(pin.has_param("openid.invalidate_handle")) {
 	    string h = pin.get_param("openid.invalidate_handle");
 	    try {
 		assoc_t assoc = retrieve_assoc(h);
 	    }catch(invalid_handle& ih) {
 		pout["invalidate_handle"] = h;
 	    }catch(failed_lookup& fl) { }
 	}
     }
 
 }
diff --git a/lib/util.cc b/lib/util.cc
index d9abca7..94f6f53 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -1,158 +1,162 @@
 #include <errno.h>
 #include <cassert>
 #include <vector>
 #include <string>
 #include <openssl/bio.h>
 #include <openssl/evp.h>
 #include <curl/curl.h>
 #include "opkele/util.h"
 #include "opkele/exception.h"
 
 namespace opkele {
     using namespace std;
 
     namespace util {
 
 	/*
 	 * base64
 	 */
 	string encode_base64(const void *data,size_t length) {
 	    BIO *b64 = 0, *bmem = 0;
 	    try {
 		b64 = BIO_new(BIO_f_base64());
 		if(!b64)
 		    throw exception_openssl(OPKELE_CP_ "failed to BIO_new() base64 encoder");
 		BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
 		bmem = BIO_new(BIO_s_mem());
 		BIO_set_flags(b64,BIO_CLOSE);
 		if(!bmem)
 		    throw exception_openssl(OPKELE_CP_ "failed to BIO_new() memory buffer");
 		BIO_push(b64,bmem);
 		if(BIO_write(b64,data,length)!=length)
 		    throw exception_openssl(OPKELE_CP_ "failed to BIO_write()");
 		BIO_flush(b64);
 		char *rvd;
 		long rvl = BIO_get_mem_data(bmem,&rvd);
 		string rv(rvd,rvl);
 		BIO_free_all(b64);
 		return rv;
 	    }catch(...) {
 		if(b64) BIO_free_all(b64);
 		throw;
 	    }
 	}
 
 	void decode_base64(const string& data,vector<unsigned char>& rv) {
 	    BIO *b64 = 0, *bmem = 0;
 	    rv.clear();
 	    try {
 		bmem = BIO_new_mem_buf((void*)data.data(),data.size());
 		if(!bmem)
 		    throw exception_openssl(OPKELE_CP_ "failed to BIO_new_mem_buf()");
 		b64 = BIO_new(BIO_f_base64());
 		if(!b64)
 		    throw exception_openssl(OPKELE_CP_ "failed to BIO_new() base64 decoder");
 		BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
 		BIO_push(b64,bmem);
 		unsigned char tmp[512];
 		size_t rb = 0;
 		while((rb=BIO_read(b64,tmp,sizeof(tmp)))>0)
 		    rv.insert(rv.end(),tmp,&tmp[rb]);
 		BIO_free_all(b64);
 	    }catch(...) {
 		if(b64) BIO_free_all(b64);
 		throw;
 	    }
 	}
 
 	/*
 	 * big numerics
 	 */
 
 	BIGNUM *base64_to_bignum(const string& b64) {
 	    vector<unsigned char> bin;
 	    decode_base64(b64,bin);
 	    BIGNUM *rv = BN_bin2bn(&(bin.front()),bin.size(),0);
 	    if(!rv)
 		throw failed_conversion(OPKELE_CP_ "failed to BN_bin2bn()");
 	    return rv;
 	}
 
 	BIGNUM *dec_to_bignum(const string& dec) {
 	    BIGNUM *rv = 0;
 	    if(!BN_dec2bn(&rv,dec.c_str()))
 		throw failed_conversion(OPKELE_CP_ "failed to BN_dec2bn()");
 	    return rv;
 	}
 
 	string bignum_to_base64(const BIGNUM *bn) {
-	    vector<unsigned char> bin(BN_num_bytes(bn));
-	    int l = BN_bn2bin(bn,&(bin.front()));
-	    return encode_base64(&(bin.front()),l);
+	    vector<unsigned char> bin(BN_num_bytes(bn)+1);
+	    unsigned char *binptr = &(bin.front())+1;
+	    int l = BN_bn2bin(bn,binptr);
+	    if(l && (*binptr)&0x80){
+		(*(--binptr)) = 0; ++l;
+	    }
+	    return encode_base64(binptr,l);
 	}
 
 	/*
 	 * w3c times
 	 */
 
 	string time_to_w3c(time_t t) {
 	    struct tm tm_t;
 	    if(!gmtime_r(&t,&tm_t))
 		throw failed_conversion(OPKELE_CP_ "failed to BN_dec2bn()");
 	    char rv[25];
 	    if(!strftime(rv,sizeof(rv)-1,"%Y-%m-%dT%H:%M:%SZ",&tm_t))
 		throw failed_conversion(OPKELE_CP_ "failed to strftime()");
 	    return rv;
 	}
 
 	time_t w3c_to_time(const string& w) {
 	    struct tm tm_t;
 	    memset(&tm_t,0,sizeof(tm_t));
 	    if(
 		    sscanf(
 			w.c_str(),
 			"%04d-%02d-%02dT%02d:%02d:%02dZ",
 			&tm_t.tm_year,&tm_t.tm_mon,&tm_t.tm_mday,
 			&tm_t.tm_hour,&tm_t.tm_min,&tm_t.tm_sec
 		    ) != 6 )
 		throw failed_conversion(OPKELE_CP_ "failed to sscanf()");
 	    tm_t.tm_mon--;
 	    tm_t.tm_year-=1900;
 	    time_t rv = mktime(&tm_t);
 	    if(rv==(time_t)-1)
 		throw failed_conversion(OPKELE_CP_ "failed to mktime()");
 	    return rv;
 	}
 
 	/*
 	 *
 	 */
 
 	string url_encode(const string& str) {
 	    char * t = curl_escape(str.c_str(),str.length());
 	    if(!t)
 		throw failed_conversion(OPKELE_CP_ "failed to curl_escape()");
 	    string rv(t);
 	    curl_free(t);
 	    return rv;
 	}
 
 	string long_to_string(long l) {
 	    char rv[32];
 	    int r=snprintf(rv,sizeof(rv),"%ld",l);
 	    if(r<0 || r>=sizeof(rv))
 		throw failed_conversion(OPKELE_CP_ "failed to snprintf()");
 	    return rv;
 	}
 
 	long string_to_long(const string& s) {
 	    char *endptr = 0;
 	    long rv = strtol(s.c_str(),&endptr,10);
 	    if((!endptr) || endptr==s.c_str())
 		throw failed_conversion(OPKELE_CP_ "failed to strtol()");
 	    return rv;
 	}
 
     }
 
 }