1 files changed, 7 insertions, 3 deletions

diff --git a/lib/util.cc b/lib/util.cc
index d9abca7..94f6f53 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -77,27 +77,31 @@ namespace opkele {
                 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))