diff options
| -rw-r--r-- | rsa.cpp | 26 |
1 files changed, 15 insertions, 11 deletions
@@ -22,17 +22,21 @@ namespace RSA{ } pair<Key,Key> genkeys(int nbits,Rng &rng){ - pair<Bigint,Bigint> pq=genprimepair(rng,nbits); - Key pubkey,privkey; - pubkey.mod=privkey.mod=pq.first*pq.second; - pubkey.exp=65537; - Bigint x; - Bigint phi((pq.first-Bigint::one)*(pq.second-Bigint::one)); - assert(egcd(phi,pubkey.exp,x,privkey.exp)==1); - privkey.exp=privkey.exp.divmod(phi).second; - // cerr<<"pubkey = {"<<pubkey.mod<<" , "<<pubkey.exp<<'}'<<endl; - // cerr<<"privkey = {"<<privkey.mod<<" , "<<privkey.exp<<'}'<<endl; - return make_pair(pubkey,privkey); + while(true){ //retry loop for if invalid primes were generated + pair<Bigint,Bigint> pq=genprimepair(rng,nbits); + Key pubkey,privkey; + pubkey.mod=privkey.mod=pq.first*pq.second; + pubkey.exp=65537; + Bigint x; + Bigint phi((pq.first-Bigint::one)*(pq.second-Bigint::one)); + if(egcd(phi,pubkey.exp,x,privkey.exp)!=1){ + continue; //p-1 or q-1 is divisible by pubkey.exp=65537 + } + privkey.exp=privkey.exp.divmod(phi).second; + // cerr<<"pubkey = {"<<pubkey.mod<<" , "<<pubkey.exp<<'}'<<endl; + // cerr<<"privkey = {"<<privkey.mod<<" , "<<privkey.exp<<'}'<<endl; + return make_pair(pubkey,privkey); + } } pair<Key,Key> genkeys(int nbits){ |