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#ifndef INCLUDED_BOBCAT_DIFFIEHELLMAN_
#define INCLUDED_BOBCAT_DIFFIEHELLMAN_
#include <iosfwd>
#include <openssl/evp.h>
#include <bobcat/bigint>
#include <bobcat/exception>
namespace FBB
{
class DiffieHellman
{
enum
{
MIN_PRIME_SIZE = 1024
};
BigInt d_prime;
BigInt d_generator;
BigInt d_privKey;
BigInt d_pubKey;
BigInt d_peerPubKey; // public key of the other party
BigInt d_common; // common secret (after calling key)
static char const *s_header;
public:
// no copy/move constructors/operations
DiffieHellman(DiffieHellman const &other) = delete;
// The initiator calls this constructor to compute the common
// DH parameters
DiffieHellman(size_t primeLength = 1024, size_t generator = 5, // 1
bool progress = false);
// uses predefined prime 'prime'
DiffieHellman(BigInt const &prime, size_t generator = 5); // 2
// this constructor reloads the public and private data
DiffieHellman(std::string const &publicFileName, // 3
std::string const &privateFileName);
// Alternatively, use this constructor expecting istreams:
DiffieHellman(std::istream &publicStream, // 4
std::istream &privateStream);
// After calling save() (see below) the public and private keys
// are available on files. Each party semds its public info to the
// other party. Next initiator and peer call 'key' to compute
// their shared (symmetric encryption) key, using their own
// private data and the other's public data.
BigInt const &key(std::string const &peerPublicFileName); // 2
BigInt const &key(std::istream &peerPublicStream); // 3
static BigInt prime(size_t primeLength, bool safe = true,
bool progress = false);
// The initiator saves the public info (i.e., prime (p), generator
// (g),and the initiator's public key (g^k % p)) on basename.pub
// and the initiator's secret key (k) on basename.sec
void save(std::string const &basename) const;
// accessors (may return 0 if not yet determined)
// use BigInt's bigEndian or littleEndian functions to obtain
// the BigInt's 'sizeInBytes' bytes, returned as a series of
// char values.
BigInt const &common() const;
BigInt const &generator() const;
BigInt const &peerPublicKey() const;
BigInt const &prime() const;
BigInt const &privateKey() const;
BigInt const &publicKey() const;
private:
static int callback(int indicator, int, BN_GENCB *); // params 2, 3
// not used.
void checkKeys(EVP_PKEY *keys);
static EVP_PKEY_CTX *cptDomainContext(OSSL_PARAM *param);
EVP_PKEY *cptDomainKey(EVP_PKEY_CTX *domainCtx, OSSL_PARAM *param);
void cptKeys();
static Exception &&exception(); // .ih
BigInt getKey(EVP_PKEY *keys, char const *type) const; // type:
BigInt const &key(); // 1
static EVP_PKEY *keyPair(EVP_PKEY *domainkey);
OSSL_PARAM *osslParamBuild();
};
#include "common.f"
#include "generator.f"
#include "peerpublickey.f"
#include "prime.f"
#include "privatekey.f"
#include "publickey.f"
} // FBB
#endif
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