/************************************************* * Discrete Logarithm Parameters Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include #include #include #include #include #include #include namespace Botan { /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group() { initialized = false; } /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group(const std::string& type) { std::string grp_contents = global_config().get("dl", type); if(grp_contents == "") throw Invalid_Argument("DL_Group: Unknown group " + type); DataSource_Memory pem(grp_contents); PEM_decode(pem); } /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group(PrimeType type, u32bit pbits, u32bit qbits) { if(pbits < 512) throw Invalid_Argument("DL_Group: prime size " + to_string(pbits) + " is too small"); if(type == Strong) { p = random_safe_prime(pbits); q = (p - 1) / 2; g = 2; } else if(type == Prime_Subgroup || type == DSA_Kosherizer) { if(type == Prime_Subgroup) { if(!qbits) qbits = 2 * dl_work_factor(pbits); q = random_prime(qbits); BigInt X; while(p.bits() != pbits || !is_prime(p)) { X = random_integer(pbits); p = X - (X % (2*q) - 1); } } else { qbits = qbits ? qbits : ((pbits == 1024) ? 160 : 256); generate_dsa_primes(p, q, pbits, qbits); } g = make_dsa_generator(p, q); } initialized = true; } /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group(const MemoryRegion& seed, u32bit pbits, u32bit qbits) { if(!generate_dsa_primes(p, q, pbits, qbits, seed)) throw Invalid_Argument("DL_Group: The seed/counter given does not " "generate a DSA group"); g = make_dsa_generator(p, q); initialized = true; } /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group(const BigInt& p1, const BigInt& g1) { initialize(p1, 0, g1); } /************************************************* * DL_Group Constructor * *************************************************/ DL_Group::DL_Group(const BigInt& p1, const BigInt& q1, const BigInt& g1) { initialize(p1, q1, g1); } /************************************************* * DL_Group Initializer * *************************************************/ void DL_Group::initialize(const BigInt& p1, const BigInt& q1, const BigInt& g1) { if(p1 < 3) throw Invalid_Argument("DL_Group: Prime invalid"); if(g1 < 2 || g1 >= p1) throw Invalid_Argument("DL_Group: Generator invalid"); if(q1 < 0 || q1 >= p1) throw Invalid_Argument("DL_Group: Subgroup invalid"); p = p1; g = g1; q = q1; if(q == 0 && check_prime((p - 1) / 2)) q = (p - 1) / 2; initialized = true; } /************************************************* * Verify that the group has been set * *************************************************/ void DL_Group::init_check() const { if(!initialized) throw Invalid_State("DLP group cannot be used uninitialized"); } /************************************************* * Verify the parameters * *************************************************/ bool DL_Group::verify_group(bool strong) const { init_check(); if(g < 2 || p < 3 || q < 0) return false; if((q != 0) && ((p - 1) % q != 0)) return false; if(!strong) return true; if(!check_prime(p)) return false; if((q > 0) && !check_prime(q)) return false; return true; } /************************************************* * Return the prime * *************************************************/ const BigInt& DL_Group::get_p() const { init_check(); return p; } /************************************************* * Return the generator * *************************************************/ const BigInt& DL_Group::get_g() const { init_check(); return g; } /************************************************* * Return the subgroup * *************************************************/ const BigInt& DL_Group::get_q() const { init_check(); if(q == 0) throw Format_Error("DLP group has no q prime specified"); return q; } /************************************************* * DER encode the parameters * *************************************************/ SecureVector DL_Group::DER_encode(Format format) const { init_check(); if((q == 0) && (format != PKCS_3)) throw Encoding_Error("The ANSI DL parameter formats require a subgroup"); if(format == ANSI_X9_57) { return DER_Encoder() .start_cons(SEQUENCE) .encode(p) .encode(q) .encode(g) .end_cons() .get_contents(); } else if(format == ANSI_X9_42) { return DER_Encoder() .start_cons(SEQUENCE) .encode(p) .encode(g) .encode(q) .end_cons() .get_contents(); } else if(format == PKCS_3) { return DER_Encoder() .start_cons(SEQUENCE) .encode(p) .encode(g) .end_cons() .get_contents(); } throw Invalid_Argument("Unknown DL_Group encoding " + to_string(format)); } /************************************************* * PEM encode the parameters * *************************************************/ std::string DL_Group::PEM_encode(Format format) const { SecureVector encoding = DER_encode(format); if(format == PKCS_3) return PEM_Code::encode(encoding, "DH PARAMETERS"); else if(format == ANSI_X9_57) return PEM_Code::encode(encoding, "DSA PARAMETERS"); else if(format == ANSI_X9_42) return PEM_Code::encode(encoding, "X942 DH PARAMETERS"); else throw Invalid_Argument("Unknown DL_Group encoding " + to_string(format)); } /************************************************* * Decode BER encoded parameters * *************************************************/ void DL_Group::BER_decode(DataSource& source, Format format) { BigInt new_p, new_q, new_g; BER_Decoder decoder(source); BER_Decoder ber = decoder.start_cons(SEQUENCE); if(format == ANSI_X9_57) { ber.decode(new_p) .decode(new_q) .decode(new_g) .verify_end(); } else if(format == ANSI_X9_42) { ber.decode(new_p) .decode(new_g) .decode(new_q) .discard_remaining(); } else if(format == PKCS_3) { ber.decode(new_p) .decode(new_g) .discard_remaining(); } else throw Invalid_Argument("Unknown DL_Group encoding " + to_string(format)); initialize(new_p, new_q, new_g); } /************************************************* * Decode PEM encoded parameters * *************************************************/ void DL_Group::PEM_decode(DataSource& source) { std::string label; DataSource_Memory ber(PEM_Code::decode(source, label)); if(label == "DH PARAMETERS") BER_decode(ber, PKCS_3); else if(label == "DSA PARAMETERS") BER_decode(ber, ANSI_X9_57); else if(label == "X942 DH PARAMETERS") BER_decode(ber, ANSI_X9_42); else throw Decoding_Error("DL_Group: Invalid PEM label " + label); } /************************************************* * Create a random DSA-style generator * *************************************************/ BigInt DL_Group::make_dsa_generator(const BigInt& p, const BigInt& q) { BigInt g, e = (p - 1) / q; for(u32bit j = 0; j != PRIME_TABLE_SIZE; ++j) { g = power_mod(PRIMES[j], e, p); if(g != 1) break; } if(g == 1) throw Exception("DL_Group: Couldn't create a suitable generator"); return g; } }