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/*
* ECC Key implemenation
* (C) 2007 Manuel Hartl, FlexSecure GmbH
* Falko Strenzke, FlexSecure GmbH
* 2008-2010 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/ecc_key.h>
#include <botan/numthry.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
#include <botan/secmem.h>
#include <botan/point_gfp.h>
#include <botan/workfactor.h>
namespace Botan {
size_t EC_PublicKey::key_length() const
{
return domain().get_p_bits();
}
size_t EC_PublicKey::estimated_strength() const
{
return ecp_work_factor(key_length());
}
EC_PublicKey::EC_PublicKey(const EC_Group& dom_par,
const PointGFp& pub_point) :
m_domain_params(dom_par), m_public_key(pub_point)
{
if (!dom_par.get_curve_oid().empty())
m_domain_encoding = EC_DOMPAR_ENC_OID;
else
m_domain_encoding = EC_DOMPAR_ENC_EXPLICIT;
#if 0
if(domain().get_curve() != public_point().get_curve())
throw Invalid_Argument("EC_PublicKey: curve mismatch in constructor");
#endif
}
EC_PublicKey::EC_PublicKey(const AlgorithmIdentifier& alg_id,
const std::vector<uint8_t>& key_bits) :
m_domain_params{EC_Group(alg_id.get_parameters())},
m_public_key{domain().OS2ECP(key_bits)}
{
if (!domain().get_curve_oid().empty())
m_domain_encoding = EC_DOMPAR_ENC_OID;
else
m_domain_encoding = EC_DOMPAR_ENC_EXPLICIT;
}
bool EC_PublicKey::check_key(RandomNumberGenerator& rng,
bool) const
{
return m_domain_params.verify_group(rng) &&
m_domain_params.verify_public_element(public_point());
}
AlgorithmIdentifier EC_PublicKey::algorithm_identifier() const
{
return AlgorithmIdentifier(get_oid(), DER_domain());
}
std::vector<uint8_t> EC_PublicKey::public_key_bits() const
{
return public_point().encode(point_encoding());
}
void EC_PublicKey::set_point_encoding(PointGFp::Compression_Type enc)
{
if(enc != PointGFp::COMPRESSED &&
enc != PointGFp::UNCOMPRESSED &&
enc != PointGFp::HYBRID)
throw Invalid_Argument("Invalid point encoding for EC_PublicKey");
m_point_encoding = enc;
}
void EC_PublicKey::set_parameter_encoding(EC_Group_Encoding form)
{
if(form != EC_DOMPAR_ENC_EXPLICIT &&
form != EC_DOMPAR_ENC_IMPLICITCA &&
form != EC_DOMPAR_ENC_OID)
throw Invalid_Argument("Invalid encoding form for EC-key object specified");
if((form == EC_DOMPAR_ENC_OID) && (m_domain_params.get_curve_oid().empty()))
throw Invalid_Argument("Invalid encoding form OID specified for "
"EC-key object whose corresponding domain "
"parameters are without oid");
m_domain_encoding = form;
}
const BigInt& EC_PrivateKey::private_value() const
{
if(m_private_key == 0)
throw Invalid_State("EC_PrivateKey::private_value - uninitialized");
return m_private_key;
}
/**
* EC_PrivateKey constructor
*/
EC_PrivateKey::EC_PrivateKey(RandomNumberGenerator& rng,
const EC_Group& ec_group,
const BigInt& x,
bool with_modular_inverse)
{
m_domain_params = ec_group;
if (!ec_group.get_curve_oid().empty())
m_domain_encoding = EC_DOMPAR_ENC_OID;
else
m_domain_encoding = EC_DOMPAR_ENC_EXPLICIT;
const BigInt& order = m_domain_params.get_order();
if(x == 0)
{
m_private_key = ec_group.random_scalar(rng);
}
else
{
m_private_key = x;
}
// Can't use rng here because ffi load functions use Null_RNG
if(with_modular_inverse)
{
// ECKCDSA
m_public_key = domain().get_base_point() * inverse_mod(m_private_key, order);
}
else
{
m_public_key = domain().get_base_point() * m_private_key;
}
BOTAN_ASSERT(m_public_key.on_the_curve(),
"Generated public key point was on the curve");
}
secure_vector<uint8_t> EC_PrivateKey::private_key_bits() const
{
return DER_Encoder()
.start_cons(SEQUENCE)
.encode(static_cast<size_t>(1))
.encode(BigInt::encode_1363(m_private_key, m_private_key.bytes()),
OCTET_STRING)
.end_cons()
.get_contents();
}
EC_PrivateKey::EC_PrivateKey(const AlgorithmIdentifier& alg_id,
const secure_vector<uint8_t>& key_bits,
bool with_modular_inverse)
{
m_domain_params = EC_Group(alg_id.get_parameters());
m_domain_encoding = EC_DOMPAR_ENC_EXPLICIT;
if (!domain().get_curve_oid().empty())
m_domain_encoding = EC_DOMPAR_ENC_OID;
else
m_domain_encoding = EC_DOMPAR_ENC_EXPLICIT;
OID key_parameters;
secure_vector<uint8_t> public_key_bits;
BER_Decoder(key_bits)
.start_cons(SEQUENCE)
.decode_and_check<size_t>(1, "Unknown version code for ECC key")
.decode_octet_string_bigint(m_private_key)
.decode_optional(key_parameters, ASN1_Tag(0), PRIVATE)
.decode_optional_string(public_key_bits, BIT_STRING, 1, PRIVATE)
.end_cons();
if(public_key_bits.empty())
{
if(with_modular_inverse)
{
// ECKCDSA
const BigInt& order = m_domain_params.get_order();
m_public_key = domain().get_base_point() * inverse_mod(m_private_key, order);
}
else
{
m_public_key = domain().get_base_point() * m_private_key;
}
BOTAN_ASSERT(m_public_key.on_the_curve(),
"Public point derived from loaded key was on the curve");
}
else
{
m_public_key = domain().OS2ECP(public_key_bits);
// OS2ECP verifies that the point is on the curve
}
}
}
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