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/*
* ECDSA via OpenSSL
* (C) 2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/build.h>
#include <botan/internal/pk_utils.h>
#include <functional>
#include <memory>
#include <openssl/x509.h>
#include <openssl/err.h>
#if defined(BOTAN_HAS_ECDSA) && !defined(OPENSSL_NO_ECDSA)
#include <botan/der_enc.h>
#include <botan/ecdsa.h>
#include <botan/pkcs8.h>
#include <botan/oids.h>
#include <openssl/ecdsa.h>
#include <openssl/ec.h>
#include <openssl/objects.h>
namespace Botan {
namespace {
secure_vector<byte> PKCS8_for_openssl(const EC_PrivateKey& ec)
{
const PointGFp& pub_key = ec.public_point();
const BigInt& priv_key = ec.private_value();
return DER_Encoder()
.start_cons(SEQUENCE)
.encode(static_cast<size_t>(1))
.encode(BigInt::encode_1363(priv_key, priv_key.bytes()), OCTET_STRING)
.start_cons(ASN1_Tag(0), PRIVATE)
.raw_bytes(ec.domain().DER_encode(EC_DOMPAR_ENC_OID))
.end_cons()
.start_cons(ASN1_Tag(1), PRIVATE)
.encode(EC2OSP(pub_key, PointGFp::UNCOMPRESSED), BIT_STRING)
.end_cons()
.end_cons()
.get_contents();
}
class OpenSSL_Error : public Exception
{
public:
OpenSSL_Error(const std::string& what) :
Exception(what + " failed: " + ERR_error_string(ERR_get_error(), nullptr)) {}
};
int OpenSSL_EC_nid_for(const OID& oid)
{
if(oid.empty())
return -1;
static const std::map<std::string, int> nid_map = {
//{ "secp160r1", NID_secp160r1 },
//{ "secp160r2", NID_secp160r2 },
{ "secp192r1", NID_X9_62_prime192v1 },
{ "secp224r1", NID_secp224r1 },
{ "secp256r1", NID_X9_62_prime256v1 },
{ "secp384r1", NID_secp384r1 },
{ "secp521r1", NID_secp521r1 }
// TODO: OpenSSL 1.0.2 added brainpool curves
};
const std::string name = OIDS::lookup(oid);
auto i = nid_map.find(name);
if(i != nid_map.end())
return i->second;
return -1;
}
class OpenSSL_ECDSA_Verification_Operation : public PK_Ops::Verification_with_EMSA
{
public:
typedef ECDSA_PublicKey Key_Type;
static OpenSSL_ECDSA_Verification_Operation* make(const Spec& spec)
{
if(const ECDSA_PublicKey* ecdsa = dynamic_cast<const ECDSA_PublicKey*>(&spec.key()))
{
const int nid = OpenSSL_EC_nid_for(ecdsa->domain().get_oid());
if(nid > 0)
return new OpenSSL_ECDSA_Verification_Operation(*ecdsa, spec.padding(), nid);
}
return nullptr;
}
OpenSSL_ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa, const std::string& emsa, int nid) :
PK_Ops::Verification_with_EMSA(emsa), m_ossl_ec(::EC_KEY_new(), ::EC_KEY_free)
{
std::unique_ptr<::EC_GROUP, std::function<void (::EC_GROUP*)>> grp(::EC_GROUP_new_by_curve_name(nid),
::EC_GROUP_free);
if(!grp)
throw OpenSSL_Error("EC_GROUP_new_by_curve_name");
::EC_KEY_set_group(m_ossl_ec.get(), grp.get());
const secure_vector<byte> enc = EC2OSP(ecdsa.public_point(), PointGFp::UNCOMPRESSED);
const byte* enc_ptr = enc.data();
EC_KEY* key_ptr = m_ossl_ec.get();
if(!::o2i_ECPublicKey(&key_ptr, &enc_ptr, enc.size()))
throw OpenSSL_Error("o2i_ECPublicKey");
const EC_GROUP* group = ::EC_KEY_get0_group(m_ossl_ec.get());
m_order_bits = ::EC_GROUP_get_degree(group);
}
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return (m_order_bits + 7) / 8; }
size_t max_input_bits() const override { return m_order_bits; }
bool with_recovery() const override { return false; }
bool verify(const byte msg[], size_t msg_len,
const byte sig_bytes[], size_t sig_len) override
{
if(sig_len != message_part_size() * message_parts())
return false;
std::unique_ptr<ECDSA_SIG, std::function<void (ECDSA_SIG*)>> sig(nullptr, ECDSA_SIG_free);
sig.reset(::ECDSA_SIG_new());
sig->r = BN_bin2bn(sig_bytes , sig_len / 2, nullptr);
sig->s = BN_bin2bn(sig_bytes + sig_len / 2, sig_len / 2, nullptr);
const int res = ECDSA_do_verify(msg, msg_len, sig.get(), m_ossl_ec.get());
if(res < 0)
throw OpenSSL_Error("ECDSA_do_verify");
return (res == 1);
}
private:
std::unique_ptr<EC_KEY, std::function<void (EC_KEY*)>> m_ossl_ec;
size_t m_order_bits = 0;
};
class OpenSSL_ECDSA_Signing_Operation : public PK_Ops::Signature_with_EMSA
{
public:
typedef ECDSA_PrivateKey Key_Type;
static OpenSSL_ECDSA_Signing_Operation* make(const Spec& spec)
{
if(const ECDSA_PrivateKey* ecdsa = dynamic_cast<const ECDSA_PrivateKey*>(&spec.key()))
{
const int nid = OpenSSL_EC_nid_for(ecdsa->domain().get_oid());
if(nid > 0)
return new OpenSSL_ECDSA_Signing_Operation(*ecdsa, spec.padding());
}
return nullptr;
}
OpenSSL_ECDSA_Signing_Operation(const ECDSA_PrivateKey& ecdsa, const std::string& emsa) :
PK_Ops::Signature_with_EMSA(emsa),
m_ossl_ec(nullptr, ::EC_KEY_free)
{
const secure_vector<byte> der = PKCS8_for_openssl(ecdsa);
const byte* der_ptr = der.data();
m_ossl_ec.reset(d2i_ECPrivateKey(nullptr, &der_ptr, der.size()));
if(!m_ossl_ec)
throw OpenSSL_Error("d2i_ECPrivateKey");
const EC_GROUP* group = ::EC_KEY_get0_group(m_ossl_ec.get());
m_order_bits = ::EC_GROUP_get_degree(group);
}
secure_vector<byte> raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator&) override
{
std::unique_ptr<ECDSA_SIG, std::function<void (ECDSA_SIG*)>> sig(nullptr, ECDSA_SIG_free);
sig.reset(::ECDSA_do_sign(msg, msg_len, m_ossl_ec.get()));
if(!sig)
throw OpenSSL_Error("ECDSA_do_sign");
const size_t order_bytes = message_part_size();
const size_t r_bytes = BN_num_bytes(sig->r);
const size_t s_bytes = BN_num_bytes(sig->s);
secure_vector<byte> sigval(2*order_bytes);
BN_bn2bin(sig->r, &sigval[order_bytes - r_bytes]);
BN_bn2bin(sig->s, &sigval[2*order_bytes - s_bytes]);
return sigval;
}
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return (m_order_bits + 7) / 8; }
size_t max_input_bits() const override { return m_order_bits; }
private:
std::unique_ptr<EC_KEY, std::function<void (EC_KEY*)>> m_ossl_ec;
size_t m_order_bits = 0;
};
BOTAN_REGISTER_TYPE(PK_Ops::Verification, OpenSSL_ECDSA_Verification_Operation, "ECDSA",
OpenSSL_ECDSA_Verification_Operation::make,
"openssl", 255);
BOTAN_REGISTER_TYPE(PK_Ops::Signature, OpenSSL_ECDSA_Signing_Operation, "ECDSA",
OpenSSL_ECDSA_Signing_Operation::make, "openssl", 255);
}
}
#endif // BOTAN_HAS_ECDSA && !OPENSSL_NO_ECDSA
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