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/*************************************************
* Default Engine PK Operations Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/eng_def.h>
#include <botan/pow_mod.h>
#include <botan/numthry.h>
#include <botan/reducer.h>
namespace Botan {
namespace {
/*************************************************
* Default IF Operation *
*************************************************/
class Default_IF_Op : public IF_Operation
{
public:
BigInt public_op(const BigInt& i) const
{ return powermod_e_n(i); }
BigInt private_op(const BigInt&) const;
IF_Operation* clone() const { return new Default_IF_Op(*this); }
Default_IF_Op(const BigInt&, const BigInt&, const BigInt&,
const BigInt&, const BigInt&, const BigInt&,
const BigInt&, const BigInt&);
private:
Fixed_Exponent_Power_Mod powermod_e_n, powermod_d1_p, powermod_d2_q;
Modular_Reducer reducer;
BigInt c, q;
};
/*************************************************
* Default_IF_Op Constructor *
*************************************************/
Default_IF_Op::Default_IF_Op(const BigInt& e, const BigInt& n, const BigInt&,
const BigInt& p, const BigInt& q,
const BigInt& d1, const BigInt& d2,
const BigInt& c)
{
powermod_e_n = Fixed_Exponent_Power_Mod(e, n);
if(d1 != 0 && d2 != 0 && p != 0 && q != 0)
{
powermod_d1_p = Fixed_Exponent_Power_Mod(d1, p);
powermod_d2_q = Fixed_Exponent_Power_Mod(d2, q);
reducer = Modular_Reducer(p);
this->c = c;
this->q = q;
}
}
/*************************************************
* Default IF Private Operation *
*************************************************/
BigInt Default_IF_Op::private_op(const BigInt& i) const
{
if(q == 0)
throw Internal_Error("Default_IF_Op::private_op: No private key");
BigInt j1 = powermod_d1_p(i);
BigInt j2 = powermod_d2_q(i);
j1 = reducer.reduce(sub_mul(j1, j2, c));
return mul_add(j1, q, j2);
}
/*************************************************
* Default DSA Operation *
*************************************************/
class Default_DSA_Op : public DSA_Operation
{
public:
bool verify(const byte[], u32bit, const byte[], u32bit) const;
SecureVector<byte> sign(const byte[], u32bit, const BigInt&) const;
DSA_Operation* clone() const { return new Default_DSA_Op(*this); }
Default_DSA_Op(const DL_Group&, const BigInt&, const BigInt&);
private:
const BigInt x, y;
const DL_Group group;
Fixed_Base_Power_Mod powermod_g_p, powermod_y_p;
Modular_Reducer mod_p, mod_q;
};
/*************************************************
* Default_DSA_Op Constructor *
*************************************************/
Default_DSA_Op::Default_DSA_Op(const DL_Group& grp, const BigInt& y1,
const BigInt& x1) : x(x1), y(y1), group(grp)
{
powermod_g_p = Fixed_Base_Power_Mod(group.get_g(), group.get_p());
powermod_y_p = Fixed_Base_Power_Mod(y, group.get_p());
mod_p = Modular_Reducer(group.get_p());
mod_q = Modular_Reducer(group.get_q());
}
/*************************************************
* Default DSA Verify Operation *
*************************************************/
bool Default_DSA_Op::verify(const byte msg[], u32bit msg_len,
const byte sig[], u32bit sig_len) const
{
const BigInt& q = group.get_q();
if(sig_len != 2*q.bytes() || msg_len > q.bytes())
return false;
BigInt r(sig, q.bytes());
BigInt s(sig + q.bytes(), q.bytes());
BigInt i(msg, msg_len);
if(r <= 0 || r >= q || s <= 0 || s >= q)
return false;
s = inverse_mod(s, q);
s = mod_p.multiply(powermod_g_p(mod_q.multiply(s, i)),
powermod_y_p(mod_q.multiply(s, r)));
return (mod_q.reduce(s) == r);
}
/*************************************************
* Default DSA Sign Operation *
*************************************************/
SecureVector<byte> Default_DSA_Op::sign(const byte in[], u32bit length,
const BigInt& k) const
{
if(x == 0)
throw Internal_Error("Default_DSA_Op::sign: No private key");
const BigInt& q = group.get_q();
BigInt i(in, length);
BigInt r = mod_q.reduce(powermod_g_p(k));
BigInt s = mod_q.multiply(inverse_mod(k, q), mul_add(x, r, i));
if(r.is_zero() || s.is_zero())
throw Internal_Error("Default_DSA_Op::sign: r or s was zero");
SecureVector<byte> output(2*q.bytes());
r.binary_encode(output + (output.size() / 2 - r.bytes()));
s.binary_encode(output + (output.size() - s.bytes()));
return output;
}
/*************************************************
* Default NR Operation *
*************************************************/
class Default_NR_Op : public NR_Operation
{
public:
SecureVector<byte> verify(const byte[], u32bit) const;
SecureVector<byte> sign(const byte[], u32bit, const BigInt&) const;
NR_Operation* clone() const { return new Default_NR_Op(*this); }
Default_NR_Op(const DL_Group&, const BigInt&, const BigInt&);
private:
const BigInt x, y;
const DL_Group group;
Fixed_Base_Power_Mod powermod_g_p, powermod_y_p;
Modular_Reducer reducer_p, reducer_q;
};
/*************************************************
* Default_NR_Op Constructor *
*************************************************/
Default_NR_Op::Default_NR_Op(const DL_Group& grp, const BigInt& y1,
const BigInt& x1) : x(x1), y(y1), group(grp)
{
powermod_g_p = Fixed_Base_Power_Mod(group.get_g(), group.get_p());
powermod_y_p = Fixed_Base_Power_Mod(y, group.get_p());
reducer_p = Modular_Reducer(group.get_p());
reducer_q = Modular_Reducer(group.get_q());
}
/*************************************************
* Default NR Verify Operation *
*************************************************/
SecureVector<byte> Default_NR_Op::verify(const byte in[], u32bit length) const
{
const BigInt& q = group.get_q();
if(length != 2*q.bytes())
return false;
BigInt c(in, q.bytes());
BigInt d(in + q.bytes(), q.bytes());
if(c.is_zero() || c >= q || d >= q)
throw Invalid_Argument("Default_NR_Op::verify: Invalid signature");
BigInt i = reducer_p.multiply(powermod_g_p(d), powermod_y_p(c));
return BigInt::encode(reducer_q.reduce(c - i));
}
/*************************************************
* Default NR Sign Operation *
*************************************************/
SecureVector<byte> Default_NR_Op::sign(const byte in[], u32bit length,
const BigInt& k) const
{
if(x == 0)
throw Internal_Error("Default_NR_Op::sign: No private key");
const BigInt& q = group.get_q();
BigInt f(in, length);
if(f >= q)
throw Invalid_Argument("Default_NR_Op::sign: Input is out of range");
BigInt c = reducer_q.reduce(powermod_g_p(k) + f);
if(c.is_zero())
throw Internal_Error("Default_NR_Op::sign: c was zero");
BigInt d = reducer_q.reduce(k - x * c);
SecureVector<byte> output(2*q.bytes());
c.binary_encode(output + (output.size() / 2 - c.bytes()));
d.binary_encode(output + (output.size() - d.bytes()));
return output;
}
/*************************************************
* Default ElGamal Operation *
*************************************************/
class Default_ELG_Op : public ELG_Operation
{
public:
SecureVector<byte> encrypt(const byte[], u32bit, const BigInt&) const;
BigInt decrypt(const BigInt&, const BigInt&) const;
ELG_Operation* clone() const { return new Default_ELG_Op(*this); }
Default_ELG_Op(const DL_Group&, const BigInt&, const BigInt&);
private:
const BigInt p;
Fixed_Base_Power_Mod powermod_g_p, powermod_y_p;
Fixed_Exponent_Power_Mod powermod_x_p;
Modular_Reducer reducer_p;
};
/*************************************************
* Default_ELG_Op Constructor *
*************************************************/
Default_ELG_Op::Default_ELG_Op(const DL_Group& group, const BigInt& y,
const BigInt& x) : p(group.get_p())
{
powermod_g_p = Fixed_Base_Power_Mod(group.get_g(), p);
powermod_y_p = Fixed_Base_Power_Mod(y, p);
reducer_p = Modular_Reducer(p);
if(x != 0)
powermod_x_p = Fixed_Exponent_Power_Mod(x, p);
}
/*************************************************
* Default ElGamal Encrypt Operation *
*************************************************/
SecureVector<byte> Default_ELG_Op::encrypt(const byte in[], u32bit length,
const BigInt& k) const
{
BigInt m(in, length);
if(m >= p)
throw Invalid_Argument("Default_ELG_Op::encrypt: Input is too large");
BigInt a = powermod_g_p(k);
BigInt b = reducer_p.multiply(m, powermod_y_p(k));
SecureVector<byte> output(2*p.bytes());
a.binary_encode(output + (p.bytes() - a.bytes()));
b.binary_encode(output + output.size() / 2 + (p.bytes() - b.bytes()));
return output;
}
/*************************************************
* Default ElGamal Decrypt Operation *
*************************************************/
BigInt Default_ELG_Op::decrypt(const BigInt& a, const BigInt& b) const
{
if(a >= p || b >= p)
throw Invalid_Argument("Default_ELG_Op: Invalid message");
return reducer_p.multiply(b, inverse_mod(powermod_x_p(a), p));
}
/*************************************************
* Default DH Operation *
*************************************************/
class Default_DH_Op : public DH_Operation
{
public:
BigInt agree(const BigInt& i) const { return powermod_x_p(i); }
DH_Operation* clone() const { return new Default_DH_Op(*this); }
Default_DH_Op(const DL_Group& group, const BigInt& x) :
powermod_x_p(x, group.get_p()) {}
private:
const Fixed_Exponent_Power_Mod powermod_x_p;
};
}
/*************************************************
* Acquire an IF op *
*************************************************/
IF_Operation* Default_Engine::if_op(const BigInt& e, const BigInt& n,
const BigInt& d, const BigInt& p,
const BigInt& q, const BigInt& d1,
const BigInt& d2, const BigInt& c) const
{
return new Default_IF_Op(e, n, d, p, q, d1, d2, c);
}
/*************************************************
* Acquire a DSA op *
*************************************************/
DSA_Operation* Default_Engine::dsa_op(const DL_Group& group, const BigInt& y,
const BigInt& x) const
{
return new Default_DSA_Op(group, y, x);
}
/*************************************************
* Acquire a NR op *
*************************************************/
NR_Operation* Default_Engine::nr_op(const DL_Group& group, const BigInt& y,
const BigInt& x) const
{
return new Default_NR_Op(group, y, x);
}
/*************************************************
* Acquire an ElGamal op *
*************************************************/
ELG_Operation* Default_Engine::elg_op(const DL_Group& group, const BigInt& y,
const BigInt& x) const
{
return new Default_ELG_Op(group, y, x);
}
/*************************************************
* Acquire a DH op *
*************************************************/
DH_Operation* Default_Engine::dh_op(const DL_Group& group,
const BigInt& x) const
{
return new Default_DH_Op(group, x);
}
}
|