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-rw-r--r--src/math/numbertheory/curve_gfp.h41
1 files changed, 37 insertions, 4 deletions
diff --git a/src/math/numbertheory/curve_gfp.h b/src/math/numbertheory/curve_gfp.h
index de6bed099..3c9eb90ca 100644
--- a/src/math/numbertheory/curve_gfp.h
+++ b/src/math/numbertheory/curve_gfp.h
@@ -34,29 +34,52 @@ class BOTAN_DLL CurveGFp
* @param b second coefficient
*/
CurveGFp(const BigInt& p, const BigInt& a, const BigInt& b) :
- p(p), a(a), b(b), reducer_p(p) {}
+ p(p), a(a), b(b), reducer_p(p)
+ {
+ r = 1;
+ r <<= p.sig_words() * BOTAN_MP_WORD_BITS;
+
+ r_inv = inverse_mod(r, p);
+
+ p_dash = ((r * r_inv) - 1) / p;
+ }
// CurveGFp(const CurveGFp& other) = default;
// CurveGFp& operator=(const CurveGFp& other) = default;
/**
* Get coefficient a
- * @result coefficient a
+ * @return coefficient a
*/
const BigInt& get_a() const { return a; }
/**
* Get coefficient b
- * @result coefficient b
+ * @return coefficient b
*/
const BigInt& get_b() const { return b; }
/**
* Get prime modulus of the field of the curve
- * @result prime modulus of the field of the curve
+ * @return prime modulus of the field of the curve
*/
const BigInt& get_p() const { return p; }
+ /**
+ * @return Montgomery parameter r
+ */
+ const BigInt& get_r() const { return r; }
+
+ /**
+ * @return Montgomery parameter r^-1
+ */
+ const BigInt& get_r_inv() const { return r_inv; }
+
+ /**
+ * @return Montgomery parameter p-dash
+ */
+ const BigInt& get_p_dash() const { return p_dash; }
+
const Modular_Reducer& mod_p() const { return reducer_p; }
/**
@@ -68,6 +91,11 @@ class BOTAN_DLL CurveGFp
std::swap(a, other.a);
std::swap(b, other.b);
std::swap(p, other.p);
+ std::swap(reducer_p, other.reducer_p);
+
+ std::swap(r, other.r);
+ std::swap(r_inv, other.r_inv);
+ std::swap(p_dash, other.p_dash);
}
bool operator==(const CurveGFp& other) const
@@ -76,7 +104,12 @@ class BOTAN_DLL CurveGFp
}
private:
+ // Curve parameters
BigInt p, a, b;
+
+ // Montgomery parameters
+ BigInt r, r_inv, p_dash;
+
Modular_Reducer reducer_p;
};