private static secp256k1_context secp256k1_context_create(Secp256K1Options flags)
{
var ret = new secp256k1_context
{
illegal_callback = IllegalCallback,
error_callback = ErrorCallback
};
if ((flags & Secp256K1Options.FlagsTypeMask) != Secp256K1Options.FlagsTypeContext)
{
ret.illegal_callback?.Invoke(null, new secp256k1_callback("Invalid flags"));
return(null);
}
ECMult.secp256k1_ecmult_context_init(ret.ecmult_ctx);
ECMultGen.secp256k1_ecmult_gen_context_init(ret.ecmult_gen_ctx);
if (flags.HasFlag(Secp256K1Options.FlagsBitContextSign))
{
ECMultGen.secp256k1_ecmult_gen_context_build(ret.ecmult_gen_ctx, ret.error_callback);
}
if (flags.HasFlag(Secp256K1Options.FlagsBitContextVerify))
{
ECMult.secp256k1_ecmult_context_build(ret.ecmult_ctx, ret.error_callback);
}
return(ret);
}
private static bool secp256k1_ecdsa_sig_sign(secp256k1_ecmult_gen_context ctx, secp256k1_scalar sigr, secp256k1_scalar sigs, secp256k1_scalar seckey,
secp256k1_scalar message, secp256k1_scalar nonce, out byte recid)
{
var b = new byte[32];
secp256k1_gej rp;
secp256k1_ge r = new secp256k1_ge();
secp256k1_scalar n = new secp256k1_scalar();
bool overflow = false;
ECMultGen.secp256k1_ecmult_gen(ctx, out rp, nonce);
Group.secp256k1_ge_set_gej(r, rp);
Field.secp256k1_fe_normalize(r.x);
Field.secp256k1_fe_normalize(r.y);
Field.secp256k1_fe_get_b32(b, r.x);
Scalar.secp256k1_scalar_set_b32(sigr, b, ref overflow);
/* These two conditions should be checked before calling */
Util.VERIFY_CHECK(!Scalar.secp256k1_scalar_is_zero(sigr));
Util.VERIFY_CHECK(!overflow);
// The overflow condition is cryptographically unreachable as hitting it requires finding the discrete log
// of some P where P.x >= order, and only 1 in about 2^127 points meet this criteria.
recid = (byte)((overflow ? 2 : 0) | (Field.secp256k1_fe_is_odd(r.y) ? 1 : 0));
Scalar.secp256k1_scalar_mul(n, sigr, seckey);
Scalar.secp256k1_scalar_add(n, n, message);
Scalar.secp256k1_scalar_inverse(sigs, nonce);
Scalar.secp256k1_scalar_mul(sigs, sigs, n);
Scalar.secp256k1_scalar_clear(n);
Group.secp256k1_gej_clear(rp);
Group.secp256k1_ge_clear(r);
if (Scalar.secp256k1_scalar_is_zero(sigs))
{
return(false);
}
if (Scalar.secp256k1_scalar_is_high(sigs))
{
Scalar.secp256k1_scalar_negate(sigs, sigs);
recid ^= 1;
}
return(true);
}
private static bool secp256k1_ecdsa_sign_recoverable(secp256k1_context ctx, secp256k1_ecdsa_recoverable_signature signature,
byte[] msg32, byte[] seckey, secp256k1_nonce_function noncefp, byte[] noncedata)
{
if (ctx == null || msg32 == null || signature == null || seckey == null)
{
throw new NullReferenceException();
}
if (!ECMultGen.secp256k1_ecmult_gen_context_is_built(ctx.ecmult_gen_ctx))
{
throw new ArithmeticException();
}
if (noncefp == null)
{
noncefp = Secp256k1.secp256k1_nonce_function_default;
}
secp256k1_scalar r, s;
secp256k1_scalar sec, non, msg;
byte recid = 1;
bool ret = false;
var overflow = false;
sec = new secp256k1_scalar();
Scalar.secp256k1_scalar_set_b32(sec, seckey, ref overflow);
r = new secp256k1_scalar();
s = new secp256k1_scalar();
/* Fail if the secret key is invalid. */
if (!overflow && !Scalar.secp256k1_scalar_is_zero(sec))
{
var nonce32 = new byte[32];
uint count = 0;
msg = new secp256k1_scalar();
Scalar.secp256k1_scalar_set_b32(msg, msg32);
non = new secp256k1_scalar();
while (true)
{
ret = noncefp(nonce32, msg32, seckey, null, noncedata, count);
if (!ret)
{
break;
}
Scalar.secp256k1_scalar_set_b32(non, nonce32, ref overflow);
if (!Scalar.secp256k1_scalar_is_zero(non) && !overflow)
{
if (secp256k1_ecdsa_sig_sign(ctx.ecmult_gen_ctx, r, s, sec, msg, non, out recid))
{
break;
}
}
count++;
}
Util.MemSet(nonce32, 0, 32); //memset(nonce32, 0, 32);
Scalar.secp256k1_scalar_clear(msg);
Scalar.secp256k1_scalar_clear(non);
Scalar.secp256k1_scalar_clear(sec);
}
if (ret)
{
secp256k1_ecdsa_recoverable_signature_save(signature, r, s, recid);
}
else
{
Util.MemSet(signature.data, 0, secp256k1_ecdsa_recoverable_signature.Size); //memset(signature, 0, sizeof(* signature));
}
return(ret);
}
