try fixing leak

libi2pd/Signature.cpp

@@ -316,7 +316,6 @@ namespace crypto
 
 			bool IsOnCurve (const EDDSAPoint& p, BN_CTX * ctx) const
 			{
-				BN_CTX_start (ctx);
 				BIGNUM * x2 = BN_CTX_get (ctx), * y2 = BN_CTX_get (ctx), * tmp = BN_CTX_get (ctx);
 				BN_sqr (x2, p.x, ctx); // x^2
 				BN_sqr (y2, p.y, ctx); // y^2
@@ -353,6 +352,7 @@ namespace crypto
 					BN_mod_mul (x, x, I, q, ctx);
 				if (BN_is_odd (x))
 					BN_sub (x, q, x);
+
 				return x;
 			}
 
@@ -370,7 +370,7 @@ namespace crypto
 					buf1[0] &= 0x7f; // clear highest bit
 				BIGNUM * y = BN_new ();
 				BN_bin2bn (buf1, EDDSA25519_PUBLIC_KEY_LENGTH, y);
-				auto x = RecoverX (y, ctx);
+				BIGNUM * x = RecoverX (y, ctx);
 				if (BN_is_bit_set (x, 0) != isHighestBitSet)
 					BN_sub (x, q, x); // x = q - x 
 				BIGNUM * z = BN_new (), * t = BN_new ();