Merge pull request #10 from zig-bitcoin/ecdsa-schnorr-split

Split schnorr + ecdsa sign impl + recovery

Author: AbdelStark

build.zig

@@ -10,6 +10,7 @@ fn buildSecp256k1(libsecp_c: *std.Build.Dependency, b: *std.Build, target: std.B
 
     lib.addIncludePath(libsecp_c.path(""));
     lib.addIncludePath(libsecp_c.path("src"));
+    lib.addIncludePath(libsecp_c.path("include"));
 
     var flags = std.ArrayList([]const u8).init(b.allocator);
     defer flags.deinit();
@@ -19,7 +20,15 @@ fn buildSecp256k1(libsecp_c: *std.Build.Dependency, b: *std.Build, target: std.B
     try flags.appendSlice(&.{"-DENABLE_MODULE_ECDH=1"});
     try flags.appendSlice(&.{"-DENABLE_MODULE_EXTRAKEYS=1"});
 
-    lib.addCSourceFiles(.{ .root = libsecp_c.path(""), .flags = flags.items, .files = &.{ "./src/secp256k1.c", "./src/precomputed_ecmult.c", "./src/precomputed_ecmult_gen.c" } });
+    lib.addCSourceFiles(.{
+        .root = libsecp_c.path(""),
+        .flags = flags.items,
+        .files = &.{
+            "./src/secp256k1.c",
+            "./src/precomputed_ecmult.c",
+            "./src/precomputed_ecmult_gen.c",
+        },
+    });
     lib.defineCMacro("USE_FIELD_10X26", "1");
     lib.defineCMacro("USE_SCALAR_8X32", "1");
     lib.defineCMacro("USE_ENDOMORPHISM", "1");

src/constants.zig

@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: CC0-1.0
+
+//! Constants related to the API and the underlying curve.
+//!
+
+/// The size (in bytes) of a message.
+pub const message_size: usize = 32;
+
+/// the size (in bytes) of a secret key.
+pub const secret_key_size: usize = 32;
+
+/// the size (in bytes) of a serialized public key.
+pub const public_key_size: usize = 33;
+
+/// the size (in bytes) of an serialized uncompressed public key.
+pub const uncompressed_public_key_size: usize = 65;
+
+/// the maximum size of a signature.
+pub const max_signature_size: usize = 72;
+
+/// the maximum size of a compact signature.
+pub const compact_signature_size: usize = 64;
+
+/// the size of a schnorr signature.
+pub const schnorr_signature_size: usize = 64;
+
+/// the size of a schnorr public key.
+pub const schnorr_public_key_size: usize = 32;
+
+/// the size of a key pair.
+pub const key_pair_size: usize = 96;
+
+/// the size of a full elligatorswift encoding.
+pub const ellswift_encoding_size: usize = 64;
+
+/// The Prime for the secp256k1 field element.
+pub const field_size: [32]u8 = .{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f };
+
+/// the order of the secp256k1 curve.
+pub const curve_order: [32]u8 = .{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xba, 0xae, 0xdc, 0xe6, 0xaf, 0x48, 0xa0, 0x3b, 0xbf, 0xd2, 0x5e, 0x8c, 0xd0, 0x36, 0x41, 0x41 };
+
+/// the x coordinate of the generator.
+pub const generator_x: [32]u8 = .{ 0x79, 0xbe, 0x66, 0x7e, 0xf9, 0xdc, 0xbb, 0xac, 0x55, 0xa0, 0x62, 0x95, 0xce, 0x87, 0x0b, 0x07, 0x02, 0x9b, 0xfc, 0xdb, 0x2d, 0xce, 0x28, 0xd9, 0x59, 0xf2, 0x81, 0x5b, 0x16, 0xf8, 0x17, 0x98 };
+
+/// the y coordinate of the generator.
+pub const generator_y: [32]u8 = .{ 0x48, 0x3a, 0xda, 0x77, 0x26, 0xa3, 0xc4, 0x65, 0x5d, 0xa4, 0xfb, 0xfc, 0x0e, 0x11, 0x08, 0xa8, 0xfd, 0x17, 0xb4, 0x48, 0xa6, 0x85, 0x54, 0x19, 0x9c, 0x47, 0xd0, 0x8f, 0xfb, 0x10, 0xd4, 0xb8 };
+
+/// the value zero as an array of bytes.
+pub const zero: [32]u8 = [_]u8{0} ** 32;
+
+/// the value one as big-endian array of bytes.
+pub const one: [32]u8 = .{
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
+};