Syndica · Rexicon226 · Feb 6, 2026
diff --git a/src/runtime/program/zk_elgamal/execute.zig b/src/runtime/program/zk_elgamal/execute.zig
@@ -156,7 +156,7 @@ fn processVerifyProof(
         break :cd proof_data.context;
     };
 
-    // create context state if additional accounts are provided with the instruction
+    // Create context state if additional accounts are provided with the instruction.
     if (ic.ixn_info.account_metas.items.len >= accessed_accounts + 2) {
         const context_authority_key = blk: {
             const context_state_authority = try ic.borrowInstructionAccount(accessed_accounts + 1);

diff --git a/src/runtime/program/zk_elgamal/lib.zig b/src/runtime/program/zk_elgamal/lib.zig
@@ -1,5 +1,6 @@
 const sig = @import("../../../sig.zig");
 
+/// [agave] https://github.com/solana-program/zk-elgamal-proof/blob/zk-sdk%40v5.0.0/zk-sdk/src/zk_elgamal_proof_program/proof_data/mod.rs#L48
 pub const ProofType = enum(u8) {
     /// Empty proof type used to distinguish if a proof context account is initialized
     uninitialized,
@@ -35,6 +36,7 @@ pub fn ProofContextState(C: type) type {
 
 pub const ID: sig.core.Pubkey = .parse("ZkE1Gama1Proof11111111111111111111111111111");
 
+// [agave] https://github.com/anza-xyz/agave/blob/master/programs/zk-elgamal-proof/src/lib.rs#L19-L31
 pub const CLOSE_CONTEXT_STATE_COMPUTE_UNITS: u64 = 3_300;
 pub const VERIFY_ZERO_CIPHERTEXT_COMPUTE_UNITS: u64 = 6_000;
 pub const VERIFY_CIPHERTEXT_CIPHERTEXT_EQUALITY_COMPUTE_UNITS: u64 = 8_000;

diff --git a/src/zksdk/elgamal.zig b/src/zksdk/elgamal.zig
@@ -54,6 +54,10 @@ pub const Pubkey = struct {
         );
         return fromBytes(buffer);
     }
+
+    pub fn rejectIdentity(self: *const Pubkey) error{IdentityElement}!void {
+        try self.point.rejectIdentity();
+    }
 };
 
 pub const Keypair = struct {
@@ -107,6 +111,11 @@ pub const Ciphertext = struct {
         );
         return fromBytes(buffer);
     }
+
+    pub fn rejectIdentity(self: *const Ciphertext) error{IdentityElement}!void {
+        try self.commitment.point.rejectIdentity();
+        try self.handle.point.rejectIdentity();
+    }
 };
 
 pub fn encrypt(comptime T: type, value: T, pubkey: *const Pubkey) Ciphertext {
@@ -168,13 +177,27 @@ pub fn GroupedElGamalCiphertext(comptime N: u64) type {
             };
         }
 
+        pub fn fromBase64(string: []const u8) !Self {
+            const base64 = std.base64.standard;
+            var buffer: [BYTE_LEN]u8 = @splat(0);
+            const decoded_length = try base64.Decoder.calcSizeForSlice(string);
+            try std.base64.standard.Decoder.decode(
+                buffer[0..decoded_length],
+                string,
+            );
+            return fromBytes(buffer);
+        }
+
         pub fn toBytes(self: Self) [BYTE_LEN]u8 {
             var handles: [N * 32]u8 = undefined;
             for (self.handles, 0..) |handle, i| {
-                const position = i * 32;
-                handles[position..][0..32].* = handle.point.toBytes();
+                handles[i * 32 ..][0..32].* = handle.point.toBytes();
             }
             return self.commitment.point.toBytes() ++ handles;
         }
+
+        pub fn rejectIdentity(self: *const Self) error{IdentityElement}!void {
+            try self.commitment.rejectIdentity();
+        }
     };
 }
diff --git a/src/zksdk/lib.zig b/src/zksdk/lib.zig
@@ -22,16 +22,16 @@ pub const PercentageWithCapData = percentage.Data;
 pub const PubkeyProofData = pubkey_validity.Data;
 pub const ZeroCiphertextData = zero_ciphertext.Data;
 
-// grouped ciphertext validity
-const grouped_cipher_handles_2 = @import("sigma_proofs/grouped_ciphertext/handles_2.zig");
-const grouped_cipher_handles_3 = @import("sigma_proofs/grouped_ciphertext/handles_3.zig");
+// // grouped ciphertext validity
+const grouped_cipher_2_handles = @import("sigma_proofs/grouped_ciphertext/2_handles.zig");
+const grouped_cipher_3_handles = @import("sigma_proofs/grouped_ciphertext/3_handles.zig");
 
-pub const GroupedCiphertext2HandlesData = grouped_cipher_handles_2.Data;
-pub const BatchedGroupedCiphertext2HandlesData = grouped_cipher_handles_2.BatchedData;
-pub const GroupedCiphertext3HandlesData = grouped_cipher_handles_3.Data;
-pub const BatchedGroupedCiphertext3HandlesData = grouped_cipher_handles_3.BatchedData;
+pub const GroupedCiphertext2HandlesData = grouped_cipher_2_handles.Data;
+pub const BatchedGroupedCiphertext2HandlesData = grouped_cipher_2_handles.BatchedData;
+pub const GroupedCiphertext3HandlesData = grouped_cipher_3_handles.Data;
+pub const BatchedGroupedCiphertext3HandlesData = grouped_cipher_3_handles.BatchedData;
 
-// range proof
+// // range proof
 pub const bulletproofs = @import("range_proof/bulletproofs.zig");
 
 pub const RangeProofU64Data = bulletproofs.Data(64);

diff --git a/src/zksdk/merlin.zig b/src/zksdk/merlin.zig
@@ -230,21 +230,26 @@ pub const Transcript = struct {
         ciphertext: zksdk.elgamal.Ciphertext,
         commitment: zksdk.pedersen.Commitment,
         u64: u64,
+        domsep: DomainSeperator,
 
         grouped_2: zksdk.elgamal.GroupedElGamalCiphertext(2),
         grouped_3: zksdk.elgamal.GroupedElGamalCiphertext(3),
     };
 
-    pub fn init(comptime seperator: DomainSeperator, inputs: []const TranscriptInput) Transcript {
+    /// [agave] https://github.com/solana-program/zk-elgamal-proof/blob/zk-sdk%40v5.0.0/zk-sdk/src/lib.rs#L36
+    const TRANSCRIPT_DOMAIN = "solana-zk-elgamal-proof-program-v1";
+
+    pub fn init(comptime seperator: DomainSeperator) Transcript {
         var transcript: Transcript = .{ .strobe = Strobe128.init("Merlin v1.0") };
-        transcript.appendDomSep(seperator);
-        for (inputs) |input| transcript.appendMessage(input.label, input.message);
+        transcript.appendBytes("dom-sep", TRANSCRIPT_DOMAIN);
+        transcript.appendBytes("dom-sep", @tagName(seperator));
         return transcript;
     }
 
     pub fn initTest(label: []const u8) Transcript {
         comptime if (!builtin.is_test) @compileError("should only be used during tests");
         var transcript: Transcript = .{ .strobe = Strobe128.init("Merlin v1.0") };
+        transcript.appendBytes("dom-sep", TRANSCRIPT_DOMAIN);
         transcript.appendBytes("dom-sep", label);
         return transcript;
     }
@@ -264,6 +269,7 @@ pub const Transcript = struct {
             .point => |*point| &point.toBytes(),
             .pubkey => |*pubkey| &pubkey.toBytes(),
             .scalar => |*scalar| &scalar.toBytes(),
+            .domsep => |t| @tagName(t),
             .ciphertext => |*ct| b: {
                 @memcpy(buffer[0..32], &ct.commitment.point.toBytes());
                 @memcpy(buffer[32..64], &ct.handle.point.toBytes());
@@ -284,26 +290,33 @@ pub const Transcript = struct {
         comptime session: *Session,
         comptime t: Input.Type,
         comptime label: []const u8,
-        data: t.Data(),
-    ) if (t == .validate_point) error{IdentityElement}!void else void {
-        // if validate_point fails to validate, we no longer want to check the contract
+        data: @FieldType(Message, @tagName(t.base())),
+    ) if (t.validates()) error{IdentityElement}!void else void {
+        // If validate_point fails to validate, we no longer want to check the contract
         // because the function calling append will now return early.
         errdefer session.cancel();
 
         if (t == .bytes and !builtin.is_test)
             @compileError("message type `bytes` only allowed in tests");
 
-        // assert correctness
+        // Get the next expected input, and inside we verify that it matches
+        // the type we're about to append to the transcript.
         const input = comptime session.nextInput(t, label);
-        if (t == .validate_point) try data.rejectIdentity();
+        // If the input requires validation, we perform it here.
+        if (comptime t.validates()) try data.rejectIdentity();
+        // Ensure that the domain seperators are added with the correct label.
+        // They should always be added through the `appendDomSep` helper function.
+        switch (t) {
+            .domsep => comptime {
+                std.debug.assert(input.seperator.? == data);
+                std.debug.assert(std.mem.eql(u8, label, "dom-sep"));
+            },
+            else => {},
+        }
 
-        // add the message
         self.appendMessage(input.label, @unionInit(
             Message,
-            @tagName(switch (t) {
-                .validate_point => .point,
-                else => t,
-            }),
+            @tagName(t.base()),
             data,
         ));
     }
@@ -314,12 +327,16 @@ pub const Transcript = struct {
     pub inline fn appendNoValidate(
         self: *Transcript,
         comptime session: *Session,
+        comptime t: Input.Type,
         comptime label: []const u8,
-        point: Ristretto255,
+        data: @FieldType(Message, @tagName(t.base())),
     ) void {
-        const input = comptime session.nextInput(.validate_point, label);
-        point.rejectIdentity() catch {}; // ignore the error
-        self.appendMessage(input.label, .{ .point = point });
+        const input = comptime session.nextInput(
+            @field(Input.Type, "validate_" ++ @tagName(t)),
+            label,
+        );
+        data.rejectIdentity() catch {}; // ignore the error
+        self.appendMessage(input.label, @unionInit(Message, @tagName(t), data));
     }
 
     fn challengeBytes(
@@ -329,7 +346,6 @@ pub const Transcript = struct {
     ) void {
         var data_len: [4]u8 = undefined;
         std.mem.writeInt(u32, &data_len, @intCast(destination.len), .little);
-
         self.strobe.metaAd(label, false);
         self.strobe.metaAd(&data_len, true);
         self.strobe.prf(destination, false);
@@ -351,64 +367,89 @@ pub const Transcript = struct {
 
     // domain seperation helpers
 
-    pub fn appendDomSep(self: *Transcript, comptime seperator: DomainSeperator) void {
-        self.appendBytes("dom-sep", @tagName(seperator));
-    }
-
-    pub fn appendHandleDomSep(
+    pub inline fn appendDomSep(
         self: *Transcript,
-        comptime mode: enum { batched, unbatched },
-        comptime handles: enum { two, three },
+        comptime session: *Session,
+        comptime seperator: DomainSeperator,
     ) void {
-        self.appendDomSep(switch (mode) {
-            .batched => .@"batched-validity-proof",
-            .unbatched => .@"validity-proof",
-        });
-        self.appendMessage("handles", .{ .u64 = switch (handles) {
-            .two => 2,
-            .three => 3,
-        } });
+        self.append(session, .domsep, "dom-sep", seperator);
     }
 
-    pub fn appendRangeProof(
+    pub inline fn appendRangeProof(
         self: *Transcript,
+        comptime session: *Session,
         comptime mode: enum { range, inner },
         n: comptime_int,
     ) void {
-        self.appendDomSep(switch (mode) {
+        self.appendDomSep(session, switch (mode) {
             .range => .@"range-proof",
             .inner => .@"inner-product",
         });
-        self.appendMessage("n", .{ .u64 = n });
+        self.append(session, .u64, "n", n);
     }
 
     // sessions
 
     pub const Input = struct {
         label: []const u8,
         type: Type,
+        seperator: ?DomainSeperator = null,
 
         const Type = enum {
             bytes,
             scalar,
-            challenge,
+            u64,
+
             point,
-            validate_point,
             pubkey,
+            ciphertext,
+            commitment,
+            grouped_2,
+            grouped_3,
 
-            pub fn Data(comptime t: Type) type {
+            validate_point,
+            validate_pubkey,
+            validate_ciphertext,
+            validate_commitment,
+            validate_grouped_2,
+            validate_grouped_3,
+
+            domsep,
+            challenge,
+
+            /// Returns whether this input type performs identity validation.
+            fn validates(t: Type) bool {
                 return switch (t) {
-                    .bytes => []const u8,
-                    .scalar => Scalar,
-                    .validate_point, .point => Ristretto255,
-                    .pubkey => zksdk.elgamal.Pubkey,
-                    .challenge => unreachable, // call `challenge*`
+                    .validate_point,
+                    .validate_pubkey,
+                    .validate_ciphertext,
+                    .validate_commitment,
+                    .validate_grouped_2,
+                    .validate_grouped_3,
+                    => true,
+                    else => false,
                 };
             }
+
+            /// For a given input type, returns the base type.
+            /// E.g. `validate_point` -> `point`
+            /// E.g. `point` -> `point`
+            fn base(t: Type) Type {
+                if (t.validates()) {
+                    return @field(Type, @tagName(t)["validate_".len..]);
+                }
+                return t;
+            }
         };
 
+        pub fn domain(sep: DomainSeperator) Input {
+            return .{ .label = "dom-sep", .type = .domsep, .seperator = sep };
+        }
+
         fn check(self: Input, t: Type, label: []const u8) void {
-            std.debug.assert(self.type == t);
+            if (self.type != t) {
+                @compileError("expected: " ++ @tagName(self.type) ++ ", found: " ++ @tagName(t));
+            }
             std.debug.assert(std.mem.eql(u8, self.label, label));
         }
     };
@@ -418,7 +459,8 @@ pub const Transcript = struct {
     pub const Session = struct {
         i: u8,
         contract: Contract,
-        err: bool, // if validate_point errors, we skip the finish() check
+        // If an identity validation errors, we skip the finish() check.
+        err: bool,
 
         pub inline fn nextInput(comptime self: *Session, t: Input.Type, label: []const u8) Input {
             comptime {
@@ -453,6 +495,14 @@ pub const Transcript = struct {
             return .{ .i = 0, .contract = contract, .err = false };
         }
     }
+
+    /// The same as `getSession`, but does not check that it ends with a challenge.
+    /// Only used in certain cases when we need an "init" contract, such as `percentage_with_cap`.
+    pub inline fn getInitSession(comptime contract: []const Input) Session {
+        comptime {
+            return .{ .i = 0, .contract = contract, .err = false };
+        }
+    }
 };
 
 test "equivalence" {
@@ -468,9 +518,9 @@ test "equivalence" {
     transcript.challengeBytes("challenge", &bytes);
 
     try std.testing.expectEqualSlices(u8, &.{
-        0xd5, 0xa2, 0x19, 0x72, 0xd0, 0xd5, 0xfe, 0x32,
-        0xc,  0xd,  0x26, 0x3f, 0xac, 0x7f, 0xff, 0xb8,
-        0x14, 0x5a, 0xa6, 0x40, 0xaf, 0x6e, 0x9b, 0xca,
-        0x17, 0x7c, 0x3,  0xc7, 0xef, 0xcf, 0x6,  0x15,
+        159, 115, 74,  116, 119, 227, 89,  42,
+        108, 83,  69,  218, 43,  29,  11,  79,
+        117, 141, 121, 172, 163, 50,  123, 92,
+        25,  21,  111, 177, 11,  232, 4,   35,
     }, &bytes);
 }
diff --git a/src/zksdk/pedersen.zig b/src/zksdk/pedersen.zig
@@ -66,6 +66,10 @@ pub const Commitment = struct {
         );
         return fromBytes(buffer);
     }
+
+    pub fn rejectIdentity(self: *const Commitment) error{IdentityElement}!void {
+        try self.point.rejectIdentity();
+    }
 };
 
 pub const DecryptHandle = struct {