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feature: randomize anti-tamper key-derivation rotation shifts (#69) #108

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Merged
mcpolo99 merged 1 commit into from
Sep 21, 2026
Merged

feature: randomize anti-tamper key-derivation rotation shifts (#69) #108

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19 changes: 13 additions & 6 deletions Confuser.Protections/AntiTamper/AntiMode.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ internal class AntiMode : IModeHandler {
List<MethodDef> methods;
uint name1, name2;
RandomGenerator random;
int[] rotShifts;
uint v;
uint x;
uint z;
Expand All @@ -35,6 +36,9 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
feedback = random.NextUInt32();
name1 = random.NextUInt32() & 0x7f7f7f7f;
name2 = random.NextUInt32() & 0x7f7f7f7f;
// Randomize the key-derivation rotation amounts (were the fixed 5/3/7/11); the same
// amounts are injected into the runtime (Mutation.KeyI6..KeyI9) below.
rotShifts = RotationKey.PickShifts(random);

switch (parameters.GetParameter(context, context.CurrentModule, "key", Mode.Normal)) {
case Mode.Normal:
Expand Down Expand Up @@ -79,8 +83,11 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
initMethod.Body.Instructions.Add(instr);

MutationHelper.InjectKeys(initMethod,
new[] { 0, 1, 2, 3, 4, 5 },
new[] { (int)(name1 * name2), (int)z, (int)x, (int)c, (int)v, (int)feedback });
new[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 },
new[] {
(int)(name1 * name2), (int)z, (int)x, (int)c, (int)v, (int)feedback,
rotShifts[0], rotShifts[1], rotShifts[2], rotShifts[3]
});

var name = context.Registry.GetService<INameService>();
var marker = context.Registry.GetService<IMarkerService>();
Expand Down Expand Up @@ -249,10 +256,10 @@ uint[] DeriveKey() {
for (int i = 0; i < 0x10; i++) {
dst[i] = v;
src[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
z = (x >> rotShifts[0]) | (x << (32 - rotShifts[0]));
x = (c >> rotShifts[1]) | (c << (32 - rotShifts[1]));
c = (v >> rotShifts[2]) | (v << (32 - rotShifts[2]));
v = (z >> rotShifts[3]) | (z << (32 - rotShifts[3]));
}
return deriver.DeriveKey(dst, src);
}
Expand Down
19 changes: 13 additions & 6 deletions Confuser.Protections/AntiTamper/JITMode.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ internal class JITMode : IModeHandler {
List<MethodDef> methods;
uint name1, name2;
RandomGenerator random;
int[] rotShifts;
uint v;
uint x;
uint z;
Expand All @@ -49,6 +50,9 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
name1 = random.NextUInt32() & 0x7f7f7f7f;
name2 = random.NextUInt32() & 0x7f7f7f7f;
key = random.NextUInt32();
// Randomize the key-derivation rotation amounts (were the fixed 5/3/7/11); the same
// amounts are injected into the runtime (Mutation.KeyI6..KeyI9) below.
rotShifts = RotationKey.PickShifts(random);

fieldLayout = new byte[6];
for (int i = 0; i < 6; i++) {
Expand Down Expand Up @@ -101,8 +105,11 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
initMethod.Body.Instructions.Add(instr);

MutationHelper.InjectKeys(initMethod,
new[] { 0, 1, 2, 3, 4 },
new[] { (int)(name1 * name2), (int)z, (int)x, (int)c, (int)v });
new[] { 0, 1, 2, 3, 4, 6, 7, 8, 9 },
new[] {
(int)(name1 * name2), (int)z, (int)x, (int)c, (int)v,
rotShifts[0], rotShifts[1], rotShifts[2], rotShifts[3]
});

var name = context.Registry.GetService<INameService>();
var marker = context.Registry.GetService<IMarkerService>();
Expand Down Expand Up @@ -316,10 +323,10 @@ uint[] DeriveKey() {
for (int i = 0; i < 0x10; i++) {
dst[i] = v;
src[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
z = (x >> rotShifts[0]) | (x << (32 - rotShifts[0]));
x = (c >> rotShifts[1]) | (c << (32 - rotShifts[1]));
c = (v >> rotShifts[2]) | (v << (32 - rotShifts[2]));
v = (z >> rotShifts[3]) | (z << (32 - rotShifts[3]));
}
return deriver.DeriveKey(dst, src);
}
Expand Down
19 changes: 13 additions & 6 deletions Confuser.Protections/AntiTamper/NormalMode.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ internal class NormalMode : IModeHandler {
List<MethodDef> methods;
uint name1, name2;
RandomGenerator random;
int[] rotShifts;
uint v;
uint x;
uint z;
Expand All @@ -35,6 +36,9 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
feedback = random.NextUInt32();
name1 = random.NextUInt32() & 0x7f7f7f7f;
name2 = random.NextUInt32() & 0x7f7f7f7f;
// Randomize the key-derivation rotation amounts (were the fixed 5/3/7/11); the same
// amounts are injected into the runtime (Mutation.KeyI6..KeyI9) below.
rotShifts = RotationKey.PickShifts(random);

switch (parameters.GetParameter(context, context.CurrentModule, "key", Mode.Normal)) {
case Mode.Normal:
Expand Down Expand Up @@ -79,8 +83,11 @@ public void HandleInject(AntiTamperProtection parent, ConfuserContext context, P
initMethod.Body.Instructions.Add(instr);

MutationHelper.InjectKeys(initMethod,
new[] { 0, 1, 2, 3, 4, 5 },
new[] { (int)(name1 * name2), (int)z, (int)x, (int)c, (int)v, (int)feedback });
new[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 },
new[] {
(int)(name1 * name2), (int)z, (int)x, (int)c, (int)v, (int)feedback,
rotShifts[0], rotShifts[1], rotShifts[2], rotShifts[3]
});

var name = context.Registry.GetService<INameService>();
var marker = context.Registry.GetService<IMarkerService>();
Expand Down Expand Up @@ -250,10 +257,10 @@ uint[] DeriveKey() {
for (int i = 0; i < 0x10; i++) {
dst[i] = v;
src[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
z = (x >> rotShifts[0]) | (x << (32 - rotShifts[0]));
x = (c >> rotShifts[1]) | (c << (32 - rotShifts[1]));
c = (v >> rotShifts[2]) | (v << (32 - rotShifts[2]));
v = (z >> rotShifts[3]) | (z << (32 - rotShifts[3]));
}
return deriver.DeriveKey(dst, src);
}
Expand Down
26 changes: 26 additions & 0 deletions Confuser.Protections/AntiTamper/RotationKey.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
using System;
using Confuser.Core.Services;

namespace Confuser.Protections.AntiTamper {
/// <summary>
/// Picks the rotation amounts for the anti-tamper key-derivation mixer, replacing the fixed
/// 5 / 3 / 7 / 11 that de4dot/AV pattern-match. A bit rotation is a bijection for any amount
/// in 1..31, so -- unlike the xorshift/prime constants -- no curated set is required; the
/// four amounts are simply chosen distinct per module to keep the 16-word key expansion
/// spread. The same amounts are injected into the runtime (Mutation.KeyI6..KeyI9), which
/// forms each rotation as (r >> amount) | (r << (32 - amount)).
/// </summary>
internal static class RotationKey {
internal static int[] PickShifts(RandomGenerator random) {
var shifts = new int[4];
for (int i = 0; i < shifts.Length; i++) {
int s;
do {
s = random.NextInt32(1, 32);
} while (Array.IndexOf(shifts, s, 0, i) != -1);
shifts[i] = s;
}
return shifts;
}
}
}
8 changes: 4 additions & 4 deletions Confuser.Runtime/AntiTamper.Anti.cs
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Expand Up @@ -61,14 +61,14 @@ static unsafe void Initialize() {
for (int i = 0; i < 0x10; i++) {
y[i] = v;
d[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
z = (x >> Mutation.KeyI6) | (x << (32 - Mutation.KeyI6));
x = (c >> Mutation.KeyI7) | (c << (32 - Mutation.KeyI7));

CheckRemoteDebuggerPresent(Process.GetCurrentProcess().Handle, ref isDebuggerPresent);
if (isDebuggerPresent) Environment.FailFast(null);

c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
c = (v >> Mutation.KeyI8) | (v << (32 - Mutation.KeyI8));
v = (z >> Mutation.KeyI9) | (z << (32 - Mutation.KeyI9));
}
Mutation.Crypt(y, d);

Expand Down
8 changes: 4 additions & 4 deletions Confuser.Runtime/AntiTamper.JIT.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,10 +52,10 @@ public static void Initialize() {
for (int i = 0; i < 0x10; i++) {
y[i] = v;
d[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
z = (x >> Mutation.KeyI6) | (x << (32 - Mutation.KeyI6));
x = (c >> Mutation.KeyI7) | (c << (32 - Mutation.KeyI7));
c = (v >> Mutation.KeyI8) | (v << (32 - Mutation.KeyI8));
v = (z >> Mutation.KeyI9) | (z << (32 - Mutation.KeyI9));
}
Mutation.Crypt(y, d);

Expand Down
8 changes: 4 additions & 4 deletions Confuser.Runtime/AntiTamper.Normal.cs
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Expand Up @@ -45,10 +45,10 @@ static unsafe void Initialize() {
for (int i = 0; i < 0x10; i++) {
y[i] = v;
d[i] = x;
z = (x >> 5) | (x << 27);
x = (c >> 3) | (c << 29);
c = (v >> 7) | (v << 25);
v = (z >> 11) | (z << 21);
z = (x >> Mutation.KeyI6) | (x << (32 - Mutation.KeyI6));
x = (c >> Mutation.KeyI7) | (c << (32 - Mutation.KeyI7));
c = (v >> Mutation.KeyI8) | (v << (32 - Mutation.KeyI8));
v = (z >> Mutation.KeyI9) | (z << (32 - Mutation.KeyI9));
}
Mutation.Crypt(y, d);

Expand Down