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fix(battle-node): NodeCrypto.GenerateKey masks rand source with & 0xF

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gamer147
2026-06-01 11:35:53 -04:00
parent e4fbb155e4
commit 34c4ca0237
2 changed files with 20 additions and 4 deletions
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9
SVSim.BattleNode/Wire/NodeCrypto.cs
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@@ -12,9 +12,10 @@ public static class NodeCrypto
{
/// <summary>
/// Generate a fresh 32-char key for server-initiated encryption.
/// Calls <paramref name="randHexDigit"/> 32 times expecting a value in [0,15],
/// formats each as a single hex char, then base64-encodes the resulting 32-char ASCII
/// string and truncates to 32 chars.
/// Calls <paramref name="randHexDigit"/> 32 times; the result is masked with
/// <c>&amp; 0xF</c> so a misbehaving caller that returns a larger int still produces
/// exactly one hex digit per iteration (the internal contract is "32 hex chars").
/// The 32-char ASCII string is then base64-encoded and truncated to 32 chars.
/// </summary>
/// <remarks>
/// Differs from the client's <c>Cryptographer.generateKeyString</c> in input shape:
@@ -29,7 +30,7 @@ public static class NodeCrypto
var sb = new StringBuilder(32);
for (var i = 0; i < 32; i++)
{
sb.Append(randHexDigit().ToString("x"));
sb.Append((randHexDigit() & 0xF).ToString("x"));
}
var ascii = Encoding.ASCII.GetBytes(sb.ToString());
return Convert.ToBase64String(ascii).Substring(0, 32);