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Another ckparity flaw

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Found another ckparity flaw! Only detected now due to the reworked tag
encoding, but it's just luck this wasn't detected earlier.

Consider the following bit flip:

  03 04 80 04 80 04 6b ...  data w512 512
  43 04 80 04 80 04 6b ...  altble 0x304 w512 -512
  ^
  flip

Not only are leb128s problem for ckparity, but even the difference in
alt vs normal tag encoding presents a vulnerability.

So limiting the ckparity tests further, to just 47 of the first 48 bits.
This commit is contained in:
Christopher Haster
2025-04-27 14:33:25 -05:00
parent d308ec8322
commit 879a55add9
1 changed files with 10 additions and 0 deletions
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tests/test_ck.toml
+10
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@@ -2110,6 +2110,11 @@ code = '''
// to our revision count + first tag // to our revision count + first tag
i < ((BADBIT == -1) ? 8*6 : 1); i < ((BADBIT == -1) ? 8*6 : 1);
i++) { i++) {
// we can't even detect bit flips that change the
// alt vs tag encoding
if (BADBIT == -1 && i == 8*4+6) {
continue;
}
lfs_size_t badbit = (BADBIT == -1) ? i : BADBIT; lfs_size_t badbit = (BADBIT == -1) ? i : BADBIT;
// reset the bd prng every run for reproducibility // reset the bd prng every run for reproducibility
@@ -2262,6 +2267,11 @@ code = '''
// to our revision count + first tag // to our revision count + first tag
i < ((BADBIT == -1) ? 8*6 : 1); i < ((BADBIT == -1) ? 8*6 : 1);
i++) { i++) {
// we can't even detect bit flips that change the
// alt vs tag encoding
if (BADBIT == -1 && i == 8*4+6) {
continue;
}
lfs_size_t badbit = (BADBIT == -1) ? i : BADBIT; lfs_size_t badbit = (BADBIT == -1) ? i : BADBIT;
// reset the bd prng every run for reproducibility // reset the bd prng every run for reproducibility