migrate: Handle HD chains that have identical seeds but different IDs #35437

1. 
   achow101 commented at 9:43 PM on June 1, 2026: member

   The seed ID is calculated from a pubkey produced by treating the seed as a private key. This calculation includes a pubkey compression parameter, even thought that compression is completely irrelevant for the usage of the seed as a BIP 32 seed. Thus migration should detect if a seed has been used multiple times by checking if the computed master key was already processed.

   The spkm_migration fuzzer needs to have it's added descriptors accounting updated for this fix.

   It should not be possible for users to actually run into this problem as all HD chains use seeds with the pubkey compression option set.

   Fixes #35434

2. 
   DrahtBot commented at 9:43 PM on June 1, 2026: contributor

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35437.

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3. DrahtBot added the label CI failed on Jun 1, 2026
4. 
   DrahtBot commented at 11:10 PM on June 1, 2026: contributor

   <!--85328a0da195eb286784d51f73fa0af9-->

   🚧 At least one of the CI tasks failed. _{Task macOS native, fuzz: https://github.com/bitcoin/bitcoin/actions/runs/26783841124/job/78954750669} _{LLM reason (✨ experimental): Fuzz test failure: spkm_migration crashed on an assertion in scriptpubkeyman.cpp (MigrateToDescriptor, line 636), exiting with code 1.}

   <details><summary>Hints</summary>

   Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

   • Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

   • A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

   • An intermittent issue.

   Leave a comment here, if you need help tracking down a confusing failure.

   </details>

5. maflcko added this to the milestone 32.0 on Jun 2, 2026
6. achow101 force-pushed on Jun 2, 2026
7. migrate: Handle HD chains that have identical seeds but different IDs

   The seed ID is calculated from a pubkey produced by treating the seed as
   a private key. This calculation includes a pubkey compression parameter,
   even thought that compression is completely irrelevant for the usage of
   the seed as a BIP 32 seed. Thus migration should detect if a seed has
   been used multiple times by checking if the computed master key was
   already processed.
   
   The spkm_migration fuzzer needs to have it's added descriptors
   accounting to be updated for this fix.

   de92208c2b
8. achow101 force-pushed on Jun 3, 2026
9. DrahtBot removed the label CI failed on Jun 3, 2026
10. 
    kevkevinpal commented at 8:38 PM on June 3, 2026: contributor

    I was able to recreate the fuzz failure on master and also test that it passed on de92208c2b508b40fa690624d026c775ed876606. Here are my steps in reproducing the error and checking this fix.

    Checking that it fails on master

    # Add input
    echo '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'   | base64 -d > spkmmigrate_input
    
    # Checkout master
    git checkout master
    cmake --preset=libfuzzer && cmake --build build_fuzz --parallel
    
    # Run failing input
    FUZZ=spkm_migration build_fuzz/bin/fuzz -runs=1 spkmmigrate_input
    

    Checking that it passes on de92208c2b508b40fa690624d026c775ed876606

    # Checkout this PR
    git fetch origin pull/35437/head:PR35437
    git checkout PR35437
    
    # Build this PR
    cmake --preset=libfuzzer && cmake --build build_fuzz --parallel
    
    # Run failing input and observe that it works
    FUZZ=spkm_migration build_fuzz/bin/fuzz -runs=1 spkmmigrate_input
    

Milestone
32.0