GH-48858: [C++][Parquet] Avoid re-serializing footer for signature verification

[pitrou]

Rationale for this change

When reading an encrypted Parquet file with a plaintext footer, the Parquet reader is able to verify footer integrity by comparing the signature in the file with the one computed by encrypting the footer.

However, the way it does this is to first re-serializes the deserialized footer using Thrift. This has several issues:

1. it's inefficient
2. it's not obvious that it will always produce the same Thrift encoding as the original, leading to spurious signature verification failures
3. if the original footer deserializes to invalid enum values, attempting to serialize it again will lead to undefined behavior

Reason 3 is what allowed this to be uncovered by OSS-Fuzz (see https://oss-fuzz.com/testcase-detail/4740205688193024).

This PR switches to reusing the original serialized metadata.

Are these changes tested?

Yes, by existing tests and new fuzz regression file.

Are there any user-facing changes?

No.

• GitHub Issue: [C++][Parquet] Plaintext footer signature verification re-serializes footer #48858

[pitrou]

I opted to deprecate this but we might also remove it, as it seems this API is meant for internal use? @adamreeve @EnricoMi

[pitrou]

I implemented this as a method of FileMetaData but the only member it uses is the FileDecryptor, so perhaps this should be moved elsewhere (or made static?).

[pitrou]

Hmm, it looks like we need to wait for #48819 for the R failures.

[rok]

If I remember correctly in rust we verify directly on decrypted buffer (skipping reserialization).

[pitrou]

If I remember correctly in rust we verify directly on decrypted buffer (skipping reserialization).

I'm not surprised that Rust is saner than C++ :-)

[pitrou]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: e853dee

Submitted crossbow builds: ursacomputing/crossbow @ actions-f90353001e

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-debian-experimental-cpp-gcc-15
test-fedora-42-cpp
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-20
test-ubuntu-22.04-cpp-bundled
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer