Implement Spark-compatible `try_aes_decrypt`

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
48/100
Tipo de issue
Nueva funcionalidad
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
rust, spark
Área
backend

Línea de trabajo

Start by reading the existing try_* functions under crates/spark/src/function/misc/ (try_to_binary, try_url_decode, try_parse_url) to see how per-row errors are turned into nulls, and confirm the state of the aes_decrypt kernel this must build on, since it is a prerequisite. Then implement the wrapper, add crates/sqllogictest/test_files/misc/try_aes_decrypt.slt with both success and error-to-NULL cases, and annotate with #[user_doc]. Done when every listed aes_decrypt error yields NULL, good rows still decrypt, and the sqllogictest file passes.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

enhancement

Part of #272 and apache/datafusion-comet#7300.

What the function does

try_aes_decrypt(expr, key[, mode[, padding[, aad]]]) behaves like aes_decrypt but returns NULL instead of
raising an error. Arguments, defaults (mode = 'GCM', padding = 'DEFAULT', aad = ''), implicit casts and the
supported (mode, padding) pairs are the same as aes_decrypt: ECB/CBC with PKCS/DEFAULT, GCM with
NONE/DEFAULT; 16/24/32-byte keys; CBC input iv(16) || ct, GCM input iv(12) || ct || tag(16).
Returns nullable BINARY. Since 3.5.0.

Spark implements it as TryEval(AesDecrypt(...)) (RuntimeReplaceable with InheritAnalysisRules). TryEval
catches every Exception thrown while evaluating the wrapped expression, so all runtime errors become NULL.
Analysis-time errors (wrong argument count or types) are still raised.

Examples
SELECT cast(try_aes_decrypt(unhex('6E7CA17BBB468D3084B5744BCA729FB7B2B7BCB8E4472847D02670489D95FA97DBBA7D3210'), '0000111122223333', 'GCM') AS STRING);
-- Spark SQL
SELECT try_aes_decrypt(unhex('----------468D3084B5744BCA729FB7B2B7BCB8E4472847D02670489D95FA97DBBA7D3210'), '0000111122223333', 'GCM');
-- NULL
SELECT cast(try_aes_decrypt(unbase64('AAAAAAAAAAAAAAAAQiYi+sTLm7KD9UcZ2nlRdYDe/PX4'), 'abcdefghijklmnop12345678ABCDEFGH', 'GCM', 'DEFAULT', 'This is an AAD mixed into the input') AS STRING);
-- Spark
SELECT cast(try_aes_decrypt(unbase64('AAAAAAAAAAAAAAAAAAAAAPSd4mWyMZ5mhvjiAPQJnfg='), 'abcdefghijklmnop12345678ABCDEFGH', 'CBC') AS STRING);
-- Spark
SELECT cast(try_aes_decrypt(unhex('83F16B2AA704794132802D248E6BFD4E380078182D1544813898AC97E709B28A94'), '0000111122223333') AS STRING);
-- Spark

The first two come from the ExpressionDescription. In the second, unhex of invalid hex already returns NULL, so
it does not exercise the error path. The others are MiscFunctionsSuite inputs whose aes_decrypt results are in
the aes_decrypt examples. The NULL cases below follow from TryEval plus the aes_decrypt error tests (code
reading):

SELECT try_aes_decrypt(unbase64('4Hv0UKCx6nfUeAoPZo1z+w=='), '12345678901234567');            -- NULL (AES_KEY_LENGTH)
SELECT try_aes_decrypt(unbase64('4Hv0UKCx6nfUeAoPZo1z+w=='), binary('1234567812345678'), 'ECB'); -- NULL (bad padding, wrong key)
SELECT try_aes_decrypt(unbase64('4Hv0UKCx6nfUeAoPZo1z+w=='), 'abcdefghijklmnop', 'GCM', 'PKCS'); -- NULL (AES_MODE)
SELECT try_aes_decrypt(unbase64('AAAAAAAAAAAAAAAAQiYi+sTLm7KD9UcZ2nlRdYDe/PX4'),
  'abcdefghijklmnop12345678ABCDEFGH', 'GCM', 'DEFAULT', 'The ciphertext is valid, but the AAD is wrong'); -- NULL (tag mismatch)
Edge cases to test
  • Every aes_decrypt error becomes NULL: INVALID_PARAMETER_VALUE.AES_KEY_LENGTH, UNSUPPORTED_FEATURE.AES_MODE,
    UNSUPPORTED_FEATURE.AES_MODE_AAD (AAD with CBC), INVALID_PARAMETER_VALUE.AES_CRYPTO_ERROR (wrong key, corrupted
    or truncated ciphertext, empty GCM input, wrong AAD).
  • Successful decrypts match aes_decrypt byte for byte, for all modes and key sizes.
  • NULL in any argument gives NULL.
  • TryEval wraps the argument expressions too, so a runtime error inside an argument (for example an ANSI cast
    failure in a CAST with ANSI on, or raise_error(...) passed as key) is also swallowed. In
    DataFusion, arguments are evaluated before the UDF runs, so this cannot be reproduced inside the UDF. Document the
    difference or handle it at plan-conversion time.
  • AAD with ECB is ignored, not an error (same as aes_decrypt).
  • Literal and column for each argument, with a mix of good and bad rows in one batch (bad rows NULL, good rows
    decrypted).
  • Deterministic.
Differences across Spark versions
  • Not available in 3.4. Added in 3.5.0 with CBC and AAD support already present.
  • 4.0: collated mode / padding accepted. No behavior change through 4.2.
Implementation notes
  • Spark: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/misc.scala (TryAesDecrypt),
    expressions/TryEval.scala, and
    sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionImplUtils.java (aesInternal).
  • DataFusion core has no AES functions.
  • Implement on top of the aes_decrypt kernel (see the aes_decrypt issue). Per-row errors become nulls instead
    of failing the batch. Existing try_* functions in datafusion-spark (try_to_binary, try_url_decode,
    try_parse_url) show the pattern.
  • Module: crates/spark/src/function/misc/.
  • Tests: add crates/sqllogictest/test_files/misc/try_aes_decrypt.slt; document with #[user_doc].

This issue was generated by an LLM (Claude) from the Apache Spark source code and tests. Examples come from Spark's ExpressionDescription examples, test suites and .sql.out golden files, but please verify them against Spark before relying on them.

Lenguaje dominante
Rust
Estrellas
7
Forks
15
Merge medio
16 h 43 min
PR fusionados (30 d)
26

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