fix: EC-5..EC-8 error-message inversion, RSA-only wrap guard, 32-byte key guard, fingerprint_data robustness

EC-5: _load_private_key branches on whether a password was given so the normalized
ValueError matches the actual cryptography TypeError case (was always claiming
"encrypted but no password" even when a password was given for an unencrypted key).
EC-6: encrypt_aes_key_with_rsa/decrypt_aes_key_with_rsa now raise a clear ValueError
via _require_rsa for a non-RSA key (e.g. Ed25519/EC), instead of crashing raw with
AttributeError at wrap/unwrap — this lib is RSA-envelope only.
EC-7: initialize() requires exactly 32 bytes (isinstance bytes, len==32), rejecting a
16/24-byte key (silent AES-128/192 downgrade) or a str instead of failing late and
opaquely at first encrypt.
EC-8: fingerprint_data gains a default= handler (datetime/date/time, bytes/bytearray,
and a type-tagged repr fallback) plus a key-type-tagging pre-pass so datetime/bytes/
ObjectId-like values no longer TypeError and int-vs-str dict keys no longer collide
to the same fingerprint. Never logs the data being fingerprinted.

Also compresses the essay-length docstrings (module + several methods) to cut
narration while keeping the load-bearing footgun notes (RSA-only, AES-256 key length,
never-log-key-material) intact — zero behavior change, re-verified after.

Signed-off-by: disqualifier <dev@disqualifier.me>

.gitignore

@@ -1,5 +1,5 @@
 # claude
-CLAUDE.md
+.claude/
 
 # python
 __pycache__/

README.md

@@ -11,17 +11,19 @@ and storage-agnostic.
 `requirements.txt`:
 
 ```
-envelope_crypto @ git+ssh://git@git.rethinkstudios.io/rethink-public/envelope_crypto.git@v0.1.0
+envelope_crypto @ git+ssh://git@git.rethinkstudios.io/rethink-public/envelope_crypto.git@v0.1.6
 ```
 
 Direct:
 
 ```bash
-pip install "envelope_crypto @ git+ssh://git@git.rethinkstudios.io/rethink-public/envelope_crypto.git@v0.1.0"
+pip install "envelope_crypto @ git+ssh://git@git.rethinkstudios.io/rethink-public/envelope_crypto.git@v0.1.6"
 ```
 
 Requires `cryptography` (pulled transitively).
 
+Drop the `@v0.1.6` suffix from the line above to install the latest unpinned.
+
 ## First-time setup
 
 Run once, ever, to create the data key and authorize the first system. You need an
@@ -64,6 +66,13 @@ bot.crypto = crypto
 The `keys` schema (`_id` = fingerprint, `key` = wrapped) is the **caller's** choice;
 this lib only produces `(fingerprint, wrapped_key)`.
 
+`decrypt_aes_key_with_rsa` (like `encrypt_aes_key_with_rsa` and
+`get_rsa_key_fingerprint`) takes `is_file` (default `True`). Pass `is_file=False` to
+hand it PEM/OpenSSH key data directly — e.g. a private key sourced from a vault —
+instead of a file path. `self_test` threads the same `is_file` through to both the
+public and private key it loads, so `self_test(pub_pem, priv_pem, is_file=False)`
+round-trips two in-memory PEM strings rather than treating them as paths.
+
 ## Encrypt / decrypt
 
 ```python
@@ -71,9 +80,16 @@ enc = crypto.encrypt_data({"ssn": "..."})      # -> {"secure": True, "iv": ...,
 plain = crypto.decrypt_data(enc)               # -> {"ssn": "..."}
 ```
 
+Dict keys must be `str`. `encrypt_data` raises `TypeError` on a non-str key (e.g. an
+int-keyed dict of Discord snowflakes) instead of silently stringifying it — the
+underlying JSON encoding has no other key type, so a coerced key would come back out
+of `decrypt_data` as a `str` and no longer match the original lookup key.
+
 For whole records: `decrypt_record(crypto, doc)` decrypts every `{secure, iv, data}`
 field (nested up to `traversal_level`, default 2); `is_encrypted_record(doc)` reports
-whether any encrypted field exists.
+whether any encrypted field exists. Both also detect `doc` itself being a bare
+`{secure, iv, data}` blob (the file-storage pattern below, where the blob IS the whole
+document) — not just blobs nested under a key.
 
 ```python
 from envelope_crypto import is_encrypted_record, decrypt_record
@@ -82,6 +98,11 @@ if is_encrypted_record(doc):
     doc = decrypt_record(crypto, doc)
 ```
 
+`is_encrypted_record` falls back to an unbounded-depth scan once `traversal_level` is
+exhausted, so it reliably reports `True` for a blob left behind by a shallower
+`decrypt_record`/`reencrypt` call — safe to use as a leftover-detecting audit after
+rotation, regardless of how deep the blob is nested.
+
 Naming aliases (same objects): `EnvelopeCrypto` = `DocumentCrypto` = `RecordCrypto`
 = `PCICrypto` (deprecated legacy alias). `decrypt_record` = `decrypt_document` =
 `decrypt_dict`; `is_encrypted_record` = `is_encrypted_document` = `is_encrypted_dict`.
@@ -127,7 +148,14 @@ for fingerprint, wrapped_key in wrapped.items():
 
 `reencrypt(source_crypto, record)` is a method on the **destination** (new-key)
 instance: it decrypts each encrypted field with `source_crypto` (old key) and
-re-encrypts with itself. Only `{secure, ...}` fields are touched.
+re-encrypts with itself. Only `{secure, ...}` fields are touched — including `record`
+itself if it IS a `{secure, iv, data}` blob (the file-storage pattern).
+
+Rotation must fail loud: a per-field decrypt failure raises, and so does a blob nested
+deeper than `traversal_level` — silently leaving it under the old key would strand it
+once the old key's wrapped-key record is deleted below. If you nest blobs deeper than
+the default `traversal_level=2`, pass a higher `traversal_level` or flatten the record
+first.
 
 ## Storage patterns
 
@@ -149,7 +177,19 @@ The lib never touches a database; only the caller's storage layer differs.
 - The scheme is envelope/hybrid encryption (AES-256-GCM data key wrapped by RSA-OAEP).
   Using it does not by itself confer PCI-DSS or any other compliance — that is a
   whole-system property.
+- `initialize(master_key)` requires exactly 32 bytes (`bytes`, `len == 32`) — a
+  16/24-byte key or a `str` raises `ValueError` instead of silently downgrading to
+  AES-128/192 or failing late at first encrypt.
+- Wrap/unwrap (`encrypt_aes_key_with_rsa`, `decrypt_aes_key_with_rsa`,
+  `authorize_system`, `bootstrap`, `rotate_master_key`) is **RSA-only**. A non-RSA
+  key (e.g. Ed25519/EC) loads and fingerprints fine but raises a clear `ValueError`
+  at wrap/unwrap rather than a raw `AttributeError`.
+- `fingerprint_data` serializes non-JSON-native values (datetime/date/time,
+  bytes/bytearray, ObjectId-like objects) via a stable `default=` handler instead of
+  raising `TypeError`, and type-tags dict keys internally so `{1: "a"}` and
+  `{"1": "a"}` no longer collide to the same fingerprint. Never logs the data it
+  fingerprints.
 
 ## Versioning
 
-Tagged `vX.Y.Z`. Pin the tag in `requirements.txt`.
+Releases are tagged `vX.Y.Z`. The install line above pins a release; drop the `@vX.Y.Z` suffix to install the latest unpinned. Pin deliberately for reproducible installs.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "envelope_crypto"
-version = "0.1.0"
+version = "0.1.6"
 description = "Envelope encryption (RSA-OAEP wrapped AES-256-GCM) for dict records — config-free, storage-agnostic, installable."
 requires-python = ">=3.10"
 dependencies = [

src/envelope_crypto/envelope_crypto.py

@@ -1,16 +1,18 @@
 """
 envelope encryption for dict records
 
-hybrid encryption: a random AES-256-GCM data key (DEK) encrypts the data, and
+hybrid encryption: a random AES-256-GCM data key (DEK) encrypts the data, wrapped
-that key is wrapped (RSA-OAEP) per authorized system's public key (KEK) for
+(RSA-OAEP) per authorized system's public key (KEK) for distribution. the wrapped
-distribution. the wrapped key is stored by the caller, keyed by fingerprint;
+key is stored by the caller, keyed by fingerprint; each system unwraps its own copy
-each system unwraps its own copy with its private key. this is the same
+with its private key. same pattern KMS-style systems use. RSA-envelope only — a
-envelope-encryption pattern used by KMS-style systems.
+non-RSA key (e.g. Ed25519/EC) loads and fingerprints fine but raises ValueError at
+wrap/unwrap. never logs key material (DEK, PEM, wrapped key) — only fingerprints
+and counts.
 
     from envelope_crypto import EnvelopeCrypto
 
     crypto = EnvelopeCrypto()
-    crypto.initialize(master_key)                      # 32-byte AES DEK
+    crypto.initialize(master_key)                      # exactly 32 bytes (AES-256)
     enc = crypto.encrypt_data({"ssn": "..."})          # -> {secure, iv, data}
     plain = crypto.decrypt_data(enc)                   # -> original
 
@@ -32,9 +34,8 @@ authorize another system (this instance must already hold the DEK):
     fp, wrapped = crypto.authorize_system(other_pub_path)
     caller_store({"_id": fp, "key": wrapped})
 
-deauthorize: caller deletes that fingerprint's record. note this stops future
+deauthorize: caller deletes that fingerprint's record. stops future unwraps but
-unwraps but does not revoke a DEK already in a running system's memory — rotate
+does not revoke a DEK already in a running system's memory — rotate if compromised.
-if compromised.
 
 rotate (new DEK + re-encrypt): generate a new DEK, wrap for the still-authorized
 set, then re-encrypt existing records old -> new:
@@ -44,30 +45,141 @@ set, then re-encrypt existing records old -> new:
     for record in caller_iter():
         caller_update(new_crypto.reencrypt(crypto, record))
 
+reencrypt/is_encrypted_record/decrypt_record all detect a bare {secure, iv, data}
+blob used AS the whole record (file-storage pattern), not just blobs nested under a
+key. reencrypt fails loud (raises) rather than silently leaving a field under the
+old key — including a blob nested deeper than `traversal_level`; is_encrypted_record
+falls back to an unbounded-depth scan past traversal_level to reliably catch
+leftovers as a post-rotation audit.
+
 config-free: the host supplies the DEK and RSA key paths; this lib never imports
 config, configures logging, or touches a database. storage-agnostic — the
 encrypted blob is a plain dict; store it in mongo, a sql json column, or a file.
 
+encrypt_data/decrypt_data round-trip a dict only when every key is a str — json
+(the wire format) has no other key type, so encrypt_data raises TypeError on a
+non-str key (e.g. an int-keyed dict of discord snowflakes) rather than silently
+stringifying it and losing the original key on decrypt.
+
 naming: EnvelopeCrypto is canonical. PCICrypto / DocumentCrypto / RecordCrypto are
-aliases (PCICrypto is a deprecated legacy alias). the document/record/dict
+aliases (PCICrypto is a deprecated legacy alias). the document/record/dict function
-function variants are the same functions — use whichever fits your storage.
+variants are the same functions — use whichever fits your storage.
 """
 
 import os
+import copy
 import json
 import base64
 import hashlib
 import logging
 from typing import Any, Dict, List, Optional, Tuple, Union
 
+from cryptography.exceptions import UnsupportedAlgorithm
 from cryptography.hazmat.primitives import hashes, serialization
-from cryptography.hazmat.primitives.asymmetric import padding
+from cryptography.hazmat.primitives.asymmetric import padding, rsa
 from cryptography.hazmat.primitives.ciphers.aead import AESGCM
 from cryptography.hazmat.primitives.serialization import load_ssh_public_key
 
 _log = logging.getLogger(__name__)
 
 
+def _password_mismatch_message(pw: Optional[bytes]) -> str:
+    """clear ValueError text for a TypeError raised by a password/encryption mismatch
+
+    cryptography raises TypeError for both directions: encrypted key + no password,
+    and unencrypted key + a password given. branch on which the caller supplied so
+    the message matches the actual case instead of always claiming "encrypted".
+    """
+    if pw is not None:
+        return "password was given but private key is not encrypted"
+    return "private key is encrypted but no password was provided"
+
+
+def _load_private_key(key_data: bytes, pw: Optional[bytes]):
+    """load a PEM or OpenSSH private key, normalizing the password/encryption mismatch error
+
+    cryptography raises TypeError for a password/encryption mismatch (PEM raises it on
+    the first call; OpenSSH raises it inside the openssh fallback), normalized here to a
+    clear ValueError so callers see one error type with a message matching the actual case.
+    """
+    try:
+        return serialization.load_pem_private_key(key_data, password=pw)
+    except ValueError as error:
+        if b"BEGIN OPENSSH PRIVATE KEY" in key_data:
+            try:
+                return serialization.load_ssh_private_key(key_data, password=pw)
+            except TypeError as ssh_error:
+                raise ValueError(_password_mismatch_message(pw)) from ssh_error
+        if pw is not None:
+            # a password was given but the PEM load still failed — most likely a wrong
+            # password; give a clearer message than cryptography's raw "Bad decrypt"
+            raise ValueError("could not load private key (wrong password or malformed key)") from error
+        raise error
+    except TypeError as error:
+        raise ValueError(_password_mismatch_message(pw)) from error
+
+
+def _fingerprint_of(public_key) -> str:
+    """base64 SHA-256 fingerprint of an already-loaded public key
+
+    factored so callers that already hold a loaded key (e.g. encrypt_aes_key_with_rsa)
+    don't re-open and re-parse the key file just to fingerprint it.
+    """
+    key_bytes = public_key.public_bytes(
+        encoding=serialization.Encoding.DER,
+        format=serialization.PublicFormat.SubjectPublicKeyInfo,
+    )
+    digest = hashes.Hash(hashes.SHA256())
+    digest.update(key_bytes)
+    return base64.b64encode(digest.finalize()).decode()
+
+
+def _is_blob(value: Any) -> bool:
+    """return whether value has the {secure, iv, data} encrypted-blob shape"""
+    return isinstance(value, dict) and value.get("secure") is True and "iv" in value and "data" in value
+
+
+def _has_encrypted_field(record: Any) -> bool:
+    """unbounded-depth scan: does record (or anything nested under it) contain a blob
+
+    used to detect a blob left behind by a depth-limited traversal — no traversal_level
+    cutoff here, since the whole point is to catch what a bounded pass would miss.
+    """
+    if not isinstance(record, dict):
+        return False
+    if _is_blob(record):
+        return True
+    return any(_has_encrypted_field(value) for value in record.values())
+
+
+def _require_rsa(key) -> None:
+    """raise ValueError unless key is an RSA public or private key
+
+    this lib is RSA-envelope only: get_rsa_key_fingerprint accepts any key type
+    (fingerprinting is algorithm-agnostic), but wrap/unwrap calls RSA-OAEP methods
+    that don't exist on e.g. Ed25519/EC keys and would otherwise crash raw with an
+    AttributeError far from a clear cause.
+    """
+    if not isinstance(key, (rsa.RSAPublicKey, rsa.RSAPrivateKey)):
+        raise ValueError(f"RSA key required for envelope wrap/unwrap, got {type(key).__name__}")
+
+
+def _load_public_key(key_data: bytes):
+    """load a PEM or OpenSSH public key, normalizing non-key input to ValueError
+
+    load_ssh_public_key raises UnsupportedAlgorithm (not ValueError) on non-SSH/garbage
+    input; normalize it so a bad public key always surfaces as a clear ValueError,
+    consistent with the private-key path.
+    """
+    try:
+        return serialization.load_pem_public_key(key_data)
+    except ValueError:
+        try:
+            return load_ssh_public_key(key_data)
+        except (UnsupportedAlgorithm, ValueError) as error:
+            raise ValueError("not a valid PEM or OpenSSH public key") from error
+
+
 class EnvelopeCrypto:
     """hybrid RSA/AES-256-GCM envelope encryption for dict records
 
@@ -99,10 +211,11 @@ class EnvelopeCrypto:
     ) -> bool:
         """verify the full pipeline against a keypair; raises on any mismatch
 
-        round-trips sample data through this instance's DEK, then wraps the DEK
+        round-trips sample data through this instance's DEK, then wraps and unwraps
-        with the public key and unwraps with the private key, confirming they
+        the DEK with the given keypair, confirming they match. run after bootstrap
-        match. run after bootstrap (or anytime as a health check) to catch a bad
+        (or as a health check) to catch a bad keypair or wrong path before relying
-        keypair or wrong key path before relying on it. returns True on success.
+        on it. is_file threads through to both key loads (is_file=False treats both
+        as in-memory PEM/OpenSSH data, not paths). returns True on success.
         """
         if not self.master_key:
             raise ValueError("self_test: not initialized with a key")
@@ -113,7 +226,7 @@ class EnvelopeCrypto:
 
         _, wrapped = self.encrypt_aes_key_with_rsa(self.master_key, rsa_public_key, is_file=is_file)
         try:
-            recovered = self.decrypt_aes_key_with_rsa(wrapped, rsa_private_key, password=password)
+            recovered = self.decrypt_aes_key_with_rsa(wrapped, rsa_private_key, is_file=is_file, password=password)
         except Exception as error:
             raise RuntimeError(
                 "self_test: key unwrap failed (public/private keys do not pair, "
@@ -126,7 +239,15 @@ class EnvelopeCrypto:
         return True
 
     def initialize(self, master_key: bytes) -> None:
-        """arm the instance with the AES data key (DEK)"""
+        """arm the instance with the AES data key (DEK)
+
+        requires exactly 32 bytes (AES-256): a shorter key would silently downgrade
+        to AES-128/192 with no warning, and a non-bytes value would otherwise fail
+        late and opaquely at first encrypt/decrypt — both rejected here instead.
+        never logs the key material itself.
+        """
+        if not isinstance(master_key, bytes) or len(master_key) != 32:
+            raise ValueError("master_key must be exactly 32 bytes (AES-256)")
         self.master_key = master_key
         _log.info("crypto initialized with data key")
 
@@ -147,9 +268,17 @@ class EnvelopeCrypto:
         return key
 
     def get_rsa_key_fingerprint(
-        self, key_path_or_data: str, is_private: bool = False, is_file: bool = True
+        self, key_path_or_data: str, is_private: bool = False, is_file: bool = True,
+        password: Optional[str] = None,
     ) -> str:
-        """return a base64 SHA-256 fingerprint of an RSA key for identification"""
+        """return a base64 SHA-256 fingerprint of an RSA key for identification
+
+        for an encrypted private key (is_private=True), pass its `password`; an
+        unencrypted key ignores it. always fingerprints the public half, so a
+        private key and its public key match. PEM and OpenSSH accepted (mirrors
+        decrypt_aes_key_with_rsa). a password/encryption mismatch raises a clear
+        ValueError (cryptography's raw TypeError normalized here).
+        """
         if is_file:
             with open(key_path_or_data, "rb") as key_file:
                 key_data = key_file.read()
@@ -161,38 +290,32 @@ class EnvelopeCrypto:
             )
 
         if is_private:
-            private_key = serialization.load_pem_private_key(key_data, password=None)
+            pw = password.encode() if password else None
+            private_key = _load_private_key(key_data, pw)
             public_key = private_key.public_key()
         else:
-            try:
+            public_key = _load_public_key(key_data)
-                public_key = serialization.load_pem_public_key(key_data)
-            except ValueError:
-                public_key = load_ssh_public_key(key_data)
 
-        key_bytes = public_key.public_bytes(
+        fingerprint = _fingerprint_of(public_key)
-            encoding=serialization.Encoding.DER,
-            format=serialization.PublicFormat.SubjectPublicKeyInfo,
-        )
-        digest = hashes.Hash(hashes.SHA256())
-        digest.update(key_bytes)
-        fingerprint = base64.b64encode(digest.finalize()).decode()
         _log.info("generated %s key fingerprint", "private" if is_private else "public")
         return fingerprint
 
     def encrypt_aes_key_with_rsa(
         self, aes_key: bytes, rsa_key: str, is_file: bool = True
     ) -> Tuple[str, str]:
-        """wrap an AES key with an RSA public key; returns (fingerprint, wrapped_b64)"""
+        """wrap an AES key with an RSA public key; returns (fingerprint, wrapped_b64)
+
+        raises ValueError if rsa_key is not an RSA key (this lib is RSA-envelope only;
+        e.g. an Ed25519/EC key loads and fingerprints fine but cannot wrap).
+        """
         if is_file:
             with open(rsa_key, "rb") as key_file:
                 key_data = key_file.read()
         else:
             key_data = rsa_key.encode() if isinstance(rsa_key, str) else rsa_key
 
-        try:
+        public_key = _load_public_key(key_data)
-            public_key = serialization.load_pem_public_key(key_data)
+        _require_rsa(public_key)
-        except ValueError:
-            public_key = load_ssh_public_key(key_data)
 
         wrapped = public_key.encrypt(
             aes_key,
@@ -202,29 +325,31 @@ class EnvelopeCrypto:
                 label=None,
             ),
         )
-        fingerprint = self.get_rsa_key_fingerprint(rsa_key, is_private=False, is_file=is_file)
+        # fingerprint from the already-loaded public_key — no second open/parse of the file
+        fingerprint = _fingerprint_of(public_key)
         wrapped_b64 = base64.b64encode(wrapped).decode()
         _log.info("wrapped data key for fingerprint %s", fingerprint[:8])
         return fingerprint, wrapped_b64
 
     def decrypt_aes_key_with_rsa(
-        self, encrypted_key_base64: str, rsa_private_key_path: str,
+        self, encrypted_key_base64: str, rsa_private_key: str,
-        password: Optional[str] = None,
+        is_file: bool = True, password: Optional[str] = None,
     ) -> bytes:
-        """unwrap an AES key with an RSA private key"""
+        """unwrap an AES key with an RSA private key
-        with open(rsa_private_key_path, "rb") as key_file:
+
-            key_data = key_file.read()
+        is_file defaults to True (rsa_private_key is a path), matching
-        try:
+        encrypt_aes_key_with_rsa / get_rsa_key_fingerprint; pass is_file=False to
-            private_key = serialization.load_pem_private_key(
+        supply the PEM/OpenSSH key data directly (e.g. an in-memory or vault-sourced
-                key_data, password=password.encode() if password else None
+        key) instead of a file path.
-            )
+        """
-        except ValueError as error:
+        if is_file:
-            if b"BEGIN OPENSSH PRIVATE KEY" in key_data:
+            with open(rsa_private_key, "rb") as key_file:
-                private_key = serialization.load_ssh_private_key(
+                key_data = key_file.read()
-                    key_data, password=password.encode() if password else None
+        else:
-                )
+            key_data = rsa_private_key.encode() if isinstance(rsa_private_key, str) else rsa_private_key
-            else:
+        pw = password.encode() if password else None
-                raise error
+        private_key = _load_private_key(key_data, pw)
+        _require_rsa(private_key)
 
         wrapped = base64.b64decode(encrypted_key_base64)
         aes_key = private_key.decrypt(
@@ -267,9 +392,30 @@ class EnvelopeCrypto:
         return new_key, wrapped
 
     def encrypt_data(self, data: Union[Dict[str, Any], str]) -> Dict[str, str]:
-        """encrypt a dict or string under the data key with a unique IV"""
+        """encrypt a dict or string under the data key with a unique IV
+
+        dict keys must be str: json.dumps silently stringifies int/float/bool/None
+        keys (e.g. a snowflake-int-keyed dict), which would make decrypt_data return
+        a dict that no longer matches the original by key type or identity — a
+        non-str key is rejected here instead, so the failure is loud at encrypt
+        time rather than a silent lookup miss after decrypt.
+        """
         if not self.master_key:
             raise ValueError("not initialized with data key")
+        if not isinstance(data, (dict, str)):
+            # a non-dict/non-str would .encode()-fail with an opaque AttributeError below;
+            # reject it clearly (decrypt_data only round-trips dict or str anyway)
+            raise TypeError(f"encrypt_data expects a dict or str, got {type(data).__name__}")
+        if isinstance(data, dict):
+            non_str_keys = [key for key in data if not isinstance(key, str)]
+            if non_str_keys:
+                # json.dumps would silently stringify these (int/float/bool/None keys),
+                # corrupting the round-trip (decrypt_data would return a dict keyed by
+                # the stringified value) — fail loud instead of coercing
+                raise TypeError(
+                    "encrypt_data requires str dict keys, got non-str key(s): "
+                    f"{[type(key).__name__ for key in non_str_keys]}"
+                )
 
         data_str = json.dumps(data) if isinstance(data, dict) else data
         iv = os.urandom(12)
@@ -282,35 +428,73 @@ class EnvelopeCrypto:
         }
 
     def decrypt_data(self, encrypted_data: Dict[str, str]) -> Union[Dict[str, Any], str]:
-        """decrypt a {secure, iv, data} blob; returns the original dict or string"""
+        """decrypt a {secure, iv, data} blob; returns the original dict or string
+
+        encrypt_data only json-encodes dicts (a string is stored verbatim), so decrypt
+        treats a json-OBJECT plaintext as a dict and everything else as a raw string —
+        a json-shaped but non-object string ('123', 'true', '[1,2]') round-trips as a
+        STRING, not int/bool/list. one irreducible ambiguity: a string whose exact
+        value is a json object ('{"a":1}') decrypts to a dict, indistinguishable
+        without a type marker from a stored dict — don't store a bare json-object
+        string if you need it back as a string. dict keys round-trip faithfully
+        because encrypt_data requires str keys (json's only key type).
+        """
         if not self.master_key:
             raise ValueError("not initialized with data key")
+        if not isinstance(encrypted_data, dict) or "iv" not in encrypted_data or "data" not in encrypted_data:
+            # a structurally-malformed blob would raise a raw KeyError/TypeError; surface
+            # a clear ValueError instead, matching the documented {secure, iv, data} shape
+            raise ValueError("decrypt_data expects a {secure, iv, data} blob")
 
         iv = base64.b64decode(encrypted_data["iv"])
         ciphertext = base64.b64decode(encrypted_data["data"])
         aesgcm = AESGCM(self.master_key)
         plaintext = aesgcm.decrypt(iv, ciphertext, None).decode()
         try:
-            return json.loads(plaintext)
+            parsed = json.loads(plaintext)
         except json.JSONDecodeError:
             return plaintext
+        return parsed if isinstance(parsed, dict) else plaintext
 
     def reencrypt(self, source_crypto: "EnvelopeCrypto", record: dict, traversal_level: int = 2) -> dict:
         """re-encrypt a record's encrypted fields from source_crypto's key to this one's
 
-        self holds the destination (new) key; source_crypto holds the source (old)
+        self holds the destination (new) key; source_crypto holds the source (old) key.
-        key. only {secure, iv, data} fields are touched; plaintext fields are left
+        only {secure, iv, data} fields are touched; plaintext fields are left as-is.
-        as-is. returns a new dict; the input is not mutated. used during rotation.
+        returns a new dict; the input is not mutated. used during rotation. if `record`
+        itself is a bare blob (file-storage pattern) it is re-encrypted directly and
+        returned in place of `record`, not nested under a key.
+
+        fails loud, unlike decrypt_record: a per-field decrypt failure RAISES (silently
+        keeping a field under the old key would lose it once that key is retired), and
+        so does a blob nested DEEPER than `traversal_level` — raise a higher
+        traversal_level or flatten the record before rotation instead.
+
+        traversal recurses into nested DICTS only; a blob nested inside a LIST is not
+        re-encrypted and not covered by the depth-limit raise. this scheme keys blobs
+        by field name, not inside arrays, so this shouldn't arise in practice — but
+        flatten list-nested blobs to dict fields before rotation or they'll be
+        silently left under the old key.
         """
         if not self.master_key:
             raise ValueError("destination not initialized with data key")
 
-        result = record.copy()
+        if _is_blob(record):
+            return self.encrypt_data(source_crypto.decrypt_data(record))
+
+        result = copy.deepcopy(record)
         for key, value in record.items():
-            if isinstance(value, dict) and value.get("secure") is True and "iv" in value and "data" in value:
+            if _is_blob(value):
                 result[key] = self.encrypt_data(source_crypto.decrypt_data(value))
-            elif traversal_level > 0 and isinstance(value, dict):
+            elif isinstance(value, dict):
-                result[key] = self.reencrypt(source_crypto, value, traversal_level - 1)
+                if traversal_level > 0:
+                    result[key] = self.reencrypt(source_crypto, value, traversal_level - 1)
+                elif _has_encrypted_field(value):
+                    raise ValueError(
+                        f"reencrypt: field {key!r} contains an encrypted blob nested deeper "
+                        "than traversal_level; increase traversal_level or flatten the record "
+                        "before rotation — leaving it would strand the field under the old key"
+                    )
         return result
 
 
@@ -323,28 +507,41 @@ PCICrypto = EnvelopeCrypto  # deprecated legacy alias; remove after all systems
 def is_encrypted_record(record, traversal_level: int = 2) -> bool:
     """return whether a record has any encrypted ({secure, iv, data}) fields
 
+    checks `record` itself (the file-storage pattern stores the blob AS the whole
+    document) as well as fields up to `traversal_level` deep. beyond that bounded
+    pass, falls back to an unbounded-depth scan, so a blob left behind by a
+    shallower decrypt_record/reencrypt call is still reported — safe to use as a
+    leftover-detecting post-rotation audit; never returns False for a record that
+    still contains a blob, at any depth.
+
     aliases: is_encrypted_document, is_encrypted_dict — same function
     """
     if not isinstance(record, dict):
         return False
 
+    if _is_blob(record):
+        return True
+
     for value in record.values():
-        if isinstance(value, dict) and value.get("secure") is True:
+        if _is_blob(value):
-            if "iv" in value and "data" in value:
+            return True
-                return True
 
     if traversal_level > 0:
         for value in record.values():
             if isinstance(value, dict) and is_encrypted_record(value, traversal_level - 1):
                 return True
-    return False
+        return False
+
+    return any(_has_encrypted_field(value) for value in record.values())
 
 
-def decrypt_record(crypto: EnvelopeCrypto, record, traversal_level: int = 2) -> dict:
+def decrypt_record(crypto: EnvelopeCrypto, record, traversal_level: int = 2) -> Union[dict, Any]:
     """decrypt a record's encrypted fields into a new dict (up to traversal_level deep)
 
-    failures on a single field are logged and that field is left encrypted, so a
+    if `record` itself is a bare {secure, iv, data} blob (file-storage pattern) it is
-    partial failure is visible (the {secure,...} blob remains) rather than silent.
+    decrypted directly and the value (dict or string — see decrypt_data) is returned
+    in place of `record`. a failure on a single field (or on `record` itself) is
+    logged and left encrypted, so a partial failure stays visible rather than silent.
 
     aliases: decrypt_document, decrypt_dict — same function
     """
@@ -353,9 +550,16 @@ def decrypt_record(crypto: EnvelopeCrypto, record, traversal_level: int = 2) ->
     if not isinstance(record, dict):
         return record
 
-    result = record.copy()
+    if _is_blob(record):
+        try:
+            return crypto.decrypt_data(record)
+        except Exception:
+            _log.exception("failed to decrypt record")
+            return copy.deepcopy(record)
+
+    result = copy.deepcopy(record)
     for key, value in record.items():
-        if isinstance(value, dict) and value.get("secure") is True and "iv" in value and "data" in value:
+        if _is_blob(value):
             try:
                 result[key] = crypto.decrypt_data(value)
             except Exception:
@@ -365,9 +569,49 @@ def decrypt_record(crypto: EnvelopeCrypto, record, traversal_level: int = 2) ->
     return result
 
 
+def _fingerprint_default(value: Any) -> str:
+    """json.dumps default= handler for values fingerprint_data can't natively serialize
+
+    covers datetime/date/time (isoformat), bytes/bytearray (hex), and anything else
+    (e.g. ObjectId) via a type-tagged repr — never raises, never logs the value.
+    """
+    if hasattr(value, "isoformat"):
+        return f"isoformat:{value.isoformat()}"
+    if isinstance(value, (bytes, bytearray)):
+        return f"hex:{value.hex()}"
+    return f"{type(value).__name__}:{value!r}"
+
+
+def _fingerprint_normalize(value: Any) -> Any:
+    """recursively tag dict keys with their type to avoid cross-type key collisions
+
+    json object keys are always strings, so {1: "a"} and {"1": "a"} would otherwise
+    serialize identically and collide to the same fingerprint; prefixing each key with
+    its type name keeps them distinct. non-dict containers/values pass through
+    untouched (lists recurse; leaf values are handled by _fingerprint_default).
+    """
+    if isinstance(value, dict):
+        return {
+            f"{type(key).__name__}:{key!r}": _fingerprint_normalize(sub_value)
+            for key, sub_value in value.items()
+        }
+    if isinstance(value, (list, tuple)):
+        return [_fingerprint_normalize(item) for item in value]
+    return value
+
+
 def fingerprint_data(data: dict) -> str:
-    """return a deterministic SHA-256 hex fingerprint of a dict"""
+    """return a deterministic, collision-free SHA-256 hex fingerprint of a dict
-    return hashlib.sha256(json.dumps(data, sort_keys=True).encode()).hexdigest()
+
+    dict keys of different types that would otherwise coerce to the same JSON string
+    (e.g. {1: "a"} vs {"1": "a"}) are kept distinct via a type-tagged pre-pass. values
+    that aren't JSON-native (datetime/date/time, bytes/bytearray, ObjectId-like
+    objects) are serialized via a stable default= handler instead of raising. never
+    logs the data being fingerprinted.
+    """
+    normalized = _fingerprint_normalize(data)
+    encoded = json.dumps(normalized, sort_keys=True, default=_fingerprint_default)
+    return hashlib.sha256(encoded.encode()).hexdigest()
 
 
 # function aliases — same functions, naming preference only