feat(sqlcipher): decrypt SQLCipher pages into the reader's stream

.gitattributes

@@ -0,0 +1,5 @@
+# Byte-exact forensic fixtures: git must never translate line endings in them.
+# core.autocrlf defaults to TRUE on GitHub windows-latest runners, and git only
+# sniffs the first 8000 bytes for a NUL before deciding a file is text.
+tests/data/** -text
+fuzz/corpus/** -text

.gitignore

@@ -1,4 +1,4 @@
-/target
+target/
 
 # mkdocs build output (generated by `mkdocs build`; the Pages workflow builds it in CI)
 /site/

core/Cargo.toml

@@ -17,6 +17,17 @@ path = "src/lib.rs"
 [dependencies]
 # Consume KNOWLEDGE-layer format constants instead of re-hardcoding them.
 forensicnomicon = { workspace = true }
+# SQLCipher decryption primitives — audited RustCrypto crates ONLY, never
+# hand-rolled (CLAUDE.core.md: "Never hand-roll a cryptographic primitive").
+# PBKDF2 key derivation (HMAC-SHA1/SHA512), AES-256-CBC page decrypt, per-page
+# HMAC authentication. All are low-MSRV and keep the reader on rust-version 1.80.
+pbkdf2 = { version = "0.12", default-features = false, features = ["hmac"] }
+hmac = "0.12"
+sha1 = "0.10"
+sha2 = "0.10"
+aes = "0.8"
+cbc = "0.1"
+cipher = "0.4"
 
 [lints]
 workspace = true

core/src/lib.rs

@@ -24,6 +24,7 @@
 pub mod attribution;
 pub mod rebuild;
 pub mod row_history;
+pub mod sqlcipher;
 
 // The page-1 header field offsets are consumed from the KNOWLEDGE leaf
 // (forensicnomicon::sqlite ≥ 1.5.0); the previously-local duplicates were promoted
@@ -70,6 +71,10 @@ pub enum Error {
     /// [`Database::open_path`], not a malformed database). Carries the
     /// [`std::io::ErrorKind`] (show-the-unrecognized-value).
     Io(std::io::ErrorKind),
+    /// `SQLCipher` decryption failed (wrong key, unsupported cipher parameters, or
+    /// a failed page authentication) via [`Database::open_encrypted`]. Carries
+    /// the underlying [`sqlcipher::DecryptError`] (show-the-unrecognized-value).
+    Decrypt(sqlcipher::DecryptError),
 }
 
 impl From<std::io::Error> for Error {
@@ -78,6 +83,12 @@ impl From<std::io::Error> for Error {
     }
 }
 
+impl From<sqlcipher::DecryptError> for Error {
+    fn from(e: sqlcipher::DecryptError) -> Self {
+        Error::Decrypt(e)
+    }
+}
+
 /// A freed overflow-page chain could not be followed to a complete, trustworthy
 /// payload (task #73): a chain page that is not a freelist leaf (live / trunk /
 /// unreachable), a cycle, a premature terminator with bytes still owed, an
@@ -657,6 +668,20 @@ impl Database {
         })
     }
 
+    /// Decrypt a **`SQLCipher`** database with `key` and open the resulting
+    /// plaintext, detecting the cipher version automatically (see
+    /// [`sqlcipher::decrypt`]). The reader then consumes the decrypted byte
+    /// stream exactly as for a plaintext file — the encryption is transparent
+    /// past this call.
+    ///
+    /// Secure-by-default and read-only: a wrong key or unsupported cipher
+    /// parameters is a loud [`Error::Decrypt`], never a silently-misread
+    /// database; nothing is written back to the evidence file.
+    pub fn open_encrypted(bytes: &[u8], key: &sqlcipher::SqlCipherKey) -> Result<Self, Error> {
+        let decrypted = sqlcipher::decrypt(bytes, key)?;
+        Self::open(decrypted.plaintext)
+    }
+
     /// Open a database from a filesystem path with a **bounded-memory paged
     /// read** (roadmap §3.1): pages are streamed on demand through a small LRU
     /// cache instead of loading the whole file into a `Vec<u8>`, so a multi-GB