Expose the LMDB Encrypt/Decrypt feature

.gitmodules

@@ -1,4 +1,4 @@
-[submodule "lmdb-master-sys/lmdb"]
-	path = lmdb-master-sys/lmdb
+[submodule "lmdb-master3-sys/lmdb"]
+	path = lmdb-master3-sys/lmdb
 	url = https://github.com/LMDB/lmdb
-	branch = mdb.master
+	branch = mdb.master3

Cargo.toml

@@ -1,3 +1,3 @@
 [workspace]
-members = ["lmdb-master-sys", "heed", "heed-traits", "heed-types"]
+members = ["lmdb-master3-sys", "heed", "heed-traits", "heed-types"]
 resolver = "2"

heed/Cargo.toml

@@ -11,21 +11,25 @@ readme = "../README.md"
 edition = "2021"
 
 [dependencies]
+aead = { version = "0.5.1", default-features = false }
 bitflags = { version = "2.3.3", features = ["serde"] }
 bytemuck = "1.12.3"
 byteorder = { version = "1.4.3", default-features = false }
+generic-array = { version = "0.14.6", features = ["serde"] }
 heed-traits = { version = "0.20.0-alpha.8", path = "../heed-traits" }
 heed-types = { version = "0.20.0-alpha.8", default-features = false, path = "../heed-types" }
 libc = "0.2.139"
-lmdb-master-sys = { version = "0.1.0", path = "../lmdb-master-sys" }
+lmdb-master3-sys = { version = "0.1.0", path = "../lmdb-master3-sys" }
 once_cell = "1.16.0"
 page_size = "0.6.0"
 serde = { version = "1.0.151", features = ["derive"], optional = true }
 synchronoise = "1.0.1"
 
 [dev-dependencies]
-serde = { version = "1.0.151", features = ["derive"] }
-bytemuck = { version = "1.12.3", features = ["derive"] }
+argon2 = { version = "0.4.1", features = ["std"] }
+bytemuck = { version = "1.12.1", features = ["derive"] }
+chacha20poly1305 = "0.10.1"
+serde = { version = "1.0.144", features = ["derive"] }
 tempfile = "3.3.0"
 
 [target.'cfg(windows)'.dependencies]
@@ -69,7 +73,7 @@ unbounded_depth = ["heed-types/unbounded_depth"]
 # There are tradeoffs for both POSIX and SysV semaphores; which you
 # should look into before enabling this feature. Also, see here:
 # <https://github.com/LMDB/lmdb/blob/3947014aed7ffe39a79991fa7fb5b234da47ad1a/libraries/liblmdb/lmdb.h#L46-L69>
-posix-sem = ["lmdb-master-sys/posix-sem"]
+posix-sem = ["lmdb-master3-sys/posix-sem"]
 
 [[example]]
 name = "rmp-serde"

heed/examples/encrypt.rs

@@ -0,0 +1,57 @@
+use std::error::Error;
+use std::fs;
+use std::path::Path;
+
+use argon2::Argon2;
+use chacha20poly1305::{ChaCha20Poly1305, Key};
+use heed::types::*;
+use heed::{Database, EnvOpenOptions};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let env_path = Path::new("target").join("encrypt.mdb");
+    let password = "This is the password that will be hashed by the argon2 algorithm";
+    let salt = "The salt added to the password hashes to add more security when stored";
+
+    let _ = fs::remove_dir_all(&env_path);
+    fs::create_dir_all(&env_path)?;
+
+    // We choose to use argon2 as our Key Derivation Function, but you can choose whatever you want.
+    // <https://github.com/RustCrypto/traits/tree/master/password-hash#supported-crates>
+    let mut key = Key::default();
+    Argon2::default().hash_password_into(password.as_bytes(), salt.as_bytes(), &mut key)?;
+
+    // We open the environment
+    let mut options = EnvOpenOptions::new().encrypt_with::<ChaCha20Poly1305>(key);
+    let env = options
+        .map_size(10 * 1024 * 1024) // 10MB
+        .max_dbs(3)
+        .open(&env_path)?;
+
+    let key1 = "first-key";
+    let val1 = "this is a secret info";
+    let key2 = "second-key";
+    let val2 = "this is another secret info";
+
+    // We create database and write secret values in it
+    let mut wtxn = env.write_txn()?;
+    let db: Database<Str, Str> = env.create_database(&mut wtxn, Some("first"))?;
+    db.put(&mut wtxn, key1, val1)?;
+    db.put(&mut wtxn, key2, val2)?;
+    wtxn.commit()?;
+    env.prepare_for_closing().wait();
+
+    // We reopen the environment now
+    let env = options.open(&env_path)?;
+
+    // We check that the secret entries are correctly decrypted
+    let rtxn = env.read_txn()?;
+    let db: Database<Str, Str> = env.open_database(&rtxn, Some("first"))?.unwrap();
+    let mut iter = db.iter(&rtxn)?;
+    assert_eq!(iter.next().transpose()?, Some((key1, val1)));
+    assert_eq!(iter.next().transpose()?, Some((key2, val2)));
+    assert_eq!(iter.next().transpose()?, None);
+
+    eprintln!("Successful test!");
+
+    Ok(())
+}