From: Howard Chu <hyc@openldap.org>
Date: Tue, 16 Jun 2026 14:24:22 +0000 (+0100)
Subject: ITS#10523 LMDB: add sample for checksum plus authenticated encryption
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ec8ad82c4e5c6b709e8bcfebea86a6451fa7aa85;p=thirdparty%2Fopenldap.git

ITS#10523 LMDB: add sample for checksum plus authenticated encryption
---

diff --git a/libraries/liblmdb/cryptoc.c b/libraries/liblmdb/cryptoc.c
new file mode 100644
index 0000000000..4403fe4ee6
--- /dev/null
+++ b/libraries/liblmdb/cryptoc.c
@@ -0,0 +1,97 @@
+/* crypto.c - LMDB encryption helper module */
+/*
+ * Copyright 2020-2024 Howard Chu, Symas Corp.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the Symas
+ * Dual-Use License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * source distribution.
+ */
+#include <string.h>
+
+#include <sodium.h>
+
+#include "lmdb.h"
+
+#define KEYBYTES	crypto_aead_chacha20poly1305_ietf_KEYBYTES
+#define NONCEBYTES	crypto_aead_chacha20poly1305_ietf_NPUBBYTES
+#define MACBYTES	crypto_aead_chacha20poly1305_ietf_ABYTES
+#define SUMBYTES	crypto_hash_sha256_BYTES
+
+MDB_crypto_hooks MDB_crypto;
+
+static int mcf_str2key(const char *passwd, MDB_val *key)
+{
+	crypto_hash_sha256_state state;
+
+	crypto_hash_sha256_init(&state);
+	crypto_hash_sha256_update(&state, (const unsigned char *)"Just a Constant", sizeof("Just a Constant"));
+	crypto_hash_sha256_update(&state, (const unsigned char *)passwd, strlen(passwd));
+	crypto_hash_sha256_final(&state, key->mv_data);
+	return 0;
+}
+
+static void mcf_sumfunc(const MDB_val *src, MDB_val *dst, const MDB_val *key)
+{
+	crypto_hash_sha256_state state;
+
+	crypto_hash_sha256_init(&state);
+	if (key)
+		crypto_hash_sha256_update(&state, (const unsigned char *)key->mv_data, key->mv_size);
+	crypto_hash_sha256_update(&state, (const unsigned char *)src->mv_data, src->mv_size);
+	crypto_hash_sha256_final(&state, dst->mv_data);
+}
+
+#define ENC(dst, src, mac, key, iv) \
+	crypto_aead_chacha20poly1305_ietf_encrypt_detached(dst->mv_data, mac, &mlen, \
+		src->mv_data, src->mv_size, NULL, 0, NULL, iv, key)
+
+#define DEC(dst, src, mac, key, iv) \
+	crypto_aead_chacha20poly1305_ietf_decrypt_detached(dst->mv_data, NULL, src->mv_data, \
+		src->mv_size, mac, NULL, 0, iv, key)
+
+static int mcf_encfunc(const MDB_val *src, MDB_val *dst, const MDB_val *key, int encdec)
+{
+	unsigned char iv[NONCEBYTES];
+	mdb_size_t *ptr;
+	int ivl, rc;
+	unsigned long long mlen;
+
+	/* the nonce is only 12 bytes */
+	ptr = key[1].mv_data;
+	ivl = ptr[0] & 0xffffffff;
+	memcpy(iv, &ivl, 4);
+	memcpy(iv+4, ptr+1, sizeof(mdb_size_t));
+
+	if (encdec) {
+		rc = ENC(dst, src, key[2].mv_data, key[0].mv_data, iv);
+	} else {
+		if (key[2].mv_size)
+			rc = DEC(dst, src, key[2].mv_data, key[0].mv_data, iv);
+		else {
+			/* Decrypting without MAC check: only used when decrypting page
+			 * headers during incremental load.
+			 */
+			rc = crypto_stream_chacha20_ietf_xor_ic(dst->mv_data, src->mv_data,
+				src->mv_size, iv, 1, key[0].mv_data);
+		}
+	}
+	return rc;
+}
+
+static const MDB_crypto_funcs mcf_table = {
+	mcf_str2key,
+	mcf_encfunc,
+	mcf_sumfunc,
+	KEYBYTES,
+	MACBYTES,
+	SUMBYTES
+};
+
+MDB_crypto_funcs *MDB_crypto()
+{
+	return (MDB_crypto_funcs *)&mcf_table;
+}