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lmdb/libraries/liblmdb/crypto.c

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/* crypto.c - LMDB encryption helper module */
/*
* Copyright 2020 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 <openssl/engine.h>
#include "lmdb.h"
MDB_crypto_hooks MDB_crypto;
static EVP_CIPHER *cipher;
static int mcf_str2key(const char *passwd, MDB_val *key)
{
unsigned int size;
EVP_MD_CTX *mdctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(mdctx, EVP_sha256(), NULL);
EVP_DigestUpdate(mdctx, "Just a Constant", sizeof("Just a Constant"));
EVP_DigestUpdate(mdctx, passwd, strlen(passwd));
EVP_DigestFinal_ex(mdctx, key->mv_data, &size);
EVP_MD_CTX_free(mdctx);
return 0;
}
/* cheats - internal OpenSSL 1.1 structures */
typedef struct evp_cipher_ctx_st {
const EVP_CIPHER *cipher;
ENGINE *engine; /* functional reference if 'cipher' is
* ENGINE-provided */
int encrypt; /* encrypt or decrypt */
int buf_len; /* number we have left */
unsigned char oiv[EVP_MAX_IV_LENGTH]; /* original iv */
unsigned char iv[EVP_MAX_IV_LENGTH]; /* working iv */
unsigned char buf[EVP_MAX_BLOCK_LENGTH]; /* saved partial block */
int num; /* used by cfb/ofb/ctr mode */
/* FIXME: Should this even exist? It appears unused */
void *app_data; /* application stuff */
int key_len; /* May change for variable length cipher */
unsigned long flags; /* Various flags */
void *cipher_data; /* per EVP data */
int final_used;
int block_mask;
unsigned char final[EVP_MAX_BLOCK_LENGTH]; /* possible final block */
} EVP_CIPHER_CTX;
#define CHACHA_KEY_SIZE 32
#define CHACHA_CTR_SIZE 16
#define CHACHA_BLK_SIZE 64
#define POLY1305_BLOCK_SIZE 16
typedef struct {
union {
double align; /* this ensures even sizeof(EVP_CHACHA_KEY)%8==0 */
unsigned int d[CHACHA_KEY_SIZE / 4];
} key;
unsigned int counter[CHACHA_CTR_SIZE / 4];
unsigned char buf[CHACHA_BLK_SIZE];
unsigned int partial_len;
} EVP_CHACHA_KEY;
typedef struct {
EVP_CHACHA_KEY key;
unsigned int nonce[12/4];
unsigned char tag[POLY1305_BLOCK_SIZE];
unsigned char tls_aad[POLY1305_BLOCK_SIZE];
struct { uint64_t aad, text; } len;
int aad, mac_inited, tag_len, nonce_len;
size_t tls_payload_length;
} EVP_CHACHA_AEAD_CTX;
static int mcf_encfunc(const MDB_val *src, MDB_val *dst, const MDB_val *key, int encdec)
{
unsigned char iv[12];
int ivl, outl, rc;
mdb_size_t *ptr;
EVP_CIPHER_CTX ctx = {0};
EVP_CHACHA_AEAD_CTX cactx;
ctx.cipher_data = &cactx;
ptr = key[1].mv_data;
ivl = ptr[0] & 0xffffffff;
memcpy(iv, &ivl, 4);
memcpy(iv+4, ptr+1, sizeof(mdb_size_t));
EVP_CipherInit_ex(&ctx, cipher, NULL, key[0].mv_data, iv, encdec);
EVP_CIPHER_CTX_set_padding(&ctx, 0);
if (!encdec) {
EVP_CIPHER_CTX_ctrl(&ctx, EVP_CTRL_AEAD_SET_TAG, key[2].mv_size, key[2].mv_data);
}
rc = EVP_CipherUpdate(&ctx, dst->mv_data, &outl, src->mv_data, src->mv_size);
if (rc)
rc = EVP_CipherFinal_ex(&ctx, key[2].mv_data, &outl);
if (rc && encdec) {
EVP_CIPHER_CTX_ctrl(&ctx, EVP_CTRL_AEAD_GET_TAG, key[2].mv_size, key[2].mv_data);
}
return rc == 0;
}
static const MDB_crypto_funcs mcf_table = {
mcf_str2key,
mcf_encfunc,
NULL,
CHACHA_KEY_SIZE,
POLY1305_BLOCK_SIZE,
0
};
MDB_crypto_funcs *MDB_crypto()
{
cipher = (EVP_CIPHER *)EVP_chacha20_poly1305();
return (MDB_crypto_funcs *)&mcf_table;
}