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Add PRAGMA cipher_add_random to source external entropy
1 parent c7986f2 commit 930b441

4 files changed

Lines changed: 44 additions & 6 deletions

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‎src/crypto.c‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -88,7 +88,14 @@ int sqlcipher_codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLef
8888
}
8989

9090
CODEC_TRACE(("sqlcipher_codec_pragma: entered db=%p iDb=%d pParse=%p zLeft=%s zRight=%s ctx=%p\n", db, iDb, pParse, zLeft, zRight, ctx));
91-
91+
92+
if( sqlite3StrICmp(zLeft, "cipher_add_random")==0 && zRight ){
93+
if(ctx) {
94+
char *add_random_status = sqlite3_mprintf("%d", sqlcipher_codec_add_random(ctx, zRight));
95+
codec_vdbe_return_static_string(pParse, "cipher_add_random", add_random_status);
96+
sqlite3_free(add_random_status);
97+
}
98+
} else
9299
if( sqlite3StrICmp(zLeft, "cipher_migrate")==0 && !zRight ){
93100
if(ctx){
94101
char *migrate_status = sqlite3_mprintf("%d", sqlcipher_codec_ctx_migrate(ctx));

‎src/crypto.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -213,6 +213,7 @@ int sqlcipher_codec_ctx_get_flag(codec_ctx *ctx, unsigned int flag, int for_ctx)
213213

214214
const char* sqlcipher_codec_get_cipher_provider(codec_ctx *ctx);
215215
int sqlcipher_codec_ctx_migrate(codec_ctx *ctx);
216+
int sqlcipher_codec_add_random(codec_ctx *ctx, const char *data);
216217
#endif
217218
#endif
218219
/* END SQLCIPHER */

‎src/crypto_impl.c‎

Lines changed: 25 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -83,6 +83,7 @@ struct codec_ctx {
8383
cipher_ctx *read_ctx;
8484
cipher_ctx *write_ctx;
8585
unsigned int skip_read_hmac;
86+
unsigned int need_kdf_salt;
8687
};
8788

8889
int sqlcipher_register_provider(sqlcipher_provider *p) {
@@ -650,8 +651,7 @@ int sqlcipher_codec_ctx_init(codec_ctx **iCtx, Db *pDb, Pager *pPager, sqlite3_f
650651
if((rc = sqlcipher_cipher_ctx_init(&ctx->write_ctx)) != SQLITE_OK) return rc;
651652

652653
if(fd == NULL || sqlite3OsRead(fd, ctx->kdf_salt, FILE_HEADER_SZ, 0) != SQLITE_OK) {
653-
/* if unable to read the bytes, generate random salt */
654-
if(ctx->read_ctx->provider->random(ctx->read_ctx->provider_ctx, ctx->kdf_salt, FILE_HEADER_SZ) != SQLITE_OK) return SQLITE_ERROR;
654+
ctx->need_kdf_salt = 1;
655655
}
656656

657657
if((rc = sqlcipher_codec_ctx_set_cipher(ctx, CIPHER, 0)) != SQLITE_OK) return rc;
@@ -823,8 +823,13 @@ static int sqlcipher_cipher_ctx_key_derive(codec_ctx *ctx, cipher_ctx *c_ctx) {
823823
c_ctx->pass, c_ctx->pass_sz, ctx->kdf_salt, ctx->kdf_salt_sz, c_ctx->kdf_iter,
824824
ctx->hmac_kdf_salt, c_ctx->fast_kdf_iter, c_ctx->key_sz));
825825

826-
826+
827827
if(c_ctx->pass && c_ctx->pass_sz) { // if pass is not null
828+
829+
if(ctx->need_kdf_salt) {
830+
if(ctx->read_ctx->provider->random(ctx->read_ctx->provider_ctx, ctx->kdf_salt, FILE_HEADER_SZ) != SQLITE_OK) return SQLITE_ERROR;
831+
ctx->need_kdf_salt = 0;
832+
}
828833
if (c_ctx->pass_sz == ((c_ctx->key_sz * 2) + 3) && sqlite3StrNICmp((const char *)c_ctx->pass ,"x'", 2) == 0) {
829834
int n = c_ctx->pass_sz - 3; /* adjust for leading x' and tailing ' */
830835
const unsigned char *z = c_ctx->pass + 2; /* adjust lead offset of x' */
@@ -1119,6 +1124,23 @@ int sqlcipher_codec_ctx_migrate(codec_ctx *ctx) {
11191124
return rc;
11201125
}
11211126

1127+
int sqlcipher_codec_add_random(codec_ctx *ctx, const char *zRight){
1128+
int random_sz = strlen(zRight);
1129+
if (random_sz == ((ctx->read_ctx->key_sz * 2) + 3) && sqlite3StrNICmp((const char *)zRight ,"x'", 2) == 0) {
1130+
unsigned char *random;
1131+
int n = random_sz - 3; /* adjust for leading x' and tailing ' */
1132+
const unsigned char *z = (const unsigned char *)zRight + 2; /* adjust lead offset of x' */
1133+
CODEC_TRACE(("sqlcipher_codec_add_random: using raw random blob from hex\n"));
1134+
random = sqlcipher_malloc(n);
1135+
memset(random, 0, n);
1136+
cipher_hex2bin(z, n, random);
1137+
int rc = ctx->read_ctx->provider->add_random(ctx->read_ctx->provider_ctx, random, n);
1138+
sqlcipher_free(random, n);
1139+
return rc;
1140+
}
1141+
return SQLITE_ERROR;
1142+
}
1143+
11221144

11231145
#endif
11241146
/* END SQLCIPHER */

‎src/crypto_libtomcrypt.c‎

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -39,12 +39,20 @@ typedef struct {
3939
prng_state prng;
4040
} ltc_ctx;
4141

42+
static unsigned int random_block_sz = 32;
4243
static unsigned int ltc_init = 0;
4344

4445
static int sqlcipher_ltc_add_random(void *ctx, void *buffer, int length) {
4546
ltc_ctx *ltc = (ltc_ctx*)ctx;
46-
int rc = fortuna_add_entropy(buffer, length, &(ltc->prng));
47-
return rc != CRYPT_OK ? SQLITE_ERROR : SQLITE_OK;
47+
int block_count = length / random_block_sz;
48+
for(int block_idx = 0; block_idx < block_count; block_idx++){
49+
int rc = fortuna_add_entropy(buffer, random_block_sz, &(ltc->prng));
50+
buffer += random_block_sz;
51+
if(rc != CRYPT_OK) {
52+
return SQLITE_ERROR;
53+
}
54+
}
55+
return SQLITE_OK;
4856
}
4957

5058
static int sqlcipher_ltc_activate(void *ctx) {

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