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hcrypto WinCNG backend: zero rgb{Hash,Key}Object on reinit

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In the interest of being paranoid, when a WinCNG crypto or digest
context is being reinitialized, zero out the backing store as well
as destroying the handle.
This commit is contained in:
Luke Howard
2018-05-12 13:54:15 +10:00
parent 934d5e09bf
commit bd2c2eb8bd
1 changed files with 11 additions and 10 deletions
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21
lib/hcrypto/evp-wincng.c
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@@ -96,8 +96,10 @@ wincng_cleanup(EVP_CIPHER_CTX *ctx)
{ {
struct wincng_key *cng = ctx->cipher_data; struct wincng_key *cng = ctx->cipher_data;
if (cng->hKey) if (cng->hKey) {
BCryptDestroyKey(cng->hKey); BCryptDestroyKey(cng->hKey);
cng->hKey = (BCRYPT_KEY_HANDLE)0;
}
SecureZeroMemory(cng->rgbKeyObject, WINCNG_KEY_OBJECT_SIZE(ctx)); SecureZeroMemory(cng->rgbKeyObject, WINCNG_KEY_OBJECT_SIZE(ctx));
return 1; return 1;
@@ -196,10 +198,7 @@ wincng_key_init(EVP_CIPHER_CTX *ctx,
if (ctx->cipher->app_data == NULL) if (ctx->cipher->app_data == NULL)
return 0; return 0;
if (cng->hKey) { wincng_cleanup(ctx);
BCryptDestroyKey(cng->hKey); /* allow reinitialization */
cng->hKey = (BCRYPT_KEY_HANDLE)0;
}
/* /*
* Note: ctx->key_len not EVP_CIPHER_CTX_key_length() for * Note: ctx->key_len not EVP_CIPHER_CTX_key_length() for
@@ -567,6 +566,9 @@ wincng_md_algorithm_init(EVP_MD *md,
return hAlgorithm; return hAlgorithm;
} }
static int
wincng_md_cleanup(EVP_MD_CTX *ctx);
static int static int
wincng_md_hash_init(BCRYPT_ALG_HANDLE hAlgorithm, wincng_md_hash_init(BCRYPT_ALG_HANDLE hAlgorithm,
EVP_MD_CTX *ctx) EVP_MD_CTX *ctx)
@@ -575,10 +577,7 @@ wincng_md_hash_init(BCRYPT_ALG_HANDLE hAlgorithm,
NTSTATUS status; NTSTATUS status;
ULONG cbData; ULONG cbData;
if (cng->hHash) { wincng_md_cleanup(ctx);
BCryptDestroyHash(cng->hHash); /* allow reinitialization */
cng->hHash = (BCRYPT_HASH_HANDLE)0;
}
status = BCryptGetProperty(hAlgorithm, status = BCryptGetProperty(hAlgorithm,
BCRYPT_OBJECT_LENGTH, BCRYPT_OBJECT_LENGTH,
@@ -643,8 +642,10 @@ wincng_md_cleanup(EVP_MD_CTX *ctx)
{ {
struct wincng_md_ctx *cng = (struct wincng_md_ctx *)ctx; struct wincng_md_ctx *cng = (struct wincng_md_ctx *)ctx;
if (cng->hHash) if (cng->hHash) {
BCryptDestroyHash(cng->hHash); BCryptDestroyHash(cng->hHash);
cng->hHash = (BCRYPT_HASH_HANDLE)0;
}
SecureZeroMemory(cng->rgbHashObject, cng->cbHashObject); SecureZeroMemory(cng->rgbHashObject, cng->cbHashObject);
return 1; return 1;