espressif/mbedtls
1
0
Fork 0
mirror of https://github.com/espressif/mbedtls.git synced 2025-05-08 19:04:04 +08:00
Code Issues Packages Projects Releases Wiki Activity

gcm: Support software fallback for non-AES ciphers in a gcm operation.

Browse Source 
When MBEDTLS_HARDWARE_GCM is enabled, we ALT all the GCM functions that are
declared in mbedtls/gcm.h with our H/W port functions, due to which even
if non-AES ciphers such as ARIA, CAMELLIA, BLOWFISH, etc. are selected
for a GCM operation, we perform an AES-GCM operation, thus resulting into
an incorrect calculation.
Thus in such cases we need to fallback to the software definitions of
GCM.

Currently, it is not directly possible to pull in software definitions of GCM
related functions directly due to gcm_alt.h, but this commit renames the
functions by appending `_soft` to their names, thus making them look different
functions in all and thus they are made available to pull in during compilation.

The change is configrable using the config MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK.
As this config is enabled by default, building the mbedtls crypto library
(libmbedcrypto.a) with this change increases its size by ~2.5KB.
This commit is contained in:
harshal.patil 2023-12-19 13:28:05 +05:30
parent 89cc7af4bb
commit 09bba150d0
No known key found for this signature in database
GPG Key ID: 5B5EC97C35B9A2E5
2 changed files with 42 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
include/mbedtls/gcm.h
View File

@ -40,12 +40,21 @@
extern "C" {
#endif
#if !defined(MBEDTLS_GCM_ALT)
#if defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK)
#define SOFT(name) name##_soft
#else
#define SOFT(name) name
#endif /* MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK */
#if defined(MBEDTLS_GCM_ALT)
#include "gcm_alt.h"
#endif /* !MBEDTLS_GCM_ALT */
#if !defined(MBEDTLS_GCM_ALT) || defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK)
/**
* \brief The GCM context structure.
*/
typedef struct mbedtls_gcm_context {
typedef struct SOFT(mbedtls_gcm_context) {
mbedtls_cipher_context_t MBEDTLS_PRIVATE(cipher_ctx); /*!< The cipher context used. */
uint64_t MBEDTLS_PRIVATE(HL)[16]; /*!< Precalculated HTable low. */
uint64_t MBEDTLS_PRIVATE(HH)[16]; /*!< Precalculated HTable high. */
@ -58,11 +67,7 @@ typedef struct mbedtls_gcm_context {
#MBEDTLS_GCM_ENCRYPT or
#MBEDTLS_GCM_DECRYPT. */
}
mbedtls_gcm_context;
#else /* !MBEDTLS_GCM_ALT */
#include "gcm_alt.h"
#endif /* !MBEDTLS_GCM_ALT */
SOFT(mbedtls_gcm_context);
/**
* \brief This function initializes the specified GCM context,
@ -350,6 +355,9 @@ int mbedtls_gcm_finish(mbedtls_gcm_context *ctx,
*/
void mbedtls_gcm_free(mbedtls_gcm_context *ctx);
#endif /* !defined(MBEDTLS_GCM_ALT) || defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK) */
#if defined(MBEDTLS_SELF_TEST)
/**

29
library/gcm.c
View File

@ -35,8 +35,33 @@
#include "aesce.h"
#endif
#if !defined(MBEDTLS_GCM_ALT)
#if defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK)
#undef mbedtls_gcm_context
#undef mbedtls_gcm_init
#undef mbedtls_gcm_setkey
#undef mbedtls_gcm_starts
#undef mbedtls_gcm_update_ad
#undef mbedtls_gcm_update
#undef mbedtls_gcm_finish
#undef mbedtls_gcm_crypt_and_tag
#undef mbedtls_gcm_auth_decrypt
#undef mbedtls_gcm_free
#define mbedtls_gcm_context mbedtls_gcm_context_soft
#define mbedtls_gcm_init mbedtls_gcm_init_soft
#define mbedtls_gcm_setkey mbedtls_gcm_setkey_soft
#define mbedtls_gcm_starts mbedtls_gcm_starts_soft
#define mbedtls_gcm_update_ad mbedtls_gcm_update_ad_soft
#define mbedtls_gcm_update mbedtls_gcm_update_soft
#define mbedtls_gcm_finish mbedtls_gcm_finish_soft
#define mbedtls_gcm_crypt_and_tag mbedtls_gcm_crypt_and_tag_soft
#define mbedtls_gcm_auth_decrypt mbedtls_gcm_auth_decrypt_soft
#define mbedtls_gcm_free mbedtls_gcm_free_soft
#endif
#if !defined(MBEDTLS_GCM_ALT) || defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK)
/*
* Initialize a context
*/
@ -618,7 +643,7 @@ void mbedtls_gcm_free(mbedtls_gcm_context *ctx)
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_gcm_context));
}
#endif /* !MBEDTLS_GCM_ALT */
#endif /* !defined(MBEDTLS_GCM_ALT) || defined(MBEDTLS_GCM_NON_AES_CIPHER_SOFT_FALLBACK) */
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
/*