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Merge pull request #246 from libtom/pr/gcm-corner-cases

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GCM allow skipping gcm_add_aad and gcm_process
This commit is contained in:
karel-m 2017-07-10 23:26:13 +02:00 committed by GitHub
commit fa4713b68e
3 changed files with 24 additions and 0 deletions
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9
src/encauth/gcm/gcm_done.c
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@ -40,6 +40,15 @@ int gcm_done(gcm_state *gcm,
return err; return err;
} }
if (gcm->mode == LTC_GCM_MODE_IV) {
/* let's process the IV */
if ((err = gcm_add_aad(gcm, NULL, 0)) != CRYPT_OK) return err;
}
if (gcm->mode == LTC_GCM_MODE_AAD) {
/* let's process the AAD */
if ((err = gcm_process(gcm, NULL, 0, NULL, 0)) != CRYPT_OK) return err;
}
if (gcm->mode != LTC_GCM_MODE_TEXT) { if (gcm->mode != LTC_GCM_MODE_TEXT) {
return CRYPT_INVALID_ARG; return CRYPT_INVALID_ARG;

5
src/encauth/gcm/gcm_process.c
View File

@ -52,6 +52,11 @@ int gcm_process(gcm_state *gcm,
return CRYPT_INVALID_ARG; return CRYPT_INVALID_ARG;
} }
if (gcm->mode == LTC_GCM_MODE_IV) {
/* let's process the IV */
if ((err = gcm_add_aad(gcm, NULL, 0)) != CRYPT_OK) return err;
}
/* in AAD mode? */ /* in AAD mode? */
if (gcm->mode == LTC_GCM_MODE_AAD) { if (gcm->mode == LTC_GCM_MODE_AAD) {
/* let's process the AAD */ /* let's process the AAD */

10
src/encauth/gcm/gcm_test.c
View File

@ -325,6 +325,7 @@ int gcm_test(void)
int idx, err; int idx, err;
unsigned long x, y; unsigned long x, y;
unsigned char out[2][128], T[2][16]; unsigned char out[2][128], T[2][16];
gcm_state gcm;
/* find aes */ /* find aes */
idx = find_cipher("aes"); idx = find_cipher("aes");
@ -335,6 +336,15 @@ int gcm_test(void)
} }
} }
/* Special test case for empty AAD + empty PT */
y = sizeof(T[0]);
if ((err = gcm_init(&gcm, idx, tests[0].K, tests[0].keylen)) != CRYPT_OK) return err;
if ((err = gcm_add_iv(&gcm, tests[0].IV, tests[0].IVlen)) != CRYPT_OK) return err;
/* intentionally skip gcm_add_aad + gcm_process */
if ((err = gcm_done(&gcm, T[0], &y)) != CRYPT_OK) return err;
if (compare_testvector(out[0], 0, tests[0].C, tests[0].ptlen, "GCM CT-special", 0)) return CRYPT_FAIL_TESTVECTOR;
if (compare_testvector(T[0], y, tests[0].T, 16, "GCM Encrypt Tag-special", 0)) return CRYPT_FAIL_TESTVECTOR;
for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) { for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) {
y = sizeof(T[0]); y = sizeof(T[0]);
if ((err = gcm_memory(idx, tests[x].K, tests[x].keylen, if ((err = gcm_memory(idx, tests[x].K, tests[x].keylen,