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Remove duplicated computation of TLS 1.3 HKDF label length

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Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2020-09-08 10:48:14 +01:00
parent e4435ea777
commit 9cb0a146f1
1 changed files with 9 additions and 8 deletions
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17
library/ssl_tls13_keys.c
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@ -73,12 +73,17 @@ struct mbedtls_ssl_tls1_3_labels_struct const mbedtls_ssl_tls1_3_labels =
* the HkdfLabel structure on success.
*/
#define SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN \
#define SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( label_len, context_len ) \
( 2 /* expansion length */ \
+ 1 /* label length */ \
+ MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN \
+ label_len \
+ 1 /* context length */ \
+ MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
+ context_len )
#define SSL_TLS1_3_KEY_SCHEDULE_MAX_HKDF_LABEL_LEN \
SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( \
MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_LABEL_LEN, \
MBEDTLS_SSL_TLS1_3_KEY_SCHEDULE_MAX_CONTEXT_LEN )
static void ssl_tls1_3_hkdf_encode_label(
size_t desired_length,
@ -89,11 +94,7 @@ static void ssl_tls1_3_hkdf_encode_label(
const char label_prefix[6] = { 't', 'l', 's', '1', '3', ' ' };
size_t total_label_len = sizeof( label_prefix ) + llen;
size_t total_hkdf_lbl_len =
2 /* length of expanded key material */
+ 1 /* label length */
+ total_label_len /* actual label, incl. prefix */
+ 1 /* context length */
+ clen; /* actual context */
SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN( total_label_len, clen );
unsigned char *p = dst;