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Improve documentation of ssl_populate_transform()

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Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2020-05-28 07:36:33 +01:00
parent c0eefa8b92
commit 447558df12
1 changed files with 6 additions and 3 deletions
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9
library/ssl_tls.c
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@ -973,9 +973,12 @@ static int ssl_populate_transform( mbedtls_ssl_transform *transform,
transform->taglen =
ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
/* All modes haves 96-bit IVs;
* GCM and CCM has 4 implicit and 8 explicit bytes
* ChachaPoly has all 12 bytes implicit
/* All modes haves 96-bit IVs, but the length of the static parts vary
* with mode and version:
* - For GCM and CCM in TLS 1.2, there's a static IV of 4 Bytes
* (to be concatenated with a dynamically chosen IV of 8 Bytes)
* - For ChaChaPoly in TLS 1.2, there's a static IV of 12 Bytes
* (to be XOR'ed with the 8 Byte record sequence number).
*/
transform->ivlen = 12;
if( cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )