In mbedtls_ssl_derive_keys, don't call mbedtls_md_hmac_starts in
ciphersuites that don't use HMAC. This doesn't change the behavior of
the code, but avoids relying on an uncaught error when attempting to
start an HMAC operation that hadn't been initialized.
Clarify what MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH and
MBEDTLS_ERR_PK_SIG_LEN_MISMATCH mean. Add comments to highlight that
this indicates that a valid signature is present, unlike other error
codes. See
https://github.com/ARMmbed/mbedtls/pull/1149#discussion_r178130705
Minor documentation improvements:
*Standardized file brief description.
*Reordered tags within documentation blocks so that params and returns are last in block.
*Some minor rephrasing.
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*Removed bullets from parameter descriptions.
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*Applied previous function documentation improvements to depracated functions.
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*p_rng descriptions changed from "parameter" to "context".
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*p_rng descriptions changed from "parameter" to "context".
*Removed bullets from parameter descriptions.
