Nicola Tuveri a16e86683e Honor OSSL_PKEY_PARAM_EC_POINT_CONVERSION_FORMAT as set and default to UNCOMPRESSED
Originally the code to im/export the EC pubkey was meant to be consumed
only by the im/export functions when crossing the provider boundary.
Having our providers exporting to a COMPRESSED format octet string made
sense to avoid memory waste, as it wasn't exposed outside the provider
API, and providers had all tools available to convert across the three
formats.

Later on, with #13139 deprecating the `EC_KEY_*` functions, more state
was added among the params imported/exported on an EC provider-native
key (including `OSSL_PKEY_PARAM_EC_POINT_CONVERSION_FORMAT`, although it
did not affect the format used to export `OSSL_PKEY_PARAM_PUB_KEY`).

Finally, in #14800, `EVP_PKEY_todata()` was introduced and prominently
exposed directly to users outside the provider API, and the choice of
COMPRESSED over UNCOMPRESSED as the default became less sensible in
light of usability, given the latter is more often needed by
applications and protocols.

This commit fixes it, by using `EC_KEY_get_conv_form()` to get the
point format from the internal state (an `EC_KEY` under the hood) of the
provider-side object, and using it on
`EVP_PKEY_export()`/`EVP_PKEY_todata()` to format
`OSSL_PKEY_PARAM_PUB_KEY`.
The default for an `EC_KEY` was already UNCOMPRESSED, and it is altered
if the user sets `OSSL_PKEY_PARAM_EC_POINT_CONVERSION_FORMAT` via
`EVP_PKEY_fromdata()`, `EVP_PKEY_set_params()`, or one of the
more specialized methods.

For symmetry, this commit also alters `ec_pkey_export_to()` in
`crypto/ec/ec_ameth.c`, part of the `EVP_PKEY_ASN1_METHOD` for legacy EC
keys: it exclusively used COMPRESSED format, and now it honors the
conversion format specified in the EC_KEY object being exported to a
provider when this function is called.

Expand documentation about `OSSL_PKEY_PARAM_PUB_KEY` and mention the
3.1 change in behavior for our providers.

Fixes #16595

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19681)

(cherry picked from commit 926db476bc669fdcc4c4d2f1cb547060bdbfa153)
2022-11-29 16:03:04 +01:00
..
2020-02-26 21:04:38 +01:00
2022-11-16 18:02:02 +11:00
2022-11-25 11:36:35 +11:00

OpenSSL Documentation

README.md This file

fingerprints.txt PGP fingerprints of authorised release signers

standards.txt standards.txt Moved to the web, https://www.openssl.org/docs/standards.html

HOWTO/ A few how-to documents; not necessarily up-to-date

man1/ The openssl command-line tools; start with openssl.pod

man3/ The SSL library and the crypto library

man5/ File formats

man7/ Overviews; start with crypto.pod and ssl.pod, for example Algorithm specific EVP_PKEY documentation.

Formatted versions of the manpages (apps,ssl,crypto) can be found at https://www.openssl.org/docs/manpages.html