crypto: sig - Introduce sig_alg backend

Commit 6cb8815f41a9 ("crypto: sig - Add interface for sign/verify")
began a transition of asymmetric sign/verify operations from
crypto_akcipher to a new crypto_sig frontend.

Internally, the crypto_sig frontend still uses akcipher_alg as backend,
however:

   "The link between sig and akcipher is meant to be temporary.  The
    plan is to create a new low-level API for sig and then migrate
    the signature code over to that from akcipher."
    https://lore.kernel.org/r/ZrG6w9wsb-iiLZIF@gondor.apana.org.au/

   "having a separate alg for sig is definitely where we want to
    be since there is very little that the two types actually share."
    https://lore.kernel.org/r/ZrHlpz4qnre0zWJO@gondor.apana.org.au/

Take the next step of that migration and augment the crypto_sig frontend
with a sig_alg backend to which all algorithms can be moved.

During the migration, there will briefly be signature algorithms that
are still based on crypto_akcipher, whilst others are already based on
crypto_sig.  Allow for that by building a fork into crypto_sig_*() API
calls (i.e. crypto_sig_maxsize() and friends) such that one of the two
backends is selected based on the transform's cra_type.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 13 insertions, 0 deletions

diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index ed1640f3e352..39dd1d558883 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -162,6 +162,19 @@ struct akcipher_testvec {
 	enum OID algo;
 };
 
+struct sig_testvec {
+	const unsigned char *key;
+	const unsigned char *params;
+	const unsigned char *m;
+	const unsigned char *c;
+	unsigned int key_len;
+	unsigned int param_len;
+	unsigned int m_size;
+	unsigned int c_size;
+	bool public_key_vec;
+	enum OID algo;
+};
+
 struct kpp_testvec {
 	const unsigned char *secret;
 	const unsigned char *b_secret;