ECC import: more useful choice of INVALID_ARGUMENT vs NOT_SUPPORTED

Attempting to create an ECC key with a curve specification that is not
valid can plausibly fail with PSA_ERROR_INVALID_ARGUMENT ("this is not
a curve specification at all") or PSA_ERROR_NOT_SUPPORTED ("this may
be a curve specification, but not one I support"). The choice of error
is somewhat subjective.

Before this commit, due to happenstance in the implementation, an
attempt to use a curve that is declared in the PSA API but not
implemented in Mbed TLS returned PSA_ERROR_INVALID_ARGUMENT, whereas
an attempt to use a curve that Mbed TLS supports but for which support
was disabled at compile-time returned PSA_ERROR_NOT_SUPPORTED. This
inconsistency made it difficult to write negative tests that could
work whether the curve is implemented via Mbed TLS code or via a
driver.

After this commit, any attempt to use parameters that are not
recognized fails with NOT_SUPPORTED, whether a curve with the
specified size might plausibly exist or not, because "might plausibly
exist" is not something Mbed TLS can determine.

To keep returning INVALID_ARGUMENT when importing an ECC key with an
explicit "bits" attribute that is inconsistent with the size of the
key material, this commit changes the way mbedtls_ecc_group_of_psa()
works: it now works on a size in bits rather than bytes, with an extra
flag indicating whether the bit-size must be exact or not.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_psa_crypto.data b/tests/suites/test_suite_psa_crypto.data
index 6af4120..35c259b 100644
--- a/tests/suites/test_suite_psa_crypto.data
+++ b/tests/suites/test_suite_psa_crypto.data
@@ -300,17 +300,41 @@
 # The spec allows either INVALID_ARGUMENT or NOT_SUPPORTED
 import_with_data:"":PSA_KEY_TYPE_RAW_DATA:8:PSA_ERROR_INVALID_ARGUMENT
 
-PSA import EC keypair: DER format
+PSA import EC keypair: explicit bit-size=255 for secp256r1
 depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
-import_with_data:"3077020101042049c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eeea00a06082a8648ce3d030107a144034200047772656f814b399279d5e1f1781fac6f099a3c5ca1b0e35351834b08b65e0b572590cdaf8f769361bcf34acfc11e5e074e8426bdde04be6e653945449617de45":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):0:PSA_ERROR_INVALID_ARGUMENT
+import_with_data:"49c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eee":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):255:PSA_ERROR_NOT_SUPPORTED
 
-PSA import EC keypair: too short
-depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
-import_with_data:"0123456789abcdef0123456789abcdef":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):0:PSA_ERROR_INVALID_ARGUMENT
+PSA import EC keypair: explicit bit-size=521 for secp521r1 (good)
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP521R1_ENABLED
+import_with_data:"01b1b6ad07bb79e7320da59860ea28e055284f6058f279de666e06d435d2af7bda28d99fa47b7dd0963e16b0073078ee8b8a38d966a582f46d19ff95df3ad9685aae":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):521:PSA_SUCCESS
 
-PSA import EC keypair: public key
+PSA import EC keypair: explicit bit-size=528 for secp521r1 (bad)
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP521R1_ENABLED
+import_with_data:"01b1b6ad07bb79e7320da59860ea28e055284f6058f279de666e06d435d2af7bda28d99fa47b7dd0963e16b0073078ee8b8a38d966a582f46d19ff95df3ad9685aae":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):528:PSA_ERROR_NOT_SUPPORTED
+
+PSA import EC keypair: explicit bit-size, DER format
 depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
-import_with_data:"04dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):0:PSA_ERROR_INVALID_ARGUMENT
+import_with_data:"3077020101042049c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eeea00a06082a8648ce3d030107a144034200047772656f814b399279d5e1f1781fac6f099a3c5ca1b0e35351834b08b65e0b572590cdaf8f769361bcf34acfc11e5e074e8426bdde04be6e653945449617de45":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):256:PSA_ERROR_INVALID_ARGUMENT
+
+PSA import EC keypair: explicit bit-size, too short
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+import_with_data:"49c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13e":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):256:PSA_ERROR_INVALID_ARGUMENT
+
+PSA import EC keypair: explicit bit-size, too long (00 start)
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+import_with_data:"0049c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eee":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):256:PSA_ERROR_INVALID_ARGUMENT
+
+PSA import EC keypair: explicit bit-size, too long (00 end)
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+import_with_data:"49c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eee00":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):256:PSA_ERROR_INVALID_ARGUMENT
+
+PSA import EC keypair: explicit bit-size, public key
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+import_with_data:"04dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):256:PSA_ERROR_INVALID_ARGUMENT
+
+PSA import EC keypair: implicit bit-size, not a valid length
+depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
+import_with_data:"0123456789abcdef0123456789abcdef":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1):0:PSA_ERROR_NOT_SUPPORTED
 
 PSA import EC keypair: secp256r1, all-bits-zero (bad)
 depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
@@ -332,10 +356,6 @@
 depends_on:PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
 import_with_data:"3078020101042100ab45435712649cb30bbddac49197eebf2740ffc7f874d9244c3460f54f322d3aa00a06082a8648ce3d030107a14403420004dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_FAMILY_SECP_R1):0:PSA_ERROR_INVALID_ARGUMENT
 
-PSA import EC keypair: valid key but RSA
-depends_on:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_DP_BP512R1_ENABLED
-import_with_data:"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":PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_BRAINPOOL_P_R1):0:PSA_ERROR_INVALID_ARGUMENT
-
 PSA import AES: bits=0 ok
 depends_on:MBEDTLS_AES_C
 import_with_data:"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa":PSA_KEY_TYPE_AES:0:PSA_SUCCESS