additional sanity checks on invalid input

[JacobBarthelmeh]

Related scripts change is here (https://github.com/wolfSSL/scripts/pull/573)

[Copilot]

Pull request overview

This PR adds additional input validation to ECC ECDSA sign/verify paths, treating an all-zero digest as invalid input and updating tests accordingly.

Changes:

• Add “zero digest” rejection checks to software/SP ECC ECDSA sign/verify implementations (returning ECC_BAD_ARG_E).
• Update the ECC test case that signs/verifies an all-zero digest to expect failures.
• Remove the test-skip macro (WC_TEST_NO_ECC_SIGN_VERIFY_ZERO_DIGEST) from settings.h.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
wolfssl/wolfcrypt/settings.h	Removes a hardware-specific test skip macro for ECC zero-digest sign/verify.
wolfcrypt/test/test.c	Changes ECC sign/verify test logic to expect failure on all-zero digests.
wolfcrypt/src/sp_x86_64.c	Adds early rejection for all-zero digests in SP sign/verify for P-256/384/521 (blocking + nonblocking).
wolfcrypt/src/sp_cortexm.c	Same SP zero-digest rejection checks for Cortex-M SP implementation.
wolfcrypt/src/sp_c64.c	Same SP zero-digest rejection checks for C64 SP implementation.
wolfcrypt/src/sp_c32.c	Same SP zero-digest rejection checks for C32 SP implementation.
wolfcrypt/src/sp_armthumb.c	Same SP zero-digest rejection checks for Arm Thumb SP implementation.
wolfcrypt/src/sp_arm64.c	Same SP zero-digest rejection checks for Arm64 SP implementation.
wolfcrypt/src/sp_arm32.c	Same SP zero-digest rejection checks for Arm32 SP implementation.
wolfcrypt/src/ecc.c	Adds mp_iszero(e) checks in software sign/verify to return ECC_BAD_ARG_E.

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[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m4-baremetal

• FLASH: .text +64 B (+0.1%, 64,371 B / 262,144 B, total: 25% used)

gcc-arm-cortex-m4-tls12

• FLASH: .text +64 B (+0.1%, 120,314 B / 262,144 B, total: 46% used)
  No memory changes detected for:
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-min-ecc