Improve PSA offset/len defines for tlv and remove some defs from bootutil

[de-nordic]

Fixes in encrypted_psa.
BOOTUTIL_CRYPTO_AES_CTR_KEY_SIZE has been replaced with BOOT_ENC_KEY_SIZE
BOOTUTIL_CRYPTO_AES_CTR_BLOCK_SIZE has been replaced with BOOT_ENC_BLOCK_SIZE

[Copilot]

Pull Request Overview

This PR improves the PSA offset/length definitions for TLV handling and removes outdated bootutil definitions, streamlining the key and block size constants used in encryption functions.

• Update key and block size constants from BOOTUTIL_CRYPTO_AES_CTR_KEY_SIZE/BOOTUTIL_CRYPTO_AES_CTR_BLOCK_SIZE to BOOT_ENC_KEY_SIZE/BOOT_ENC_BLOCK_SIZE.
• Adjust associated index and length calculations in encryption and decryption routines.
• Refactor crypto header definitions for consistency across crypto branches.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
boot/bootutil/src/encrypted_psa.c	Updated key derivation and decryption routines to use the new BOOT_ENC_* definitions.
boot/bootutil/src/encrypted.c	Revised AES key unwrap and decryption functions to consistently reflect the updated defines.
boot/bootutil/include/bootutil/crypto/aes_ctr.h	Modified macro definitions to use BOOT_ENC_BLOCK_SIZE (and ensure compatibility with new sizes).

Comments suppressed due to low confidence (3)

boot/bootutil/src/encrypted_psa.c:184

• The updated argument in psa_key_derivation_key_agreement has changed from BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE to EC_PUBK_LEN; please confirm that using the public key length here is intentional and matches the expected input size for key derivation. Adding a clarifying comment could aid future maintainers.

psa_ret = psa_key_derivation_key_agreement(&key_do, PSA_KEY_DERIVATION_INPUT_SECRET, kid, &buf[EC_PUBK_INDEX], EC_PUBK_LEN);

boot/bootutil/src/encrypted.c:537

• Ensure that there are adequate tests covering the new key derivation logic with the updated key size constants, including both success and failure scenarios for the hkdf function.

if (rc != 0 || len != (BOOT_ENC_KEY_SIZE + BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE)) {

boot/bootutil/include/bootutil/crypto/aes_ctr.h:25

• Review the consistency of macro definitions across different crypto branches; verify that BOOT_ENC_KEY_SIZE is defined for the MBEDTLS and PSA branches, as it is not explicitly declared in this header.

#define BOOT_ENC_BLOCK_SIZE (16)