nrf_security: drivers: cracen: Fix Ed25519ph bug for 54H

Hashing operation would fail due to dom2 being stored in
memory inaccessible by cracen.
Changed const to static to enforce storage in ram until
operation is completed.

Signed-off-by: Dag Erik Gjørvad <[email protected]>

Author: degjorva

subsys/nrf_security/src/drivers/cracen/sicrypto/src/ed25519ph.c

@@ -48,15 +48,13 @@
 /* This is the ASCII string with the
  * PHflag 1 and context size 0 appended as defined in:
  * https://datatracker.ietf.org/doc/html/rfc8032.html#section-2
- * used for domain seperation between Ed25519 and Ed25519ph
+ * used for domain seperation between Ed25519 and Ed25519ph.
+ * Due to hardware limitations dom2 needs to be stored in RAM
+ * Therefore is not stored as a const.
  */
-const char dom2[34] = {
-	0x53, 0x69, 0x67, 0x45, 0x64, 0x32, 0x35,
-	0x35, 0x31, 0x39, 0x20, 0x6e, 0x6f, 0x20,
-	0x45, 0x64, 0x32, 0x35, 0x35, 0x31, 0x39,
-	0x20, 0x63, 0x6f, 0x6c, 0x6c, 0x69, 0x73,
-	0x69, 0x6f, 0x6e, 0x73, 0x01, 0x00
-};
+static char dom2[34] = {0x53, 0x69, 0x67, 0x45, 0x64, 0x32, 0x35, 0x35, 0x31, 0x39, 0x20, 0x6e,
+			0x6f, 0x20, 0x45, 0x64, 0x32, 0x35, 0x35, 0x31, 0x39, 0x20, 0x63, 0x6f,
+			0x6c, 0x6c, 0x69, 0x73, 0x69, 0x6f, 0x6e, 0x73, 0x01, 0x00};
 
 static int finish_ed25519ph_ver(struct sitask *t, struct siwq *wq)
 {
@@ -103,7 +101,7 @@ static void run_ed25519ph_ver(struct sitask *t)
 }
 
 static void si_sig_create_ed25519ph_verify(struct sitask *t, const struct si_sig_pubkey *pubkey,
-					 const struct si_sig_signature *signature)
+					   const struct si_sig_signature *signature)
 {
 	if (t->workmemsz < SX_ED25519_DGST_SZ) {
 		si_task_mark_final(t, SX_ERR_WORKMEM_BUFFER_TOO_SMALL);