+ case EOP_SHA3:
+#ifdef EXIM_HAVE_SHA3
+ {
+ hctx h;
+ blob b;
+ char st[3];
+ hashmethod m = !arg ? HASH_SHA3_256
+ : Ustrcmp(arg, "224") == 0 ? HASH_SHA3_224
+ : Ustrcmp(arg, "256") == 0 ? HASH_SHA3_256
+ : Ustrcmp(arg, "384") == 0 ? HASH_SHA3_384
+ : Ustrcmp(arg, "512") == 0 ? HASH_SHA3_512
+ : HASH_BADTYPE;
+
+ if (m == HASH_BADTYPE)
+ {
+ expand_string_message = US"unrecognised sha3 variant";
+ goto EXPAND_FAILED;
+ }
+
+ exim_sha_init(&h, m);
+ exim_sha_update(&h, sub, Ustrlen(sub));
+ exim_sha_finish(&h, &b);
+ while (b.len-- > 0)
+ {
+ sprintf(st, "%02X", *b.data++);
+ yield = string_catn(yield, &size, &ptr, US st, 2);
+ }
+ }
+ continue;
+#else
+ expand_string_message = US"sha3 only supported with GnuTLS 3.5.0 +";
+ goto EXPAND_FAILED;
+#endif
+