s390x: Fix keccak xofs via CPACF
CPACF does not directly support xofs.  Emulate this by using single block
operations on an empty input block.
Fixes: ("s390x: Optimize kmac")
@@ -182,6 +182,8 @@ static int s390x_keccakc_final(unsigned char *md, void *vctx, int padding)
KECCAK1600_CTX *ctx = vctx;
size_t bsz = ctx->block_size;
size_t num = ctx->bufsz;
+ size_t needed = ctx->md_size;
+ static const unsigned char empty[KECCAK1600_WIDTH / 8] = {0};
if (!ossl_prov_is_running())
return 0;
@@ -191,7 +193,14 @@ static int s390x_keccakc_final(unsigned char *md, void *vctx, int padding)
ctx->buf[num] = padding;
ctx->buf[bsz - 1] |= 0x80;
s390x_kimd(ctx->buf, bsz, ctx->pad, ctx->A);
- memcpy(md, ctx->A, ctx->md_size);
+ while (needed > bsz) {
+ memcpy(md, ctx->A, bsz);
+ needed -= bsz;
+ md += bsz;
+ s390x_kimd(empty, bsz, ctx->pad, ctx->A);
+ }
+ memcpy(md, ctx->A, needed);
+
return 1;
}
