[PULL 02/20] target/arm: Fix PAuth sbox functions

[Peter Maydell]

From: Vincent Dehors <address@hidden>

In the PAC computation, sbox was applied over wrong bits.
As this is a 4-bit sbox, bit index should be incremented by 4 instead of 16.

Test vector from QARMA paper (https://eprint.iacr.org/2016/444.pdf) was
used to verify one computation of the pauth_computepac() function which
uses sbox2.

Launchpad: https://bugs.launchpad.net/bugs/1859713
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Vincent DEHORS <address@hidden>
Signed-off-by: Adrien GRASSEIN <address@hidden>
Message-id: address@hidden
Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>
---
 target/arm/pauth_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index d3194f20437..0a5f41e10c5 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -89,7 +89,7 @@ static uint64_t pac_sub(uint64_t i)
     uint64_t o = 0;
     int b;
 
-    for (b = 0; b < 64; b += 16) {
+    for (b = 0; b < 64; b += 4) {
         o |= (uint64_t)sub[(i >> b) & 0xf] << b;
     }
     return o;
@@ -104,7 +104,7 @@ static uint64_t pac_inv_sub(uint64_t i)
     uint64_t o = 0;
     int b;
 
-    for (b = 0; b < 64; b += 16) {
+    for (b = 0; b < 64; b += 4) {
         o |= (uint64_t)inv_sub[(i >> b) & 0xf] << b;
     }
     return o;
-- 
2.20.1