Rework DES encryption/decryption loops.

Use a slightly unrolled loop, which gets us half way between DES_UNROLL and
no DES_UNROLL. While we're not terribly concerned by DES performance, this
gets us a small gain on aarch64 and a small loss on arm. But above all, we
end up with simpler code.

ok tb@

2 files changed, 31 insertions, 124 deletions

diff --git a/src/lib/libcrypto/des/des_enc.c b/src/lib/libcrypto/des/des_enc.c
index deec50bffb..cb89784fb0 100644
--- a/src/lib/libcrypto/des/des_enc.c
+++ b/src/lib/libcrypto/des/des_enc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: des_enc.c,v 1.20 2024/08/31 16:17:13 jsing Exp $ */
+/* $OpenBSD: des_enc.c,v 1.21 2025/07/27 13:26:24 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -210,10 +210,8 @@ void
 DES_encrypt1(DES_LONG *data, DES_key_schedule *ks, int enc)
 {
         DES_LONG l, r, t, u;
-#ifndef DES_UNROLL
-        int i;
-#endif
         DES_LONG *s;
+        int i;
 
         r = data[0];
         l = data[1];
@@ -231,56 +229,21 @@ DES_encrypt1(DES_LONG *data, DES_key_schedule *ks, int enc)
         l = ROTATE(l, 29) & 0xffffffffL;
 
         s = ks->ks->deslong;
-        /* I don't know if it is worth the effort of loop unrolling the
-         * inner loop */
+
         if (enc) {
-#ifdef DES_UNROLL
-                D_ENCRYPT(l, r, 0); /*  1 */
-                D_ENCRYPT(r, l, 2); /*  2 */
-                D_ENCRYPT(l, r, 4); /*  3 */
-                D_ENCRYPT(r, l, 6); /*  4 */
-                D_ENCRYPT(l, r, 8); /*  5 */
-                D_ENCRYPT(r, l, 10); /*  6 */
-                D_ENCRYPT(l, r, 12); /*  7 */
-                D_ENCRYPT(r, l, 14); /*  8 */
-                D_ENCRYPT(l, r, 16); /*  9 */
-                D_ENCRYPT(r, l, 18); /*  10 */
-                D_ENCRYPT(l, r, 20); /*  11 */
-                D_ENCRYPT(r, l, 22); /*  12 */
-                D_ENCRYPT(l, r, 24); /*  13 */
-                D_ENCRYPT(r, l, 26); /*  14 */
-                D_ENCRYPT(l, r, 28); /*  15 */
-                D_ENCRYPT(r, l, 30); /*  16 */
-#else
-                for (i = 0; i < 32; i += 4) {
-                        D_ENCRYPT(l, r, i + 0); /*  1 */
-                        D_ENCRYPT(r, l, i + 2); /*  2 */
+                for (i = 0; i < 32; i += 8) {
+                        D_ENCRYPT(l, r, i + 0);
+                        D_ENCRYPT(r, l, i + 2);
+                        D_ENCRYPT(l, r, i + 4);
+                        D_ENCRYPT(r, l, i + 6);
                 }
-#endif
         } else {
-#ifdef DES_UNROLL
-                D_ENCRYPT(l, r, 30); /* 16 */
-                D_ENCRYPT(r, l, 28); /* 15 */
-                D_ENCRYPT(l, r, 26); /* 14 */
-                D_ENCRYPT(r, l, 24); /* 13 */
-                D_ENCRYPT(l, r, 22); /* 12 */
-                D_ENCRYPT(r, l, 20); /* 11 */
-                D_ENCRYPT(l, r, 18); /* 10 */
-                D_ENCRYPT(r, l, 16); /*  9 */
-                D_ENCRYPT(l, r, 14); /*  8 */
-                D_ENCRYPT(r, l, 12); /*  7 */
-                D_ENCRYPT(l, r, 10); /*  6 */
-                D_ENCRYPT(r, l, 8); /*  5 */
-                D_ENCRYPT(l, r, 6); /*  4 */
-                D_ENCRYPT(r, l, 4); /*  3 */
-                D_ENCRYPT(l, r, 2); /*  2 */
-                D_ENCRYPT(r, l, 0); /*  1 */
-#else
-                for (i = 30; i > 0; i -= 4) {
-                        D_ENCRYPT(l, r, i - 0); /* 16 */
-                        D_ENCRYPT(r, l, i - 2); /* 15 */
+                for (i = 32; i > 0; i -= 8) {
+                        D_ENCRYPT(l, r, i - 2);
+                        D_ENCRYPT(r, l, i - 4);
+                        D_ENCRYPT(l, r, i - 6);
+                        D_ENCRYPT(r, l, i - 8);
                 }
-#endif
         }
 
         /* rotate and clear the top bits on machines with 8byte longs */
@@ -298,10 +261,8 @@ void
 DES_encrypt2(DES_LONG *data, DES_key_schedule *ks, int enc)
 {
         DES_LONG l, r, t, u;
-#ifndef DES_UNROLL
-        int i;
-#endif
         DES_LONG *s;
+        int i;
 
         r = data[0];
         l = data[1];
@@ -320,53 +281,19 @@ DES_encrypt2(DES_LONG *data, DES_key_schedule *ks, int enc)
         /* I don't know if it is worth the effort of loop unrolling the
          * inner loop */
         if (enc) {
-#ifdef DES_UNROLL
-                D_ENCRYPT(l, r, 0); /*  1 */
-                D_ENCRYPT(r, l, 2); /*  2 */
-                D_ENCRYPT(l, r, 4); /*  3 */
-                D_ENCRYPT(r, l, 6); /*  4 */
-                D_ENCRYPT(l, r, 8); /*  5 */
-                D_ENCRYPT(r, l, 10); /*  6 */
-                D_ENCRYPT(l, r, 12); /*  7 */
-                D_ENCRYPT(r, l, 14); /*  8 */
-                D_ENCRYPT(l, r, 16); /*  9 */
-                D_ENCRYPT(r, l, 18); /*  10 */
-                D_ENCRYPT(l, r, 20); /*  11 */
-                D_ENCRYPT(r, l, 22); /*  12 */
-                D_ENCRYPT(l, r, 24); /*  13 */
-                D_ENCRYPT(r, l, 26); /*  14 */
-                D_ENCRYPT(l, r, 28); /*  15 */
-                D_ENCRYPT(r, l, 30); /*  16 */
-#else
-                for (i = 0; i < 32; i += 4) {
-                        D_ENCRYPT(l, r, i + 0); /*  1 */
-                        D_ENCRYPT(r, l, i + 2); /*  2 */
+                for (i = 0; i < 32; i += 8) {
+                        D_ENCRYPT(l, r, i + 0);
+                        D_ENCRYPT(r, l, i + 2);
+                        D_ENCRYPT(l, r, i + 4);
+                        D_ENCRYPT(r, l, i + 6);
                 }
-#endif
         } else {
-#ifdef DES_UNROLL
-                D_ENCRYPT(l, r, 30); /* 16 */
-                D_ENCRYPT(r, l, 28); /* 15 */
-                D_ENCRYPT(l, r, 26); /* 14 */
-                D_ENCRYPT(r, l, 24); /* 13 */
-                D_ENCRYPT(l, r, 22); /* 12 */
-                D_ENCRYPT(r, l, 20); /* 11 */
-                D_ENCRYPT(l, r, 18); /* 10 */
-                D_ENCRYPT(r, l, 16); /*  9 */
-                D_ENCRYPT(l, r, 14); /*  8 */
-                D_ENCRYPT(r, l, 12); /*  7 */
-                D_ENCRYPT(l, r, 10); /*  6 */
-                D_ENCRYPT(r, l, 8); /*  5 */
-                D_ENCRYPT(l, r, 6); /*  4 */
-                D_ENCRYPT(r, l, 4); /*  3 */
-                D_ENCRYPT(l, r, 2); /*  2 */
-                D_ENCRYPT(r, l, 0); /*  1 */
-#else
-                for (i = 30; i > 0; i -= 4) {
-                        D_ENCRYPT(l, r, i - 0); /* 16 */
-                        D_ENCRYPT(r, l, i - 2); /* 15 */
+                for (i = 32; i > 0; i -= 8) {
+                        D_ENCRYPT(l, r, i - 2);
+                        D_ENCRYPT(r, l, i - 4);
+                        D_ENCRYPT(l, r, i - 6);
+                        D_ENCRYPT(r, l, i - 8);
                 }
-#endif
         }
         /* rotate and clear the top bits on machines with 8byte longs */
         data[0] = ROTATE(l, 3) & 0xffffffffL;
diff --git a/src/lib/libcrypto/des/des_fcrypt.c b/src/lib/libcrypto/des/des_fcrypt.c
index b33b1240c2..2dd071f5d0 100644
--- a/src/lib/libcrypto/des/des_fcrypt.c
+++ b/src/lib/libcrypto/des/des_fcrypt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: des_fcrypt.c,v 1.4 2024/08/31 16:22:18 jsing Exp $ */
+/* $OpenBSD: des_fcrypt.c,v 1.5 2025/07/27 13:26:24 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -90,8 +90,8 @@ fcrypt_body(DES_LONG *out, DES_key_schedule *ks, DES_LONG Eswap0,
 {
         DES_LONG l, r, t, u;
         DES_LONG *s;
-        int j;
         DES_LONG E0, E1;
+        int i, j;
 
         l = 0;
         r = 0;
@@ -101,32 +101,12 @@ fcrypt_body(DES_LONG *out, DES_key_schedule *ks, DES_LONG Eswap0,
         E1 = Eswap1;
 
         for (j = 0; j < 25; j++) {
-#ifndef DES_UNROLL
-                int i;
-
-                for (i = 0; i < 32; i += 4) {
-                        D_ENCRYPT(l, r, i + 0); /*  1 */
-                        D_ENCRYPT(r, l, i + 2); /*  2 */
+                for (i = 0; i < 32; i += 8) {
+                        D_ENCRYPT(l, r, i + 0);
+                        D_ENCRYPT(r, l, i + 2);
+                        D_ENCRYPT(l, r, i + 4);
+                        D_ENCRYPT(r, l, i + 6);
                 }
-#else
-                D_ENCRYPT(l, r, 0); /*  1 */
-                D_ENCRYPT(r, l, 2); /*  2 */
-                D_ENCRYPT(l, r, 4); /*  3 */
-                D_ENCRYPT(r, l, 6); /*  4 */
-                D_ENCRYPT(l, r, 8); /*  5 */
-                D_ENCRYPT(r, l, 10); /*  6 */
-                D_ENCRYPT(l, r, 12); /*  7 */
-                D_ENCRYPT(r, l, 14); /*  8 */
-                D_ENCRYPT(l, r, 16); /*  9 */
-                D_ENCRYPT(r, l, 18); /*  10 */
-                D_ENCRYPT(l, r, 20); /*  11 */
-                D_ENCRYPT(r, l, 22); /*  12 */
-                D_ENCRYPT(l, r, 24); /*  13 */
-                D_ENCRYPT(r, l, 26); /*  14 */
-                D_ENCRYPT(l, r, 28); /*  15 */
-                D_ENCRYPT(r, l, 30); /*  16 */
-#endif
-
                 t = l;
                 l = r;
                 r = t;