Cleanups in Poly1305

1 files changed, 23 insertions, 23 deletions

diff --git a/src/lib/mac/poly1305/poly1305.cpp b/src/lib/mac/poly1305/poly1305.cpp
index bdda3720c..32027b8d0 100644
--- a/src/lib/mac/poly1305/poly1305.cpp
+++ b/src/lib/mac/poly1305/poly1305.cpp
@@ -12,6 +12,7 @@
 #include <botan/loadstor.h>
 #include <botan/mul128.h>
 #include <botan/internal/donna128.h>
+#include <botan/internal/ct_utils.h>
 
 namespace Botan {
 
@@ -49,15 +50,15 @@ void poly1305_blocks(secure_vector<uint64_t>& X, const uint8_t *m, size_t blocks
    const uint64_t r1 = X[1];
    const uint64_t r2 = X[2];
 
-   const uint64_t M44 = 0xfffffffffff;
-   const uint64_t M42 = 0x3ffffffffff;
+   const uint64_t M44 = 0xFFFFFFFFFFF;
+   const uint64_t M42 = 0x3FFFFFFFFFF;
 
    uint64_t h0 = X[3+0];
    uint64_t h1 = X[3+1];
    uint64_t h2 = X[3+2];
 
-   const uint64_t s1 = r1 * (5 << 2);
-   const uint64_t s2 = r2 * (5 << 2);
+   const uint64_t s1 = r1 * 20;
+   const uint64_t s2 = r2 * 20;
 
    for(size_t i = 0; i != blocks; ++i)
       {
@@ -95,42 +96,41 @@ void poly1305_blocks(secure_vector<uint64_t>& X, const uint8_t *m, size_t blocks
 
 void poly1305_finish(secure_vector<uint64_t>& X, uint8_t mac[16])
    {
+   const uint64_t M44 = 0xFFFFFFFFFFF;
+   const uint64_t M42 = 0x3FFFFFFFFFF;
+
    /* fully carry h */
    uint64_t h0 = X[3+0];
    uint64_t h1 = X[3+1];
    uint64_t h2 = X[3+2];
 
    uint64_t c;
-                c = (h1 >> 44); h1 &= 0xfffffffffff;
-   h2 += c;     c = (h2 >> 42); h2 &= 0x3ffffffffff;
-   h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
-   h1 += c;     c = (h1 >> 44); h1 &= 0xfffffffffff;
-   h2 += c;     c = (h2 >> 42); h2 &= 0x3ffffffffff;
-   h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
+                c = (h1 >> 44); h1 &= M44;
+   h2 += c;     c = (h2 >> 42); h2 &= M42;
+   h0 += c * 5; c = (h0 >> 44); h0 &= M44;
+   h1 += c;     c = (h1 >> 44); h1 &= M44;
+   h2 += c;     c = (h2 >> 42); h2 &= M42;
+   h0 += c * 5; c = (h0 >> 44); h0 &= M44;
    h1 += c;
 
    /* compute h + -p */
-   uint64_t g0 = h0 + 5; c = (g0 >> 44); g0 &= 0xfffffffffff;
-   uint64_t g1 = h1 + c; c = (g1 >> 44); g1 &= 0xfffffffffff;
+   uint64_t g0 = h0 + 5; c = (g0 >> 44); g0 &= M44;
+   uint64_t g1 = h1 + c; c = (g1 >> 44); g1 &= M44;
    uint64_t g2 = h2 + c - (static_cast<uint64_t>(1) << 42);
 
    /* select h if h < p, or h + -p if h >= p */
-   c = (g2 >> ((sizeof(uint64_t) * 8) - 1)) - 1;
-   g0 &= c;
-   g1 &= c;
-   g2 &= c;
-   c = ~c;
-   h0 = (h0 & c) | g0;
-   h1 = (h1 & c) | g1;
-   h2 = (h2 & c) | g2;
+   c = CT::expand_mask<uint64_t>(c);
+   h0 = CT::select(c, g0, h0);
+   h1 = CT::select(c, g1, h1);
+   h2 = CT::select(c, g2, h2);
 
    /* h = (h + pad) */
    const uint64_t t0 = X[6];
    const uint64_t t1 = X[7];
 
-   h0 += (( t0                    ) & 0xfffffffffff)    ; c = (h0 >> 44); h0 &= 0xfffffffffff;
-   h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c; c = (h1 >> 44); h1 &= 0xfffffffffff;
-   h2 += (((t1 >> 24)             ) & 0x3ffffffffff) + c;                 h2 &= 0x3ffffffffff;
+   h0 += (( t0                    ) & M44)    ; c = (h0 >> 44); h0 &= M44;
+   h1 += (((t0 >> 44) | (t1 << 20)) & M44) + c; c = (h1 >> 44); h1 &= M44;
+   h2 += (((t1 >> 24)             ) & M42) + c;                 h2 &= M42;
 
    /* mac = h % (2^128) */
    h0 = ((h0      ) | (h1 << 44));