diff options
| -rw-r--r-- | doc/news.rst | 4 | ||||
| -rw-r--r-- | src/lib/utils/donna128.h | 18 |
2 files changed, 16 insertions, 6 deletions
diff --git a/doc/news.rst b/doc/news.rst index 8c4db8b09..a5f6cba72 100644 --- a/doc/news.rst +++ b/doc/news.rst @@ -12,6 +12,10 @@ Version 1.11.31, Not Yet Released * Add KDF1 from ISO 18033 (GH #483) +* Fix undefined behavior in Curve25519 on platforms without a native 128-bit + integer type. This was known to produce incorrect results on 32-bit ARM + under Clang. GH #532 + * Fixes for FreeBSD (GH #517) and OpenBSD (GH #523) * Support for getting entropy from EGD is deprecated, and will be removed in diff --git a/src/lib/utils/donna128.h b/src/lib/utils/donna128.h index c2a3e0d2e..2a2d1e339 100644 --- a/src/lib/utils/donna128.h +++ b/src/lib/utils/donna128.h @@ -23,18 +23,24 @@ class donna128 friend donna128 operator>>(const donna128& x, size_t shift) { donna128 z = x; - const u64bit carry = z.h << (64 - shift); - z.h = (z.h >> shift); - z.l = (z.l >> shift) | carry; + if(shift > 0) + { + const u64bit carry = z.h << (64 - shift); + z.h = (z.h >> shift); + z.l = (z.l >> shift) | carry; + } return z; } friend donna128 operator<<(const donna128& x, size_t shift) { donna128 z = x; - const u64bit carry = z.l >> (64 - shift); - z.l = (z.l << shift); - z.h = (z.h << shift) | carry; + if(shift > 0) + { + const u64bit carry = z.l >> (64 - shift); + z.l = (z.l << shift); + z.h = (z.h << shift) | carry; + } return z; } |