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-rw-r--r--crypto/gf128mul.c111
1 files changed, 47 insertions, 64 deletions
diff --git a/crypto/gf128mul.c b/crypto/gf128mul.c
index 72015fee533d..dc012129c063 100644
--- a/crypto/gf128mul.c
+++ b/crypto/gf128mul.c
@@ -44,7 +44,7 @@
---------------------------------------------------------------------------
Issue 31/01/2006
- This file provides fast multiplication in GF(128) as required by several
+ This file provides fast multiplication in GF(2^128) as required by several
cryptographic authentication modes
*/
@@ -88,76 +88,59 @@
q(0xf8), q(0xf9), q(0xfa), q(0xfb), q(0xfc), q(0xfd), q(0xfe), q(0xff) \
}
-/* Given the value i in 0..255 as the byte overflow when a field element
- in GHASH is multiplied by x^8, this function will return the values that
- are generated in the lo 16-bit word of the field value by applying the
- modular polynomial. The values lo_byte and hi_byte are returned via the
- macro xp_fun(lo_byte, hi_byte) so that the values can be assembled into
- memory as required by a suitable definition of this macro operating on
- the table above
-*/
-
-#define xx(p, q) 0x##p##q
+/*
+ * Given a value i in 0..255 as the byte overflow when a field element
+ * in GF(2^128) is multiplied by x^8, the following macro returns the
+ * 16-bit value that must be XOR-ed into the low-degree end of the
+ * product to reduce it modulo the polynomial x^128 + x^7 + x^2 + x + 1.
+ *
+ * There are two versions of the macro, and hence two tables: one for
+ * the "be" convention where the highest-order bit is the coefficient of
+ * the highest-degree polynomial term, and one for the "le" convention
+ * where the highest-order bit is the coefficient of the lowest-degree
+ * polynomial term. In both cases the values are stored in CPU byte
+ * endianness such that the coefficients are ordered consistently across
+ * bytes, i.e. in the "be" table bits 15..0 of the stored value
+ * correspond to the coefficients of x^15..x^0, and in the "le" table
+ * bits 15..0 correspond to the coefficients of x^0..x^15.
+ *
+ * Therefore, provided that the appropriate byte endianness conversions
+ * are done by the multiplication functions (and these must be in place
+ * anyway to support both little endian and big endian CPUs), the "be"
+ * table can be used for multiplications of both "bbe" and "ble"
+ * elements, and the "le" table can be used for multiplications of both
+ * "lle" and "lbe" elements.
+ */
-#define xda_bbe(i) ( \
- (i & 0x80 ? xx(43, 80) : 0) ^ (i & 0x40 ? xx(21, c0) : 0) ^ \
- (i & 0x20 ? xx(10, e0) : 0) ^ (i & 0x10 ? xx(08, 70) : 0) ^ \
- (i & 0x08 ? xx(04, 38) : 0) ^ (i & 0x04 ? xx(02, 1c) : 0) ^ \
- (i & 0x02 ? xx(01, 0e) : 0) ^ (i & 0x01 ? xx(00, 87) : 0) \
+#define xda_be(i) ( \
+ (i & 0x80 ? 0x4380 : 0) ^ (i & 0x40 ? 0x21c0 : 0) ^ \
+ (i & 0x20 ? 0x10e0 : 0) ^ (i & 0x10 ? 0x0870 : 0) ^ \
+ (i & 0x08 ? 0x0438 : 0) ^ (i & 0x04 ? 0x021c : 0) ^ \
+ (i & 0x02 ? 0x010e : 0) ^ (i & 0x01 ? 0x0087 : 0) \
)
-#define xda_lle(i) ( \
- (i & 0x80 ? xx(e1, 00) : 0) ^ (i & 0x40 ? xx(70, 80) : 0) ^ \
- (i & 0x20 ? xx(38, 40) : 0) ^ (i & 0x10 ? xx(1c, 20) : 0) ^ \
- (i & 0x08 ? xx(0e, 10) : 0) ^ (i & 0x04 ? xx(07, 08) : 0) ^ \
- (i & 0x02 ? xx(03, 84) : 0) ^ (i & 0x01 ? xx(01, c2) : 0) \
+#define xda_le(i) ( \
+ (i & 0x80 ? 0xe100 : 0) ^ (i & 0x40 ? 0x7080 : 0) ^ \
+ (i & 0x20 ? 0x3840 : 0) ^ (i & 0x10 ? 0x1c20 : 0) ^ \
+ (i & 0x08 ? 0x0e10 : 0) ^ (i & 0x04 ? 0x0708 : 0) ^ \
+ (i & 0x02 ? 0x0384 : 0) ^ (i & 0x01 ? 0x01c2 : 0) \
)
-static const u16 gf128mul_table_lle[256] = gf128mul_dat(xda_lle);
-static const u16 gf128mul_table_bbe[256] = gf128mul_dat(xda_bbe);
+static const u16 gf128mul_table_le[256] = gf128mul_dat(xda_le);
+static const u16 gf128mul_table_be[256] = gf128mul_dat(xda_be);
-/* These functions multiply a field element by x, by x^4 and by x^8
- * in the polynomial field representation. It uses 32-bit word operations
- * to gain speed but compensates for machine endianess and hence works
+/*
+ * The following functions multiply a field element by x^8 in
+ * the polynomial field representation. They use 64-bit word operations
+ * to gain speed but compensate for machine endianness and hence work
* correctly on both styles of machine.
*/
-static void gf128mul_x_lle(be128 *r, const be128 *x)
-{
- u64 a = be64_to_cpu(x->a);
- u64 b = be64_to_cpu(x->b);
- u64 _tt = gf128mul_table_lle[(b << 7) & 0xff];
-
- r->b = cpu_to_be64((b >> 1) | (a << 63));
- r->a = cpu_to_be64((a >> 1) ^ (_tt << 48));
-}
-
-static void gf128mul_x_bbe(be128 *r, const be128 *x)
-{
- u64 a = be64_to_cpu(x->a);
- u64 b = be64_to_cpu(x->b);
- u64 _tt = gf128mul_table_bbe[a >> 63];
-
- r->a = cpu_to_be64((a << 1) | (b >> 63));
- r->b = cpu_to_be64((b << 1) ^ _tt);
-}
-
-void gf128mul_x_ble(be128 *r, const be128 *x)
-{
- u64 a = le64_to_cpu(x->a);
- u64 b = le64_to_cpu(x->b);
- u64 _tt = gf128mul_table_bbe[b >> 63];
-
- r->a = cpu_to_le64((a << 1) ^ _tt);
- r->b = cpu_to_le64((b << 1) | (a >> 63));
-}
-EXPORT_SYMBOL(gf128mul_x_ble);
-
static void gf128mul_x8_lle(be128 *x)
{
u64 a = be64_to_cpu(x->a);
u64 b = be64_to_cpu(x->b);
- u64 _tt = gf128mul_table_lle[b & 0xff];
+ u64 _tt = gf128mul_table_le[b & 0xff];
x->b = cpu_to_be64((b >> 8) | (a << 56));
x->a = cpu_to_be64((a >> 8) ^ (_tt << 48));
@@ -167,7 +150,7 @@ static void gf128mul_x8_bbe(be128 *x)
{
u64 a = be64_to_cpu(x->a);
u64 b = be64_to_cpu(x->b);
- u64 _tt = gf128mul_table_bbe[a >> 56];
+ u64 _tt = gf128mul_table_be[a >> 56];
x->a = cpu_to_be64((a << 8) | (b >> 56));
x->b = cpu_to_be64((b << 8) ^ _tt);
@@ -251,7 +234,7 @@ EXPORT_SYMBOL(gf128mul_bbe);
/* This version uses 64k bytes of table space.
A 16 byte buffer has to be multiplied by a 16 byte key
- value in GF(128). If we consider a GF(128) value in
+ value in GF(2^128). If we consider a GF(2^128) value in
the buffer's lowest byte, we can construct a table of
the 256 16 byte values that result from the 256 values
of this byte. This requires 4096 bytes. But we also
@@ -315,7 +298,7 @@ void gf128mul_free_64k(struct gf128mul_64k *t)
}
EXPORT_SYMBOL(gf128mul_free_64k);
-void gf128mul_64k_bbe(be128 *a, struct gf128mul_64k *t)
+void gf128mul_64k_bbe(be128 *a, const struct gf128mul_64k *t)
{
u8 *ap = (u8 *)a;
be128 r[1];
@@ -330,7 +313,7 @@ EXPORT_SYMBOL(gf128mul_64k_bbe);
/* This version uses 4k bytes of table space.
A 16 byte buffer has to be multiplied by a 16 byte key
- value in GF(128). If we consider a GF(128) value in a
+ value in GF(2^128). If we consider a GF(2^128) value in a
single byte, we can construct a table of the 256 16 byte
values that result from the 256 values of this byte.
This requires 4096 bytes. If we take the highest byte in
@@ -388,7 +371,7 @@ out:
}
EXPORT_SYMBOL(gf128mul_init_4k_bbe);
-void gf128mul_4k_lle(be128 *a, struct gf128mul_4k *t)
+void gf128mul_4k_lle(be128 *a, const struct gf128mul_4k *t)
{
u8 *ap = (u8 *)a;
be128 r[1];
@@ -403,7 +386,7 @@ void gf128mul_4k_lle(be128 *a, struct gf128mul_4k *t)
}
EXPORT_SYMBOL(gf128mul_4k_lle);
-void gf128mul_4k_bbe(be128 *a, struct gf128mul_4k *t)
+void gf128mul_4k_bbe(be128 *a, const struct gf128mul_4k *t)
{
u8 *ap = (u8 *)a;
be128 r[1];
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-22 05:50:55 +0300