crypto: speck - add support for the Speck block cipher

Add a generic implementation of Speck, including the Speck128 and
Speck64 variants.  Speck is a lightweight block cipher that can be much
faster than AES on processors that don't have AES instructions.

We are planning to offer Speck-XTS (probably Speck128/256-XTS) as an
option for dm-crypt and fscrypt on Android, for low-end mobile devices
with older CPUs such as ARMv7 which don't have the Cryptography
Extensions.  Currently, such devices are unencrypted because AES is not
fast enough, even when the NEON bit-sliced implementation of AES is
used.  Other AES alternatives such as Twofish, Threefish, Camellia,
CAST6, and Serpent aren't fast enough either; it seems that only a
modern ARX cipher can provide sufficient performance on these devices.

This is a replacement for our original proposal
(https://patchwork.kernel.org/patch/10101451/) which was to offer
ChaCha20 for these devices.  However, the use of a stream cipher for
disk/file encryption with no space to store nonces would have been much
more insecure than we thought initially, given that it would be used on
top of flash storage as well as potentially on top of F2FS, neither of
which is guaranteed to overwrite data in-place.

Speck has been somewhat controversial due to its origin.  Nevertheless,
it has a straightforward design (it's an ARX cipher), and it appears to
be the leading software-optimized lightweight block cipher currently,
with the most cryptanalysis.  It's also easy to implement without side
channels, unlike AES.  Moreover, we only intend Speck to be used when
the status quo is no encryption, due to AES not being fast enough.

We've also considered a novel length-preserving encryption mode based on
ChaCha20 and Poly1305.  While theoretically attractive, such a mode
would be a brand new crypto construction and would be more complicated
and difficult to implement efficiently in comparison to Speck-XTS.

There is confusion about the byte and word orders of Speck, since the
original paper doesn't specify them.  But we have implemented it using
the orders the authors recommended in a correspondence with them.  The
test vectors are taken from the original paper but were mapped to byte
arrays using the recommended byte and word orders.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 128 insertions, 0 deletions

diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index 69fb51e7b6f1..6b15a8ab743b 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -14323,6 +14323,134 @@ static const struct cipher_testvec serpent_xts_dec_tv_template[] = {
 	},
 };
 
+/*
+ * Speck test vectors taken from the original paper:
+ * "The Simon and Speck Families of Lightweight Block Ciphers"
+ * https://eprint.iacr.org/2013/404.pdf
+ *
+ * Note that the paper does not make byte and word order clear.  But it was
+ * confirmed with the authors that the intended orders are little endian byte
+ * order and (y, x) word order.  Equivalently, the printed test vectors, when
+ * looking at only the bytes (ignoring the whitespace that divides them into
+ * words), are backwards: the left-most byte is actually the one with the
+ * highest memory address, while the right-most byte is actually the one with
+ * the lowest memory address.
+ */
+
+static const struct cipher_testvec speck128_enc_tv_template[] = {
+	{ /* Speck128/128 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.klen	= 16,
+		.input	= "\x20\x6d\x61\x64\x65\x20\x69\x74"
+			  "\x20\x65\x71\x75\x69\x76\x61\x6c",
+		.ilen	= 16,
+		.result	= "\x18\x0d\x57\x5c\xdf\xfe\x60\x78"
+			  "\x65\x32\x78\x79\x51\x98\x5d\xa6",
+		.rlen	= 16,
+	}, { /* Speck128/192 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+			  "\x10\x11\x12\x13\x14\x15\x16\x17",
+		.klen	= 24,
+		.input	= "\x65\x6e\x74\x20\x74\x6f\x20\x43"
+			  "\x68\x69\x65\x66\x20\x48\x61\x72",
+		.ilen	= 16,
+		.result	= "\x86\x18\x3c\xe0\x5d\x18\xbc\xf9"
+			  "\x66\x55\x13\x13\x3a\xcf\xe4\x1b",
+		.rlen	= 16,
+	}, { /* Speck128/256 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+			  "\x10\x11\x12\x13\x14\x15\x16\x17"
+			  "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
+		.klen	= 32,
+		.input	= "\x70\x6f\x6f\x6e\x65\x72\x2e\x20"
+			  "\x49\x6e\x20\x74\x68\x6f\x73\x65",
+		.ilen	= 16,
+		.result	= "\x43\x8f\x18\x9c\x8d\xb4\xee\x4e"
+			  "\x3e\xf5\xc0\x05\x04\x01\x09\x41",
+		.rlen	= 16,
+	},
+};
+
+static const struct cipher_testvec speck128_dec_tv_template[] = {
+	{ /* Speck128/128 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.klen	= 16,
+		.input	= "\x18\x0d\x57\x5c\xdf\xfe\x60\x78"
+			  "\x65\x32\x78\x79\x51\x98\x5d\xa6",
+		.ilen	= 16,
+		.result	= "\x20\x6d\x61\x64\x65\x20\x69\x74"
+			  "\x20\x65\x71\x75\x69\x76\x61\x6c",
+		.rlen	= 16,
+	}, { /* Speck128/192 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+			  "\x10\x11\x12\x13\x14\x15\x16\x17",
+		.klen	= 24,
+		.input	= "\x86\x18\x3c\xe0\x5d\x18\xbc\xf9"
+			  "\x66\x55\x13\x13\x3a\xcf\xe4\x1b",
+		.ilen	= 16,
+		.result	= "\x65\x6e\x74\x20\x74\x6f\x20\x43"
+			  "\x68\x69\x65\x66\x20\x48\x61\x72",
+		.rlen	= 16,
+	}, { /* Speck128/256 */
+		.key	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+			  "\x10\x11\x12\x13\x14\x15\x16\x17"
+			  "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f",
+		.klen	= 32,
+		.input	= "\x43\x8f\x18\x9c\x8d\xb4\xee\x4e"
+			  "\x3e\xf5\xc0\x05\x04\x01\x09\x41",
+		.ilen	= 16,
+		.result	= "\x70\x6f\x6f\x6e\x65\x72\x2e\x20"
+			  "\x49\x6e\x20\x74\x68\x6f\x73\x65",
+		.rlen	= 16,
+	},
+};
+
+static const struct cipher_testvec speck64_enc_tv_template[] = {
+	{ /* Speck64/96 */
+		.key	= "\x00\x01\x02\x03\x08\x09\x0a\x0b"
+			  "\x10\x11\x12\x13",
+		.klen	= 12,
+		.input	= "\x65\x61\x6e\x73\x20\x46\x61\x74",
+		.ilen	= 8,
+		.result	= "\x6c\x94\x75\x41\xec\x52\x79\x9f",
+		.rlen	= 8,
+	}, { /* Speck64/128 */
+		.key	= "\x00\x01\x02\x03\x08\x09\x0a\x0b"
+			  "\x10\x11\x12\x13\x18\x19\x1a\x1b",
+		.klen	= 16,
+		.input	= "\x2d\x43\x75\x74\x74\x65\x72\x3b",
+		.ilen	= 8,
+		.result	= "\x8b\x02\x4e\x45\x48\xa5\x6f\x8c",
+		.rlen	= 8,
+	},
+};
+
+static const struct cipher_testvec speck64_dec_tv_template[] = {
+	{ /* Speck64/96 */
+		.key	= "\x00\x01\x02\x03\x08\x09\x0a\x0b"
+			  "\x10\x11\x12\x13",
+		.klen	= 12,
+		.input	= "\x6c\x94\x75\x41\xec\x52\x79\x9f",
+		.ilen	= 8,
+		.result	= "\x65\x61\x6e\x73\x20\x46\x61\x74",
+		.rlen	= 8,
+	}, { /* Speck64/128 */
+		.key	= "\x00\x01\x02\x03\x08\x09\x0a\x0b"
+			  "\x10\x11\x12\x13\x18\x19\x1a\x1b",
+		.klen	= 16,
+		.input	= "\x8b\x02\x4e\x45\x48\xa5\x6f\x8c",
+		.ilen	= 8,
+		.result	= "\x2d\x43\x75\x74\x74\x65\x72\x3b",
+		.rlen	= 8,
+	},
+};
+
 /* Cast6 test vectors from RFC 2612 */
 static const struct cipher_testvec cast6_enc_tv_template[] = {
 	{