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authorEric Biggers <ebiggers@google.com>2018-02-14 21:42:19 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2018-02-22 17:16:53 +0300
commitda7a0ab5b4babbe5d7a46f852582be06a00a28f0 (patch)
treee065d238cb3a7eeada0c4283e7603576bb64bc7c /crypto/Kconfig
parente845520707f85c539ce04bb73c6070e9441480be (diff)
downloadlinux-da7a0ab5b4babbe5d7a46f852582be06a00a28f0.tar.xz
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>
Diffstat (limited to 'crypto/Kconfig')
-rw-r--r--crypto/Kconfig14
1 files changed, 14 insertions, 0 deletions
diff --git a/crypto/Kconfig b/crypto/Kconfig
index b75264b09a46..558eff07b799 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1508,6 +1508,20 @@ config CRYPTO_SERPENT_AVX2_X86_64
See also:
<http://www.cl.cam.ac.uk/~rja14/serpent.html>
+config CRYPTO_SPECK
+ tristate "Speck cipher algorithm"
+ select CRYPTO_ALGAPI
+ help
+ Speck is a lightweight block cipher that is tuned for optimal
+ performance in software (rather than hardware).
+
+ Speck may not be as secure as AES, and should only be used on systems
+ where AES is not fast enough.
+
+ See also: <https://eprint.iacr.org/2013/404.pdf>
+
+ If unsure, say N.
+
config CRYPTO_TEA
tristate "TEA, XTEA and XETA cipher algorithms"
select CRYPTO_ALGAPI