crypto: x86/chacha20 - add XChaCha20 support

Add an XChaCha20 implementation that is hooked up to the x86_64 SIMD
implementations of ChaCha20.  This can be used by Adiantum.

An SSSE3 implementation of single-block HChaCha20 is also added so that
XChaCha20 can use it rather than the generic implementation.  This
required refactoring the ChaCha permutation into its own function.

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

1 files changed, 3 insertions, 9 deletions

diff --git a/crypto/Kconfig b/crypto/Kconfig
index d0bff6ea6b10..dc3a0e3ea2ac 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1468,19 +1468,13 @@ config CRYPTO_CHACHA20
           in some performance-sensitive scenarios.
 
 config CRYPTO_CHACHA20_X86_64
-        tristate "ChaCha20 cipher algorithm (x86_64/SSSE3/AVX2)"
+        tristate "ChaCha stream cipher algorithms (x86_64/SSSE3/AVX2/AVX-512VL)"
         depends on X86 && 64BIT
         select CRYPTO_BLKCIPHER
         select CRYPTO_CHACHA20
         help
-          ChaCha20 cipher algorithm, RFC7539.
-
-          ChaCha20 is a 256-bit high-speed stream cipher designed by Daniel J.
-          Bernstein and further specified in RFC7539 for use in IETF protocols.
-          This is the x86_64 assembler implementation using SIMD instructions.
-
-          See also:
-          <http://cr.yp.to/chacha/chacha-20080128.pdf>
+          SSSE3, AVX2, and AVX-512VL optimized implementations of the ChaCha20
+          and XChaCha20 stream ciphers.
 
 config CRYPTO_SEED
         tristate "SEED cipher algorithm"