Commit 9ae433bc79 ("crypto: chacha20 - convert generic and x86 versions
to skcipher") ported the existing chacha20 code to use the new skcipher
API, and introduced a bug along the way. Unfortunately, the tcrypt tests
did not catch the error, and it was only found recently by Tobias.
Stefan kindly diagnosed the error, and proposed a fix which is similar
to the one below, with the exception that 'walk.stride' is used rather
than the hardcoded block size. This does not actually matter in this
case, but it's a better example of how to use the skcipher walk API.
Fixes: 9ae433bc79 ("crypto: chacha20 - convert generic and x86 ...")
Cc: <stable@vger.kernel.org> # v4.11+
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This converts the ChaCha20 code from a blkcipher to a skcipher, which
is now the preferred way to implement symmetric block and stream ciphers.
This ports the generic and x86 versions at the same time because the
latter reuses routines of the former.
Note that the skcipher_walk() API guarantees that all presented blocks
except the final one are a multiple of the chunk size, so we can simplify
the encrypt() routine somewhat.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
As architecture specific drivers need a software fallback, export a
ChaCha20 en-/decryption function together with some helpers in a header
file.
Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
ChaCha20 is a high speed 256-bit key size stream cipher algorithm designed by
Daniel J. Bernstein. It is further specified in RFC7539 for use in IETF
protocols as a building block for the ChaCha20-Poly1305 AEAD.
This is a portable C implementation without any architecture specific
optimizations. It uses a 16-byte IV, which includes the 12-byte ChaCha20 nonce
prepended by the initial block counter. Some algorithms require an explicit
counter value, for example the mentioned AEAD construction.
Signed-off-by: Martin Willi <martin@strongswan.org>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Ard Biesheuvel