crypto: arm/chacha - add XChaCha12 support

Now that the 32-bit ARM NEON implementation of ChaCha20 and XChaCha20
has been refactored to support varying the number of rounds, add support
for XChaCha12.  This is identical to XChaCha20 except for the number of
rounds, which is 12 instead of 20.

XChaCha12 is faster than XChaCha20 but has a lower security margin,
though still greater than AES-256's since the best known attacks make it
through only 7 rounds.  See the patch "crypto: chacha - add XChaCha12
support" for more details about why we need XChaCha12 support.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/arm/crypto/Kconfig b/arch/arm/crypto/Kconfig
index a08759c32cb94ab051322ecd724f5352a5c5f2f8..59c674cf08efb807e755e6778adfc85e1ab95e35 100644 (file)
--- a/arch/arm/crypto/Kconfig
+++ b/arch/arm/crypto/Kconfig
@@ -126,7 +126,7 @@ config CRYPTO_CRC32_ARM_CE
        select CRYPTO_HASH
 
 config CRYPTO_CHACHA20_NEON
-       tristate "NEON accelerated ChaCha20 stream cipher algorithms"
+       tristate "NEON accelerated ChaCha stream cipher algorithms"
        depends on KERNEL_MODE_NEON
        select CRYPTO_BLKCIPHER
        select CRYPTO_CHACHA20

diff --git a/arch/arm/crypto/chacha-neon-glue.c b/arch/arm/crypto/chacha-neon-glue.c
index 385557d3863418d46d1e21e93a86a454235d3092..9d6fda81986da6b4e3470ebcb2ded59f7a6966e8 100644 (file)
--- a/arch/arm/crypto/chacha-neon-glue.c
+++ b/arch/arm/crypto/chacha-neon-glue.c
@@ -1,5 +1,6 @@
 /*
- * ChaCha20 (RFC7539) and XChaCha20 stream ciphers, NEON accelerated
+ * ARM NEON accelerated ChaCha and XChaCha stream ciphers,
+ * including ChaCha20 (RFC7539)
  *
  * Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
  *
@@ -154,6 +155,22 @@ static struct skcipher_alg algs[] = {
                .setkey                 = crypto_chacha20_setkey,
                .encrypt                = xchacha_neon,
                .decrypt                = xchacha_neon,
+       }, {
+               .base.cra_name          = "xchacha12",
+               .base.cra_driver_name   = "xchacha12-neon",
+               .base.cra_priority      = 300,
+               .base.cra_blocksize     = 1,
+               .base.cra_ctxsize       = sizeof(struct chacha_ctx),
+               .base.cra_module        = THIS_MODULE,
+
+               .min_keysize            = CHACHA_KEY_SIZE,
+               .max_keysize            = CHACHA_KEY_SIZE,
+               .ivsize                 = XCHACHA_IV_SIZE,
+               .chunksize              = CHACHA_BLOCK_SIZE,
+               .walksize               = 4 * CHACHA_BLOCK_SIZE,
+               .setkey                 = crypto_chacha12_setkey,
+               .encrypt                = xchacha_neon,
+               .decrypt                = xchacha_neon,
        }
 };
 
@@ -180,3 +197,5 @@ MODULE_ALIAS_CRYPTO("chacha20");
 MODULE_ALIAS_CRYPTO("chacha20-neon");
 MODULE_ALIAS_CRYPTO("xchacha20");
 MODULE_ALIAS_CRYPTO("xchacha20-neon");
+MODULE_ALIAS_CRYPTO("xchacha12");
+MODULE_ALIAS_CRYPTO("xchacha12-neon");