[PATCH v2] sha256: add support for Nettle
- From
brian m. carlson <sandals@crustytoothpaste.net>
- Date
- Jul 10, 2022, 13:29 UTC
- Message-ID
- <20220710132907.1499365-1-sandals@crustytoothpaste.net>
- In-Reply-To
- <20220705230518.713218-1-sandals@crustytoothpaste.net>
For SHA-256, we currently have support for OpenSSL and libgcrypt because these two libraries contain optimized implementations that can take advantage of native processor instructions. However, OpenSSL is not suitable for linking against for Linux distros due to licensing incompatibilities with the GPLv2, and libgcrypt has been less favored by cryptographers due to some security-related implementation issues, which, while not affecting our use of hash algorithms, has affected its reputation.
Let's add another option that's compatible with the GPLv2, which is Nettle. This is an option which is generally better than libgcrypt because on many distros GnuTLS (which uses Nettle) is used for HTTPS and therefore as a practical matter it will be available on most systems. As a result, prefer it over libgcrypt and our built-in implementation.
Nettle also has recently gained support for Intel's SHA-NI instructions, which compare very favorably to other implementations, as well as assembly implementations for when SHA-NI is not available.
A git gc on git.git sees a 12% performance improvement with Nettle over our block SHA-256 implementation due to general assembly improvements. With SHA-NI, the performance of raw SHA-256 on a 2 GiB file goes from 7.296 seconds with block SHA-256 to 1.523 seconds with Nettle.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> ---
Changes from v1:
* Improve commit message to provide better statistics and rationale. * Fix include guard typo. * Exclude header in Makefile unless we're building it.
Makefile | 10 ++++++++++ hash.h | 4 +++- sha256/nettle.h | 31 +++++++++++++++++++++++++++++++ 3 files changed, 44 insertions(+), 1 deletion(-) create mode 100644 sha256/nettle.h
diff --git a/Makefile b/Makefile index 04d0fd1fe6..52a9f97997 100644 --- a/Makefile +++ b/Makefile @@ -182,6 +182,8 @@ include shared.mak # # Define BLK_SHA256 to use the built-in SHA-256 routines. # +# Define NETTLE_SHA256 to use the SHA-256 routines in libnettle. +# # Define GCRYPT_SHA256 to use the SHA-256 routines in libgcrypt. # # Define OPENSSL_SHA256 to use the SHA-256 routines in OpenSSL. @@ -1842,6 +1844,10 @@ ifdef OPENSSL_SHA256 EXTLIBS += $(LIB_4_CRYPTO) BASIC_CFLAGS += -DSHA256_OPENSSL else +ifdef NETTLE_SHA256 + BASIC_CFLAGS += -DSHA256_NETTLE + EXTLIBS += -lnettle +else ifdef GCRYPT_SHA256 BASIC_CFLAGS += -DSHA256_GCRYPT EXTLIBS += -lgcrypt @@ -1850,6 +1856,7 @@ else BASIC_CFLAGS += -DSHA256_BLK endif endif +endif ifdef SHA1_MAX_BLOCK_SIZE LIB_OBJS += compat/sha1-chunked.o @@ -3091,6 +3098,9 @@ $(SP_OBJ): %.sp: %.c %.o sparse: $(SP_OBJ) EXCEPT_HDRS := $(GENERATED_H) unicode-width.h compat/% xdiff/% +ifndef NETTLE_SHA256 + EXCEPT_HDRS += sha256/nettle.h +endif ifndef GCRYPT_SHA256 EXCEPT_HDRS += sha256/gcrypt.h endif diff --git a/hash.h b/hash.h index 5d40368f18..ea87ae9d92 100644 --- a/hash.h +++ b/hash.h @@ -16,7 +16,9 @@ #include "block-sha1/sha1.h" #endif -#if defined(SHA256_GCRYPT) +#if defined(SHA256_NETTLE) +#include "sha256/nettle.h" +#elif defined(SHA256_GCRYPT) #define SHA256_NEEDS_CLONE_HELPER #include "sha256/gcrypt.h" #elif defined(SHA256_OPENSSL) diff --git a/sha256/nettle.h b/sha256/nettle.h new file mode 100644 index 0000000000..b63e1c8190 --- /dev/null +++ b/sha256/nettle.h @@ -0,0 +1,31 @@ +#ifndef SHA256_NETTLE_H +#define SHA256_NETTLE_H + +#include <nettle/sha2.h> + +typedef struct sha256_ctx nettle_SHA256_CTX; + +static inline void nettle_SHA256_Init(nettle_SHA256_CTX *ctx) +{ + sha256_init(ctx); +} + +static inline void nettle_SHA256_Update(nettle_SHA256_CTX *ctx, + const void *data, + size_t len) +{ + sha256_update(ctx, len, data); +} + +static inline void nettle_SHA256_Final(unsigned char *digest, + nettle_SHA256_CTX *ctx) +{ + sha256_digest(ctx, SHA256_DIGEST_SIZE, digest); +} + +#define platform_SHA256_CTX nettle_SHA256_CTX +#define platform_SHA256_Init nettle_SHA256_Init +#define platform_SHA256_Update nettle_SHA256_Update +#define platform_SHA256_Final nettle_SHA256_Final + +#endif