Re: [FFmpeg-devel] [PATCH 3/3] avutil/aes: add an OpenSSL-libcrypto backed implementation

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

James Almer:
> OpenSSL has optimizations for more architectures than x86-AESNI, so use it if
> libavutil is configured with libcrypto explicitly (Enabling OpenSSL alone will
> not make use of it).
> 
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>  configure                |  8 +++++++-
>  libavutil/aes.c          | 37 ++++++++++++++++++++++++++++++++++---
>  libavutil/aes_internal.h | 11 ++++++++++-
>  libavutil/x86/aes_init.c |  2 ++
>  4 files changed, 53 insertions(+), 5 deletions(-)
> 
> diff --git a/configure b/configure
> index 534b443f7d..c7b4fbb2fe 100755
> --- a/configure
> +++ b/configure
> @@ -223,6 +223,7 @@ External library support:
>    --enable-libcelt         enable CELT decoding via libcelt [no]
>    --enable-libcdio         enable audio CD grabbing with libcdio [no]
>    --enable-libcodec2       enable codec2 en/decoding using libcodec2 [no]
> +  --enable-libcrypto       enable crypto via libcrypto (AES only) [no]
>    --enable-libdav1d        enable AV1 decoding via libdav1d [no]
>    --enable-libdavs2        enable AVS2 decoding via libdavs2 [no]
>    --enable-libdc1394       enable IIDC-1394 grabbing using libdc1394
> @@ -1931,6 +1932,7 @@ EXTERNAL_LIBRARY_LIST="
>      libcaca
>      libcelt
>      libcodec2
> +    libcrypto
>      libdav1d
>      libdc1394
>      libflite
> @@ -4091,7 +4093,7 @@ avfilter_deps="avutil"
>  avfilter_suggest="libm stdatomic spirv_compiler"
>  avformat_deps="avcodec avutil"
>  avformat_suggest="libm network zlib stdatomic"
> -avutil_suggest="clock_gettime ffnvcodec gcrypt libm libdrm libmfx opencl openssl user32 vaapi vulkan videotoolbox corefoundation corevideo coremedia bcrypt stdatomic"
> +avutil_suggest="clock_gettime ffnvcodec gcrypt libcrypto libm libdrm libmfx opencl openssl user32 vaapi vulkan videotoolbox corefoundation corevideo coremedia bcrypt stdatomic"
>  swresample_deps="avutil"
>  swresample_suggest="libm libsoxr stdatomic"
>  swscale_deps="avutil"
> @@ -7193,6 +7195,10 @@ enabled openssl           && { { check_pkg_config openssl "openssl >= 3.0.0" ope
>                                 check_lib openssl openssl/ssl.h SSL_library_init -lssl32 -leay32 ||
>                                 check_lib openssl openssl/ssl.h SSL_library_init -lssl -lcrypto -lws2_32 -lgdi32 ||
>                                 die "ERROR: openssl not found"; }
> +enabled libcrypto         && { { check_pkg_config libcrypto "libcrypto >= 3.0.0" openssl/aes.h AES_set_encrypt_key &&
> +                                 { enabled gplv3 || ! enabled gpl || enabled nonfree || die "ERROR: OpenSSL-libcrypto >= 3.0.0 requires --enable-version3"; }; } ||
> +                               { enabled gpl && ! enabled nonfree && die "ERROR: OpenSSL-libcrypto < 3.0.0 is incompatible with the gpl"; } ||
> +                               require_pkg_config libcrypto libcrypto openssl/aes.h AES_set_encrypt_key; }
>  enabled pocketsphinx      && require_pkg_config pocketsphinx pocketsphinx pocketsphinx/pocketsphinx.h ps_init
>  enabled rkmpp             && { require_pkg_config rkmpp rockchip_mpp  rockchip/rk_mpi.h mpp_create &&
>                                 require_pkg_config rockchip_mpp "rockchip_mpp >= 1.3.7" rockchip/rk_mpi.h mpp_create &&
> diff --git a/libavutil/aes.c b/libavutil/aes.c
> index 7fe42a5548..3a0d4e1385 100644
> --- a/libavutil/aes.c
> +++ b/libavutil/aes.c
> @@ -39,6 +39,7 @@ struct AVAES *av_aes_alloc(void)
>      return av_mallocz(sizeof(struct AVAES));
>  }
>  
> +#if !CONFIG_LIBCRYPTO
>  static const uint8_t rcon[10] = {
>      0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
>  };
> @@ -137,7 +138,7 @@ static inline void aes_crypt(AVAES *a, int s, const uint8_t *sbox,
>  }
>  
>  static void aes_encrypt(AVAES *a, uint8_t *dst, const uint8_t *src,
> -                        int count, uint8_t *iv)
> +                        int count, uint8_t *iv, int decrypt)
>  {
>      while (count--) {
>          addkey_s(&a->state[1], src, &a->round_key[a->rounds]);
> @@ -153,7 +154,7 @@ static void aes_encrypt(AVAES *a, uint8_t *dst, const uint8_t *src,
>  }
>  
>  static void aes_decrypt(AVAES *a, uint8_t *dst, const uint8_t *src,
> -                        int count, uint8_t *iv)
> +                        int count, uint8_t *iv, int decrypt)
>  {
>      while (count--) {
>          addkey_s(&a->state[1], src, &a->round_key[a->rounds]);
> @@ -168,12 +169,32 @@ static void aes_decrypt(AVAES *a, uint8_t *dst, const uint8_t *src,
>      }
>  }
>  
> +#else
> +
> +static void aes_libcrypto(AVAES *a, uint8_t *dst, const uint8_t *src,
> +                          int count, uint8_t *iv, int decrypt)
> +{
> +    if (iv)
> +        AES_cbc_encrypt((const unsigned char *)src,
> +                        (unsigned char *)dst,
> +                        count, &a->key,
> +                        (unsigned char *)iv, !decrypt);
> +    else {
> +        for (int i = 0; i < count; i++)
> +            AES_ecb_encrypt((const unsigned char *)&src[i*16],
> +                            (unsigned char *)&dst[i*16],

Casts seem pointless. Lots of other part of the code presume that
uint8_t* and unsigned char* are compatible.

> +                            &a->key, !decrypt);
> +    }
> +}
> +#endif
> +
>  void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,
>                    int count, uint8_t *iv, int decrypt)
>  {
> -    a->crypt(a, dst, src, count, iv);
> +    a->crypt(a, dst, src, count, iv, decrypt);

This new argument can be #if'ed away.

>  }
>  
> +#if !CONFIG_LIBCRYPTO
>  static void init_multbl2(uint32_t tbl[][256], const int c[4],
>                           const uint8_t *log8, const uint8_t *alog8,
>                           const uint8_t *sbox)
> @@ -226,10 +247,19 @@ static av_cold void aes_init_static(void)
>      init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 },
>                   log8, alog8, sbox);
>  }
> +#endif
>  
>  // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
>  int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
>  {
> +#if CONFIG_LIBCRYPTO
> +    int ret = decrypt ? AES_set_decrypt_key(key, key_bits, &a->key) :
> +                        AES_set_encrypt_key(key, key_bits, &a->key);
> +    if (ret < 0)
> +        return AVERROR_EXTERNAL;
> +
> +    a->crypt = aes_libcrypto;
> +#else
>      int i, j, t, rconpointer = 0;
>      uint8_t tk[8][4];
>      int KC = key_bits >> 5;
> @@ -278,6 +308,7 @@ int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
>          for (i = 0; i < (rounds + 1) >> 1; i++)
>              FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds - i]);
>      }
> +#endif
>  
>      return 0;
>  }
> diff --git a/libavutil/aes_internal.h b/libavutil/aes_internal.h
> index e2de382f26..6713798ce2 100644
> --- a/libavutil/aes_internal.h
> +++ b/libavutil/aes_internal.h
> @@ -21,8 +21,13 @@
>  #ifndef AVUTIL_AES_INTERNAL_H
>  #define AVUTIL_AES_INTERNAL_H
>  
> +#include "config.h"
> +
>  #include "mem_internal.h"
>  #include <stdint.h>
> +#if CONFIG_LIBCRYPTO
> +#include <openssl/aes.h>
> +#endif
>  
>  typedef union {
>      uint64_t u64[2];
> @@ -32,12 +37,16 @@ typedef union {
>  } av_aes_block;
>  
>  typedef struct AVAES {
> +#if CONFIG_LIBCRYPTO
> +    AES_KEY key;
> +#else
>      // Note: round_key[16] is accessed in the init code, but this only
>      // overwrites state, which does not matter (see also commit ba554c0).
>      DECLARE_ALIGNED(16, av_aes_block, round_key)[15];
>      DECLARE_ALIGNED(16, av_aes_block, state)[2];
>      int rounds;
> -    void (*crypt)(struct AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv);
> +#endif
> +    void (*crypt)(struct AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decript);
>  } AVAES;
>  
>  void ff_init_aes_x86(AVAES *a, int decrypt);
> diff --git a/libavutil/x86/aes_init.c b/libavutil/x86/aes_init.c
> index f825e0799c..54487e8832 100644
> --- a/libavutil/x86/aes_init.c
> +++ b/libavutil/x86/aes_init.c
> @@ -37,6 +37,7 @@ void ff_aes_encrypt_14_aesni(AVAES *a, uint8_t *dst, const uint8_t *src,
>  
>  void ff_init_aes_x86(AVAES *a, int decrypt)
>  {
> +#if !CONFIG_LIBCRYPTO
>      int cpu_flags = av_get_cpu_flags();
>  
>      if (EXTERNAL_AESNI(cpu_flags)) {
> @@ -47,4 +48,5 @@ void ff_init_aes_x86(AVAES *a, int decrypt)
>          else if (a->rounds == 14)
>              a->crypt = decrypt ? ff_aes_decrypt_14_aesni : ff_aes_encrypt_14_aesni;
>      }
> +#endif
>  }

Is this better than our implementation for x86 with AESNI?
Apart from that: If you don't need anything from ff_init_aes_x86(), then
it should not be exist, i.e. it should not be compiled (and neither
should the asm file).

- Andreas

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