[FFmpeg-devel] libavutil: Added cbc mode to cast5.c

supraja reddy supraja0493 at gmail.com
Fri Dec 19 07:03:04 CET 2014


Updated patch .

Thanks,

Supraja

On Fri, Dec 19, 2014 at 3:01 AM, Giorgio Vazzana <mywing81 at gmail.com> wrote:
>
> 2014-12-18 11:09 GMT+01:00 supraja reddy <supraja0493 at gmail.com>:
> > Sorry for the mistake . I seem to have got cbc completely wrong.
> > I have made the changes . Please let me know if there is anything
> missing.
>
> > From 0bf794bc43ed7055f83bcd07cb5c1e2f4445e813 Mon Sep 17 00:00:00 2001
> > From: Supraja Meedinti <supraja0493 at gmail.com>
> > Date: Thu, 18 Dec 2014 15:26:32 +0530
> > Subject: [PATCH] libavutil: Added cbc mode to cast128
> >
> > Signed-off-by: Supraja Meedinti <supraja0493 at gmail.com>
> > ---
> >  libavutil/cast5.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
> >  libavutil/cast5.h | 14 +++++++++++++-
> >  2 files changed, 55 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavutil/cast5.c b/libavutil/cast5.c
> > index 14dd701..e338037 100644
> > --- a/libavutil/cast5.c
> > +++ b/libavutil/cast5.c
> > @@ -416,7 +416,7 @@ static void encipher(AVCAST5* cs, uint8_t* dst,
> const uint8_t* src)
> >      AV_WB32(dst + 4, l);
> >  }
> >
> > -static void decipher(AVCAST5* cs, uint8_t* dst, const uint8_t* src)
> > +static void decipher(AVCAST5* cs, uint8_t* dst, const uint8_t* src,
> uint8_t *iv)
> >  {
> >      uint32_t f, I, r, l;
> >      l = AV_RB32(src);
> > @@ -439,6 +439,11 @@ static void decipher(AVCAST5* cs, uint8_t* dst,
> const uint8_t* src)
> >      F3(r, l, 3);
> >      F2(l, r, 2);
> >      F1(r, l, 1);
> > +    if (iv) {
> > +        r ^= AV_RB32(iv);
> > +        l ^= AV_RB32(iv + 4);
> > +        memcpy(iv, src, 8);
> > +    }
> >      AV_WB32(dst, r);
> >      AV_WB32(dst + 4, l);
> >  }
> > @@ -468,11 +473,31 @@ av_cold int av_cast5_init(AVCAST5* cs, const
> uint8_t *key, int key_bits)
> >      return 0;
> >  }
> >
> > +void av_cast5_crypt2(AVCAST5* cs, uint8_t* dst, const uint8_t* src, int
> count, uint8_t *iv, int decrypt)
> > +{
> > +    int i;
> > +    while (count--) {
> > +        if (decrypt) {
> > +            decipher(cs, dst, src, iv);
> > +        } else {
> > +            if (iv) {
> > +                for (i = 0; i < 8; i++)
> > +                    dst[i] = src[i] ^ iv[i];
> > +                encipher(cs, dst, dst);
> > +                memcpy(iv, dst, 8);
> > +            } else {
> > +                encipher(cs, dst, src);
> > +            }
> > +        }
> > +        src = src + 8;
> > +        dst = dst + 8;
> > +    }
> > +}
> >  void av_cast5_crypt(AVCAST5* cs, uint8_t* dst, const uint8_t* src, int
> count, int decrypt)
> >  {
> >      while (count--) {
> >          if (decrypt){
> > -            decipher(cs, dst, src);
> > +            decipher(cs, dst, src, NULL);
> >          } else {
> >              encipher(cs, dst, src);
> >          }
> > @@ -504,6 +529,7 @@ int main(int argc, char** argv)
> >          {0xee, 0xa9, 0xd0, 0xa2, 0x49, 0xfd, 0x3b, 0xa6, 0xb3, 0x43,
> 0x6f, 0xb8, 0x9d, 0x6d, 0xca, 0x92},
> >          {0xb2, 0xc9, 0x5e, 0xb0, 0x0c, 0x31, 0xad, 0x71, 0x80, 0xac,
> 0x05, 0xb8, 0xe8, 0x3d, 0x69, 0x6e}
> >      };
> > +    static uint8_t temp2[8] = {0xee, 0xa9, 0xd0, 0xa2, 0x49, 0xfd,
> 0x3b, 0xa6};
>
> I would call this variable iv instead of temp2, so: const uint8_t iv[2] =
> ...
>
> (for another patch: we can probably remove the keyword 'static' from
> all variables in main, and make key_bits const)
>
> >      static uint8_t rpt2[2][16];
> >      int i, j, err = 0;
> >      static int key_bits[3] = {128, 80, 40};
> > @@ -547,6 +573,20 @@ int main(int argc, char** argv)
> >              }
> >          }
> >      }
> > +    for (j = 0; j < 3; j++) {
> > +
> > +        av_cast5_init(cs, Key[j], key_bits[j]);
> > +        memcpy(temp, temp2, 8);
> > +        av_cast5_crypt2(cs, rpt2[0], rct2[0], 2, temp, 0);
> > +        memcpy(temp, temp2, 8);
> > +        av_cast5_crypt2(cs, rpt2[0], rpt2[0], 2, temp, 1);
> > +        for (i =0; i < 16; i++) {
>
> Missing space between = and 0.
>
> > +            if (rct2[0][i] != rpt2[0][i]) {
> > +                av_log(NULL, AV_LOG_ERROR, "%d %02x %02x\n", i,
> rct2[0][i], rpt2[0][i]);
> > +                err = 1;
> > +            }
> > +        }
> > +    }
> >      av_free(cs);
> >      return err;
> >  }
> > diff --git a/libavutil/cast5.h b/libavutil/cast5.h
> > index 913d048..e5cc8b1 100644
> > --- a/libavutil/cast5.h
> > +++ b/libavutil/cast5.h
> > @@ -52,7 +52,7 @@ struct AVCAST5 *av_cast5_alloc(void);
> >  int av_cast5_init(struct AVCAST5 *ctx, const uint8_t *key, int
> key_bits);
> >
> >  /**
> > -  * Encrypt or decrypt a buffer using a previously initialized context
> > +  * Encrypt or decrypt a buffer using a previously initialized context,
> ECB mode only
> >    *
> >    * @param ctx an AVCAST5 context
> >    * @param dst destination array, can be equal to src
> > @@ -61,6 +61,18 @@ int av_cast5_init(struct AVCAST5 *ctx, const uint8_t
> *key, int key_bits);
> >    * @param decrypt 0 for encryption, 1 for decryption
> >   */
> >  void av_cast5_crypt(struct AVCAST5 *ctx, uint8_t *dst, const uint8_t
> *src, int count, int decrypt);
> > +
> > +/**
> > +  * Encrypt or decrypt a buffer using a previously initialized context
> > +  *
> > +  * @param ctx an AVCAST5 context
> > +  * @param dst destination array, can be equal to src
> > +  * @param src source array, can be equal to dst
> > +  * @param count number of 8 byte blocks
> > +  * @param iv initialization vector for CBC mode, NULL for ECB mode
> > +  * @param decrypt 0 for encryption, 1 for decryption
> > + */
> > +void av_cast5_crypt2(struct AVCAST5 *ctx, uint8_t *dst, const uint8_t
> *src, int count, uint8_t *iv, int decrypt);
> >  /**
> >   * @}
> >   */
> > --
> > 1.8.3.2
> >
>
> the rest LGTM, thanks.
>
> Giorgio Vazzana
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
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