Using libgcrypt1.2.0 for 3DES, ECB mode of encryption/decryption.

[Vishal Rao]

Hi,

Also, when decrypting you are using both params as dest and dest
instead of src and dest...

I see towards the end of your code sample is gcry_cipher_decrypt (hd,
dest, strlen(dest), dest, strlen(dest));

But I've never done GNUPG development so that may not be the problem,
or see my earlier reply about not using strlen() on either ciphertext
or plaintext... since its not really "text" even if your input plain
text is just a "string"...

Cheers,
Vishal

On Thu, 9 Dec 2004 09:58:04 -0500, Madhavi.Gandavarapu at equifax.com
<Madhavi.Gandavarapu at equifax.com> wrote:
> 
> 
> Hi,
> 
> I have a string that I am trying to encrypt using 3DES,ECB mode.  I have a
> specific 24 byte key that I need to use to encrypt or decrypt.
> I am not getting good encrypted string back, since I can't even decrypt what I
> encrypted with the same key and same library.
> 
> Can you point me to what I am doing wrong here.
> 
> Here is the code segment.
> 
> unsigned char enc_key[24] =
> {0x12,0x34,0x51,0x23,0x45,0x12,0x34,0x51,0x15,0x43,0x21,0x54,0x32,0x15,0x43,0x21,0x45,0x12,0x34,0x51,0x12,
> 0x34,0x51,0x23};
> 
> static int do_encrypt(unsigned char* dest,unsigned char* src)
> {
>    //GCRY_CIPHER_3DES is the algorithm type
>    //GCRY_CIPHER_MODE_ECB is the algorithem mode
>    //0(zero) is the flags value to send
>    int retVal =0;
>    gcry_cipher_hd_t hd;
> 
>    int keylen;
>    int i =0,x=0;
>    gcry_error_t err = 0;
> 
>    keylen = gcry_cipher_get_algo_keylen(GCRY_CIPHER_3DES);
>    if (!keylen)
>    {
> //    fail ("algo %d, mode %d, gcry_cipher_get_algo_keylen failed\n", algo,
> mode);
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, gcry_cipher_get_algo_keylen
> failed","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB" );
>       retVal = -1;
>       return retVal;
>    }
>    if (keylen < 40 / 8 || keylen > 32)
>    {
> //    fail ("algo %d, mode %d, keylength problem (%d)\n", algo, mode, keylen);
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, keylength problem
> (%d)","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB",keylen );
>       retVal = -1;
>       return retVal;
>    }
>    err = gcry_cipher_open (&hd, GCRY_CIPHER_3DES, GCRY_CIPHER_MODE_ECB, 0);
>    if (err)
>    {
> //    fail ("algo %d, mode %d, grcy_open_cipher failed: %s\n", algo, mode,
> gpg_strerror (err));
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, grcy_open_cipher failed:
> %s","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB",gpg_strerror(err)
> );
>       return err;
> 
>  }
>    err = gcry_cipher_setkey (hd, &enc_key, keylen);
>    if (err)
>    {
> //    fail ("algo %d, mode %d, gcry_cipher_setkey failed: %s\n",  algo, mode,
> gpg_strerror (err));
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, gcry_cipher_setkey failed:
> %s","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB",gpg_strerror(er
> r));
>       gcry_cipher_close (hd);
>       return err;
>    }
>    //err = gcry_cipher_encrypt (hd, dest, strlen(dest), NULL,strlen(dest));
>    err = gcry_cipher_encrypt (hd, dest, strlen(dest), src, strlen(src));
>    if (err)
>    {
> //    fail ("algo %d, mode %d, gcry_cipher_encrypt failed: %s\n", algo, mode,
> gpg_strerror (err));
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, gcry_cipher_encrypt failed:
> %s","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB",gpg_strerror(e
> rr));
>       gcry_cipher_close (hd);
>       return err;
>    }
>    i =0; x=0;
>    if((x = (strlen(dest)%bsize)))
>    {
>       x = (bsize - x);
>       for(i = 0; i < x; i++)
>          strcat(dest," ");
>    }
> 
>    err = gcry_cipher_decrypt (hd, dest, strlen(dest), dest, strlen(dest));
>    if (err)
>    {
> //    fail ("algo %d, mode %d, gcry_cipher_decrypt failed: %s\n", algo, mode,
> gpg_strerror (err));
>       logf(&bLog, LF_ERROR, "algo %s, mode %s, gcry_cipher_decrypt failed:
> %s","GCRY_CIPHER_3DES" ,"GCRY_CIPHER_MODE_ECB",gpg_strerror(e
> rr));
>       gcry_cipher_close (hd);
>       return err;
>    }
> 
>    gcry_cipher_close (hd);
> 
> Thanks and Regards
> Madhavi
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