Dear Sir:
In the IDEA cryption test program cfb64_test, I don't know why we must
use encrytion key as decryption key. can you tell me the reason.
static int cfb64_test(unsigned char *cfb_cipher)
{
IDEA_KEY_SCHEDULE eks,dks;
int err=0,i,n;
idea_set_encrypt_key(cfb_key,&eks);
idea_set_decrypt_key(&eks,&dks);
memcpy(cfb_tmp,cfb_iv,8);
n=0;
idea_cfb64_encrypt(plain,cfb_buf1,(long)12,&eks, cfb_tmp,&n,IDEA_ENCRYPT);
idea_cfb64_encrypt(&(plain[12]),&(cfb_buf1[12]), (long)CFB_TEST_SIZE-12,&eks,
cfb_tmp,&n,IDEA_ENCRYPT);
if (memcmp(cfb_cipher,cfb_buf1,CFB_TEST_SIZE) != 0)
{
err=1;
printf("idea_cfb64_encrypt encrypt error\n");
for (i=0; i<CFB_TEST_SIZE; i+=8)
printf("%s\n",pt(&(cfb_buf1[i])));
}
memcpy(cfb_tmp,cfb_iv,8);
n=0;
//Why we must first use encryption key to decrypt the 17 bytes data at the
begining of the encrypted data
idea_cfb64_encrypt(cfb_buf1,cfb_buf2,(long)17,&eks, cfb_tmp,&n,IDEA_DECRYPT);
~~~~encryption key
//Then we use decryption key to decrypt the else encrypted data
idea_cfb64_encrypt(&(cfb_buf1[17]),&(cfb_buf2[17]),
(long)CFB_TEST_SIZE-17,&dks, cfb_tmp,&n,IDEA_DECRYPT);
~~~~decryption key
if (memcmp(plain,cfb_buf2,CFB_TEST_SIZE) != 0)
{
err=1;
printf("idea_cfb_encrypt decrypt error\n");
for (i=0; i<24; i+=8)
printf("%s\n",pt(&(cfb_buf2[i])));
}
return(err);
}
______________________________________________________________________
OpenSSL Project http://www.openssl.org
Development Mailing List [EMAIL PROTECTED]
Automated List Manager [EMAIL PROTECTED]
