Hello,
I have a simple client-server program and am using blowfish. I'm using the
EVP_* routines to initialize, encrypt, and decrypt. Variable-length data is
taken in from the client through stdin and sent to the server socket after
encryption. One question I have is how I clear what's already been
decrypted on the server-side from the buffer. It appears that the data I've
already read out of the buffer (post-decryption) is not being discarded,
thus when data is received, it starts back at the beginning and I get the
same data back. Any insight would be much appreciated!
On my client side, my code is (simplified)
EVP_EncryptInit(&context,EVP_bf_cbc(),key,iv):
while(1) {
fgets(buffer,sizeof(buffer),stdin);
padBuffer(buffer,paddedBuffer); (my own routine just to pad to length that
is multiplier of 8-bytes)
writeBuffer=encrypt(&context,paddedBuffer,strlen(paddedBuffer),&i);
writeData=sendto(connfd,writeBuffer,strlen(writeBuffer),0,(struct sockaddr
*)&serveraddress,sizeof(serveraddress));
}
and on the server side, my code is (simplified):
EVP_DecryptInit(&context,EVP_bf_cbc(),key,iv);
while(1) {
dataRead=recvfrom(connfd,readBuffer,sizeof(readBuffer),0,NULL,NULL);
for (i=0;i<strlen(readBuffer);i++) {
readBufferClear=decrypt(&context,readBuffer+i,1);
if (readBufferClear!=0)
strncat(readBufferFinal,readBufferClear,strlen(readBufferClear));
}
unpadBuffer(readBufferFinal,readBufferPadded);
printf("cleartext=%s\n",readBufferPadded);
}
