Securing Data Flow in Communication Channel

Security in data flow in communication channel is one of the greatest challenge for the Information security team. A lot of attempts have succeeded for the information leakage from communication channel.
The last useful model we are familiarize with is the encrypting the data and decrypting in the target model. Linux developers came up with the public key/private key concept. That worked fine with mails, if used properly but, can't we mechanize the encryption and decryption process for each flow of information ? and can't it be safe ?
Now my answer is YES it can be.
We can use the data encryption/decryption mechanism to each kind of data that flow in communication channel. For example
A message sent to abc@xyz.com can be crypted with an algorithm created with the word "abc@xyz.com" and we can use the algorithm to check whether the data was tempered in the channel or not, and even decrypt it in the hand of abc@xyz.com.
Shall we see the code ?
abc@xyz.com has user abc "literal character of 3 alphabets", the 3 numerical value can encrypt the 'data to flow' according to communication channel structure, that can easily be processed in abc@xyz.com's hand knowing if some cracking attempts are done. The encryption mechanism can be applied in any communication model.
This model can also be used securely for intracommunication.
I just dealt with the secure data flow, and common encryption mechanism or want to create the mechanism for your own, you can send me mail, if you have more queries at
mailbymarq@yahoo.com.