Once an agreement is made between two parties both of them becomes bound to its terms and condition provided both signed willingly and without any force and coercion.

Now in your case you have willingly accepted the offer letter making a full contract coming into force and hence if now you wish to violate its terms you can surely be brought to court seeking compliance of the terms of seeking damages out of its breach.

So I think you have a long career lying ahead and in that event do not invite unnecessary legal wrangles just now.

1) company may refuse to give you relieving letter and experience certificate

2) company may issue you legal notice to recover 3 months salary as per terms of your appointment letter

3) company may file summary suit to recover 3 months salary if it is substantial amount

No doubt you may not utilise this experience or any purpose in future but the law has to be respected.

The company may take legal action to recover the money through civil suit, they cannot initiate criminal action for this.

When you receive a legal notice then you may negotiate with the company about the amount to be paid in this regard.

This will not hamper your future employment with government or private.

Notice period mentioned in the contract is sacrosanct and binds the employer as well as employee. If you wish to dishonour it and further conceal the factum of having worked with your current employer then you may do so at your risk. Remember that if your lie is discovered in background check by subsequent employer(s) your career prospects will be permanently jeopardized.