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Although the digital signature technique is a very effective method of
maintaining integrity and authentication of data, there are some
drawbacks associated with this method. They are discussed in this
section.

1. The private key must be kept in a secured manner. The loss of
private key can cause severe damage since, anyone who gets the private
key can use it to send signed messages to the public key holders and
the public key will recognize these messages as valid and so the
receivers will feel that the message was sent by the authentic private
key holder.

2. The process of generation and verification of digital signature
requires considerable amount of time. So, for frequent exchange of
messages the speed of communication will reduce.

3. When the digital signature is not verified by the public key, then
the receiver simply marks the message as invalid but he does not know
whether the message was corrupted or the false private key was used.

4. For using the digital signature the user has to obtain private and
public key, the receiver has to obtain the digital signature
certificate also. This requires them to pay additional amount of
money.

5. If a user changes his private key after every fixed interval of
time, then the record of all these changes must be kept. If a dispute
arises over a previously sent message then the old key pair needs to
be referred. Thus storage of all the previous keys is another
overhead.

6. Although digital signature provides authenticity, it does not
ensure secrecy of the data. To provide the secrecy, some other
technique such as encryption and decryption needs to be used.