When we generate a public-private key pair in PGP/GPG, it gives us the option of selecting DSA and RSA to generate the public and private key pair. We are often confused about which one to select. What is the difference, actually? And what are the pros and cons of selecting DSA and RSA? And which one should you select, and in which scenario? Let’s understand that in more detail.

DSA vs RSA

If we think about the cryptographic strength, both the algorithms DSA and RSA are almost the same. So, in that regard, one can select any of DSA and RSA. However, if performance is an issue, it can make a difference.

DSA (How does DSA work?) was originally intended for signing, but now it can be used for encryption and decryption also. On the other hand, RSA (How does RSA work?) has long been used for both encryption and signing.

Here are a few facts about DSA and RSA:

• If we think about the key generation, DSA is faster than RSA.
• In terms of encrypting, RSA is faster than DSA.
• In decryption, DSA is faster than RSA.
• DSA is faster than RSA in generating a digital signature.
• RSA is faster than DSA in verifying a digital signature.

Now, the key generation is faster for DSA. But in a server-client communication, key generation is done once for server keys and once for client keys. So even if DSA is faster at the time of key generation, it should not be counted as a big point against RSA.

For encryption and decryption, data can be encrypted on the client side with the public key of the server and sent to the server side. Decryption can be done on the server side with the private key of the server. Encryption is faster in RSA, and decryption is faster in DSA. So, if performance is a concern on the client side, RSA should be used. On the other hand, if the server is slow, we would want to use DSA

However, public and private keys are used to encrypt and decrypt the session key at the start of a session. At the time of actual file transfer between the server and the client, a symmetric key called …