Comparison of the SSH Key Algorithms

How far the main algorithms are, cryptologically speaking, from each other ?

DSA vs RSA vs ECDSA vs Ed25519

Moore Law

How long do you want to be protected ?

Legacy standard level

Near term protection

Long-term protection


Never use DSA or ECDSA.

  • Ed25519 is probably the strongest mathematically (and also the fastest), but not yet widely supported. At least 256 bits long.
  • RSA is the best bet if you can’t use Ed25519. At least 3072 bits long.

Why not use SSH Certificate ?

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Nicolas Béguier

Nicolas Béguier

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