Does ssh-keygen really allow 521 bit ECDSA key generation?

Eugene Bright hexumg at
Wed Feb 25 23:12:39 AEDT 2015


I found strange sentence in ssh-keygen man page. There is may be a misprint.

*-b* *bits*Specifies the number of bits in the key to create. For RSA keys,
the minimum size is 768 bits and the default is 2048 bits. Generally, 2048
bits is considered sufficient. DSA keys must be exactly 1024 bits as
specified by FIPS 186-2. For ECDSA keys, the *-b* flag determines the key
length by selecting from one of three elliptic curve sizes: 256, 384 or 521
bits. Attempting to use bit lengths other than these three values for ECDSA
keys will fail. Ed25519 keys have a fixed length and the *-b* flag will be

Eugene Bright.

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