ssh-keygen fails to create RSA keys of length in bits not dividable by 8

This document (7015284) is provided subject to the disclaimer at the end of this document.


SUSE Linux Enterprise Server 11 SP3
SUSE Linux Enterprise Server 11 SP2


Running ssh-keygen with an "odd" (not dividable by 8) key length may fail without further explanation in FIPS mode:

$ ssh-keygen -v -b 2049 -t rsa -N  "1234" -f testkey.rsa
Generating public/private rsa key pair.
rsa_generate_private_key: key generation failed.



Use an RSA key length dividable by 256 as defined by ANSI X9.31.


According to ANSI X9.31, the length of an RSA key must be a multiple of 32 bytes, or 256 bits. Keys having a length that is not a multiple of 8 bits do not work and fail the FIPS RSA key validation of OpenSSL 0.9.8j.


This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7015284
  • Creation Date: 27-Jun-2014
  • Modified Date:05-Mar-2021
    • SUSE Linux Enterprise Server

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