FYI, 

If you have -v (debug1) enabled, you will see something like this when starting 
the connection:

debug1(): cipher_init: aes128-ctr from source CPACF, used in non-FIPS mode
...
debug1(): mac_setup_by_alg: hmac-sha2-256 from source CPACF, used in non-FIPS 
mode


Kirk Wolf
Dovetailed Technologies
https://coztoolkit.com

On Thu, Aug 28, 2025, at 2:25 PM, Kirk Wolf wrote:
> For Ciphers and (H)Macs, IBM z/OS OpenSSH (not the sftp component) will use 
> either 
> 
> a) CPACF instructions, for the popular Ciphers and MACs
> 
> b) ICSF calls (an ICSF uses CPACF where it can).  CPACF instructions are GP 
> instructions.
> 
> c) unassisted algorithms in OpenSSH/LibreSSL code.    CPACF (the default) is 
> the fastest, followed by ICSF, followed by software algs.    
> 
> Under no circumstances will Crypto Copressors be used for Ciphers and Macs.
> 
> See the IBM z/OS OpenSSH User's Guide for more details.   See "Ciphers" and 
> "MACs" options as well as CiphersSource and MACsSource options for ssh and 
> sshd.
> 
> Kirk Wolf
> Dovetailed Technologies
> https://coztoolkit.com
> 
> On Tue, Aug 26, 2025, at 10:50 AM, Steve Beaver wrote:
> > Because I don't know,
> > 
> >  
> > 
> > Using SFTP under BPX on zOS.  Do those Cyphers use the CRYPTO-Coprocessors
> > or do they only use the GP's?
> > 
> >  
> > 
> > TIA
> > 
> >  
> > 
> > Steve
> > 
> > 
> > ----------------------------------------------------------------------
> > For IBM-MAIN subscribe / signoff / archive access instructions,
> > send email to [email protected] with the message: INFO IBM-MAIN
> > 
> 
> ----------------------------------------------------------------------
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