You are probably right about that, but those are HW instructions that would require a new assembler subroutine to exploit. My employer is trying to avoid new assembler application programming if possible.
Not that I can’t do that – I can – but if it can be done without new assembler coding, they will be much happier about it. Peter From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Mark Jacobs Sent: Saturday, February 7, 2026 8:17 PM To: [email protected] Subject: Re: Is it safe to call ICSF service CSNBOWH in CICS? Look at the CHECKSUM or CIPHER MESSAGE instructions it might do what you want too. Mark Jacobs Sent from ProtonMail, Swiss-based encrypted email. GPG Public Key - https://urldefense.com/v3/__https://api.protonmail.ch/pks/lookup?op=get&[email protected]__;!!Ebr-cpPeAnfNniQ8HSAI-g_K5b7VKg!K2eIc_fJVcKVCfAr00BRUtMU-8MLR5hGw4F9AFT1YJcHZqlUToZXStGv7EgpuDN9pLv78DCzhvtp-qGjXrfXMGzdHLjK3f74XWDn-2xz$<https://urldefense.com/v3/__https:/api.protonmail.ch/pks/lookup?op=get&[email protected]__;!!Ebr-cpPeAnfNniQ8HSAI-g_K5b7VKg!K2eIc_fJVcKVCfAr00BRUtMU-8MLR5hGw4F9AFT1YJcHZqlUToZXStGv7EgpuDN9pLv78DCzhvtp-qGjXrfXMGzdHLjK3f74XWDn-2xz$> On Saturday, February 7th, 2026 at 7:10 PM, Farley, Peter <[email protected]> wrote: > Cross posted to CICS-L and IBM-MAIN. > > I have a POC that will require me to compute a simple SHA-1 hash of a text > value less than 64 bytes long to create a 20-byte value that is unique enough > for purposes of the POC. As far as I can tell so far, more complex hashes are > not needed for the expected text values. In my testing so far, the first 10 > bytes of the SHA-1 value turn out to be unique enough. > > The ICSF callable service CSNBOWH is what I am using to compute the SHA-1 > value, and the batch testing I have done so far shows acceptable performance > and 100% uniqueness for purposes of the POC. > > The hash function will be invoked fairly frequently, at least multiple times > (probably less than 20 though) in a single CICS transaction or batch record > process. > > My question is whether it safe to directly call CSNBOWH in a CICS application > (dynamic CALL, not CICS LINK) that is running in the QR task? The SHA-1 > function of CSNBOWH is documented as only requiring CPACF hardware so I have > been ASSUMING that calling this service will not cause a wait in the QR task, > but I felt it would be better to ask the assembled expertise on these lists. > > Alternatively, is there a CICS function or command that I should use instead > of calling CSNBOWH to compute a SHA-1 hash? > > Peter -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
