we use several cryptographic functions in our operations, e.g. MD5 to create unique customer IDs (instead of logging original data we store only the hash), or to create one-time passwords where we combine date/time with input from the user. Another common function is of course to calculate file integrity, which many others do too.
The function is already implemneted in an extension to OO3: “Cryptographic Hash Functions UNO Component for OpenOffice.org” See more at: http://extensions.openoffice.org/en/project/cryptographic-hash-functions-uno-component-openofficeorg#sthash.42nVdsJE.dpuf
We hope it can be added as a native function into Calc and thereby beat the other productivity suites in the market, which is still miss this valuable functionality.