Simple Sample and TIPs - STEP 7 - SHA2 instruction

Hi

As from TIA V19, it is possible to generate a SHA-2 hash value for some user data.

SHA-2 is a cryptographic hash function, that means it generates a sequence of numbers based on an input sequence of the numbers (it is a type of CRC (Cyclic Redundancy Check) for files). SHA-2 can be employed to check the  integrity of files.

TIPs

• The instruction is available in TIA Portal V19 just for S7-1500 CPUs.
• There are different types of SHA-2 depending on the size of the output hash.The supported sizes are: 224, 256, 384 and 512 bits.
• The input should not be a bool or array of bools.
• The output should be an array of bytes.
• The instruction is acyclick that means you start with a positive edge on req and should wait up to done is true (one scan)
• The "Data" data area must not be changed until the "SHA2" instruction has been completed.
• Just one SHA2 instruction should be active “simultaneously” on the PLC (error 80c3)
• It is possible to generate a SHA-2 of a file from Windows, see FAQ https://support.industry.siemens.com/cs/br/en/view/109483101, it could be useful to debug

In this example the array of chars “banana” generates a  B493D48364AFE44D11C0165CF470A4164D1E2609911EF998BE868D46ADE3DE4E (hex) hash.

Sample project (archived from TIA Portal as .zap19 and after that compacted in .zip format to be uploaded here) user= User, all password = Password1