CPACF supports DES, TDES, AES-128, AES-256, SHA-1, SHA-2, SHA-3, and True  Random Number Generator. With the z15, CPACF supports Elliptic Curve  Cryptography clear key, improving the performance of Elliptic Curve algorithms. The  following algorithms are supported: EdDSA (Ed448, Ed25519), ECDSA (P-256, P-384,  P-521), ECDH(P-256, P-384, P521, X25519, X448). Protected key signature creation  is also supported. The IBM Integrated Accelerator for zEnterprise Data Compression (zEDC) provides  on-chip compression (DEFLATE/gzip/zlib) services for all LPARs, whereas the zEDC  Express PCIe feature was assigned to 15 LPARs only. This innovation results in improved compression performance and simplified  management (no need to manage the zEDC Express PCIe features), on a processor  chip level, without any delays associated with I/O requests, and with minimal CPU  costs. The enhancement preserves the compatibility with an earlier version with the  data that is compressed by zEDC Express features; data, which is compressed and  written by zEDC Express features, is read and decompressed on the z15 and vice  versa. This simplifies the migration to the z15 (on-chip compression removes the need  to acquire zEDC Express PCIe features). The Transactional Execution Facility, which is known in the industry as  hardware  transactional memory , allows instructions to be issued automatically. Therefore,  all results  of  the instructions in the group are committed or  no results  are committed, in a truly  transactional manner. The execution is optimistic.  The instructions are issued, but previous state values are saved in transactional memory. If  the transaction succeeds, the saved values are discarded. If it fails, they are used to restore  the original values. Software can test the success of execution and redrive the code (if  needed) by using the same or a different path. The Transactional Execution Facility provides several instructions, including instructions to  declare the start and end of a transaction and to cancel the transaction. This capability can  provide performance benefits and scalability to workloads by helping to avoid most of the  locks on data. This ability is especially important for heavily threaded applications, such as  Java. Also known as less-pausing garbage collection, Guarded Storage Facility is a function that  was introduced with the z14 to enable enterprise scale Java applications to run without  periodic pause for garbage collection on larger heaps. This facility improves Java  performance by reducing program pauses during Java Garbage Collection. Simultaneous multithreading (SMT) is built into the z15 IFLs, zIIPs, and SAPs, which allows  more than one thread to simultaneously run in the same core and share all of its resources.  This function improves the use of the cores and increases processing capacity. Simultaneous multithreading Guarded Storage Facility Transactional Execution Facility – IBM Integrated Accelerator for zEDC (On-chip Compression): The z15 is enhancing  the compression by taking it from the I/O device level (zEDC Express feature) and  moving it to the Nest Accelerator Unit on the processor chip, adding the Deflate  compliant (lossless data compression algorithm), and GZIP (GNU zip - UNIX  compression utility) compression and decompression support as hardware  instructions. 18  IBM z15 (8561) Technical Guide