Quite a lot of ARM64 SoC have cryptography extensions, in Linux look for `sha2` feature in `/proc/cpuinfo` or `getauxval(AT_HWCAP) & HWCAP_SHA2` .

Apparently some impressive speed-ups can be achieved, I've heard of 4× to 8× on some SoCs.

Here is some public domain code by Jeffrey Walton that demonstrates how to use it, using intrinsics (which are the best way to do this kind of thing on ARM): https://github.com/noloader/SHA-Intrinsics/blob/master/sha256-arm.c

(I'm creating this issue mostly as reminder to myself but if someone wants to pick it up, fine :smile: )
static const uint32_t init[8] = {
        0x6a09e667ul, 0xbb67ae85ul, 0x3c6ef372ul, 0xa54ff53aul, 0x510e527ful, 0x9b05688cul, 0x1f83d9abul, 0x5be0cd19ul
    };
    
    static const unsigned char data[641] = "-" 
        "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do "
        "eiusmod tempor incididunt ut labore et dolore magna aliqua. Et m"
        "olestie ac feugiat sed lectus vestibulum mattis ullamcorper. Mor"
        "bi blandit cursus risus at ultrices mi tempus imperdiet nulla. N"
        "unc congue nisi vita suscipit tellus mauris. Imperdiet proin fer"
        "mentum leo vel orci. Massa tempor nec feugiat nisl pretium fusce"
        " id velit. Telus in metus vulputate eu scelerisque felis. Mi tem"
        "pus imperdiet nulla malesuada pellentesque. Tristique magna sit.";
    
    static const uint32_t result[9][8] = {
        {0x6a09e667ul, 0xbb67ae85ul, 0x3c6ef372ul, 0xa54ff53aul, 0x510e527ful, 0x9b05688cul, 0x1f83d9abul, 0x5be0cd19ul},
        {0x91f8ec6bul, 0x4da10fe3ul, 0x1c9c292cul, 0x45e18185ul, 0x435cc111ul, 0x3ca26f09ul, 0xeb954caeul, 0x402a7069ul},
        {0xcabea5acul, 0x374fb97cul, 0x182ad996ul, 0x7bd69cbful, 0x450ff900ul, 0xc1d2be8aul, 0x6a41d505ul, 0xe6212dc3ul},
        {0xbcff09d6ul, 0x3e76f36eul, 0x3ecb2501ul, 0x78866e97ul, 0xe1c1e2fdul, 0x32f4eafful, 0x8aa6c4e5ul, 0xdfc024bcul},
        {0xa08c5d94ul, 0x0a862f93ul, 0x6b7f2f40ul, 0x8f9fae76ul, 0x6d40439ful, 0x79dcee0cul, 0x3e39ff3aul, 0xdc3bdbb1ul},
        {0x216a0895ul, 0x9f1a3662ul, 0xe99946f9ul, 0x87ba4364ul, 0x0fb5db2cul, 0x12bed3d3ul, 0x6689c0c7ul, 0x292f1b04ul},
        {0xca3067f8ul, 0xbc8c2656ul, 0x37cb7e0dul, 0x9b6b8b0ful, 0x46dc380bul, 0xf1287f57ul, 0xc42e4b23ul, 0x3fefe94dul},
        {0x3e4c4039ul, 0xbb6fca8cul, 0x6f27d2f7ul, 0x301e44a4ul, 0x8352ba14ul, 0x5769ce37ul, 0x48a1155ful, 0xc0e1c4c6ul},
        {0xfe2fa9ddul, 0x69d0862bul, 0x1ae0db23ul, 0x471f9244ul, 0xf55c0145ul, 0xc30f9c3bul, 0x40a84ea0ul, 0x5b8a266cul},
    };