You’ve seen the spec sheet bragging about “cryptography extensions” on the new Pi 5, and now you’re wondering what that actually buys you.
Raspberry Pi has never been shy about the phrase, and it shows up next to the Cortex-A76 chip in almost every listing.
The trouble is that “cryptography extensions” sounds like a blanket promise, covering every algorithm you might throw at OpenSSL.
If you assume RSA gets the same boost as everything else, you might misjudge how fast your Pi 5 can actually handle certificate signing or SSH key work.
Here’s exactly what that hardware speeds up, what it leaves untouched, and where RSA performance on the Pi 5 really comes from.
The Short Answer
No, RSA operations in OpenSSL do not get dedicated hardware acceleration on the Raspberry Pi 5.
The cryptography extensions built into its Cortex-A76 chip target a specific, narrow set of algorithms.
RSA isn’t one of them, since it relies on a completely different kind of math than the instructions were designed for.
You’ll still see RSA run faster on a Pi 5 than on older Pi boards, but that speed comes from general CPU improvements, not a crypto-specific circuit.
What the Pi 5’s Crypto Extensions Actually Speed Up?
The Broadcom BCM2712 chip inside the Pi 5 includes what Raspberry Pi’s own spec sheet calls cryptography extensions on its Cortex-A76 cores.
These extensions add special instructions built directly into the chip’s SIMD unit, the same unit used for other bulk vector math.
Specifically, they accelerate AES encryption and decryption, along with the SHA-1 and SHA-2 hashing functions.
A related instruction called PMULL also speeds up the multiplication step used inside AES-GCM, a common mode paired with TLS traffic.
Earlier Pi boards, including the Pi 3 and Pi 4, shipped without these extensions enabled, so this really is new territory for the Pi 5.
Why RSA Is Different From AES and SHA?
AES and SHA both work in fixed, repetitive blocks, which makes them perfect candidates for dedicated silicon instructions.
RSA works completely differently. It relies on modular exponentiation across very large numbers, often over 2,000 bits long.
That kind of math needs a long chain of multiplications and reductions rather than a short, fixed sequence of steps.
According to ARM’s own documentation on the Cortex processor line, the Cryptographic Extension specifically adds instructions for AES encryption, decryption, and the SHA hash functions, nothing more.
Big number math like RSA’s modular exponentiation simply isn’t part of that extension, on the Pi 5 or on any other ARM chip using the same instruction set.
Where Your RSA Speed Gains on the Pi 5 Actually Come From?
RSA on the Pi 5 still runs noticeably faster than on a Pi 4, and that improvement comes from three separate sources.
- A higher clock speed, running at 2.4GHz compared to the Pi 4’s 1.8GHz.
- A newer core design, since the Cortex-A76 completes more work per clock cycle than the Cortex-A72.
- Wider general-purpose math units, which speed up the plain multiplication routines RSA depends on.
- OpenSSL’s own hand-tuned ARM64 assembly, which uses NEON vector instructions for bignum operations, separate from the crypto extensions entirely.
None of these are RSA-specific hardware, but together they add up to a real, measurable gain over older boards.
A build comparison from Traverse Technologies illustrated this same pattern on a different ARM chip, showing that missing AES acceleration can leave a chip badly behind on symmetric ciphers while general CPU gains still help asymmetric ones like RSA.
How to Check This Yourself?
You can confirm all of this on your own Pi 5 in under a minute, without installing anything extra.
Run cat /proc/cpuinfo | grep Features and look for flags labeled aes, sha1, sha2, and pmull in the output.
Those flags confirm the crypto extensions are active, but they only ever apply to the algorithms named in the flags themselves.
Then run openssl speed rsa2048 and compare the sign and verify numbers against a Pi 4 running the same OpenSSL version.
You’ll see a real jump, but it tracks with overall CPU benchmarks rather than the dramatic leap you’d see in an AES test.
The Bottom Line
The Pi 5’s cryptography extensions are real, and they genuinely help anything built around AES or SHA hashing.
RSA sits outside that boost entirely, since modular exponentiation isn’t the kind of operation those instructions were built to handle.
Any RSA speedup you notice on the Pi 5 comes from a faster, more efficient CPU core, not a hardware crypto engine working behind the scenes.
If your workload leans heavily on RSA, and especially larger key sizes, it’s worth weighing whether elliptic curve algorithms might suit the Pi 5’s strengths better.