How could I use any rust RSA crate at anchor for encrypt/decrypt?

Question

I want to decrypt some encrypted RSA payload at the anchor program. So I've tried to cargo add some RSA libraries such as rsa, ring, and openssl. But when I tried to build the anchor, it all failed. I think it's not supported for solana program. Is there a way to build these libraries for solana/anchor? How could I use RSA at the program?

Answer 1

Unfortunately, the answer is simple: you can't. Even if you manage to compile the crates, your program won't be able to perform decryption on-chain without going over the compute limit.

Any cryptographic operation must use the Solana platform syscalls. Here are some examples:

• secp256k1_recover: https://github.com/anza-xyz/agave/blob/3b9e7a3ca53e73f066be058edae0ccaffda852f3/curves/secp256k1-recover/src/lib.rs#L397
• alt bn128 addition: https://github.com/anza-xyz/agave/blob/3b9e7a3ca53e73f066be058edae0ccaffda852f3/curves/bn254/src/lib.rs#L310
• alt bn128 multiplication: https://github.com/anza-xyz/agave/blob/3b9e7a3ca53e73f066be058edae0ccaffda852f3/curves/bn254/src/lib.rs#L330
• curve 25519 operations: https://github.com/anza-xyz/agave/blob/3b9e7a3ca53e73f066be058edae0ccaffda852f3/sdk/program/src/syscalls/definitions.rs#L37