How to sign arbitrary message such as proof challenges using rust sdk ?

[aptgetgit]

Unable to figure out how to actually sign a rotation proof challenge, for verifying capability to rotate the authentication key.

My rotation proof challenge -

let rotation_proof_challenge = RotationProofChallenge {
        account_address: PeerId::from_str("0x1").unwrap(),
        module_name: "account".to_string(),
        struct_name: "RotationProofChallenge".to_string(),
        sequence_number: alice_account_info.sequence_number,
        originator: alice_local_account.address(),
        current_auth_key: 
        PeerId::from_bytes( alice_local_account.public_key().to_bytes().to_vec())
            .unwrap(),
        new_public_key: multi_ed25519_public_key.to_bytes()
    };

need to pass the signed challenge to the aptos_framework_sdk_builder rotate function, here

pub fn account_rotate_authentication_key(
    from_scheme: u8,
    from_public_key_bytes: Vec<u8>,
    to_scheme: u8,
    to_public_key_bytes: Vec<u8>,
    cap_rotate_key: Vec<u8>,
    cap_update_table: Vec<u8>,
) -> TransactionPayload {}

I am trying to use the sign_arbitrary_message exposed on the Ed25519PrivateKey struct here, but the function is private.

trying to find a workaround but seems like serialization is needed for the proof to be signed by other key types.

searching on discord, yields results for the typescript sdk here but confused how to do it in rust
any help/guide/examples would be appreciated
Thanks

[gregnazario]

The original authors of the crypto code were very protective against signing arbitrary data, but you can do one of two things:

1. Enable the fuzzing feature, and use this function from the trait https://github.com/aptos-labs/aptos-core/blob/42d905a335a32002820253a993b4357b68a0a1de/crates/aptos-crypto/src/ed25519/ed25519_keys.rs#L152-L155
2. Implement CryptoHash for the struct you want and then use this function. https://github.com/aptos-labs/aptos-core/blob/42d905a335a32002820253a993b4357b68a0a1de/crates/aptos-crypto/src/ed25519/ed25519_keys.rs#L142-L150

Here's an example of how key rotation is handled in the Aptos CLI https://github.com/aptos-labs/aptos-core/blob/main/crates/aptos/src/account/key_rotation.rs#L118-L136

[aptgetgit]

Hey @gregnazario , thanks for the reply.
Unable to do both, I might be missing something but here's what i did -

• I followed the docs on how to install the aptos rust sdk - https://aptos.dev/sdks/rust-sdk/
• Enabling the fuzzing feature throws error -
  • Updated my cargo.toml file to this -
    • aptos-sdk = { git = "https://github.com/aptos-labs/aptos-core", branch = "devnet", features = ['fuzzing']}
  • which throws error -
    • the package `my-package` depends on `aptos-sdk`, with features: `fuzzing` but `aptos-sdk` does not have these features.
• For implementing CryptoHash and BCSCryptoHashneed to use the package aptos-crypto-derive which is not exposed for aptos-sdk installation i followed.

I think the aptos-sdk installation steps are wrong , but the crates were yanked from crates.io and the aptos docs suggests this way, so not sure what else to do.