Shouldn't be able to call sign_oneshot twice.

[gaetan-sbt]

We shouldn't be able to call EVP_DigestSign twice with the same signer. Calling sign_oneshot twice fails with a panic with 'ED25519' (see test code below).

After openssl commit 3fc2b7d this should fail for all signing algorithms.

To prevent users from using sign_oneshot twice (which is always a mistake), we could change the sign_oneshot function to take ownership of signer. Since that breaks backward compatibilty we should probably consider deprecating sign_oneshot and replace it with a function that takes ownership.

More information about EVP_DigestSign is available on this openssl issue.

WDYT?

---

Failing test case

use openssl::{bn::BigNum, hash::MessageDigest, pkey::{self, PKey}, rsa::Rsa, sign::Signer};

fn test_issue_23075() {
    let key =
        BigNum::from_hex_str("f5e5767cf153319517630f226876b86c8160cc583bc013744c6bf255f5cc0ee5")
            .unwrap()
            .to_vec();
    let msg = BigNum::from_hex_str(
    "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"
).unwrap().to_vec();
    let sig = BigNum::from_hex_str("0aab4c900501b3e24d7cdf4663326a3a87df5e4843b2cbdb67cbf6e460fec350aa5371b1508f9f4528ecea23c436d94b5e8fcd4f681e30a6ac00a9704a188a03").unwrap().to_vec();
    let pkey = openssl::pkey::PKey::private_key_from_raw_bytes(&key, pkey::Id::ED25519).unwrap();

    let mut signer = Signer::new_without_digest(&pkey).unwrap();
    assert_eq!(signer.sign_oneshot_to_vec(&msg).unwrap(), sig);

    assert_eq!(signer.sign_oneshot_to_vec(&msg).unwrap(), sig);
}

fn main() {
    test_issue_23075();
}

Here is the Cargo.toml:

[package]
name = "test-openssl"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
openssl = { version = "=0.10.64", features = ["vendored"] }
openssl-sys = "0.9.102"

Error message:

thread 'main' panicked at src/main.rs:17:49:
called `Result::unwrap()` on an `Err` value: ErrorStack([Error { code: 50331836, library: "digital envelope routines", function: "EVP_DigestSign", reason: "final error", file: "crypto/evp/m_sigver.c", line: 585 }])
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace