rsa/

pkcs1v15.rs

//! PKCS#1 v1.5 support as described in [RFC8017 § 8.2].
//!
//! <div class="warning">
//! <b>Warning</b>
//!
//! PKCS#1 v1.5 padding has a longstanding history of issues generally classed as
//! [Bleichenbacher Attacks] which were originally discovered in 1998 but keep reappearing in
//! various forms again and again over the course of decades, including most recently in the 2023
//! [Marvin Attack], which the `rsa` crate is [still vulnerable] to.
//!
//! These attacks can result in complete plaintext recovery for encryption, or signature forgery,
//! leading to a total failure of either confidentiality or integrity.
//!
//! Unless explicitly needed for compatibility reasons, we recommend against using PKCS#1 v1.5,
//! and suggest using [PSS][`super::pss`] or [OAEP][`super::oaep`] instead (if there is a
//! requirement to use RSA).
//! </div>
//!
//! [Bleichenbacher Attacks]: https://en.wikipedia.org/wiki/Adaptive_chosen-ciphertext_attack#Practical_attacks
//! [Marvin Attack]: https://people.redhat.com/~hkario/marvin/
//! [still vulnerable]: https://github.com/RustCrypto/RSA/issues/626
//!
//! # Usage
//!
//! See [code example in the toplevel rustdoc](../index.html#pkcs1-v15-signatures).
//!
//! [RFC8017 § 8.2]: https://datatracker.ietf.org/doc/html/rfc8017#section-8.2

#[cfg(feature = "alloc")]
mod decrypting_key;
mod encrypting_key;
mod generic_signing_key;
mod signature;
#[cfg(feature = "alloc")]
mod signing_key;
mod verifying_key;

pub use self::generic_signing_key::GenericSigningKey;
#[cfg(feature = "alloc")]
pub use self::{
    decrypting_key::DecryptingKey,
    encrypting_key::GenericEncryptingKey,
    signature::{GenericSignature, SignatureBytes},
    signing_key::SigningKey,
    verifying_key::GenericVerifyingKey,
};
#[cfg(not(feature = "alloc"))]
pub use self::{
    encrypting_key::GenericEncryptingKey,
    signature::{GenericSignature, SignatureBytes},
    verifying_key::GenericVerifyingKey,
};

#[cfg(feature = "alloc")]
pub use self::{encrypting_key::EncryptingKey, signature::Signature, verifying_key::VerifyingKey};

#[cfg(feature = "alloc")]
use alloc::{boxed::Box, vec, vec::Vec};
use const_oid::AssociatedOid;
use core::fmt::Debug;
#[cfg(feature = "alloc")]
use crypto_bigint::BoxedUint;
use digest::Digest;
use rand_core::TryCryptoRng;

use crate::algorithms::pad::uint_to_be_pad_into;
#[cfg(feature = "alloc")]
use crate::algorithms::pad::uint_to_zeroizing_be_pad;
use crate::algorithms::pkcs1v15::*;
#[cfg(not(feature = "alloc"))]
use crate::algorithms::rsa::rsa_encrypt;
#[cfg(feature = "alloc")]
use crate::algorithms::rsa::{rsa_decrypt_and_check, rsa_encrypt};
use crate::errors::{Error, Result};
#[cfg(feature = "alloc")]
use crate::key::{self, RsaPrivateKey};
use crate::traits::{PaddingScheme, PublicKeyParts, SignatureScheme, UnsignedModularInt};

/// Encryption using PKCS#1 v1.5 padding.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct Pkcs1v15Encrypt;

impl Pkcs1v15Encrypt {
    /// Encrypts the given message with RSA and PKCS#1 v1.5 padding into caller-provided storage.
    ///
    /// The message must be no longer than the length of the public modulus minus 11 bytes.
    pub fn encrypt_into<'a, R, K, T>(
        self,
        rng: &mut R,
        pub_key: &K,
        msg: &[u8],
        storage: &'a mut [u8],
    ) -> Result<&'a [u8]>
    where
        R: TryCryptoRng + ?Sized,
        T: UnsignedModularInt,
        K: PublicKeyParts<T>,
        K::MontyParams: crate::traits::modular::CtModulusParams,
    {
        let padded_len = pub_key.size();
        let em = pkcs1v15_encrypt_pad_into(rng, msg, padded_len, storage)?;
        let int = T::try_from_be_bytes_vartime(em)?;

        uint_to_be_pad_into(rsa_encrypt(pub_key, &int)?, padded_len, storage)
    }
}

/// Encrypts the given message with RSA and the padding
/// scheme from PKCS#1 v1.5. The message must be no longer than the
/// length of the public modulus minus 11 bytes.
#[cfg(feature = "alloc")]
#[inline]
#[allow(dead_code)] // Vec-returning convenience wrapper; kept alongside the buffer-taking `encrypt_into`.
fn encrypt<R: TryCryptoRng + ?Sized, K, T>(rng: &mut R, pub_key: &K, msg: &[u8]) -> Result<Vec<u8>>
where
    T: UnsignedModularInt,
    K: PublicKeyParts<T>,
    K::MontyParams: crate::traits::modular::CtModulusParams,
{
    let mut storage = vec![0u8; pub_key.size()];
    let ciphertext = Pkcs1v15Encrypt.encrypt_into(rng, pub_key, msg, &mut storage)?;
    Ok(ciphertext.to_vec())
}

#[cfg(not(feature = "alloc"))]
#[derive(Clone, Debug, Eq, PartialEq)]
pub(super) struct Prefix<const N: usize = 32> {
    data: [u8; N],
    len: usize,
}

#[cfg(not(feature = "alloc"))]
impl<const N: usize> Prefix<N> {
    pub const fn new() -> Self {
        Self {
            data: [0u8; N],
            len: 0,
        }
    }

    pub fn from_slice(input: &[u8]) -> Result<Self> {
        if input.len() > N {
            return Err(Error::OutputBufferTooSmall);
        }

        let mut out = Self::new();
        out.data[..input.len()].copy_from_slice(input);
        out.len = input.len();
        Ok(out)
    }
}

#[cfg(not(feature = "alloc"))]
impl<const N: usize> AsRef<[u8]> for Prefix<N> {
    fn as_ref(&self) -> &[u8] {
        &self.data[..self.len]
    }
}

#[cfg(not(feature = "alloc"))]
pub(super) fn pkcs1v15_generate_prefix_helper<D: Digest>() -> Prefix
where
    D: Digest + AssociatedOid,
{
    let mut tmp_prefix = [0u8; 64];
    let prefix =
        pkcs1v15_generate_prefix_into::<D>(&mut tmp_prefix).expect("prefix buffer is too small");
    Prefix::from_slice(prefix).expect("prefix buffer is too small")
}

impl PaddingScheme for Pkcs1v15Encrypt {
    #[cfg(feature = "alloc")]
    fn decrypt<Rng: TryCryptoRng + ?Sized>(
        self,
        rng: Option<&mut Rng>,
        priv_key: &RsaPrivateKey,
        ciphertext: &[u8],
    ) -> Result<Vec<u8>> {
        decrypt(rng, priv_key, ciphertext)
    }

    #[cfg(feature = "alloc")]
    fn encrypt<Rng, K, T>(self, rng: &mut Rng, pub_key: &K, msg: &[u8]) -> Result<Vec<u8>>
    where
        Rng: TryCryptoRng + ?Sized,
        T: UnsignedModularInt,
        K: PublicKeyParts<T>,
        K::MontyParams: crate::traits::modular::CtModulusParams,
    {
        let mut storage = vec![0u8; pub_key.size()];
        let ciphertext = self.encrypt_into(rng, pub_key, msg, &mut storage)?;
        Ok(ciphertext.to_vec())
    }
}

/// `RSASSA-PKCS1-v1_5`: digital signatures using PKCS#1 v1.5 padding.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Pkcs1v15Sign {
    /// Length of hash to use.
    pub hash_len: Option<usize>,

    /// Prefix.
    #[cfg(feature = "alloc")]
    prefix: Box<[u8]>,
    #[cfg(not(feature = "alloc"))]
    prefix: Prefix,
}

impl Pkcs1v15Sign {
    /// Create new PKCS#1 v1.5 padding for the given digest.
    ///
    /// The digest must have an [`AssociatedOid`]. Make sure to enable the `oid`
    /// feature of the relevant digest crate.
    pub fn new<D>() -> Self
    where
        D: Digest + AssociatedOid,
    {
        Self {
            hash_len: Some(<D as Digest>::output_size()),
            #[cfg(feature = "alloc")]
            prefix: pkcs1v15_generate_prefix::<D>().into_boxed_slice(),
            #[cfg(not(feature = "alloc"))]
            prefix: pkcs1v15_generate_prefix_helper::<D>(),
        }
    }

    /// Create new PKCS#1 v1.5 padding for computing an unprefixed signature.
    ///
    /// This sets `hash_len` to `None` and uses an empty `prefix`.
    pub fn new_unprefixed() -> Self {
        Self {
            hash_len: None,
            #[cfg(feature = "alloc")]
            prefix: Box::new([]),
            #[cfg(not(feature = "alloc"))]
            prefix: Prefix::new(),
        }
    }
}

impl SignatureScheme for Pkcs1v15Sign {
    #[cfg(feature = "alloc")]
    fn sign<Rng: TryCryptoRng + ?Sized>(
        self,
        rng: Option<&mut Rng>,
        priv_key: &RsaPrivateKey,
        hashed: &[u8],
    ) -> Result<Vec<u8>> {
        if let Some(hash_len) = self.hash_len {
            if hashed.len() != hash_len {
                return Err(Error::InputNotHashed);
            }
        }

        sign(rng, priv_key, &self.prefix, hashed)
    }

    fn verify<K, T>(self, pub_key: &K, hashed: &[u8], sig: &[u8]) -> Result<()>
    where
        T: UnsignedModularInt,
        K: PublicKeyParts<T>,
    {
        if let Some(hash_len) = self.hash_len {
            if hashed.len() != hash_len {
                return Err(Error::InputNotHashed);
            }
        }

        if sig.len() != pub_key.size() {
            return Err(Error::Verification);
        }

        let mut storage = pub_key.n().as_ref().to_be_bytes();
        let sig = T::try_from_be_bytes_vartime(sig).map_err(|_| Error::Verification)?;
        verify_generic(
            pub_key,
            self.prefix.as_ref(),
            hashed,
            &sig,
            storage.as_mut(),
        )
    }
}

/// Encrypts the given message with RSA and the padding
/// scheme from PKCS#1 v1.5.  The message must be no longer than the
/// length of the public modulus minus 11 bytes.
#[inline]
pub fn encrypt_into<'a, R, K, T>(
    rng: &mut R,
    pub_key: &K,
    msg: &[u8],
    storage: &'a mut [u8],
) -> Result<&'a [u8]>
where
    R: TryCryptoRng + ?Sized,
    T: UnsignedModularInt,
    K: PublicKeyParts<T>,
    K::MontyParams: crate::traits::modular::CtModulusParams,
{
    Pkcs1v15Encrypt.encrypt_into(rng, pub_key, msg, storage)
}

/// Decrypts a plaintext using RSA and the padding scheme from PKCS#1 v1.5.
///
/// If an `rng` is passed, it uses RSA blinding to avoid timing side-channel attacks.
///
/// Note that whether this function returns an error or not discloses secret
/// information. If an attacker can cause this function to run repeatedly and
/// learn whether each instance returned an error then they can decrypt and
/// forge signatures as if they had the private key. See
/// `decrypt_session_key` for a way of solving this problem.
#[cfg(feature = "alloc")]
#[inline]
fn decrypt<R: TryCryptoRng + ?Sized>(
    rng: Option<&mut R>,
    priv_key: &RsaPrivateKey,
    ciphertext: &[u8],
) -> Result<Vec<u8>> {
    key::check_public(priv_key)?;

    let ciphertext = BoxedUint::from_be_slice(ciphertext, priv_key.n_bits_precision())?;
    let em = rsa_decrypt_and_check(priv_key, rng, &ciphertext)?;
    let em = uint_to_zeroizing_be_pad(em, priv_key.size())?;

    pkcs1v15_encrypt_unpad(em, priv_key.size())
}

/// Calculates the signature of hashed using
/// RSASSA-PKCS1-V1_5-SIGN from RSA PKCS#1 v1.5. Note that `hashed` must
/// be the result of hashing the input message using the given hash
/// function. If hash is `None`, hashed is signed directly. This isn't
/// advisable except for interoperability.
///
/// If `rng` is not `None` then RSA blinding will be used to avoid timing
/// side-channel attacks.
///
/// This function is deterministic. Thus, if the set of possible
/// messages is small, an attacker may be able to build a map from
/// messages to signatures and identify the signed messages. As ever,
/// signatures provide authenticity, not confidentiality.
#[cfg(feature = "alloc")]
#[inline]
fn sign<R: TryCryptoRng + ?Sized>(
    rng: Option<&mut R>,
    priv_key: &RsaPrivateKey,
    prefix: &[u8],
    hashed: &[u8],
) -> Result<Vec<u8>> {
    let em = pkcs1v15_sign_pad(prefix, hashed, priv_key.size())?;

    let em = BoxedUint::from_be_slice(&em, priv_key.n_bits_precision())?;
    uint_to_zeroizing_be_pad(rsa_decrypt_and_check(priv_key, rng, &em)?, priv_key.size())
}

/// Verifies an RSA PKCS#1 v1.5 signature.
#[inline]
pub(crate) fn verify_generic<K, T>(
    pub_key: &K,
    prefix: &[u8],
    hashed: &[u8],
    sig: &T,
    storage: &mut [u8],
) -> Result<()>
where
    T: UnsignedModularInt,
    K: PublicKeyParts<T>,
{
    let n = pub_key.n();
    if sig >= n.as_ref() || sig.bits_precision() != pub_key.n_bits_precision() {
        return Err(Error::Verification);
    }

    let em = uint_to_be_pad_into(rsa_encrypt(pub_key, sig)?, pub_key.size(), storage)?;

    pkcs1v15_sign_unpad(prefix, hashed, em, pub_key.size())
}

mod oid {
    use const_oid::ObjectIdentifier;

    /// A trait which associates an RSA-specific OID with a type.
    pub trait RsaSignatureAssociatedOid {
        /// The OID associated with this type.
        const OID: ObjectIdentifier;
    }

    #[cfg(feature = "sha1")]
    impl RsaSignatureAssociatedOid for sha1::Sha1 {
        const OID: ObjectIdentifier =
            const_oid::ObjectIdentifier::new_unwrap("1.2.840.113549.1.1.5");
    }

    #[cfg(feature = "sha2")]
    impl RsaSignatureAssociatedOid for sha2::Sha224 {
        const OID: ObjectIdentifier =
            const_oid::ObjectIdentifier::new_unwrap("1.2.840.113549.1.1.14");
    }

    #[cfg(feature = "sha2")]
    impl RsaSignatureAssociatedOid for sha2::Sha256 {
        const OID: ObjectIdentifier =
            const_oid::ObjectIdentifier::new_unwrap("1.2.840.113549.1.1.11");
    }

    #[cfg(feature = "sha2")]
    impl RsaSignatureAssociatedOid for sha2::Sha384 {
        const OID: ObjectIdentifier =
            const_oid::ObjectIdentifier::new_unwrap("1.2.840.113549.1.1.12");
    }

    #[cfg(feature = "sha2")]
    impl RsaSignatureAssociatedOid for sha2::Sha512 {
        const OID: ObjectIdentifier =
            const_oid::ObjectIdentifier::new_unwrap("1.2.840.113549.1.1.13");
    }
}

pub use oid::RsaSignatureAssociatedOid;

#[cfg(test)]
#[cfg(feature = "alloc")]
mod tests {
    use super::*;
    use ::signature::{
        hazmat::{PrehashSigner, PrehashVerifier},
        DigestSigner, DigestVerifier, Keypair, RandomizedDigestSigner, RandomizedSigner,
        SignatureEncoding, Signer, Verifier,
    };
    use base64ct::{Base64, Encoding};
    use hex_literal::hex;
    use rand::rngs::ChaCha8Rng;
    use rand_core::{Rng, SeedableRng};
    use rstest::rstest;
    use sha1::{Digest, Sha1};
    use sha2::Sha256;
    use sha3::Sha3_256;

    use crate::traits::{
        Decryptor, EncryptingKeypair, PublicKeyParts, RandomizedDecryptor, RandomizedEncryptor,
    };
    use crate::{RsaPrivateKey, RsaPublicKey};

    fn get_private_key() -> RsaPrivateKey {
        // In order to generate new test vectors you'll need the PEM form of this key:
        // -----BEGIN RSA PRIVATE KEY-----
        // MIIBOgIBAAJBALKZD0nEffqM1ACuak0bijtqE2QrI/KLADv7l3kK3ppMyCuLKoF0
        // fd7Ai2KW5ToIwzFofvJcS/STa6HA5gQenRUCAwEAAQJBAIq9amn00aS0h/CrjXqu
        // /ThglAXJmZhOMPVn4eiu7/ROixi9sex436MaVeMqSNf7Ex9a8fRNfWss7Sqd9eWu
        // RTUCIQDasvGASLqmjeffBNLTXV2A5g4t+kLVCpsEIZAycV5GswIhANEPLmax0ME/
        // EO+ZJ79TJKN5yiGBRsv5yvx5UiHxajEXAiAhAol5N4EUyq6I9w1rYdhPMGpLfk7A
        // IU2snfRJ6Nq2CQIgFrPsWRCkV+gOYcajD17rEqmuLrdIRexpg8N1DOSXoJ8CIGlS
        // tAboUGBxTDq3ZroNism3DaMIbKPyYrAqhKov1h5V
        // -----END RSA PRIVATE KEY-----

        RsaPrivateKey::from_components(
            BoxedUint::from_be_hex("B2990F49C47DFA8CD400AE6A4D1B8A3B6A13642B23F28B003BFB97790ADE9A4CC82B8B2A81747DDEC08B6296E53A08C331687EF25C4BF4936BA1C0E6041E9D15", 512).unwrap(),
            BoxedUint::from(65_537u64),
            BoxedUint::from_be_hex("8ABD6A69F4D1A4B487F0AB8D7AAEFD38609405C999984E30F567E1E8AEEFF44E8B18BDB1EC78DFA31A55E32A48D7FB131F5AF1F44D7D6B2CED2A9DF5E5AE4535", 512).unwrap(),
            vec![
                BoxedUint::from_be_hex("DAB2F18048BAA68DE7DF04D2D35D5D80E60E2DFA42D50A9B04219032715E46B3", 256).unwrap(),
                BoxedUint::from_be_hex("D10F2E66B1D0C13F10EF9927BF5324A379CA218146CBF9CAFC795221F16A3117", 256).unwrap()
            ],
        ).unwrap()
    }

    #[rstest]
    #[case(
        "gIcUIoVkD6ATMBk/u/nlCZCCWRKdkfjCgFdo35VpRXLduiKXhNz1XupLLzTXAybEq15juc+EgY5o0DHv/nt3yg==",
        "x"
    )]
    #[case(
        "Y7TOCSqofGhkRb+jaVRLzK8xw2cSo1IVES19utzv6hwvx+M8kFsoWQm5DzBeJCZTCVDPkTpavUuEbgp8hnUGDw==",
        "testing."
    )]
    #[case(
        "arReP9DJtEVyV2Dg3dDp4c/PSk1O6lxkoJ8HcFupoRorBZG+7+1fDAwT1olNddFnQMjmkb8vxwmNMoTAT/BFjQ==",
        "testing.\n"
    )]
    #[case(
        "WtaBXIoGC54+vH0NH0CHHE+dRDOsMc/6BrfFu2lEqcKL9+uDuWaf+Xj9mrbQCjjZcpQuX733zyok/jsnqe/Ftw==",
        "01234567890123456789012345678901234567890123456789012"
    )]
    fn test_decrypt_pkcs1v15(#[case] ciphertext: &str, #[case] plaintext: &str) {
        let priv_key = get_private_key();

        let out = priv_key
            .decrypt(Pkcs1v15Encrypt, &Base64::decode_vec(ciphertext).unwrap())
            .unwrap();
        assert_eq!(out, plaintext.as_bytes());
    }

    #[test]
    fn test_encrypt_decrypt_pkcs1v15() {
        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let priv_key = get_private_key();
        let k = priv_key.size();

        for i in 1..100 {
            let mut input = vec![0u8; i * 8];
            rng.fill_bytes(&mut input);
            if input.len() > k - 11 {
                input = input[0..k - 11].to_vec();
            }

            let pub_key: RsaPublicKey = priv_key.clone().into();
            let ciphertext = encrypt(&mut rng, &pub_key, &input).unwrap();
            assert_ne!(input, ciphertext);

            let blind: bool = rng.next_u32() < (1u32 << 31);
            let blinder = if blind { Some(&mut rng) } else { None };
            let plaintext = decrypt(blinder, &priv_key, &ciphertext).unwrap();
            assert_eq!(input, plaintext);
        }
    }

    #[rstest]
    #[case(
        "gIcUIoVkD6ATMBk/u/nlCZCCWRKdkfjCgFdo35VpRXLduiKXhNz1XupLLzTXAybEq15juc+EgY5o0DHv/nt3yg==",
        "x"
    )]
    #[case(
        "Y7TOCSqofGhkRb+jaVRLzK8xw2cSo1IVES19utzv6hwvx+M8kFsoWQm5DzBeJCZTCVDPkTpavUuEbgp8hnUGDw==",
        "testing."
    )]
    #[case(
        "arReP9DJtEVyV2Dg3dDp4c/PSk1O6lxkoJ8HcFupoRorBZG+7+1fDAwT1olNddFnQMjmkb8vxwmNMoTAT/BFjQ==",
        "testing.\n"
    )]
    #[case(
        "WtaBXIoGC54+vH0NH0CHHE+dRDOsMc/6BrfFu2lEqcKL9+uDuWaf+Xj9mrbQCjjZcpQuX733zyok/jsnqe/Ftw==",
        "01234567890123456789012345678901234567890123456789012"
    )]
    fn test_decrypt_pkcs1v15_traits(#[case] ciphertext: &str, #[case] plaintext: &str) {
        let priv_key = get_private_key();
        let decrypting_key = DecryptingKey::new(priv_key);

        let out = decrypting_key
            .decrypt(&Base64::decode_vec(ciphertext).unwrap())
            .unwrap();
        assert_eq!(out, plaintext.as_bytes());
    }

    #[test]
    fn test_encrypt_decrypt_pkcs1v15_traits() {
        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let priv_key = get_private_key();
        let k = priv_key.size();
        let decrypting_key = DecryptingKey::new(priv_key);

        for i in 1..100 {
            let mut input = vec![0u8; i * 8];
            rng.fill_bytes(&mut input);
            if input.len() > k - 11 {
                input = input[0..k - 11].to_vec();
            }

            let encrypting_key = decrypting_key.encrypting_key();
            let ciphertext = encrypting_key.encrypt_with_rng(&mut rng, &input).unwrap();
            assert_ne!(input, ciphertext);

            let blind: bool = rng.next_u32() < (1u32 << 31);
            let plaintext = if blind {
                decrypting_key
                    .decrypt_with_rng(&mut rng, &ciphertext)
                    .unwrap()
            } else {
                decrypting_key.decrypt(&ciphertext).unwrap()
            };
            assert_eq!(input, plaintext);
        }
    }

    #[rstest]
    #[case("Test.\n", hex!(
        "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
        "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"))
    ]
    fn test_sign_pkcs1v15(#[case] text: &str, #[case] expected: [u8; 64]) {
        let priv_key = get_private_key();

        let digest = Sha1::digest(text.as_bytes()).to_vec();

        let out = priv_key.sign(Pkcs1v15Sign::new::<Sha1>(), &digest).unwrap();
        assert_ne!(out, digest);
        assert_eq!(out, expected);

        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let out2 = priv_key
            .sign_with_rng(&mut rng, Pkcs1v15Sign::new::<Sha1>(), &digest)
            .unwrap();
        assert_eq!(out2, expected);
    }

    #[rstest]
    #[case("Test.\n", hex!(
        "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
        "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"))
    ]
    fn test_sign_pkcs1v15_signer(#[case] text: &str, #[case] expected: [u8; 64]) {
        let priv_key = get_private_key();

        let signing_key = SigningKey::<Sha1>::new(priv_key);
        let out = signing_key.sign(text.as_bytes()).to_bytes();
        assert_ne!(out.as_ref(), text.as_bytes());
        assert_ne!(out.as_ref(), &Sha1::digest(text.as_bytes()).to_vec());
        assert_eq!(out.as_ref(), expected);

        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let out2 = signing_key
            .sign_with_rng(&mut rng, text.as_bytes())
            .to_bytes();
        assert_eq!(out2.as_ref(), expected);
    }

    #[rstest]
    #[case("Test.\n", hex!(
        "2ffae3f3e130287b3a1dcb320e46f52e8f3f7969b646932273a7e3a6f2a182ea"
        "02d42875a7ffa4a148aa311f9e4b562e4e13a2223fb15f4e5bf5f2b206d9451b"))
    ]
    fn test_sign_pkcs1v15_signer_sha2_256(#[case] text: &str, #[case] expected: [u8; 64]) {
        let priv_key = get_private_key();
        let signing_key = SigningKey::<Sha256>::new(priv_key);

        let out = signing_key.sign(text.as_bytes()).to_bytes();
        assert_ne!(out.as_ref(), text.as_bytes());
        assert_eq!(out.as_ref(), expected);

        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let out2 = signing_key
            .sign_with_rng(&mut rng, text.as_bytes())
            .to_bytes();
        assert_eq!(out2.as_ref(), expected);
    }

    #[rstest]
    #[case("Test.\n", hex!(
        "55e9fba3354dfb51d2c8111794ea552c86afc2cab154652c03324df8c2c51ba7"
        "2ff7c14de59a6f9ba50d90c13a7537cc3011948369f1f0ec4a49d21eb7e723f9"))
    ]
    fn test_sign_pkcs1v15_signer_sha3_256(#[case] text: &str, #[case] expected: [u8; 64]) {
        let priv_key = get_private_key();
        let signing_key = SigningKey::<Sha3_256>::new(priv_key);

        let out = signing_key.sign(text.as_bytes()).to_bytes();
        assert_ne!(out.as_ref(), text.as_bytes());
        assert_eq!(out.as_ref(), expected);

        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let out2 = signing_key
            .sign_with_rng(&mut rng, text.as_bytes())
            .to_bytes();
        assert_eq!(out2.as_ref(), expected);
    }

    #[rstest]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"
        )
    )]
    fn test_sign_pkcs1v15_digest_signer(#[case] text: &str, #[case] expected: [u8; 64]) {
        let priv_key = get_private_key();
        let signing_key = SigningKey::new(priv_key);

        let mut digest = Sha1::new();
        digest.update(text.as_bytes());
        let out = signing_key
            .sign_digest(|digest: &mut Sha1| digest.update(text.as_bytes()))
            .to_bytes();
        assert_ne!(out.as_ref(), text.as_bytes());
        assert_ne!(out.as_ref(), &Sha1::digest(text.as_bytes()).to_vec());
        assert_eq!(out.as_ref(), expected);

        let mut rng = ChaCha8Rng::from_seed([42; 32]);
        let out2 = signing_key
            .sign_digest_with_rng(&mut rng, |digest: &mut Sha1| digest.update(text.as_bytes()))
            .to_bytes();
        assert_eq!(out2.as_ref(), expected);
    }

    #[rstest]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"
        ),
        true
    )]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362af"
        ),
        false
    )]
    fn test_verify_pkcs1v15(#[case] text: &str, #[case] sig: [u8; 64], #[case] expected: bool) {
        let priv_key = get_private_key();
        let pub_key: RsaPublicKey = priv_key.into();

        let digest = Sha1::digest(text.as_bytes()).to_vec();

        let result = pub_key.verify(Pkcs1v15Sign::new::<Sha1>(), &digest, &sig);
        match expected {
            true => result.expect("failed to verify"),
            false => {
                result.expect_err("expected verifying error");
            }
        }
    }

    #[rstest]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"
        ),
        true
    )]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362af"
        ),
        false
    )]
    fn test_verify_pkcs1v15_signer(
        #[case] text: &str,
        #[case] sig: [u8; 64],
        #[case] expected: bool,
    ) {
        let priv_key = get_private_key();

        let pub_key: RsaPublicKey = priv_key.into();
        let verifying_key = VerifyingKey::<Sha1>::new(pub_key);

        let result = verifying_key.verify(
            text.as_bytes(),
            &Signature::try_from(sig.as_slice()).unwrap(),
        );
        match expected {
            true => result.expect("failed to verify"),
            false => {
                result.expect_err("expected verifying error");
            }
        }
    }

    #[rstest]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362ae"
        ),
        true
    )]
    #[case(
        "Test.\n",
        hex!(
            "a4f3fa6ea93bcdd0c57be020c1193ecbfd6f200a3d95c409769b029578fa0e33"
            "6ad9a347600e40d3ae823b8c7e6bad88cc07c1d54c3a1523cbbb6d58efc362af"
        ),
        false
    )]
    fn test_verify_pkcs1v15_digest_signer(
        #[case] text: &str,
        #[case] sig: [u8; 64],
        #[case] expected: bool,
    ) {
        let priv_key = get_private_key();

        let pub_key: RsaPublicKey = priv_key.into();
        let verifying_key = VerifyingKey::new(pub_key);

        let result = verifying_key.verify_digest(
            |digest: &mut Sha1| {
                digest.update(text.as_bytes());
                Ok(())
            },
            &Signature::try_from(sig.as_slice()).unwrap(),
        );
        match expected {
            true => result.expect("failed to verify"),
            false => {
                result.expect_err("expected verifying error");
            }
        }
    }

    #[test]
    fn test_unpadded_signature() {
        let msg = b"Thu Dec 19 18:06:16 EST 2013\n";
        let expected_sig = Base64::decode_vec("pX4DR8azytjdQ1rtUiC040FjkepuQut5q2ZFX1pTjBrOVKNjgsCDyiJDGZTCNoh9qpXYbhl7iEym30BWWwuiZg==").unwrap();
        let priv_key = get_private_key();

        let sig = priv_key.sign(Pkcs1v15Sign::new_unprefixed(), msg).unwrap();
        assert_eq!(expected_sig, sig);

        let pub_key: RsaPublicKey = priv_key.into();
        pub_key
            .verify(Pkcs1v15Sign::new_unprefixed(), msg, &sig)
            .expect("failed to verify");
    }

    #[test]
    fn test_unpadded_signature_hazmat() {
        let msg = b"Thu Dec 19 18:06:16 EST 2013\n";
        let expected_sig = Base64::decode_vec("pX4DR8azytjdQ1rtUiC040FjkepuQut5q2ZFX1pTjBrOVKNjgsCDyiJDGZTCNoh9qpXYbhl7iEym30BWWwuiZg==").unwrap();
        let priv_key = get_private_key();

        let signing_key = SigningKey::<Sha1>::new_unprefixed(priv_key);
        let sig = signing_key
            .sign_prehash(msg)
            .expect("Failure during sign")
            .to_bytes();
        assert_eq!(sig.as_ref(), expected_sig);

        let verifying_key = signing_key.verifying_key();
        verifying_key
            .verify_prehash(msg, &Signature::try_from(expected_sig.as_slice()).unwrap())
            .expect("failed to verify");
    }
}