src/crypto/rsaes_oaep.rs

use crate::compact::{JweAlg, JweCompact};
use crate::jwe::Jwe;
use crate::JwtError;

use crate::compact::JweProtectedHeader;
use crate::traits::{JweEncipherInner, JweEncipherOuter};

use openssl::encrypt::{Decrypter, Encrypter};
use openssl::hash::MessageDigest;
use openssl::pkey::PKey;
use openssl::pkey::Private;
use openssl::pkey::Public;
use openssl::rsa::{Padding, Rsa};

/// A JWE outer decipher for RSA-OAEP.
/// You should prefer [crate::crypto::JweEcdhEsA128KWEncipher] or
/// [crate::crypto::JweA128KWEncipher]
pub struct JweRSAOAEPDecipher {
    rsa_priv_key: PKey<Private>,
}

impl TryFrom<Rsa<Private>> for JweRSAOAEPDecipher {
    type Error = JwtError;

    fn try_from(value: Rsa<Private>) -> Result<Self, Self::Error> {
        let rsa_priv_key = PKey::from_rsa(value).map_err(|ossl_err| {
            debug!(?ossl_err);
            JwtError::OpenSSLError
        })?;

        Ok(JweRSAOAEPDecipher { rsa_priv_key })
    }
}

impl JweRSAOAEPDecipher {
    pub(crate) fn unwrap_key(&self, jwec: &JweCompact) -> Result<Vec<u8>, JwtError> {
        let expected_wrap_key_buffer_len = jwec.header.enc.key_len();

        trace!(?expected_wrap_key_buffer_len);

        // Decrypt cek
        let mut wrap_key_decrypter = Decrypter::new(&self.rsa_priv_key).map_err(|ossl_err| {
            debug!(?ossl_err);
            JwtError::OpenSSLError
        })?;

        wrap_key_decrypter
            .set_rsa_padding(Padding::PKCS1_OAEP)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        wrap_key_decrypter
            .set_rsa_mgf1_md(MessageDigest::sha1())
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        wrap_key_decrypter
            .set_rsa_oaep_md(MessageDigest::sha1())
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        // Rsa oaep will often work on bigger block sizes, so we need a larger buffer and then we
        // can copy later. First we check the expected length of the decryption.
        let buf_len = wrap_key_decrypter
            .decrypt_len(&jwec.content_enc_key)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        trace!(?jwec.content_enc_key);

        trace!(enc_len = ?jwec.content_enc_key.len());

        let mut unwrapped_key = vec![0; buf_len];

        trace!(?buf_len);

        wrap_key_decrypter
            .decrypt(&jwec.content_enc_key, &mut unwrapped_key)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        trace!(?unwrapped_key);

        unwrapped_key.truncate(expected_wrap_key_buffer_len);

        Ok(unwrapped_key)
    }

    /// Given a JWE in compact form, decipher and authenticate its content.
    pub fn decipher(&self, jwec: &JweCompact) -> Result<Jwe, JwtError> {
        let unwrapped_key = self.unwrap_key(jwec)?;

        let payload = jwec
            .header
            .enc
            .decipher_inner(unwrapped_key.as_slice(), jwec)?;

        Ok(Jwe {
            header: jwec.header.clone(),
            payload,
        })
    }
}

/// A JWE outer encipher for RSA-OAEP. This type can only encipher.
/// You should prefer [crate::crypto::JweEcdhEsA128KWEncipher] or [crate::crypto::JweA128KWEncipher]
pub struct JweRSAOAEPEncipher {
    rsa_pub_key: PKey<Public>,
}

impl TryFrom<Rsa<Public>> for JweRSAOAEPEncipher {
    type Error = JwtError;

    fn try_from(value: Rsa<Public>) -> Result<Self, Self::Error> {
        let rsa_pub_key = PKey::from_rsa(value).map_err(|ossl_err| {
            debug!(?ossl_err);
            JwtError::OpenSSLError
        })?;

        Ok(JweRSAOAEPEncipher { rsa_pub_key })
    }
}

impl JweRSAOAEPEncipher {
    /// Given a JWE, encipher its content to a compact form.
    pub fn encipher<E: JweEncipherInner>(&self, jwe: &Jwe) -> Result<JweCompact, JwtError> {
        let encipher = E::new_ephemeral()?;
        encipher.encipher_inner(self, jwe)
    }
}

impl JweEncipherOuter for JweRSAOAEPEncipher {
    fn set_header_alg(&self, hdr: &mut JweProtectedHeader) -> Result<(), JwtError> {
        hdr.alg = JweAlg::RSA_OAEP;
        Ok(())
    }

    fn wrap_key(&self, key_to_wrap: &[u8]) -> Result<Vec<u8>, JwtError> {
        let mut wrap_key_encrypter = Encrypter::new(&self.rsa_pub_key).map_err(|ossl_err| {
            debug!(?ossl_err);
            JwtError::OpenSSLError
        })?;

        wrap_key_encrypter
            .set_rsa_padding(Padding::PKCS1_OAEP)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        wrap_key_encrypter
            .set_rsa_mgf1_md(MessageDigest::sha1())
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        wrap_key_encrypter
            .set_rsa_oaep_md(MessageDigest::sha1())
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        let buf_len = wrap_key_encrypter
            .encrypt_len(key_to_wrap)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        let mut wrapped_key = vec![0; buf_len];

        let encoded_len = wrap_key_encrypter
            .encrypt(key_to_wrap, &mut wrapped_key)
            .map_err(|ossl_err| {
                debug!(?ossl_err);
                JwtError::OpenSSLError
            })?;

        wrapped_key.truncate(encoded_len);

        Ok(wrapped_key)
    }
}

#[cfg(test)]
mod tests {
    use super::{JweRSAOAEPDecipher, JweRSAOAEPEncipher};
    use crate::compact::JweCompact;
    use crate::crypto::a256gcm::JweA256GCMEncipher;
    use base64::{engine::general_purpose, Engine as _};
    use std::convert::TryFrom;
    use std::str::FromStr;

    use crate::jwe::JweBuilder;

    use openssl::bn;
    use openssl::pkey::Private;
    use openssl::rsa::Rsa;

    fn rsa_from_private_components(
        n: &str,
        e: &str,
        d: &str,
        p: &str,
        q: &str,
        dmp1: &str,
        dmq1: &str,
        iqmp: &str,
    ) -> Rsa<Private> {
        let n = general_purpose::URL_SAFE_NO_PAD
            .decode(n)
            .expect("Invalid Key");

        let e = general_purpose::URL_SAFE_NO_PAD
            .decode(e)
            .expect("Invalid Key");

        let d = general_purpose::URL_SAFE_NO_PAD
            .decode(d)
            .expect("Invalid Key");

        let p = general_purpose::URL_SAFE_NO_PAD
            .decode(p)
            .expect("Invalid Key");

        let q = general_purpose::URL_SAFE_NO_PAD
            .decode(q)
            .expect("Invalid Key");

        let dmp1 = general_purpose::URL_SAFE_NO_PAD
            .decode(dmp1)
            .expect("Invalid Key");

        let dmq1 = general_purpose::URL_SAFE_NO_PAD
            .decode(dmq1)
            .expect("Invalid Key");

        let iqmp = general_purpose::URL_SAFE_NO_PAD
            .decode(iqmp)
            .expect("Invalid Key");

        let nbn = bn::BigNum::from_slice(&n).expect("Invalid bignumber");
        let ebn = bn::BigNum::from_slice(&e).expect("Invalid bignumber");
        let dbn = bn::BigNum::from_slice(&d).expect("Invalid bignumber");
        let pbn = bn::BigNum::from_slice(&p).expect("Invalid bignumber");
        let qbn = bn::BigNum::from_slice(&q).expect("Invalid bignumber");

        let dpbn = bn::BigNum::from_slice(&dmp1).expect("Invalid bignumber");
        let dqbn = bn::BigNum::from_slice(&dmq1).expect("Invalid bignumber");
        let dibn = bn::BigNum::from_slice(&iqmp).expect("Invalid bignumber");

        Rsa::from_private_components(nbn, ebn, dbn, pbn, qbn, dpbn, dqbn, dibn)
            .expect("Invalid parameters")
    }

    #[test]
    fn rfc7516_rsa_oaep_validation_example() {
        // Taken from https://www.rfc-editor.org/rfc/rfc7516.html#appendix-A.3

        let _ = tracing_subscriber::fmt::try_init();

        let test_jwe = "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGeipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDbSv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaVmqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je81860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi6UklfCpIMfIjf7iGdXKHzg.48V1_ALb6US04U3b.5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6jiSdiwkIr3ajwQzaBtQD_A.XFBoMYUZodetZdvTiFvSkQ";

        let rsa_priv_key = rsa_from_private_components(
"oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUWcJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3Spsk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2asbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMStPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2djYgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw",
"AQAB",
"kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5NWV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD93Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghkqDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vlt3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSndVTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ",
"1r52Xk46c-LsfB5P442p7atdPUrxQSy4mti_tZI3Mgf2EuFVbUoDBvaRQ-SWxkbkmoEzL7JXroSBjSrK3YIQgYdMgyAEPTPjXv_hI2_1eTSPVZfzL0lffNn03IXqWF5MDFuoUYE0hzb2vhrlN_rKrbfDIwUbTrjjgieRbwC6Cl0",
"wLb35x7hmQWZsWJmB_vle87ihgZ19S8lBEROLIsZG4ayZVe9Hi9gDVCOBmUDdaDYVTSNx_8Fyw1YYa9XGrGnDew00J28cRUoeBB_jKI1oma0Orv1T9aXIWxKwd4gvxFImOWr3QRL9KEBRzk2RatUBnmDZJTIAfwTs0g68UZHvtc",
"ZK-YwE7diUh0qR1tR7w8WHtolDx3MZ_OTowiFvgfeQ3SiresXjm9gZ5KLhMXvo-uz-KUJWDxS5pFQ_M0evdo1dKiRTjVw_x4NyqyXPM5nULPkcpU827rnpZzAJKpdhWAgqrXGKAECQH0Xt4taznjnd_zVpAmZZq60WPMBMfKcuE",
"Dq0gfgJ1DdFGXiLvQEZnuKEN0UUmsJBxkjydc3j4ZYdBiMRAy86x0vHCjywcMlYYg4yoC4YZa9hNVcsjqA3FeiL19rk8g6Qn29Tt0cj8qqyFpz9vNDBUfCAiJVeESOjJDZPYHdHY8v1b-o-Z2X5tvLx-TCekf7oxyeKDUqKWjis",
"VIMpMYbPf47dT1w_zDUXfPimsSegnMOA1zTaX7aGk_8urY6R8-ZW1FxU7AlWAyLWybqq6t16VFd7hQd0y6flUK4SlOydB61gwanOsXGOAOv82cHq0E3eL4HrtZkUuKvnPrMnsUUFlfUdybVzxyjz9JF_XyaY14ardLSjf4L_FNY"
);

        // Check key parameters
        assert!(rsa_priv_key.check_key().unwrap());

        // let der_bytes = rsa_priv_key.private_key_to_der().unwrap();
        // error!(?der_bytes);

        let jwec = JweCompact::from_str(test_jwe).unwrap();

        assert!(jwec.to_string() == test_jwe);

        // Check vectors
        jwec.check_vectors(
            // Content Encryption Key
            &[
                56, 163, 154, 192, 58, 53, 222, 4, 105, 218, 136, 218, 29, 94, 203, 22, 150, 92,
                129, 94, 211, 232, 53, 89, 41, 60, 138, 56, 196, 216, 82, 98, 168, 76, 37, 73, 70,
                7, 36, 8, 191, 100, 136, 196, 244, 220, 145, 158, 138, 155, 4, 117, 141, 230, 199,
                247, 173, 45, 182, 214, 74, 177, 107, 211, 153, 11, 205, 196, 171, 226, 162, 128,
                171, 182, 13, 237, 239, 99, 193, 4, 91, 219, 121, 223, 107, 167, 61, 119, 228, 173,
                156, 137, 134, 200, 80, 219, 74, 253, 56, 185, 91, 177, 34, 158, 89, 154, 205, 96,
                55, 18, 138, 43, 96, 218, 215, 128, 124, 75, 138, 243, 85, 25, 109, 117, 140, 26,
                155, 249, 67, 167, 149, 231, 100, 6, 41, 65, 214, 251, 232, 87, 72, 40, 182, 149,
                154, 168, 31, 193, 126, 215, 89, 28, 111, 219, 125, 182, 139, 235, 195, 197, 23,
                234, 55, 58, 63, 180, 68, 202, 206, 149, 75, 205, 248, 176, 67, 39, 178, 60, 98,
                193, 32, 238, 122, 96, 158, 222, 57, 183, 111, 210, 55, 188, 215, 206, 180, 166,
                150, 166, 106, 250, 55, 229, 72, 40, 69, 214, 216, 104, 23, 40, 135, 212, 28, 127,
                41, 80, 175, 174, 168, 115, 171, 197, 89, 116, 92, 103, 246, 83, 216, 182, 176, 84,
                37, 147, 35, 45, 219, 172, 99, 226, 233, 73, 37, 124, 42, 72, 49, 242, 35, 127,
                184, 134, 117, 114, 135, 206,
            ],
            // IV
            &[227, 197, 117, 252, 2, 219, 233, 68, 180, 225, 77, 219],
            // Cipher Text
            &[
                229, 236, 166, 241, 53, 191, 115, 196, 174, 43, 73, 109, 39, 122, 233, 96, 140,
                206, 120, 52, 51, 237, 48, 11, 190, 219, 186, 80, 111, 104, 50, 142, 47, 167, 59,
                61, 181, 127, 196, 21, 40, 82, 242, 32, 123, 143, 168, 226, 73, 216, 176, 144, 138,
                247, 106, 60, 16, 205, 160, 109, 64, 63, 192,
            ],
            // Authentication Tag
            &[
                92, 80, 104, 49, 133, 25, 161, 215, 173, 101, 219, 211, 136, 91, 210, 145,
            ],
        );

        assert!(jwec.get_jwk_pubkey_url().is_none());
        assert!(jwec.get_jwk_pubkey().is_none());

        let rsa_oaep_decipher =
            JweRSAOAEPDecipher::try_from(rsa_priv_key).expect("Unable to create decipher");

        let released = rsa_oaep_decipher
            .decipher(&jwec)
            .expect("Unable to decipher jwe");

        assert_eq!(
            released.payload(),
            &[
                84, 104, 101, 32, 116, 114, 117, 101, 32, 115, 105, 103, 110, 32, 111, 102, 32,
                105, 110, 116, 101, 108, 108, 105, 103, 101, 110, 99, 101, 32, 105, 115, 32, 110,
                111, 116, 32, 107, 110, 111, 119, 108, 101, 100, 103, 101, 32, 98, 117, 116, 32,
                105, 109, 97, 103, 105, 110, 97, 116, 105, 111, 110, 46
            ]
        );
    }

    #[test]
    fn reflexive_rsa_oaep_validation() {
        let _ = tracing_subscriber::fmt::try_init();

        let input = vec![1; 256];
        let jweb = JweBuilder::from(input.clone()).build();

        let rsa_priv_key = Rsa::generate(2048).unwrap();

        let rsa_pub_key = Rsa::from_public_components(
            rsa_priv_key.n().to_owned().unwrap(),
            rsa_priv_key.e().to_owned().unwrap(),
        )
        .unwrap();

        let jwe_rsa_oaep_decipher = JweRSAOAEPDecipher::try_from(rsa_priv_key).unwrap();

        let jwe_rsa_oaep_encipher = JweRSAOAEPEncipher::try_from(rsa_pub_key).unwrap();

        let jwe_encrypted = jwe_rsa_oaep_encipher
            .encipher::<JweA256GCMEncipher>(&jweb)
            .expect("Unable to encrypt.");

        // Decrypt with the partner.
        let decrypted = jwe_rsa_oaep_decipher
            .decipher(&jwe_encrypted)
            .expect("Unable to decrypt.");

        assert_eq!(decrypted.payload(), input);
    }
}