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use alloc::boxed::Box;
use alloc::string::{String, ToString};
use core::fmt;
use digest::{Digest, DynDigest};
use rand::RngCore;
use crate::hash::Hash;
/// Available padding schemes.
pub enum PaddingScheme {
/// Encryption and Decryption using PKCS1v15 padding.
PKCS1v15Encrypt,
/// Sign and Verify using PKCS1v15 padding.
PKCS1v15Sign { hash: Option<Hash> },
/// Encryption and Decryption using [OAEP padding](https://datatracker.ietf.org/doc/html/rfc3447#section-7.1.1).
///
/// - `digest` is used to hash the label. The maximum possible plaintext length is `m = k - 2 * h_len - 2`,
/// where `k` is the size of the RSA modulus.
/// - `mgf_digest` specifies the hash function that is used in the [MGF1](https://datatracker.ietf.org/doc/html/rfc2437#section-10.2.1).
/// - `label` is optional data that can be associated with the message.
///
/// The two hash functions can, but don't need to be the same.
/// A prominent example is the [`AndroidKeyStore`](https://developer.android.com/guide/topics/security/cryptography#oaep-mgf1-digest).
/// It uses SHA-1 for `mgf_digest` and a user-chosen SHA flavour for `digest`.
OAEP {
digest: Box<dyn DynDigest>,
mgf_digest: Box<dyn DynDigest>,
label: Option<String>,
},
/// Sign and Verify using PSS padding.
PSS {
salt_rng: Box<dyn RngCore>,
digest: Box<dyn DynDigest>,
salt_len: Option<usize>,
},
}
impl fmt::Debug for PaddingScheme {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
PaddingScheme::PKCS1v15Encrypt => write!(f, "PaddingScheme::PKCS1v15Encrypt"),
PaddingScheme::PKCS1v15Sign { ref hash } => {
write!(f, "PaddingScheme::PKCS1v15Sign({:?})", hash)
}
PaddingScheme::OAEP { ref label, .. } => {
// TODO: How to print the digest name?
write!(f, "PaddingScheme::OAEP({:?})", label)
}
PaddingScheme::PSS { ref salt_len, .. } => {
// TODO: How to print the digest name?
write!(f, "PaddingScheme::PSS(salt_len: {:?})", salt_len)
}
}
}
}
impl PaddingScheme {
pub fn new_pkcs1v15_encrypt() -> Self {
PaddingScheme::PKCS1v15Encrypt
}
pub fn new_pkcs1v15_sign(hash: Option<Hash>) -> Self {
PaddingScheme::PKCS1v15Sign { hash }
}
/// Create a new OAEP `PaddingScheme`, using `T` as the hash function for the default (empty) label, and `U` as the hash function for MGF1.
/// If a label is needed use `PaddingScheme::new_oaep_with_label` or `PaddingScheme::new_oaep_with_mgf_hash_with_label`.
///
/// # Example
/// ```
/// use sha1::Sha1;
/// use sha2::Sha256;
/// use rand::rngs::OsRng;
/// use rsa::{BigUint, RSAPublicKey, PaddingScheme, PublicKey};
///
/// let n = base64::decode("ALHgDoZmBQIx+jTmgeeHW6KsPOrj11f6CvWsiRleJlQpW77AwSZhd21ZDmlTKfaIHBSUxRUsuYNh7E2SHx8rkFVCQA2/gXkZ5GK2IUbzSTio9qXA25MWHvVxjMfKSL8ZAxZyKbrG94FLLszFAFOaiLLY8ECs7g+dXOriYtBwLUJK+lppbd+El+8ZA/zH0bk7vbqph5pIoiWggxwdq3mEz4LnrUln7r6dagSQzYErKewY8GADVpXcq5mfHC1xF2DFBub7bFjMVM5fHq7RK+pG5xjNDiYITbhLYrbVv3X0z75OvN0dY49ITWjM7xyvMWJXVJS7sJlgmCCL6RwWgP8PhcE=").unwrap();
/// let e = base64::decode("AQAB").unwrap();
///
/// let key = RSAPublicKey::new(BigUint::from_bytes_be(&n), BigUint::from_bytes_be(&e)).unwrap();
/// let padding = PaddingScheme::new_oaep_with_mgf_hash::<Sha256, Sha1>();
/// let encrypted_data = key.encrypt(&mut OsRng, padding, b"secret").unwrap();
/// ```
pub fn new_oaep_with_mgf_hash<
T: 'static + Digest + DynDigest,
U: 'static + Digest + DynDigest,
>() -> Self {
PaddingScheme::OAEP {
digest: Box::new(T::new()),
mgf_digest: Box::new(U::new()),
label: None,
}
}
/// Create a new OAEP `PaddingScheme`, using `T` as the hash function for both the default (empty) label and for MGF1.
///
/// # Example
/// ```
/// use sha1::Sha1;
/// use sha2::Sha256;
/// use rand::rngs::OsRng;
/// use rsa::{BigUint, RSAPublicKey, PaddingScheme, PublicKey};
/// let n = base64::decode("ALHgDoZmBQIx+jTmgeeHW6KsPOrj11f6CvWsiRleJlQpW77AwSZhd21ZDmlTKfaIHBSUxRUsuYNh7E2SHx8rkFVCQA2/gXkZ5GK2IUbzSTio9qXA25MWHvVxjMfKSL8ZAxZyKbrG94FLLszFAFOaiLLY8ECs7g+dXOriYtBwLUJK+lppbd+El+8ZA/zH0bk7vbqph5pIoiWggxwdq3mEz4LnrUln7r6dagSQzYErKewY8GADVpXcq5mfHC1xF2DFBub7bFjMVM5fHq7RK+pG5xjNDiYITbhLYrbVv3X0z75OvN0dY49ITWjM7xyvMWJXVJS7sJlgmCCL6RwWgP8PhcE=").unwrap();
/// let e = base64::decode("AQAB").unwrap();
///
/// let key = RSAPublicKey::new(BigUint::from_bytes_be(&n), BigUint::from_bytes_be(&e)).unwrap();
/// let padding = PaddingScheme::new_oaep::<Sha256>();
/// let encrypted_data = key.encrypt(&mut OsRng, padding, b"secret").unwrap();
/// ```
pub fn new_oaep<T: 'static + Digest + DynDigest>() -> Self {
PaddingScheme::OAEP {
digest: Box::new(T::new()),
mgf_digest: Box::new(T::new()),
label: None,
}
}
/// Create a new OAEP `PaddingScheme` with an associated `label`, using `T` as the hash function for the label, and `U` as the hash function for MGF1.
pub fn new_oaep_with_mgf_hash_with_label<
T: 'static + Digest + DynDigest,
U: 'static + Digest + DynDigest,
S: AsRef<str>,
>(
label: S,
) -> Self {
PaddingScheme::OAEP {
digest: Box::new(T::new()),
mgf_digest: Box::new(U::new()),
label: Some(label.as_ref().to_string()),
}
}
/// Create a new OAEP `PaddingScheme` with an associated `label`, using `T` as the hash function for both the label and for MGF1.
pub fn new_oaep_with_label<T: 'static + Digest + DynDigest, S: AsRef<str>>(label: S) -> Self {
PaddingScheme::OAEP {
digest: Box::new(T::new()),
mgf_digest: Box::new(T::new()),
label: Some(label.as_ref().to_string()),
}
}
pub fn new_pss<T: 'static + Digest + DynDigest, S: 'static + RngCore>(rng: S) -> Self {
PaddingScheme::PSS {
salt_rng: Box::new(rng),
digest: Box::new(T::new()),
salt_len: None,
}
}
pub fn new_pss_with_salt<T: 'static + Digest + DynDigest, S: 'static + RngCore>(
rng: S,
len: usize,
) -> Self {
PaddingScheme::PSS {
salt_rng: Box::new(rng),
digest: Box::new(T::new()),
salt_len: Some(len),
}
}
}