// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

// option. This file may not be copied, modified, or distributed

// except according to those terms.

use std::{os::raw::c_int, ptr::null_mut};

use crate::{

    Error, SECItemBorrowed,

    hmac::{HmacAlgorithm, hmac_alg_to_prf_oid},

    p11::{

        PK11_CreatePBEV2AlgorithmID, PK11_PBEKeyGen, PRBool, SECOID_DestroyAlgorithmID, SECOidTag,

        Slot, SymKey,

    },

};

/// Derive a key using PBKDF2.

///

/// Returns the derived key bytes as a `Vec<u8>`.

///

/// # Errors

///

/// Returns an error if inputs have invalid lengths, or if NSS functions fail.

pub fn pbkdf2(

    alg: &HmacAlgorithm,

    password: &[u8],

    salt: &[u8],

    iterations: u32,

    key_len: usize,

) -> Result<Vec<u8>, Error> {

    crate::init()?;

    let iterations = c_int::try_from(iterations)?;

    let key_len_int = c_int::try_from(key_len)?;

    let mut salt_item = SECItemBorrowed::wrap(salt)?;

    let slot = Slot::internal()?;

    let mut pw_item = SECItemBorrowed::wrap(password)?;

    let algid = unsafe {

        PK11_CreatePBEV2AlgorithmID(

            SECOidTag::SEC_OID_PKCS5_PBKDF2,

            hmac_alg_to_prf_oid(alg),

            hmac_alg_to_prf_oid(alg),

            key_len_int,

            iterations,

            salt_item.as_mut(),

        )

    };

    if algid.is_null() {

        return Err(Error::last_nss_error());

    }

    let key_ptr = unsafe {

        PK11_PBEKeyGen(

            *slot,

            algid,

            pw_item.as_mut(),

            PRBool::from(false),

            null_mut(),

        )

    };

    unsafe {

        SECOID_DestroyAlgorithmID(algid, PRBool::from(true));

    }

    let key = SymKey::from_ptr(key_ptr)?;

    let data = key.key_data()?;

    Ok(Vec::from(data))

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn rfc_7914_vector_1() {

        // RFC 7914 §11 provides PBKDF2-HMAC-SHA256 vectors. Using a common one:

        // password="password", salt="salt", iter=1, dkLen=32.

        let dk = pbkdf2(&HmacAlgorithm::HMAC_SHA2_256, b"password", b"salt", 1, 32).unwrap();

        let expected = [

            0x12, 0x0f, 0xb6, 0xcf, 0xfc, 0xf8, 0xb3, 0x2c, 0x43, 0xe7, 0x22, 0x52, 0x56, 0xc4,

            0xf8, 0x37, 0xa8, 0x65, 0x48, 0xc9, 0x2c, 0xcc, 0x35, 0x48, 0x08, 0x05, 0x98, 0x7c,

            0xb7, 0x0b, 0xe1, 0x7b,

        ];

        assert_eq!(dk, expected);

    }

    #[test]

    fn rfc_7914_vector_iter_2() {

        let dk = pbkdf2(&HmacAlgorithm::HMAC_SHA2_256, b"password", b"salt", 2, 32).unwrap();

        let expected = [

            0xae, 0x4d, 0x0c, 0x95, 0xaf, 0x6b, 0x46, 0xd3, 0x2d, 0x0a, 0xdf, 0xf9, 0x28, 0xf0,

            0x6d, 0xd0, 0x2a, 0x30, 0x3f, 0x8e, 0xf3, 0xc2, 0x51, 0xdf, 0xd6, 0xe2, 0xd8, 0x5a,

            0x95, 0x47, 0x4c, 0x43,

        ];

        assert_eq!(dk, expected);

    }

    #[test]

    fn pbkdf2_sha384_vector() {

        let dk = pbkdf2(&HmacAlgorithm::HMAC_SHA2_384, b"password", b"salt", 1, 20).unwrap();

        let expected = [

            0xc0, 0xe1, 0x4f, 0x06, 0xe4, 0x9e, 0x32, 0xd7, 0x3f, 0x9f, 0x52, 0xdd, 0xf1, 0xd0,

            0xc5, 0xc7, 0x19, 0x16, 0x09, 0x23,

        ];

        assert_eq!(dk, expected);

    }

    #[test]

    fn pbkdf2_sha512_vector() {

        let dk = pbkdf2(&HmacAlgorithm::HMAC_SHA2_512, b"password", b"salt", 1, 20).unwrap();

        let expected = [

            0x86, 0x7f, 0x70, 0xcf, 0x1a, 0xde, 0x02, 0xcf, 0xf3, 0x75, 0x25, 0x99, 0xa3, 0xa5,

            0x3d, 0xc4, 0xaf, 0x34, 0xc7, 0xa6,

        ];

        assert_eq!(dk, expected);

    }

    #[test]

    fn deterministic_across_calls() {

        let a = pbkdf2(

            &HmacAlgorithm::HMAC_SHA2_256,

            b"hello",

            b"saltysalt0000000",

            10_000,

            32,

        )

        .unwrap();

        let b = pbkdf2(

            &HmacAlgorithm::HMAC_SHA2_256,

            b"hello",

            b"saltysalt0000000",

            10_000,

            32,

        )

        .unwrap();

        assert_eq!(a, b);

    }

    #[test]

    fn different_salt_different_key() {

        let a = pbkdf2(

            &HmacAlgorithm::HMAC_SHA2_256,

            b"hello",

            b"saltysalt0000000",

            10_000,

            32,

        )

        .unwrap();

        let b = pbkdf2(

            &HmacAlgorithm::HMAC_SHA2_256,

            b"hello",

            b"saltysalt0000001",

            10_000,

            32,

        )

        .unwrap();

        assert_ne!(a, b);

    }

}