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//! The XChaCha20-Poly1305 construction can safely encrypt a practically
//! unlimited number of messages with the same key, without any practical limit
//! to the size of the message (up to ~ 2^64 bytes).
//!
//! As an alternative to counters, its large nonce size (192-bit) allows random
//! nonces to be safely used
//!
//! For this reason, and if interoperability with other libraries is not a
//! concern, this is the recommended AEAD construction.

use crypto::nonce::gen_random_nonce;
use ffi::{
    crypto_aead_xchacha20poly1305_ietf_ABYTES, crypto_aead_xchacha20poly1305_ietf_KEYBYTES,
    crypto_aead_xchacha20poly1305_ietf_NPUBBYTES, crypto_aead_xchacha20poly1305_ietf_decrypt,
    crypto_aead_xchacha20poly1305_ietf_decrypt_detached,
    crypto_aead_xchacha20poly1305_ietf_encrypt,
    crypto_aead_xchacha20poly1305_ietf_encrypt_detached,
};

aead_module!(
    crypto_aead_xchacha20poly1305_ietf_encrypt,
    crypto_aead_xchacha20poly1305_ietf_decrypt,
    crypto_aead_xchacha20poly1305_ietf_encrypt_detached,
    crypto_aead_xchacha20poly1305_ietf_decrypt_detached,
    crypto_aead_xchacha20poly1305_ietf_KEYBYTES as usize,
    crypto_aead_xchacha20poly1305_ietf_NPUBBYTES as usize,
    crypto_aead_xchacha20poly1305_ietf_ABYTES as usize,
    true
);

/// `gen_nonce` randomly generates a nonce
///
/// THREAD SAFETY: `gen_nonce()` is thread-safe provided that you have
/// called `sodiumoxide::init()` once before using any other function
/// from sodiumoxide.
pub fn gen_nonce() -> Nonce {
    gen_random_nonce()
}

#[cfg(test)]
mod test {
    use super::*;
    #[test]
    fn test_vector_1() {
        let m = &[
            0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e,
            0x74, 0x6c, 0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20, 0x74, 0x68, 0x65, 0x20,
            0x63, 0x6c, 0x61, 0x73, 0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39, 0x3a, 0x20,
            0x49, 0x66, 0x20, 0x49, 0x20, 0x63, 0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66,
            0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f, 0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e,
            0x65, 0x20, 0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20, 0x74, 0x68, 0x65, 0x20,
            0x66, 0x75, 0x74, 0x75, 0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73, 0x63, 0x72,
            0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f, 0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69,
            0x74, 0x2e,
        ];
        let ad = &[
            0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
        ];
        let k = Key([
            0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d,
            0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
            0x9c, 0x9d, 0x9e, 0x9f,
        ]);
        let n = Nonce([
            0xf2, 0x8a, 0x50, 0xa7, 0x8a, 0x7e, 0x23, 0xc9, 0xcb, 0xa6, 0x78, 0x34, 0x66, 0xf8,
            0x03, 0x59, 0x0f, 0x04, 0xe9, 0x22, 0x31, 0xa3, 0x2d, 0x5d,
        ]);
        let c_expected = &[
            0x20, 0xf1, 0xae, 0x75, 0xe1, 0xe5, 0xe0, 0x00, 0x40, 0x29, 0x4f, 0x0f, 0xb1, 0x0e,
            0xbb, 0x08, 0x10, 0xc5, 0x93, 0xc7, 0xdb, 0xa4, 0xec, 0x10, 0x4c, 0x1e, 0x5e, 0xf9,
            0x50, 0x7f, 0xae, 0xef, 0x58, 0xfc, 0x28, 0x98, 0xbb, 0xd0, 0xe4, 0x7b, 0x2f, 0x53,
            0x31, 0xfb, 0xc3, 0x67, 0xd3, 0xc2, 0x78, 0x4e, 0x36, 0x48, 0xce, 0x1e, 0xaa, 0x77,
            0x87, 0xad, 0x18, 0x6d, 0xb2, 0x68, 0x5e, 0xe8, 0x9a, 0xe4, 0xd3, 0x44, 0x1f, 0x6e,
            0xa0, 0xb2, 0x22, 0x4c, 0xd5, 0xa1, 0x34, 0x16, 0x1b, 0x55, 0x4d, 0x8b, 0x48, 0x35,
            0x0b, 0x4a, 0xd4, 0x01, 0x15, 0xdb, 0x81, 0xea, 0x82, 0x09, 0x68, 0xe9, 0x43, 0x89,
            0x2f, 0x2b, 0x80, 0x51, 0xcb, 0x5f, 0x7a, 0x86, 0x66, 0xe7, 0xe7, 0xef, 0x7f, 0x84,
            0xc0, 0xa2, 0xf8, 0x0a, 0x12, 0xd0, 0x66, 0x80, 0xc8, 0xee, 0xbb, 0xd9, 0x30, 0x04,
            0x10, 0x9d, 0xe8, 0x42,
        ];
        let c = seal(m, Some(ad), &n, &k);
        assert_eq!(&c[..], &c_expected[..]);
    }

    #[test]
    fn test_nonce_length() {
        assert_eq!(192 / 8, gen_nonce().as_ref().len());
    }
}