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//! Implementation of AEAD using OpenSSL cryptographic library.
use crate::{Error, Result};
use crate::crypto::aead::{Aead, CipherOp};
use crate::types::{AEADAlgorithm, SymmetricAlgorithm};
use openssl::cipher::Cipher;
use openssl::cipher_ctx::CipherCtx;
struct OpenSslContext {
ctx: CipherCtx,
}
impl Aead for OpenSslContext {
fn encrypt_seal(&mut self, dst: &mut [u8], src: &[u8]) -> Result<()> {
debug_assert_eq!(dst.len(), src.len() + self.digest_size());
// SAFETY: Process completely one full chunk. Since `update`
// is not being called again with partial block info and the
// cipher is finalized afterwards these two calls are safe.
let size = unsafe { self.ctx.cipher_update_unchecked(src, Some(dst))? };
unsafe { self.ctx.cipher_final_unchecked(&mut dst[size..])? };
self.ctx.tag(&mut dst[src.len()..])?;
Ok(())
}
fn decrypt_verify(&mut self, dst: &mut [u8], src: &[u8]) -> Result<()> {
debug_assert!(src.len() >= self.digest_size());
debug_assert_eq!(dst.len() + self.digest_size(), src.len());
// Split src into ciphertext and tag.
let l = self.digest_size();
let ciphertext = &src[..src.len().saturating_sub(l)];
let tag = &src[src.len().saturating_sub(l)..];
// SAFETY: Process completely one full chunk. Since `update`
// is not being called again with partial block info and the
// cipher is finalized afterwards these two calls are safe.
let size = unsafe {
self.ctx.cipher_update_unchecked(ciphertext, Some(dst))?
};
self.ctx.set_tag(tag)?;
unsafe { self.ctx.cipher_final_unchecked(&mut dst[size..])? };
Ok(())
}
fn digest_size(&self) -> usize {
self.ctx.block_size()
}
}
impl crate::seal::Sealed for OpenSslContext {}
impl AEADAlgorithm {
pub(crate) fn context(
&self,
sym_algo: SymmetricAlgorithm,
key: &[u8],
aad: &[u8],
nonce: &[u8],
op: CipherOp,
) -> Result<Box<dyn Aead>> {
match self {
AEADAlgorithm::OCB => {
let cipher = match sym_algo {
SymmetricAlgorithm::AES128 => Cipher::aes_128_ocb(),
SymmetricAlgorithm::AES192 => Cipher::aes_192_ocb(),
SymmetricAlgorithm::AES256 => Cipher::aes_256_ocb(),
_ => return Err(Error::UnsupportedSymmetricAlgorithm(sym_algo).into()),
};
let mut ctx = CipherCtx::new()?;
match op {
CipherOp::Encrypt =>
ctx.encrypt_init(Some(cipher), Some(key), None)?,
CipherOp::Decrypt =>
ctx.decrypt_init(Some(cipher), Some(key), None)?,
}
// We have to set the IV length before supplying the
// IV. Otherwise, it will be silently truncated.
ctx.set_iv_length(self.nonce_size()?)?;
match op {
CipherOp::Encrypt =>
ctx.encrypt_init(None, None, Some(nonce))?,
CipherOp::Decrypt =>
ctx.decrypt_init(None, None, Some(nonce))?,
}
ctx.set_padding(false);
ctx.cipher_update(aad, None)?;
Ok(Box::new(OpenSslContext {
ctx,
}))
}
_ => Err(Error::UnsupportedAEADAlgorithm(*self).into()),
}
}
}
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