2019-06-08 07:51:49 +00:00
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//! Wrappers for OpenSSL crypto functions
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//!
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//! We use this to encrypt and decryprt data chunks. Cipher is
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//! AES_256_GCM, which is fast and provides authenticated encryption.
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//!
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//! See the Wikipedia Artikel for [Authenticated
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//! encryption](https://en.wikipedia.org/wiki/Authenticated_encryption)
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//! for a short introduction.
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use failure::*;
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use proxmox::tools;
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2019-06-18 09:17:22 +00:00
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use openssl::pkcs5::pbkdf2_hmac;
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2019-06-08 07:51:49 +00:00
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use openssl::hash::MessageDigest;
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2019-06-10 07:56:06 +00:00
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use openssl::symm::{decrypt_aead, Cipher, Crypter, Mode};
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2019-06-13 10:47:54 +00:00
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use std::io::Write;
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2019-06-08 07:51:49 +00:00
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/// Encryption Configuration with secret key
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///
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/// This structure stores the secret key and provides helpers for
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/// authenticated encryption.
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pub struct CryptConfig {
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// the Cipher
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cipher: Cipher,
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// A secrect key use to provide the chunk digest name space.
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id_key: Vec<u8>,
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// The private key used by the cipher.
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enc_key: [u8; 32],
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}
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impl CryptConfig {
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/// Create a new instance.
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///
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/// We compute a derived 32 byte key using pbkdf2_hmac. This second
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/// key is used in compute_digest.
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pub fn new(enc_key: [u8; 32]) -> Result<Self, Error> {
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let mut id_key = tools::vec::undefined(32);
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pbkdf2_hmac(
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&enc_key,
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b"_id_key",
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10,
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MessageDigest::sha256(),
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&mut id_key)?;
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Ok(Self { id_key, enc_key, cipher: Cipher::aes_256_gcm() })
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}
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/// Compute a chunk digest using a secret name space.
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///
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/// Computes an SHA256 checksum over some secret data (derived
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/// from the secret key) and the provided data. This ensures that
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/// chunk digest values do not clash with values computed for
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/// other sectret keys.
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pub fn compute_digest(&self, data: &[u8]) -> [u8; 32] {
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2019-06-13 05:35:59 +00:00
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// FIXME: use HMAC-SHA256 instead??
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2019-06-08 07:51:49 +00:00
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let mut hasher = openssl::sha::Sha256::new();
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hasher.update(&self.id_key);
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hasher.update(data);
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let digest = hasher.finish();
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digest
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}
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2019-06-22 10:25:04 +00:00
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/// Encrypt data using a random 16 byte IV.
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///
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/// Writes encrypted data to ``output``, Return the used IV and computed MAC.
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pub fn encrypt_to<W: Write>(
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&self,
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data: &[u8],
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mut output: W,
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) -> Result<([u8;16], [u8;16]), Error> {
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let mut iv = [0u8; 16];
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proxmox::sys::linux::fill_with_random_data(&mut iv)?;
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let mut tag = [0u8; 16];
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let mut c = Crypter::new(self.cipher, Mode::Encrypt, &self.enc_key, Some(&iv))?;
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c.aad_update(b"")?; //??
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const BUFFER_SIZE: usize = 32*1024;
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let mut encr_buf = [0u8; BUFFER_SIZE];
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let max_encoder_input = BUFFER_SIZE - self.cipher.block_size();
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let mut start = 0;
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loop {
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let mut end = start + max_encoder_input;
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if end > data.len() { end = data.len(); }
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if end > start {
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let count = c.update(&data[start..end], &mut encr_buf)?;
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output.write_all(&encr_buf[..count])?;
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start = end;
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} else {
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break;
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}
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}
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let rest = c.finalize(&mut encr_buf)?;
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if rest > 0 { output.write_all(&encr_buf[..rest])?; }
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output.flush()?;
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c.get_tag(&mut tag)?;
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Ok((iv, tag))
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}
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2019-06-09 09:44:17 +00:00
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/// Decompress and decrypt chunk, verify MAC.
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2019-06-08 07:51:49 +00:00
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///
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2019-06-21 08:41:39 +00:00
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/// Binrary ``data`` is expected to be in format returned by encode_chunk. The magic number
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/// is not used here.
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pub fn decode_compressed_chunk(&self, data: &[u8]) -> Result<Vec<u8>, Error> {
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2019-06-09 09:44:17 +00:00
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2019-06-21 15:24:21 +00:00
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if data.len() < 44 {
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bail!("Invalid chunk len (<44)");
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2019-06-09 09:44:17 +00:00
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}
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2019-06-21 08:41:39 +00:00
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// let magic = &data[0..8];
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2019-06-21 15:24:21 +00:00
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// let crc = &data[8..12];
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let iv = &data[12..28];
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let mac = &data[28..44];
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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let dec = Vec::with_capacity(1024*1024);
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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let mut decompressor = zstd::stream::write::Decoder::new(dec)?;
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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let mut c = Crypter::new(self.cipher, Mode::Decrypt, &self.enc_key, Some(iv))?;
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c.aad_update(b"")?; //??
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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const BUFFER_SIZE: usize = 32*1024;
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let mut decr_buf = [0u8; BUFFER_SIZE];
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let max_decoder_input = BUFFER_SIZE - self.cipher.block_size();
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2019-06-21 15:24:21 +00:00
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let mut start = 44;
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2019-06-21 08:41:39 +00:00
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loop {
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let mut end = start + max_decoder_input;
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if end > data.len() { end = data.len(); }
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if end > start {
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let count = c.update(&data[start..end], &mut decr_buf)?;
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decompressor.write_all(&decr_buf[0..count])?;
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start = end;
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} else {
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break;
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}
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}
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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c.set_tag(mac)?;
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let rest = c.finalize(&mut decr_buf)?;
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if rest > 0 { decompressor.write_all(&decr_buf[..rest])?; }
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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decompressor.flush()?;
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2019-06-09 09:44:17 +00:00
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2019-06-21 08:41:39 +00:00
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Ok(decompressor.into_inner())
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}
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/// Decrypt chunk, verify MAC.
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///
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/// Binrary ``data`` is expected to be in format returned by encode_chunk. The magic number
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/// is not used here.
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pub fn decode_uncompressed_chunk(&self, data: &[u8]) -> Result<Vec<u8>, Error> {
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2019-06-09 09:44:17 +00:00
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2019-06-21 15:24:21 +00:00
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if data.len() < 44 {
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bail!("Invalid chunk len (<44)");
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2019-06-10 06:27:35 +00:00
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}
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2019-06-21 08:41:39 +00:00
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// let magic = &data[0..8];
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2019-06-21 15:24:21 +00:00
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// let crc = &data[8..12];
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let iv = &data[12..28];
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let mac = &data[28..44];
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2019-06-21 08:41:39 +00:00
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let decr_data = decrypt_aead(
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self.cipher,
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&self.enc_key,
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Some(iv),
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b"", //??
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2019-06-21 15:24:21 +00:00
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&data[44..],
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2019-06-21 08:41:39 +00:00
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mac,
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)?;
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Ok(decr_data)
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2019-06-08 07:51:49 +00:00
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}
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}
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