Merge pull request #143 from agourlay/expose-aes-info

feat: Expose AES information

src/aes.rs

@@ -15,7 +15,7 @@ use std::io::{self, Error, ErrorKind, Read, Write};
 use zeroize::{Zeroize, Zeroizing};
 
 /// The length of the password verifcation value in bytes
-const PWD_VERIFY_LENGTH: usize = 2;
+pub const PWD_VERIFY_LENGTH: usize = 2;
 /// The length of the authentication code in bytes
 const AUTH_CODE_LENGTH: usize = 10;
 /// The number of iterations used with PBKDF2
@@ -124,6 +124,25 @@ impl<R: Read> AesReader<R> {
             finalized: false,
         })
     }
+
+    /// Read the AES header bytes and returns the verification value and salt.
+    ///
+    /// # Returns
+    ///
+    /// the verification value and the salt
+    pub fn get_verification_value_and_salt(
+        mut self,
+    ) -> io::Result<([u8; PWD_VERIFY_LENGTH], Vec<u8>)> {
+        let salt_length = self.aes_mode.salt_length();
+
+        let mut salt = vec![0; salt_length];
+        self.reader.read_exact(&mut salt)?;
+
+        // next are 2 bytes used for password verification
+        let mut pwd_verification_value = [0; PWD_VERIFY_LENGTH];
+        self.reader.read_exact(&mut pwd_verification_value)?;
+        Ok((pwd_verification_value, salt))
+    }
 }
 
 /// A reader for aes encrypted files, which has already passed the first password check.

src/read.rs

@@ -82,6 +82,8 @@ pub(crate) mod zip_archive {
     }
 }
 
+#[cfg(feature = "aes-crypto")]
+use crate::aes::PWD_VERIFY_LENGTH;
 #[cfg(feature = "lzma")]
 use crate::read::lzma::LzmaDecoder;
 use crate::result::ZipError::{InvalidPassword, UnsupportedArchive};
@@ -648,6 +650,41 @@ impl<R: Read + Seek> ZipArchive<R> {
         Ok(shared)
     }
 
+    /// Returns the verification value and salt for the AES encryption of the file
+    ///
+    /// It fails if the file number is invalid.
+    ///
+    /// # Returns
+    ///
+    /// - None if the file is not encrypted with AES
+    #[cfg(feature = "aes-crypto")]
+    pub fn get_aes_verification_key_and_salt(
+        &mut self,
+        file_number: usize,
+    ) -> ZipResult<Option<AesInfo>> {
+        let (_, data) = self
+            .shared
+            .files
+            .get_index(file_number)
+            .ok_or(ZipError::FileNotFound)?;
+
+        let limit_reader = find_content(data, &mut self.reader)?;
+        match data.aes_mode {
+            None => Ok(None),
+            Some((aes_mode, _, _)) => {
+                let (verification_value, salt) =
+                    AesReader::new(limit_reader, aes_mode, data.compressed_size)
+                        .get_verification_value_and_salt()?;
+                let aes_info = AesInfo {
+                    aes_mode,
+                    verification_value,
+                    salt,
+                };
+                Ok(Some(aes_info))
+            }
+        }
+    }
+
     /// Read a ZIP archive, collecting the files it contains
     ///
     /// This uses the central directory record of the ZIP file, and ignores local file headers
@@ -940,6 +977,18 @@ impl<R: Read + Seek> ZipArchive<R> {
     }
 }
 
+/// Holds the AES information of a file in the zip archive
+#[derive(Debug)]
+#[cfg(feature = "aes-crypto")]
+pub struct AesInfo {
+    /// The AES encryption mode
+    pub aes_mode: AesMode,
+    /// The verification key
+    pub verification_value: [u8; PWD_VERIFY_LENGTH],
+    /// The salt
+    pub salt: Vec<u8>,
+}
+
 const fn unsupported_zip_error<T>(detail: &'static str) -> ZipResult<T> {
     Err(ZipError::UnsupportedArchive(detail))
 }