[apkverify] Merge idsig into apkverify package
This CL merges idsig into apkverify package as apkverify is
supposed to cover apk signature verification v3 and v4.
Bug: 248999133
Test: libapkverify.test apkdmverity.test microdroid_manager_test
Change-Id: Ieef2dcf93496164f8bb72cd4ee819ebb822f6142
diff --git a/libs/apkverify/src/v4.rs b/libs/apkverify/src/v4.rs
index 9012479..33e666f 100644
--- a/libs/apkverify/src/v4.rs
+++ b/libs/apkverify/src/v4.rs
@@ -18,10 +18,16 @@
//!
//! [v4]: https://source.android.com/security/apksigning/v4
-use anyhow::{ensure, Context, Result};
-use std::io::{Read, Seek};
+use anyhow::{anyhow, bail, ensure, Context, Result};
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use num_derive::{FromPrimitive, ToPrimitive};
+use num_traits::{FromPrimitive, ToPrimitive};
+use std::fs;
+use std::io::{copy, Cursor, Read, Seek, SeekFrom, Write};
+use std::path::Path;
use crate::algorithms::SignatureAlgorithmID;
+use crate::hashtree::*;
use crate::v3::extract_signer_and_apk_sections;
/// Gets the v4 [apk_digest]. If `verify` is true, we verify that digest computed
@@ -48,3 +54,353 @@
}
Ok((strongest_algorithm_id, extracted_digest))
}
+
+/// `V4Signature` provides access to the various fields in an idsig file.
+#[derive(Default)]
+pub struct V4Signature<R: Read + Seek> {
+ /// Version of the header. Should be 2.
+ pub version: Version,
+ /// Provides access to the information about how the APK is hashed.
+ pub hashing_info: HashingInfo,
+ /// Provides access to the information that can be used to verify this file
+ pub signing_info: SigningInfo,
+ /// Total size of the merkle tree
+ pub merkle_tree_size: u32,
+ /// Offset of the merkle tree in the idsig file
+ pub merkle_tree_offset: u64,
+
+ // Provides access to the underlying data
+ data: R,
+}
+
+/// `HashingInfo` provides information about how the APK is hashed.
+#[derive(Default)]
+pub struct HashingInfo {
+ /// Hash algorithm used when creating the merkle tree for the APK.
+ pub hash_algorithm: HashAlgorithm,
+ /// The log size of a block used when creating the merkle tree. 12 if 4k block was used.
+ pub log2_blocksize: u8,
+ /// The salt used when creating the merkle tree. 32 bytes max.
+ pub salt: Box<[u8]>,
+ /// The root hash of the merkle tree created.
+ pub raw_root_hash: Box<[u8]>,
+}
+
+/// `SigningInfo` provides information that can be used to verify the idsig file.
+#[derive(Default)]
+pub struct SigningInfo {
+ /// Digest of the APK that this idsig file is for.
+ pub apk_digest: Box<[u8]>,
+ /// Certificate of the signer that signed this idsig file. ASN.1 DER form.
+ pub x509_certificate: Box<[u8]>,
+ /// A free-form binary data
+ pub additional_data: Box<[u8]>,
+ /// Public key of the signer in ASN.1 DER form. This must match the `x509_certificate` field.
+ pub public_key: Box<[u8]>,
+ /// Signature algorithm used to sign this file.
+ pub signature_algorithm_id: SignatureAlgorithmID,
+ /// The signature of this file.
+ pub signature: Box<[u8]>,
+}
+
+/// Version of the idsig file format
+#[derive(Debug, PartialEq, Eq, FromPrimitive, ToPrimitive)]
+#[repr(u32)]
+pub enum Version {
+ /// Version 2, the only supported version.
+ V2 = 2,
+}
+
+impl Version {
+ fn from(val: u32) -> Result<Version> {
+ Self::from_u32(val).ok_or_else(|| anyhow!("{} is an unsupported version", val))
+ }
+}
+
+impl Default for Version {
+ fn default() -> Self {
+ Version::V2
+ }
+}
+
+/// Hash algorithm that can be used for idsig file.
+#[derive(Debug, PartialEq, Eq, FromPrimitive, ToPrimitive)]
+#[repr(u32)]
+pub enum HashAlgorithm {
+ /// SHA2-256
+ SHA256 = 1,
+}
+
+impl HashAlgorithm {
+ fn from(val: u32) -> Result<HashAlgorithm> {
+ Self::from_u32(val).ok_or_else(|| anyhow!("{} is an unsupported hash algorithm", val))
+ }
+}
+
+impl Default for HashAlgorithm {
+ fn default() -> Self {
+ HashAlgorithm::SHA256
+ }
+}
+
+impl V4Signature<fs::File> {
+ /// Creates a `V4Signature` struct from the given idsig path.
+ pub fn from_idsig_path<P: AsRef<Path>>(idsig_path: P) -> Result<Self> {
+ let idsig = fs::File::open(idsig_path).context("Cannot find idsig file")?;
+ Self::from_idsig(idsig)
+ }
+}
+
+impl<R: Read + Seek> V4Signature<R> {
+ /// Consumes a stream for an idsig file into a `V4Signature` struct.
+ pub fn from_idsig(mut r: R) -> Result<V4Signature<R>> {
+ Ok(V4Signature {
+ version: Version::from(r.read_u32::<LittleEndian>()?)?,
+ hashing_info: HashingInfo::from(&mut r)?,
+ signing_info: SigningInfo::from(&mut r)?,
+ merkle_tree_size: r.read_u32::<LittleEndian>()?,
+ merkle_tree_offset: r.stream_position()?,
+ data: r,
+ })
+ }
+
+ /// Read a stream for an APK file and creates a corresponding `V4Signature` struct that digests
+ /// the APK file. Note that the signing is not done.
+ pub fn create(
+ mut apk: &mut R,
+ block_size: usize,
+ salt: &[u8],
+ algorithm: HashAlgorithm,
+ ) -> Result<V4Signature<Cursor<Vec<u8>>>> {
+ // Determine the size of the apk
+ let start = apk.stream_position()?;
+ let size = apk.seek(SeekFrom::End(0))? as usize;
+ apk.seek(SeekFrom::Start(start))?;
+
+ // Create hash tree (and root hash)
+ let algorithm = match algorithm {
+ HashAlgorithm::SHA256 => openssl::hash::MessageDigest::sha256(),
+ };
+ let hash_tree = HashTree::from(&mut apk, size, salt, block_size, algorithm)?;
+
+ let mut ret = V4Signature {
+ version: Version::default(),
+ hashing_info: HashingInfo::default(),
+ signing_info: SigningInfo::default(),
+ merkle_tree_size: hash_tree.tree.len() as u32,
+ merkle_tree_offset: 0, // merkle tree starts from the beginning of `data`
+ data: Cursor::new(hash_tree.tree),
+ };
+ ret.hashing_info.raw_root_hash = hash_tree.root_hash.into_boxed_slice();
+ ret.hashing_info.log2_blocksize = log2(block_size);
+
+ apk.seek(SeekFrom::Start(start))?;
+ let (signature_algorithm_id, apk_digest) = get_apk_digest(apk, /*verify=*/ false)?;
+ ret.signing_info.signature_algorithm_id = signature_algorithm_id;
+ ret.signing_info.apk_digest = apk_digest;
+ // TODO(jiyong): add a signature to the signing_info struct
+
+ Ok(ret)
+ }
+
+ /// Writes the data into a writer
+ pub fn write_into<W: Write + Seek>(&mut self, mut w: &mut W) -> Result<()> {
+ // Writes the header part
+ w.write_u32::<LittleEndian>(self.version.to_u32().unwrap())?;
+ self.hashing_info.write_into(&mut w)?;
+ self.signing_info.write_into(&mut w)?;
+ w.write_u32::<LittleEndian>(self.merkle_tree_size)?;
+
+ // Writes the merkle tree
+ self.data.seek(SeekFrom::Start(self.merkle_tree_offset))?;
+ let copied_size = copy(&mut self.data, &mut w)?;
+ if copied_size != self.merkle_tree_size as u64 {
+ bail!(
+ "merkle tree is {} bytes, but only {} bytes are written.",
+ self.merkle_tree_size,
+ copied_size
+ );
+ }
+ Ok(())
+ }
+
+ /// Returns the bytes that represents the merkle tree
+ pub fn merkle_tree(&mut self) -> Result<Vec<u8>> {
+ self.data.seek(SeekFrom::Start(self.merkle_tree_offset))?;
+ let mut out = Vec::new();
+ self.data.read_to_end(&mut out)?;
+ Ok(out)
+ }
+}
+
+impl HashingInfo {
+ fn from(mut r: &mut dyn Read) -> Result<HashingInfo> {
+ // Size of the entire hashing_info struct. We don't need this because each variable-sized
+ // fields in the struct are also length encoded.
+ r.read_u32::<LittleEndian>()?;
+ Ok(HashingInfo {
+ hash_algorithm: HashAlgorithm::from(r.read_u32::<LittleEndian>()?)?,
+ log2_blocksize: r.read_u8()?,
+ salt: read_sized_array(&mut r)?,
+ raw_root_hash: read_sized_array(&mut r)?,
+ })
+ }
+
+ fn write_into<W: Write + Seek>(&self, mut w: &mut W) -> Result<()> {
+ let start = w.stream_position()?;
+ // Size of the entire hashing_info struct. Since we don't know the size yet, fill the place
+ // with 0. The exact size will then be written below.
+ w.write_u32::<LittleEndian>(0)?;
+
+ w.write_u32::<LittleEndian>(self.hash_algorithm.to_u32().unwrap())?;
+ w.write_u8(self.log2_blocksize)?;
+ write_sized_array(&mut w, &self.salt)?;
+ write_sized_array(&mut w, &self.raw_root_hash)?;
+
+ // Determine the size of hashing_info, and write it in front of the struct where the value
+ // was initialized to zero.
+ let end = w.stream_position()?;
+ let size = end - start - std::mem::size_of::<u32>() as u64;
+ w.seek(SeekFrom::Start(start))?;
+ w.write_u32::<LittleEndian>(size as u32)?;
+ w.seek(SeekFrom::Start(end))?;
+ Ok(())
+ }
+}
+
+impl SigningInfo {
+ fn from(mut r: &mut dyn Read) -> Result<SigningInfo> {
+ // Size of the entire signing_info struct. We don't need this because each variable-sized
+ // fields in the struct are also length encoded.
+ r.read_u32::<LittleEndian>()?;
+ Ok(SigningInfo {
+ apk_digest: read_sized_array(&mut r)?,
+ x509_certificate: read_sized_array(&mut r)?,
+ additional_data: read_sized_array(&mut r)?,
+ public_key: read_sized_array(&mut r)?,
+ signature_algorithm_id: SignatureAlgorithmID::from_u32(r.read_u32::<LittleEndian>()?)
+ .context("Unsupported signature algorithm")?,
+ signature: read_sized_array(&mut r)?,
+ })
+ }
+
+ fn write_into<W: Write + Seek>(&self, mut w: &mut W) -> Result<()> {
+ let start = w.stream_position()?;
+ // Size of the entire signing_info struct. Since we don't know the size yet, fill the place
+ // with 0. The exact size will then be written below.
+ w.write_u32::<LittleEndian>(0)?;
+
+ write_sized_array(&mut w, &self.apk_digest)?;
+ write_sized_array(&mut w, &self.x509_certificate)?;
+ write_sized_array(&mut w, &self.additional_data)?;
+ write_sized_array(&mut w, &self.public_key)?;
+ w.write_u32::<LittleEndian>(self.signature_algorithm_id.to_u32())?;
+ write_sized_array(&mut w, &self.signature)?;
+
+ // Determine the size of signing_info, and write it in front of the struct where the value
+ // was initialized to zero.
+ let end = w.stream_position()?;
+ let size = end - start - std::mem::size_of::<u32>() as u64;
+ w.seek(SeekFrom::Start(start))?;
+ w.write_u32::<LittleEndian>(size as u32)?;
+ w.seek(SeekFrom::Start(end))?;
+ Ok(())
+ }
+}
+
+fn read_sized_array(r: &mut dyn Read) -> Result<Box<[u8]>> {
+ let size = r.read_u32::<LittleEndian>()?;
+ let mut data = vec![0; size as usize];
+ r.read_exact(&mut data)?;
+ Ok(data.into_boxed_slice())
+}
+
+fn write_sized_array(w: &mut dyn Write, data: &[u8]) -> Result<()> {
+ w.write_u32::<LittleEndian>(data.len() as u32)?;
+ Ok(w.write_all(data)?)
+}
+
+fn log2(n: usize) -> u8 {
+ let num_bits = std::mem::size_of::<usize>() * 8;
+ (num_bits as u32 - n.leading_zeros() - 1) as u8
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use std::io::Cursor;
+
+ const TEST_APK_PATH: &str = "tests/data/v4-digest-v3-Sha256withEC.apk";
+
+ fn hexstring_from(s: &[u8]) -> String {
+ s.iter().map(|byte| format!("{:02x}", byte)).reduce(|i, j| i + &j).unwrap_or_default()
+ }
+
+ #[test]
+ fn parse_idsig_file() {
+ let parsed = V4Signature::from_idsig_path(format!("{}.idsig", TEST_APK_PATH)).unwrap();
+
+ assert_eq!(Version::V2, parsed.version);
+
+ let hi = parsed.hashing_info;
+ assert_eq!(HashAlgorithm::SHA256, hi.hash_algorithm);
+ assert_eq!(12, hi.log2_blocksize);
+ assert_eq!("", hexstring_from(hi.salt.as_ref()));
+ assert_eq!(
+ "77f063b48b63f846690fa76450a8d3b61a295b6158f50592e873f76dbeeb0201",
+ hexstring_from(hi.raw_root_hash.as_ref())
+ );
+
+ let si = parsed.signing_info;
+ assert_eq!(
+ "c02fe2eddeb3078801828b930de546ea4f98d37fb98b40c7c7ed169b0d713583",
+ hexstring_from(si.apk_digest.as_ref())
+ );
+ assert_eq!("", hexstring_from(si.additional_data.as_ref()));
+ assert_eq!(
+ "3046022100fb6383ba300dc7e1e6931a25b381398a16e5575baefd82afd12ba88660d9a6\
+ 4c022100ebdcae13ab18c4e30bf6ae634462e526367e1ba26c2647a1d87a0f42843fc128",
+ hexstring_from(si.signature.as_ref())
+ );
+ assert_eq!(SignatureAlgorithmID::EcdsaWithSha256, si.signature_algorithm_id);
+
+ assert_eq!(4096, parsed.merkle_tree_size);
+ assert_eq!(648, parsed.merkle_tree_offset);
+ }
+
+ /// Parse an idsig file into V4Signature and write it. The written date must be the same as
+ /// the input file.
+ #[test]
+ fn parse_and_compose() {
+ let idsig_path = format!("{}.idsig", TEST_APK_PATH);
+ let mut v4_signature = V4Signature::from_idsig_path(&idsig_path).unwrap();
+
+ let mut output = Cursor::new(Vec::new());
+ v4_signature.write_into(&mut output).unwrap();
+
+ assert_eq!(fs::read(&idsig_path).unwrap(), output.get_ref().as_slice());
+ }
+
+ /// Create V4Signature by hashing an APK. Merkle tree and the root hash should be the same
+ /// as those in the idsig file created by the signapk tool.
+ #[test]
+ fn digest_from_apk() {
+ let mut input = Cursor::new(include_bytes!("../tests/data/v4-digest-v3-Sha256withEC.apk"));
+ let mut created =
+ V4Signature::create(&mut input, 4096, &[], HashAlgorithm::SHA256).unwrap();
+
+ let mut golden = V4Signature::from_idsig_path(format!("{}.idsig", TEST_APK_PATH)).unwrap();
+
+ // Compare the root hash
+ assert_eq!(
+ created.hashing_info.raw_root_hash.as_ref(),
+ golden.hashing_info.raw_root_hash.as_ref()
+ );
+
+ // Compare the merkle tree
+ assert_eq!(
+ created.merkle_tree().unwrap().as_slice(),
+ golden.merkle_tree().unwrap().as_slice()
+ );
+ }
+}