diff --git a/libs/apkverify/src/sigutil.rs b/libs/apkverify/src/sigutil.rs
index 23dd91e..009154f 100644
--- a/libs/apkverify/src/sigutil.rs
+++ b/libs/apkverify/src/sigutil.rs
@@ -19,7 +19,7 @@
 use anyhow::{anyhow, bail, Result};
 use byteorder::{LittleEndian, ReadBytesExt};
 use bytes::{Buf, BufMut, Bytes, BytesMut};
-use ring::digest;
+use openssl::hash::{DigestBytes, Hasher, MessageDigest};
 use std::cmp::min;
 use std::io::{Cursor, Read, Seek, SeekFrom, Take};
 
@@ -107,12 +107,12 @@
                 let slice = &mut chunk[..(chunk_size as usize)];
                 data.read_exact(slice)?;
                 digests_of_chunks.put_slice(
-                    digester.digest(slice, CHUNK_HEADER_MID, chunk_size as u32).as_ref(),
+                    digester.digest(slice, CHUNK_HEADER_MID, chunk_size as u32)?.as_ref(),
                 );
                 chunk_count += 1;
             }
         }
-        Ok(digester.digest(&digests_of_chunks, CHUNK_HEADER_TOP, chunk_count).as_ref().into())
+        Ok(digester.digest(&digests_of_chunks, CHUNK_HEADER_TOP, chunk_count)?.as_ref().into())
     }
 
     fn zip_entries(&mut self) -> Result<Take<Box<dyn Read + '_>>> {
@@ -157,7 +157,7 @@
 }
 
 struct Digester {
-    algorithm: &'static digest::Algorithm,
+    algorithm: MessageDigest,
 }
 
 const CHUNK_HEADER_TOP: &[u8] = &[0x5a];
@@ -167,8 +167,8 @@
     fn new(signature_algorithm_id: u32) -> Result<Digester> {
         let digest_algorithm_id = to_content_digest_algorithm(signature_algorithm_id)?;
         let algorithm = match digest_algorithm_id {
-            CONTENT_DIGEST_CHUNKED_SHA256 => &digest::SHA256,
-            CONTENT_DIGEST_CHUNKED_SHA512 => &digest::SHA512,
+            CONTENT_DIGEST_CHUNKED_SHA256 => MessageDigest::sha256(),
+            CONTENT_DIGEST_CHUNKED_SHA512 => MessageDigest::sha512(),
             // TODO(jooyung): implement
             CONTENT_DIGEST_VERITY_CHUNKED_SHA256 => {
                 bail!("TODO(b/190343842): CONTENT_DIGEST_VERITY_CHUNKED_SHA256: not implemented")
@@ -179,12 +179,12 @@
     }
 
     // v2/v3 digests are computed after prepending "header" byte and "size" info.
-    fn digest(&self, data: &[u8], header: &[u8], size: u32) -> digest::Digest {
-        let mut ctx = digest::Context::new(self.algorithm);
-        ctx.update(header);
-        ctx.update(&size.to_le_bytes());
-        ctx.update(data);
-        ctx.finish()
+    fn digest(&self, data: &[u8], header: &[u8], size: u32) -> Result<DigestBytes> {
+        let mut ctx = Hasher::new(self.algorithm)?;
+        ctx.update(header)?;
+        ctx.update(&size.to_le_bytes())?;
+        ctx.update(data)?;
+        Ok(ctx.finish()?)
     }
 }
 
diff --git a/libs/apkverify/src/v3.rs b/libs/apkverify/src/v3.rs
index eb12498..16530be 100644
--- a/libs/apkverify/src/v3.rs
+++ b/libs/apkverify/src/v3.rs
@@ -19,12 +19,12 @@
 // TODO(jooyung) remove this
 #![allow(dead_code)]
 
-use anyhow::{anyhow, bail, Context, Result};
+use anyhow::{anyhow, bail, ensure, Context, Result};
 use bytes::Bytes;
-use ring::signature::{
-    UnparsedPublicKey, VerificationAlgorithm, ECDSA_P256_SHA256_ASN1, RSA_PKCS1_2048_8192_SHA256,
-    RSA_PKCS1_2048_8192_SHA512, RSA_PSS_2048_8192_SHA256, RSA_PSS_2048_8192_SHA512,
-};
+use openssl::hash::MessageDigest;
+use openssl::pkey::{self, PKey};
+use openssl::rsa::Padding;
+use openssl::sign::Verifier;
 use std::fs::File;
 use std::io::{Read, Seek};
 use std::ops::Range;
@@ -200,14 +200,22 @@
     signature: &Signature,
     key_info: &SubjectPublicKeyInfo,
 ) -> Result<()> {
-    let verification_alg: &dyn VerificationAlgorithm = match signature.signature_algorithm_id {
-        SIGNATURE_RSA_PSS_WITH_SHA256 => &RSA_PSS_2048_8192_SHA256,
-        SIGNATURE_RSA_PSS_WITH_SHA512 => &RSA_PSS_2048_8192_SHA512,
-        SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256 | SIGNATURE_VERITY_RSA_PKCS1_V1_5_WITH_SHA256 => {
-            &RSA_PKCS1_2048_8192_SHA256
+    let (pkey_id, padding, digest) = match signature.signature_algorithm_id {
+        SIGNATURE_RSA_PSS_WITH_SHA256 => {
+            (pkey::Id::RSA, Padding::PKCS1_PSS, MessageDigest::sha256())
         }
-        SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512 => &RSA_PKCS1_2048_8192_SHA512,
-        SIGNATURE_ECDSA_WITH_SHA256 | SIGNATURE_VERITY_ECDSA_WITH_SHA256 => &ECDSA_P256_SHA256_ASN1,
+        SIGNATURE_RSA_PSS_WITH_SHA512 => {
+            (pkey::Id::RSA, Padding::PKCS1_PSS, MessageDigest::sha512())
+        }
+        SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256 | SIGNATURE_VERITY_RSA_PKCS1_V1_5_WITH_SHA256 => {
+            (pkey::Id::RSA, Padding::PKCS1, MessageDigest::sha256())
+        }
+        SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512 => {
+            (pkey::Id::RSA, Padding::PKCS1, MessageDigest::sha512())
+        }
+        SIGNATURE_ECDSA_WITH_SHA256 | SIGNATURE_VERITY_ECDSA_WITH_SHA256 => {
+            (pkey::Id::EC, Padding::NONE, MessageDigest::sha256())
+        }
         // TODO(b/190343842) not implemented signature algorithm
         SIGNATURE_ECDSA_WITH_SHA512
         | SIGNATURE_DSA_WITH_SHA256
@@ -219,8 +227,15 @@
         }
         _ => bail!("Unsupported signature algorithm: {:#x}", signature.signature_algorithm_id),
     };
-    let key = UnparsedPublicKey::new(verification_alg, &key_info.subject_public_key);
-    key.verify(data.as_ref(), signature.signature.as_ref())?;
+    let key = PKey::public_key_from_der(key_info.raw)?;
+    ensure!(key.id() == pkey_id, "Public key has the wrong ID");
+    let mut verifier = Verifier::new(digest, &key)?;
+    if pkey_id == pkey::Id::RSA {
+        verifier.set_rsa_padding(padding)?;
+    }
+    verifier.update(data)?;
+    let verified = verifier.verify(&signature.signature)?;
+    ensure!(verified, "Signature is invalid ");
     Ok(())
 }