diff --git a/tests/component/verifier_test.cpp b/tests/component/verifier_test.cpp
index 3246ecd..c460cbe 100644
--- a/tests/component/verifier_test.cpp
+++ b/tests/component/verifier_test.cpp
@@ -27,6 +27,7 @@
 #include <android-base/file.h>
 #include <android-base/stringprintf.h>
 #include <android-base/test_utils.h>
+#include <android-base/unique_fd.h>
 #include <gtest/gtest.h>
 
 #include "common/test_constants.h"
@@ -35,6 +36,89 @@
 
 using namespace std::string_literals;
 
+static void LoadKeyFromFile(const std::string& file_name, Certificate* cert) {
+  std::string testkey_string;
+  ASSERT_TRUE(android::base::ReadFileToString(file_name, &testkey_string));
+  ASSERT_TRUE(LoadCertificateFromBuffer(
+      std::vector<uint8_t>(testkey_string.begin(), testkey_string.end()), cert));
+}
+
+static void VerifyPackageWithCertificate(const std::string& name, Certificate&& cert) {
+  std::string package = from_testdata_base(name);
+  MemMapping memmap;
+  if (!memmap.MapFile(package)) {
+    FAIL() << "Failed to mmap " << package << ": " << strerror(errno) << "\n";
+  }
+
+  std::vector<Certificate> certs;
+  certs.emplace_back(std::move(cert));
+  ASSERT_EQ(VERIFY_SUCCESS, verify_file(memmap.addr, memmap.length, certs));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_failure) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  std::string testkey_string;
+  ASSERT_TRUE(
+      android::base::ReadFileToString(from_testdata_base("testkey_v1.txt"), &testkey_string));
+  ASSERT_FALSE(LoadCertificateFromBuffer(
+      std::vector<uint8_t>(testkey_string.begin(), testkey_string.end()), &cert));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_sha1_exponent3) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_v1.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_RSA, cert.key_type);
+  ASSERT_EQ(nullptr, cert.ec);
+
+  VerifyPackageWithCertificate("otasigned_v1.zip", std::move(cert));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_sha1_exponent65537) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_v2.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_RSA, cert.key_type);
+  ASSERT_EQ(nullptr, cert.ec);
+
+  VerifyPackageWithCertificate("otasigned_v2.zip", std::move(cert));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_sha256_exponent3) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_v3.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA256_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_RSA, cert.key_type);
+  ASSERT_EQ(nullptr, cert.ec);
+
+  VerifyPackageWithCertificate("otasigned_v3.zip", std::move(cert));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_sha256_exponent65537) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_v4.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA256_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_RSA, cert.key_type);
+  ASSERT_EQ(nullptr, cert.ec);
+
+  VerifyPackageWithCertificate("otasigned_v4.zip", std::move(cert));
+}
+
+TEST(VerifierTest, LoadCertificateFromBuffer_sha256_ec256bits) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_v5.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA256_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_EC, cert.key_type);
+  ASSERT_EQ(nullptr, cert.rsa);
+
+  VerifyPackageWithCertificate("otasigned_v5.zip", std::move(cert));
+}
+
 class VerifierTest : public testing::TestWithParam<std::vector<std::string>> {
  protected:
   void SetUp() override {
diff --git a/verifier.cpp b/verifier.cpp
index 283e043..1dc52a0 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -27,9 +27,13 @@
 #include <vector>
 
 #include <android-base/logging.h>
+#include <openssl/bio.h>
 #include <openssl/bn.h>
 #include <openssl/ecdsa.h>
+#include <openssl/evp.h>
 #include <openssl/obj_mac.h>
+#include <openssl/pem.h>
+#include <openssl/rsa.h>
 
 #include "asn1_decoder.h"
 #include "otautil/print_sha1.h"
@@ -441,6 +445,70 @@
     return key;
 }
 
+bool LoadCertificateFromBuffer(const std::vector<uint8_t>& pem_content, Certificate* cert) {
+  std::unique_ptr<BIO, decltype(&BIO_free)> content(
+      BIO_new_mem_buf(pem_content.data(), pem_content.size()), BIO_free);
+
+  std::unique_ptr<X509, decltype(&X509_free)> x509(
+      PEM_read_bio_X509(content.get(), nullptr, nullptr, nullptr), X509_free);
+  if (!x509) {
+    LOG(ERROR) << "Failed to read x509 certificate";
+    return false;
+  }
+
+  int nid = X509_get_signature_nid(x509.get());
+  switch (nid) {
+    // SignApk has historically accepted md5WithRSA certificates, but treated them as
+    // sha1WithRSA anyway. Continue to do so for backwards compatibility.
+    case NID_md5WithRSA:
+    case NID_md5WithRSAEncryption:
+    case NID_sha1WithRSA:
+    case NID_sha1WithRSAEncryption:
+      cert->hash_len = SHA_DIGEST_LENGTH;
+      break;
+    case NID_sha256WithRSAEncryption:
+    case NID_ecdsa_with_SHA256:
+      cert->hash_len = SHA256_DIGEST_LENGTH;
+      break;
+    default:
+      LOG(ERROR) << "Unrecognized signature nid " << OBJ_nid2ln(nid);
+      return false;
+  }
+
+  std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)> public_key(X509_get_pubkey(x509.get()),
+                                                                 EVP_PKEY_free);
+  if (!public_key) {
+    LOG(ERROR) << "Failed to extract the public key from x509 certificate";
+    return false;
+  }
+
+  int key_type = EVP_PKEY_id(public_key.get());
+  // TODO(xunchang) check the rsa key has exponent 3 or 65537 with RSA_get0_key; and ec key is
+  // 256 bits.
+  if (key_type == EVP_PKEY_RSA) {
+    cert->key_type = Certificate::KEY_TYPE_RSA;
+    cert->ec.reset();
+    cert->rsa.reset(EVP_PKEY_get1_RSA(public_key.get()));
+    if (!cert->rsa) {
+      LOG(ERROR) << "Failed to get the rsa key info from public key";
+      return false;
+    }
+  } else if (key_type == EVP_PKEY_EC) {
+    cert->key_type = Certificate::KEY_TYPE_EC;
+    cert->rsa.reset();
+    cert->ec.reset(EVP_PKEY_get1_EC_KEY(public_key.get()));
+    if (!cert->ec) {
+      LOG(ERROR) << "Failed to get the ec key info from the public key";
+      return false;
+    }
+  } else {
+    LOG(ERROR) << "Unrecognized public key type " << OBJ_nid2ln(key_type);
+    return false;
+  }
+
+  return true;
+}
+
 // Reads a file containing one or more public keys as produced by
 // DumpPublicKey:  this is an RSAPublicKey struct as it would appear
 // as a C source literal, eg:
diff --git a/verifier.h b/verifier.h
index 6fa8f2b..b134241 100644
--- a/verifier.h
+++ b/verifier.h
@@ -17,6 +17,8 @@
 #ifndef _RECOVERY_VERIFIER_H
 #define _RECOVERY_VERIFIER_H
 
+#include <stdint.h>
+
 #include <functional>
 #include <memory>
 #include <vector>
@@ -70,6 +72,10 @@
 
 bool load_keys(const char* filename, std::vector<Certificate>& certs);
 
+// Parses a PEM-encoded x509 certificate from the given buffer and saves it into |cert|. Returns
+// false if there is a parsing failure or the signature's encryption algorithm is not supported.
+bool LoadCertificateFromBuffer(const std::vector<uint8_t>& pem_content, Certificate* cert);
+
 #define VERIFY_SUCCESS        0
 #define VERIFY_FAILURE        1