signature_verifier.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CRYPTO_SIGNATURE_VERIFIER_H_
#define CRYPTO_SIGNATURE_VERIFIER_H_

#include <stdint.h>

#include <memory>
#include <vector>

#include "base/containers/span.h"
#include "build/build_config.h"
#include "crypto/crypto_export.h"

namespace crypto {

// The SignatureVerifier class verifies a signature using a bare public key
// (as opposed to a certificate).
class CRYPTO_EXPORT SignatureVerifier {
 public:
  // The set of supported signature algorithms. Extend as required.
  enum SignatureAlgorithm {
    RSA_PKCS1_SHA1,
    RSA_PKCS1_SHA256,
    ECDSA_SHA256,
    // This is RSA-PSS with SHA-256 as both signing hash and MGF-1 hash, and the
    // salt length matching the hash length.
    RSA_PSS_SHA256,
  };

  SignatureVerifier();
  ~SignatureVerifier();

  // Streaming interface:

  // Initiates a signature verification operation.  This should be followed
  // by one or more VerifyUpdate calls and a VerifyFinal call.
  //
  // The signature is encoded according to the signature algorithm.
  //
  // The public key is specified as a DER encoded ASN.1 SubjectPublicKeyInfo
  // structure, which contains not only the public key but also its type
  // (algorithm):
  //   SubjectPublicKeyInfo  ::=  SEQUENCE  {
  //       algorithm            AlgorithmIdentifier,
  //       subjectPublicKey     BIT STRING  }
  bool VerifyInit(SignatureAlgorithm signature_algorithm,
                  base::span<const uint8_t> signature,
                  base::span<const uint8_t> public_key_info);

  // Feeds a piece of the data to the signature verifier.
  void VerifyUpdate(base::span<const uint8_t> data_part);

  // Concludes a signature verification operation.  Returns true if the
  // signature is valid.  Returns false if the signature is invalid or an
  // error occurred.
  bool VerifyFinal();

 private:
  void Reset();

  std::vector<uint8_t> signature_;

  struct VerifyContext;
  std::unique_ptr<VerifyContext> verify_context_;
};

}  // namespace crypto

#endif  // CRYPTO_SIGNATURE_VERIFIER_H_