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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CRYPTO_SIGNATURE_VERIFIER_H_
      6 #define CRYPTO_SIGNATURE_VERIFIER_H_
      7 
      8 #include "build/build_config.h"
      9 
     10 #include <vector>
     11 
     12 #include "base/basictypes.h"
     13 #include "crypto/crypto_export.h"
     14 
     15 #if defined(USE_OPENSSL)
     16 typedef struct env_md_st EVP_MD;
     17 typedef struct evp_pkey_ctx_st EVP_PKEY_CTX;
     18 #else
     19 typedef struct HASHContextStr HASHContext;
     20 typedef struct SECKEYPublicKeyStr SECKEYPublicKey;
     21 typedef struct VFYContextStr VFYContext;
     22 #endif
     23 
     24 namespace crypto {
     25 
     26 // The SignatureVerifier class verifies a signature using a bare public key
     27 // (as opposed to a certificate).
     28 class CRYPTO_EXPORT SignatureVerifier {
     29  public:
     30   // The set of supported hash functions. Extend as required.
     31   enum HashAlgorithm {
     32     SHA1,
     33     SHA256,
     34   };
     35 
     36   SignatureVerifier();
     37   ~SignatureVerifier();
     38 
     39   // Streaming interface:
     40 
     41   // Initiates a signature verification operation.  This should be followed
     42   // by one or more VerifyUpdate calls and a VerifyFinal call.
     43   // NOTE: for RSA-PSS signatures, use VerifyInitRSAPSS instead.
     44   //
     45   // The signature algorithm is specified as a DER encoded ASN.1
     46   // AlgorithmIdentifier structure:
     47   //   AlgorithmIdentifier  ::=  SEQUENCE  {
     48   //       algorithm               OBJECT IDENTIFIER,
     49   //       parameters              ANY DEFINED BY algorithm OPTIONAL  }
     50   //
     51   // The signature is encoded according to the signature algorithm, but it
     52   // must not be further encoded in an ASN.1 BIT STRING.
     53   // Note: An RSA signature is actually a big integer.  It must be in
     54   // big-endian byte order.
     55   //
     56   // The public key is specified as a DER encoded ASN.1 SubjectPublicKeyInfo
     57   // structure, which contains not only the public key but also its type
     58   // (algorithm):
     59   //   SubjectPublicKeyInfo  ::=  SEQUENCE  {
     60   //       algorithm            AlgorithmIdentifier,
     61   //       subjectPublicKey     BIT STRING  }
     62   bool VerifyInit(const uint8* signature_algorithm,
     63                   int signature_algorithm_len,
     64                   const uint8* signature,
     65                   int signature_len,
     66                   const uint8* public_key_info,
     67                   int public_key_info_len);
     68 
     69   // Initiates a RSA-PSS signature verification operation.  This should be
     70   // followed by one or more VerifyUpdate calls and a VerifyFinal call.
     71   //
     72   // The RSA-PSS signature algorithm parameters are specified with the
     73   // |hash_alg|, |mask_hash_alg|, and |salt_len| arguments.
     74   //
     75   // An RSA-PSS signature is a nonnegative integer encoded as a byte string
     76   // (of the same length as the RSA modulus) in big-endian byte order. It
     77   // must not be further encoded in an ASN.1 BIT STRING.
     78   //
     79   // The public key is specified as a DER encoded ASN.1 SubjectPublicKeyInfo
     80   // structure, which contains not only the public key but also its type
     81   // (algorithm):
     82   //   SubjectPublicKeyInfo  ::=  SEQUENCE  {
     83   //       algorithm            AlgorithmIdentifier,
     84   //       subjectPublicKey     BIT STRING  }
     85   bool VerifyInitRSAPSS(HashAlgorithm hash_alg,
     86                         HashAlgorithm mask_hash_alg,
     87                         int salt_len,
     88                         const uint8* signature,
     89                         int signature_len,
     90                         const uint8* public_key_info,
     91                         int public_key_info_len);
     92 
     93   // Feeds a piece of the data to the signature verifier.
     94   void VerifyUpdate(const uint8* data_part, int data_part_len);
     95 
     96   // Concludes a signature verification operation.  Returns true if the
     97   // signature is valid.  Returns false if the signature is invalid or an
     98   // error occurred.
     99   bool VerifyFinal();
    100 
    101   // Note: we can provide a one-shot interface if there is interest:
    102   //   bool Verify(const uint8* data,
    103   //               int data_len,
    104   //               const uint8* signature_algorithm,
    105   //               int signature_algorithm_len,
    106   //               const uint8* signature,
    107   //               int signature_len,
    108   //               const uint8* public_key_info,
    109   //               int public_key_info_len);
    110 
    111  private:
    112 #if defined(USE_OPENSSL)
    113   bool CommonInit(const EVP_MD* digest,
    114                   const uint8* signature,
    115                   int signature_len,
    116                   const uint8* public_key_info,
    117                   int public_key_info_len,
    118                   EVP_PKEY_CTX** pkey_ctx);
    119 #else
    120   static SECKEYPublicKey* DecodePublicKeyInfo(const uint8* public_key_info,
    121                                               int public_key_info_len);
    122 #endif
    123 
    124   void Reset();
    125 
    126   std::vector<uint8> signature_;
    127 
    128 #if defined(USE_OPENSSL)
    129   struct VerifyContext;
    130   VerifyContext* verify_context_;
    131 #else
    132   // Used for all signature types except RSA-PSS.
    133   VFYContext* vfy_context_;
    134 
    135   // Used for RSA-PSS signatures.
    136   HashAlgorithm hash_alg_;
    137   HashAlgorithm mask_hash_alg_;
    138   unsigned int salt_len_;
    139   SECKEYPublicKey* public_key_;
    140   HASHContext* hash_context_;
    141 #endif
    142 };
    143 
    144 }  // namespace crypto
    145 
    146 #endif  // CRYPTO_SIGNATURE_VERIFIER_H_
    147