79e39b482d
Widevine ECM v3 is redesigned mainly based on protobuf, and supports new features including carrying fingerprinting and service blocking information. Existing clients must upgrade the Widevine CAS plugin to use the new ECM v3.
108 lines
4.4 KiB
C++
108 lines
4.4 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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// Copyright 2016 Google LLC.
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//
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// This software is licensed under the terms defined in the Widevine Master
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// License Agreement. For a copy of this agreement, please contact
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// widevine-licensing@google.com.
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////////////////////////////////////////////////////////////////////////////////
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// Contains common crypto routines for widevine protocols. These routines are
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// used as part of licensing and provisioning request handling.
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#ifndef COMMON_CRYPTO_UTIL_H_
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#define COMMON_CRYPTO_UTIL_H_
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#include <string>
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#include "absl/strings/escaping.h"
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#include "absl/strings/string_view.h"
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#include "openssl/digest.h"
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namespace widevine {
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namespace crypto_util {
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// Default constants used for key derivation for encryption and signing.
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// TODO(user): These are duplicated in session.cc in the sdk. de-dup.
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extern const char kWrappingKeyLabel[];
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extern const int kWrappingKeySizeBits;
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extern const char kSigningKeyLabel[];
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extern const int kSigningKeySizeBits;
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extern const size_t kSigningKeySizeBytes;
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extern const char kIvMasterKey[];
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extern const char kIvLabel[];
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extern const int kIvSizeBits;
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extern const int kAes128KeySizeBits;
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extern const int kAes128KeySizeBytes;
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extern const char kKeyboxV3Label[];
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extern const uint32_t kCENCSchemeID; // 'cenc' (AES-CTR): 0x63656E63
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extern const uint32_t kCBC1SchemeID; // 'cbc1' (AES-CBC): 0x63626331
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extern const uint32_t kCENSSchemeID; // 'cens' (AES-CTR subsample): 0x63656E73
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extern const uint32_t kCBCSSchemeID; // 'cbcs' (AES-CBC subsample): 0x63626373
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// DeriveKey uses the NIST 800-108 KDF recommendation, using AES-CMAC PRF.
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// NIST 800-108:
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// http://csrc.nist.gov/publications/nistpubs/800-108/sp800-108.pdf
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// AES-CMAC:
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// http://tools.ietf.org/html/rfc4493
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std::string DeriveKey(absl::string_view key, absl::string_view label,
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absl::string_view context, const uint32_t size_bits);
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// Derives an IV from the provided |context|.
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std::string DeriveIv(absl::string_view context);
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// Derives a key ID from the provided |context|.
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std::string DeriveKeyId(absl::string_view context);
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// Helper function to derive a key using the group master key and context.
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std::string DeriveGroupSessionKey(absl::string_view context,
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const uint32_t size_bits);
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// Helper function to derive a signing key for from the signing context.
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std::string DeriveSigningKey(absl::string_view key, absl::string_view context,
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const uint32_t size_bits);
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// Helper function to create a SHA-256 HMAC signature for the given message.
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std::string CreateSignatureHmacSha256(absl::string_view key,
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absl::string_view message);
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// Helper function to create a SHA-384 HMAC signature for the given message.
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std::string CreateSignatureHmacSha384(absl::string_view key,
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absl::string_view message);
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// Helper function to create a HMAC signature for the specified hash algorithm
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// and message.
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std::string CreateSignatureHmac(const EVP_MD* hash_algorithm,
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unsigned char* digest, absl::string_view key,
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absl::string_view message);
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// Helper function which compares the SHA-256 HMAC against the provided
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// signature.
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bool VerifySignatureHmacSha256(absl::string_view key,
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absl::string_view signature,
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absl::string_view message);
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// Helper function which compares the SHA-384 HMAC against the provided
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// signature.
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bool VerifySignatureHmacSha384(absl::string_view key,
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absl::string_view signature,
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absl::string_view message);
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// Helper function to create a SHA-1 HMAC signature for the given message.
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std::string CreateSignatureHmacSha1(absl::string_view key,
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absl::string_view message);
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// Helper function which compares the SHA-1 HMAC against the provided
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// signature.
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bool VerifySignatureHmacSha1(absl::string_view key, absl::string_view signature,
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absl::string_view message);
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// Converts a requested 4CC encryption scheme ID from a std::string to a uint32_t and
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// verifies it is a correct value.
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bool FourCCEncryptionSchemeIDFromString(const std::string& requested,
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uint32_t* four_cc_code);
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} // namespace crypto_util
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} // namespace widevine
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#endif // COMMON_CRYPTO_UTIL_H_
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