d874fffaec
[ Merge of http://go/wvgerrit/149849 ] With ECC based DRM cert, the session key is expected to be 32, as compared to 16 bytes in RSA case. This CL adds supports for 32 bytes session key. Bug: 236317198 Test: oemcrypto_test Change-Id: I657fdd92d17736a23375ddcd457f83efa6ca6d1f
96 lines
3.6 KiB
C++
96 lines
3.6 KiB
C++
// Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
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// source code may only be used and distributed under the Widevine
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// License Agreement.
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//
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#ifndef CDM_OEC_KEY_DERIVER_H_
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#define CDM_OEC_KEY_DERIVER_H_
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#include <openssl/aes.h>
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#include <openssl/rsa.h>
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#include <time.h>
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#include <string>
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#include <vector>
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#include "oec_device_features.h"
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#include "oemcrypto_types.h"
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#include "pst_report.h"
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namespace wvoec {
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constexpr size_t kMaxTestRSAKeyLength = 2000; // Rough estimate.
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constexpr size_t kMaxCoreProvRequest = 150; // Rough estimate.
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// This structure will be signed to simulate a provisioning response from the
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// server.
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struct RSAPrivateKeyMessage {
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uint8_t rsa_key[kMaxTestRSAKeyLength];
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uint8_t rsa_key_iv[KEY_IV_SIZE];
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size_t rsa_key_length;
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uint8_t enc_message_key[kMaxTestRSAKeyLength];
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size_t enc_message_key_length;
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uint32_t nonce;
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};
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// Holds an encryption key and can encrypt a provisioning message. It also can
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// encrypt short buffers using CBC, such as content keys in a license.
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class Encryptor {
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public:
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Encryptor() : enc_key_(KEY_SIZE, 0) {}
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Encryptor(const std::vector<uint8_t>& enc_key) { set_enc_key(enc_key); };
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Encryptor& operator=(const Encryptor&) = default;
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void set_enc_key(const std::vector<uint8_t>& enc_key);
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// This encrypts an RSAPrivateKeyMessage with encryption_key so that it may be
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// loaded with OEMCrypto_LoadProvisioningResponse.
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// This modifies the clear data: it adds padding and generates a random iv.
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void PadAndEncryptProvisioningMessage(RSAPrivateKeyMessage* data,
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RSAPrivateKeyMessage* encrypted) const;
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void CBCEncrypt(const uint8_t* data, uint8_t* encrypted_data,
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size_t data_length, const uint8_t (&iv)[KEY_IV_SIZE]) const;
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private:
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std::vector<uint8_t> enc_key_;
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};
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// Holds encryption and mac keys derived from a master key.
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// Can be used to sign a buffer as either a server or client.
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class KeyDeriver : public Encryptor {
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public:
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KeyDeriver()
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: mac_key_server_(MAC_KEY_SIZE, 0), mac_key_client_(MAC_KEY_SIZE, 0) {}
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KeyDeriver& operator=(const KeyDeriver&) = default;
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// Generate mac and enc keys give the master key.
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void DeriveKeys(const uint8_t* master_key, size_t master_key_size,
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const std::vector<uint8_t>& mac_key_context,
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const std::vector<uint8_t>& enc_key_context);
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// Sign the buffer with server's mac key.
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void ServerSignBuffer(const uint8_t* data, size_t data_length,
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std::vector<uint8_t>* signature) const;
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// Sign the buffer with client's known mac key. Known test keys must be
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// installed first. This uses HMAC with SHA256, so is suitable for a message.
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void ClientSignBuffer(const std::vector<uint8_t>& buffer,
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std::vector<uint8_t>* signature) const;
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// Sign the pst buffer with client's known mac key. Known test keys must be
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// installed first. This uses HMAC with SHA128, and skips the beginning of the
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// buffer, so is only suitable for a pst report.
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void ClientSignPstReport(const std::vector<uint8_t>& pst_report_buffer,
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std::vector<uint8_t>* signature) const;
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void set_mac_keys(const uint8_t* mac_keys);
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private:
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// Internal utility function to derive key using CMAC-128 or CMAC-256 based on
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// master_key_size.
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void DeriveKey(const uint8_t* key, size_t master_key_size,
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const std::vector<uint8_t>& context, int counter,
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std::vector<uint8_t>* out);
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std::vector<uint8_t> mac_key_server_;
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std::vector<uint8_t> mac_key_client_;
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};
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} // namespace wvoec
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#endif // CDM_OEC_KEY_DERIVER_H_
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