1 Introduction 1
1.1 Security Requirements of Communication 1
1.2 Overview of Quantum Private Communicatio 5
1.3 Private Communication Models 10
1.3.1 Classic Secure Communication Model 10
1.3.2 Quantum Private Communication Model 11
1.4 History of Quantum Private Communication 13
1.5 Relationship with Other Subjects 15
1.6 Notations and Conventions 17
1.6.1 Random Variables 17
1.6.2 CryptosystemandCipher 18
References 19
2 Quantum Security Theory 23
2.1 Introduction 23
2.2 Mathematical Background 24
2.2.1 Hilbert Space 25
2.2.2 Properties of Hilbert Space 26
2.2.3 Operators 29
2.2.4 Several Important Operator 32
2.2.5 Matrices Decomposition 36
2.3 Introduction to Quantum Mechanics 37
2.3.1 Quantum Systems 37
2.3.2 Dynamic Characteristics of Quantum Systems 40
2.3.3 Information Retrieval of Quantum Systems 42
2.3.4 Fundament of Quantum Optics 45
2.4 Introduction to Information Theory 48
2.4.1 Entropy 49
2.4.2 Mutual Information 50
2.4.3 Quantum Fano Inequality 53
2.5 Introduction to Complexity Theory 54
2.5.1 Turing Machine 54
2.5.2 Classic Complexit 56
2.5.3 Quantum Complexity 58
2.6 Security Model 60
2.6.1 Information-theoretic Securit 60
2.6.2 Computational Security 62
2.6.3 Attack Strategy Analysis 63
References 65
3 Quantum Bits 67
3.1 Classic Bits 68
3.2 Quantum Bit Definition 69
3.2.1 Binary Qubit 70
3.2.2 P-ary Qubit 70
3.2.3 Composite Qubit 71
3.3 Quantum Bit Transformation 72
3.3.1 Quantum Logic Gates 73
3.3.2 Quantum Circuits 82
3.4 Mathematical Property 83
3.4.1 BlochSphere 84
3.4.2 Orthogonality of Opposite Points 85
3.4.3 Rotations onBlochSphere 85
3.5 Physical Property 87
3.5.1 Superposition 87
3.5.2 Entanglement 89
3.5.3 Distinguishability 92
3.5.4 Quantum No-cloning 96
3.6 Information Property 99
3.6.1 Single Qubit Information 99
3.6.2 Nonorthogonal Qubits Information 100
References 100
4 Quantum Key Distribution 103
4.1 Intuition on QKD 103
4.2 Standard QKDSchemes 106
4.2.1 BB84Protocol 107
4.2.2 B92Protocol 110
4.3 Quantum Communication Model for QKD 112
4.3.1 Quantum Source 112
4.3.2 Quantum Channel 114
4.3.3 Quantum Sink 117
4.4 Reconciliation 117
4.4.1 Reconciliation Model 117
4.4.2 Binary Reconciliation Protocol 119
4.4.3 Non-Binary Reconciliation Protoco 120
4.5 Privacy Amplification 125
4.5.1 Privacy Amplification Principle 126
4.5.2 Privacy Amplification Techniques 127
4.6 Security Model for QKD 128
4.6.1 Security Theory 128
4.6.2 Typical Attack Strategies 131
References 133
5 Quantum Cryptosystem 135
5.1 Introduction 136
5.2 QKD-based Cryptosystem 137
5.3 Quantum VernamCipher 139
5.3.1 Classic Vernam Algorithm 141
5.3.2 Quantum VernamCipher 141
5.3.3 Private Quantum Channel 143
5.3.4 Security Model 144
5.4 Typical Quantum Vernam Ciphers 144
5.4.1 Classic-key-based Quantum Vernam Cipher 145
5.4.2 Bell-key-based Quantum Vernam Cipher 146
5.4.3 Teleportation as Quantum Vernam Cipher 151
5.5 Quantum Block Cipher 152
5.5.1 Theoretical Model 153
5.5.2 Quantum Block Algorithm for Binary Bits 155
5.6 Quantum Public Key Cryptosystem 158
5.7 Typical Quantum Public-key Algorithms 160
5.7.1 Algorithm based Subset-sum Problem 160
5.7.2 Algorithm based Quantum Coding 162
References 164
6 Quantum Authentication 167
6.1 Introduction 167
6.2 Authentication Theory 169
6.2.1 Authentication Categories 169
6.2.2 Security Model 172
6.3 Message Authentication Code 173
6.3.1 Encoding Approach 174
6.3.2 Hash Function Approach 174
6.4 Quantum Identity Authentication 175
6.4.1 Scheme Description 175
6.4.2 Security Analysis 177
6.4.3 In Imperfect Channel 183
6.5 Quantum Signature Principle 186
6.6 Arbitrated Quantum Signature 189
6.6.1 Algorithm Description 189
6.6.2 Security Analysis 195
6.7 True Quantum Signature 196
6.7.1 Algorithm Description 196
6.7.2 Security Analysis 202
6.8 Quantum Channel Authenticatio 210
References 213
7 Private Communication Using Single Photon Signal 217
7.1 Single Photon Source 217
7.1.1 Basic Principle 218
7.1.2 Faint Laser Pulses 219
7.1.3 Single Photon Source with Quantum Dots 220
7.1.4 Other Single Photon Source 222
7.1.5 Entangled Photon Pairs 223
7.2 Transmission of Single Photon Signal 224
7.2.1 Transmission Mechanism 224
7.2.2 Quantum Repeater 226
7.3 Single Photon Detection 230
7.3.1 Photomultiplier Tubes 230
7.3.2 Single Photon Avalanche Diod 232
7.3.3 Frequency Up-conversion 237
7.3.4 Quantum Dots Single Photon Detector 239
7.3.5 Superconducting Single Photon Detector 240
7.4 Encoding with Discrete Variable Qubits 243
7.4.1 Polarization Modulation 243
7.4.2 Phase Modulation 244
7.4.3 Frequency Modulation 246
7.5 QKDwith Single Photon Signal 246
7.5.1 QKDinOptical Fiber 247
7.5.2 QKD in Free Space 250
7.6 QKDwith Entangled Photon Pairs 252
7.7 Secret Sharing with Single Photon Signal 254
References 257
8 Private Communication Using Continuous Variable Signal 259
8.1 Continuous Variable Signal 260
8.1.1 Coherent State Signal 260
8.1.2 Squeezed State Signal 264
8.2 Continuous Variable Signal Transmission 268
8.3 Continuous Variable Signal Detection 271
8.3.1 Direct Intensity Measurement 271
8.3.2 Coherent Detection 273
8.3.3 HomodyneDetection 274
8.3.4 Imperfect Homodyne Detection 277
8.4 Encoding with Continuous Variable Qubits 279
8.4.1 Continuous Variable Qubits 279
8.4.2 Amplitude-Phase Encoding Rule 281
8.4.3 PSK Encoding Rule 283
8.4.4 Polarization Encoding Rul 285
8.5 QKD with Continuous Variable Signa 289
8.5.1 QKD with Squeezed State 290
8.5.2 QKD with Coherent State 293
8.5.3 Private Communication with EPR Correlations 297
8.6 Quantum Encryption with Coherent States 299
8.6.1 Algorithm Descriptions 299
8.6.2 Polarization Encoding Implementation 304
8.6.3 Phase Encoding Implementation 306
8.7 Quantum Identification with Coherent State 307
References 309
9 Practical Private Communication Systems 313
9.1 Introduction 313
9.2 Transmission Loss 316
9.2.1 In Single Mode Fiber 316
9.2.2 In Free Space 321
9.3 Private Communication Over Fiber 324
9.3.1 Point-to-point Private Communication 325
9.3.2 Private Communication Networ 329
9.4 Private Communication Over Free-Space 334
9.4.1 Transmitter，Receiver，and Relay 335
9.4.2 Link Attenuations 337
9.4.3 Atmosphere-based Private Communication 340
9.4.4 Stratosphere-based Private Communication 343
9.4.5 Satellite-based Private Communication 348
9.5 Private Communication over IP Networks 350
9.5.1 IPsec Extensions with QKD Protocols 350
9.5.2 Quantum Virtual Private Network 353
9.6 Applications in Mobile Communication 354
9.7 Limitations onAvailabilities 357
9.7.1 Limitations on Communication Systems 357
9.7.2 Limitations on Security 359
References 360
Index 365