Single Photon Quantum Encryption
description
Transcript of Single Photon Quantum Encryption
Single Photon Quantum Single Photon Quantum EncryptionEncryption
Rob GroveRob GroveApril 25, 2005April 25, 2005
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
• Telephone
• Internet
• Courier
• In person
Bob needs to get a secure message to Alice
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Private Key
Private Key Private Key CryptographyCryptography
Bob Alice
Eve
• Private key encryption uses permutations and other reversible mathematical operations to encode the message.
Private Key Encrypt/DecryptPrivate Key Encrypt/Decrypt
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Public Key Public Key CryptographyCryptography
Bob Alice
Eve
Public Key
Encrypted Message
Public Key EncryptPrivate Key Decrypt
• Public key encryption uses prime multiplication and other very hard to reverse mathematical operations to encode the message.
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
1.1. In conventional data transmission every bit In conventional data transmission every bit has a definite value of 0 or 1.has a definite value of 0 or 1.
2.2. Linearly polarized atomic particles can be Linearly polarized atomic particles can be used as data bits for quantum data used as data bits for quantum data transmission.transmission.
3.3. Qubits can change their state when Qubits can change their state when measured.measured.
4.4. Linear polarized photons are natural Linear polarized photons are natural qubits.qubits.
5.5. Qubits are extremely delicate.Qubits are extremely delicate.
Quantum bits (Qubits)Quantum bits (Qubits)
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Polarization of PhotonsPolarization of Photons
-1-0.500.51
-1
0
1
0
20
40
60
80
100 Polarization
-1-0.5
00.5
1
-1
0
1
0
20
40
60
80
100
Polarization
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Wave PolarizationWave PolarizationCircular Polarization
Linear Polarization
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Polarizing Polarizing FiltersFilters
Filters can be used Filters can be used to measure photon to measure photon polarizationpolarization
Polarized at 45 degrees
Filters can be used Filters can be used to polarize photons to polarize photons into qubits for data into qubits for data transmissiontransmission
Background
Alice’s Receiving Filters
Key 1 11 1Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations Predictions
Bob’s Values 0 1 1 1 0 1 1 0
Alice’s Measured Values 1 1 1 1 1 1 1 0
Encryption ExampleEncryption Example
Bob’s Sending Filters
0 10
1
Bob Confirms Correct Filters
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
MethodMethod
Bob
Alice
1. Bob generates two random number sequences.
Bob’s Filter100101010001 010111100111
Alice’s Filter110011000100
2. Alice generates one random sequence and uses it to filter Bob’s data.
3. Alice tells Bob her filter sequence and Bob tells her which ones are wrong.
Subset of Bob’s Key
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Introduces gross error > 25%
Quantum EncryptionQuantum EncryptionBob Alice
Eve
Key
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Shannon’s Secure Cryptography Shannon’s Secure Cryptography EquationEquation
0)|()();( MCHCHCMI
entropy is
tcipher tex theis
message theis
ninformatio is
H
C
M
IThe only way this can happen is if a totally random key of equal length to the message is XOR’d with the message.
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Quantum Encryption ProblemsQuantum Encryption Problems
• Restricted to fiber-optics cable
• Greatest distance proven is under 62 miles
• Hardware is expensive
• Individual photons have not been demonstrated
• Data throughput is not very high, 1~10 kb / s
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
Specific Application EncryptionSpecific Application Encryption
• Will not be a substitute for public key encryption for most applications
• Will not directly impact 99% of internet users
• Will be a useful tool against massive internet attacks on back bone structure
• Will be a solution for line of sight business encryption
Background
Current Encryption
Quantum Mechanics
Quantum Encryption
Limitations
Predictions
ReferencesReferences• http://www.wsi.tum.de/E24/research/spintronics/spintronics.htm
• http://www.mycrypto.net/encryption/crypto_algorithms.html
• http://www.tryagain.com/humcivil/qntmencr.htm
• http://www.idquantique.com/files/introduction.pdf
• http://www.cs.jhu.edu/~scheideler/courses/600.471_S03/lecture_6.pdf
• http://www.cs.dartmouth.edu/~jford/crypto.html
• http://www-theory.chem.washington.edu/~trstedl/quantum/quantum.html
• http://scienceworld.wolfram.com/physics/WaveEquation.html
• http://www.wordless.com/CGI/article.asp?ArticleId=21
• http://www.mtnmath.com/whatrh/node78.html
• http://www.th.physik.uni-frankfurt.de/~jr/physpicquant.html
• http://www.trnmag.com/Stories/2002/112702/Fast_quantum_crypto_demoed_112702.html