quantrs2_ml/
crypto.rs

1use crate::error::{MLError, Result};
2use quantrs2_circuit::prelude::Circuit;
3use quantrs2_sim::statevector::StateVectorSimulator;
4use scirs2_core::ndarray::{Array1, Array2};
5use scirs2_core::random::prelude::*;
6use std::collections::HashMap;
7use std::fmt;
8
9/// Types of quantum key distribution protocols
10#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
11pub enum ProtocolType {
12    /// BB84 protocol (Bennett and Brassard, 1984)
13    BB84,
14
15    /// E91 protocol (Ekert, 1991)
16    E91,
17
18    /// B92 protocol (Bennett, 1992)
19    B92,
20
21    /// BBM92 protocol (Bennett, Brassard, and Mermin, 1992)
22    BBM92,
23
24    /// SARG04 protocol (Scarani, Acin, Ribordy, and Gisin, 2004)
25    SARG04,
26}
27
28/// Represents a party in a quantum cryptographic protocol
29#[derive(Debug, Clone)]
30pub struct Party {
31    /// Party's name
32    pub name: String,
33
34    /// Party's key (if generated)
35    pub key: Option<Vec<u8>>,
36
37    /// Party's chosen bases (for BB84-like protocols)
38    pub bases: Option<Vec<usize>>,
39
40    /// Party's quantum state (if applicable)
41    pub state: Option<Vec<f64>>,
42}
43
44/// Quantum key distribution protocol
45#[derive(Debug, Clone)]
46pub struct QuantumKeyDistribution {
47    /// Type of QKD protocol
48    pub protocol: ProtocolType,
49
50    /// Number of qubits to use in the protocol
51    pub num_qubits: usize,
52
53    /// Alice party
54    pub alice: Party,
55
56    /// Bob party
57    pub bob: Party,
58
59    /// Error rate for the quantum channel
60    pub error_rate: f64,
61
62    /// Security parameter (number of bits to use for security checks)
63    pub security_bits: usize,
64}
65
66impl QuantumKeyDistribution {
67    /// Creates a new QKD protocol instance
68    pub fn new(protocol: ProtocolType, num_qubits: usize) -> Self {
69        QuantumKeyDistribution {
70            protocol,
71            num_qubits,
72            alice: Party {
73                name: "Alice".to_string(),
74                key: None,
75                bases: None,
76                state: None,
77            },
78            bob: Party {
79                name: "Bob".to_string(),
80                key: None,
81                bases: None,
82                state: None,
83            },
84            error_rate: 0.0,
85            security_bits: num_qubits / 10,
86        }
87    }
88
89    /// Sets the error rate for the quantum channel
90    pub fn with_error_rate(mut self, error_rate: f64) -> Self {
91        self.error_rate = error_rate;
92        self
93    }
94
95    /// Sets the security parameter
96    pub fn with_security_bits(mut self, security_bits: usize) -> Self {
97        self.security_bits = security_bits;
98        self
99    }
100
101    /// Distributes a key using the specified QKD protocol
102    pub fn distribute_key(&mut self) -> Result<usize> {
103        match self.protocol {
104            ProtocolType::BB84 => self.bb84_protocol(),
105            ProtocolType::E91 => self.e91_protocol(),
106            ProtocolType::B92 => self.b92_protocol(),
107            ProtocolType::BBM92 => Err(MLError::NotImplemented(
108                "BBM92 protocol not implemented yet".to_string(),
109            )),
110            ProtocolType::SARG04 => Err(MLError::NotImplemented(
111                "SARG04 protocol not implemented yet".to_string(),
112            )),
113        }
114    }
115
116    /// Implements the BB84 protocol
117    fn bb84_protocol(&mut self) -> Result<usize> {
118        // This is a dummy implementation
119        // In a real implementation, this would simulate the BB84 protocol
120
121        // Generate random bits for Alice
122        let alice_bits = (0..self.num_qubits)
123            .map(|_| {
124                if thread_rng().gen::<f64>() > 0.5 {
125                    1u8
126                } else {
127                    0u8
128                }
129            })
130            .collect::<Vec<_>>();
131
132        // Generate random bases for Alice and Bob
133        let alice_bases = (0..self.num_qubits)
134            .map(|_| {
135                if thread_rng().gen::<f64>() > 0.5 {
136                    1usize
137                } else {
138                    0usize
139                }
140            })
141            .collect::<Vec<_>>();
142
143        let bob_bases = (0..self.num_qubits)
144            .map(|_| {
145                if thread_rng().gen::<f64>() > 0.5 {
146                    1usize
147                } else {
148                    0usize
149                }
150            })
151            .collect::<Vec<_>>();
152
153        // Determine where Alice and Bob used the same basis
154        let matching_bases = alice_bases
155            .iter()
156            .zip(bob_bases.iter())
157            .enumerate()
158            .filter_map(|(i, (a, b))| if a == b { Some(i) } else { None })
159            .collect::<Vec<_>>();
160
161        // Get the key bits from matching bases positions
162        let mut key_bits = Vec::new();
163        for &i in &matching_bases {
164            // Apply error rate
165            if thread_rng().gen::<f64>() > self.error_rate {
166                key_bits.push(alice_bits[i]);
167            } else {
168                // Flip the bit to simulate an error
169                key_bits.push(alice_bits[i] ^ 1);
170            }
171        }
172
173        // Convert bits to bytes
174        let mut key_bytes = Vec::new();
175        for chunk in key_bits.chunks(8) {
176            let byte = chunk
177                .iter()
178                .enumerate()
179                .fold(0u8, |acc, (i, &bit)| acc | (bit << i));
180            key_bytes.push(byte);
181        }
182
183        // Store keys
184        self.alice.key = Some(key_bytes.clone());
185        self.bob.key = Some(key_bytes);
186
187        // Store bases
188        self.alice.bases = Some(alice_bases);
189        self.bob.bases = Some(bob_bases);
190
191        Ok(matching_bases.len())
192    }
193
194    /// Implements the E91 protocol
195    fn e91_protocol(&mut self) -> Result<usize> {
196        // This is a dummy implementation
197        // In a real implementation, this would simulate the E91 protocol
198        let key_length = self.num_qubits / 3; // Roughly 1/3 of qubits become key bits
199
200        // Generate random key bytes
201        let key_bytes = (0..key_length / 8 + 1)
202            .map(|_| thread_rng().gen::<u8>())
203            .collect::<Vec<_>>();
204
205        // Store keys
206        self.alice.key = Some(key_bytes.clone());
207        self.bob.key = Some(key_bytes);
208
209        Ok(key_length)
210    }
211
212    /// Implements the B92 protocol
213    fn b92_protocol(&mut self) -> Result<usize> {
214        // This is a dummy implementation
215        // In a real implementation, this would simulate the B92 protocol
216        let key_length = self.num_qubits / 4; // Roughly 1/4 of qubits become key bits
217
218        // Generate random key bytes
219        let key_bytes = (0..key_length / 8 + 1)
220            .map(|_| thread_rng().gen::<u8>())
221            .collect::<Vec<_>>();
222
223        // Store keys
224        self.alice.key = Some(key_bytes.clone());
225        self.bob.key = Some(key_bytes);
226
227        Ok(key_length)
228    }
229
230    /// Verifies that Alice and Bob have identical keys
231    pub fn verify_keys(&self) -> bool {
232        match (&self.alice.key, &self.bob.key) {
233            (Some(alice_key), Some(bob_key)) => alice_key == bob_key,
234            _ => false,
235        }
236    }
237
238    /// Gets Alice's key (if generated)
239    pub fn get_alice_key(&self) -> Option<Vec<u8>> {
240        self.alice.key.clone()
241    }
242
243    /// Gets Bob's key (if generated)
244    pub fn get_bob_key(&self) -> Option<Vec<u8>> {
245        self.bob.key.clone()
246    }
247}
248
249/// Quantum digital signature
250#[derive(Debug, Clone)]
251pub struct QuantumSignature {
252    /// Security parameter (key size in bits)
253    security_bits: usize,
254
255    /// Signature algorithm
256    algorithm: String,
257
258    /// Public key
259    public_key: Vec<u8>,
260
261    /// Private key
262    private_key: Vec<u8>,
263}
264
265impl QuantumSignature {
266    /// Creates a new quantum signature
267    pub fn new(security_bits: usize, algorithm: &str) -> Result<Self> {
268        // This is a dummy implementation
269        // In a real implementation, this would generate actual keys
270
271        // Generate random keys
272        let public_key = (0..security_bits / 8 + 1)
273            .map(|_| thread_rng().gen::<u8>())
274            .collect::<Vec<_>>();
275
276        let private_key = (0..security_bits / 8 + 1)
277            .map(|_| thread_rng().gen::<u8>())
278            .collect::<Vec<_>>();
279
280        Ok(QuantumSignature {
281            security_bits,
282            algorithm: algorithm.to_string(),
283            public_key,
284            private_key,
285        })
286    }
287
288    /// Signs a message
289    pub fn sign(&self, message: &[u8]) -> Result<Vec<u8>> {
290        // This is a dummy implementation
291        // In a real implementation, this would use the private key to sign the message
292
293        // Generate a random signature
294        let mut signature = self.private_key.clone();
295
296        // XOR with the message (simplified)
297        for (i, &byte) in message.iter().enumerate() {
298            if i < signature.len() {
299                signature[i] ^= byte;
300            }
301        }
302
303        Ok(signature)
304    }
305
306    /// Verifies a signature
307    pub fn verify(&self, message: &[u8], signature: &[u8]) -> Result<bool> {
308        // This is a dummy implementation
309        // In a real implementation, this would use the public key to verify the signature
310
311        // Generate the expected signature
312        let expected_signature = self.sign(message)?;
313
314        // Compare signatures
315        let is_valid = signature.len() == expected_signature.len()
316            && signature
317                .iter()
318                .zip(expected_signature.iter())
319                .all(|(a, b)| a == b);
320
321        Ok(is_valid)
322    }
323}
324
325/// Quantum authentication
326#[derive(Debug, Clone)]
327pub struct QuantumAuthentication {
328    /// Protocol type
329    protocol: String,
330
331    /// Security parameter
332    security_bits: usize,
333
334    /// Authentication keys
335    keys: HashMap<String, Vec<u8>>,
336}
337
338impl QuantumAuthentication {
339    /// Creates a new quantum authentication protocol
340    pub fn new(protocol: &str, security_bits: usize) -> Self {
341        QuantumAuthentication {
342            protocol: protocol.to_string(),
343            security_bits,
344            keys: HashMap::new(),
345        }
346    }
347
348    /// Adds a party to the authentication system
349    pub fn add_party(&mut self, party_name: &str) -> Result<()> {
350        // Generate a random key
351        let key = (0..self.security_bits / 8 + 1)
352            .map(|_| thread_rng().gen::<u8>())
353            .collect::<Vec<_>>();
354
355        self.keys.insert(party_name.to_string(), key);
356
357        Ok(())
358    }
359
360    /// Authenticates a message from a party
361    pub fn authenticate(&self, party_name: &str, message: &[u8]) -> Result<Vec<u8>> {
362        // Get the party's key
363        let key = self
364            .keys
365            .get(party_name)
366            .ok_or_else(|| MLError::InvalidParameter(format!("Party {} not found", party_name)))?;
367
368        // Generate a random authentication tag
369        let mut tag = key.clone();
370
371        // XOR with the message (simplified)
372        for (i, &byte) in message.iter().enumerate() {
373            if i < tag.len() {
374                tag[i] ^= byte;
375            }
376        }
377
378        Ok(tag)
379    }
380
381    /// Verifies an authentication tag
382    pub fn verify(&self, party_name: &str, message: &[u8], tag: &[u8]) -> Result<bool> {
383        // Generate the expected tag
384        let expected_tag = self.authenticate(party_name, message)?;
385
386        // Compare tags
387        let is_valid = tag.len() == expected_tag.len()
388            && tag.iter().zip(expected_tag.iter()).all(|(a, b)| a == b);
389
390        Ok(is_valid)
391    }
392}
393
394/// Quantum Secure Direct Communication protocol
395#[derive(Debug, Clone)]
396pub struct QSDC {
397    /// Number of qubits to use
398    pub num_qubits: usize,
399
400    /// Error rate for the quantum channel
401    pub error_rate: f64,
402}
403
404impl QSDC {
405    /// Creates a new QSDC protocol instance
406    pub fn new(num_qubits: usize) -> Self {
407        QSDC {
408            num_qubits,
409            error_rate: 0.01, // Default 1% error rate
410        }
411    }
412
413    /// Sets the error rate for the quantum channel
414    pub fn with_error_rate(mut self, error_rate: f64) -> Self {
415        self.error_rate = error_rate;
416        self
417    }
418
419    /// Transmits a message directly using the quantum channel
420    pub fn transmit_message(&self, message: &[u8]) -> Result<Vec<u8>> {
421        // This is a dummy implementation
422        // In a real implementation, this would use quantum entanglement
423        // to directly transmit the message
424
425        // Create a copy of the message
426        let mut received = message.to_vec();
427
428        // Apply the error rate to simulate channel noise
429        for byte in &mut received {
430            for bit_pos in 0..8 {
431                if thread_rng().gen::<f64>() < self.error_rate {
432                    // Flip the bit
433                    *byte ^= 1 << bit_pos;
434                }
435            }
436        }
437
438        Ok(received)
439    }
440}
441
442/// Encrypts a message using a quantum key
443pub fn encrypt_with_qkd(message: &[u8], key: Vec<u8>) -> Vec<u8> {
444    // Simple XOR encryption
445    message
446        .iter()
447        .enumerate()
448        .map(|(i, &byte)| byte ^ key[i % key.len()])
449        .collect()
450}
451
452/// Decrypts a message using a quantum key
453pub fn decrypt_with_qkd(encrypted: &[u8], key: Vec<u8>) -> Vec<u8> {
454    // XOR is symmetric, so encryption and decryption are the same
455    encrypt_with_qkd(encrypted, key)
456}
457
458impl fmt::Display for ProtocolType {
459    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
460        match self {
461            ProtocolType::BB84 => write!(f, "BB84"),
462            ProtocolType::E91 => write!(f, "E91"),
463            ProtocolType::B92 => write!(f, "B92"),
464            ProtocolType::BBM92 => write!(f, "BBM92"),
465            ProtocolType::SARG04 => write!(f, "SARG04"),
466        }
467    }
468}
quantrs2_ml/crypto.rs

quantrs2_ml/
crypto.rs
