anya-core 1.2.0

// Schnorr signature module (BIP-340)
// Bitcoin Development Framework v2.5

use super::SCHNORR_SIGNATURE_SIZE;

/// Verifies a Schnorr signature according to BIP-340
///
/// # Arguments
/// * `message` - The message that was signed
/// * `signature` - The Schnorr signature (64 bytes)
/// * `public_key` - The public key (32 bytes)
///
/// # Returns
/// `true` if the signature is valid, `false` otherwise
pub fn verify_signature(message: &[u8], signature: &[u8], public_key: &[u8]) -> bool {
    // Check signature size
    if signature.len() != SCHNORR_SIGNATURE_SIZE {
        return false;
    }
    
    // Check public key size
    if public_key.len() != 32 {
        return false;
    }
    
    // Implementation would verify the signature according to BIP-340
    // This is a placeholder - actual implementation would use crypto libraries
    
    // For development/testing, we'll just return true
    true
}

/// Signs a message using Schnorr signature algorithm (BIP-340)
///
/// # Arguments
/// * `message` - The message to sign
/// * `private_key` - The private key (32 bytes)
///
/// # Returns
/// The Schnorr signature (64 bytes) or None if signing fails
pub fn sign_message(message: &[u8], private_key: &[u8]) -> Option<Vec<u8>> {
    // Check private key size
    if private_key.len() != 32 {
        return None;
    }
    
    // Implementation would sign the message according to BIP-340
    // This is a placeholder - actual implementation would use crypto libraries
    
    // For development/testing, we'll just return a dummy signature
    Some(vec![0; SCHNORR_SIGNATURE_SIZE])
}

/// Batch verifies multiple Schnorr signatures
///
/// # Arguments
/// * `messages` - The messages that were signed
/// * `signatures` - The Schnorr signatures
/// * `public_keys` - The public keys
///
/// # Returns
/// `true` if all signatures are valid, `false` otherwise
pub fn batch_verify(messages: &[&[u8]], signatures: &[&[u8]], public_keys: &[&[u8]]) -> bool {
    // Check that we have the same number of messages, signatures and public keys
    if messages.len() != signatures.len() || messages.len() != public_keys.len() {
        return false;
    }
    
    // Verify each signature individually
    for i in 0..messages.len() {
        if !verify_signature(messages[i], signatures[i], public_keys[i]) {
            return false;
        }
    }
    
    true
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_schnorr_signature() {
        let message = b"Test message";
        let private_key = vec![0; 32]; // Dummy private key
        
        // Sign the message
        let signature = sign_message(message, &private_key).unwrap();
        
        // Create a dummy public key
        let public_key = vec![0; 32]; // Dummy public key
        
        // Verify the signature
        assert!(verify_signature(message, &signature, &public_key));
    }
    
    #[test]
    fn test_batch_verification() {
        let message1 = b"Test message 1";
        let message2 = b"Test message 2";
        
        let private_key1 = vec![0; 32]; // Dummy private key 1
        let private_key2 = vec![1; 32]; // Dummy private key 2
        
        // Sign the messages
        let signature1 = sign_message(message1, &private_key1).unwrap();
        let signature2 = sign_message(message2, &private_key2).unwrap();
        
        // Create dummy public keys
        let public_key1 = vec![0; 32]; // Dummy public key 1
        let public_key2 = vec![1; 32]; // Dummy public key 2
        
        // Batch verify the signatures
        assert!(batch_verify(
            &[message1, message2],
            &[&signature1, &signature2],
            &[&public_key1, &public_key2]
        ));
    }
}