herta/src/advanced/cryptography.js

Advanced mathematics framework for scientific, engineering, and financial applications

/**
 * cryptography.js
 * Cryptographic operations for Herta.js
 */

// Utility function for string to byte array conversion
function stringToBytes(str) {
  const bytes = [];
  for (let i = 0; i < str.length; i++) {
    bytes.push(str.charCodeAt(i));
  }
  return bytes;
}

// Utility function for byte array to string conversion
function bytesToString(bytes) {
  return String.fromCharCode(...bytes);
}

// Utility function for byte array to hex string conversion
function bytesToHex(bytes) {
  return Array.from(bytes)
    .map((byte) => byte.toString(16).padStart(2, '0'))
    .join('');
}

// Utility function for hex string to byte array conversion
function hexToBytes(hex) {
  const bytes = [];
  for (let i = 0; i < hex.length; i += 2) {
    bytes.push(parseInt(hex.substr(i, 2), 16));
  }
  return bytes;
}

/**
 * Hash functions
 */
const hash = {
  /**
   * Simple SHA-256 implementation
   * Note: In a production environment, use a well-tested library
   * @param {String|Array} message - Message to hash
   * @returns {String} - Hex string of hash
   */
  sha256(message) {
    // This is a placeholder. In a real implementation, we would use a proper SHA-256 algorithm
    // For demonstration purposes, we'll use a simple hash function
    const bytes = typeof message === 'string' ? stringToBytes(message) : message;

    // In a real implementation, we would compute the actual SHA-256 hash
    // For now, we'll return a placeholder
    return `sha256-hash-placeholder-${bytesToHex(bytes).substring(0, 10)}`;
  },

  /**
   * Simple MD5 implementation
   * Note: In a production environment, use a well-tested library
   * @param {String|Array} message - Message to hash
   * @returns {String} - Hex string of hash
   */
  md5(message) {
    // This is a placeholder. In a real implementation, we would use a proper MD5 algorithm
    const bytes = typeof message === 'string' ? stringToBytes(message) : message;

    // In a real implementation, we would compute the actual MD5 hash
    return `md5-hash-placeholder-${bytesToHex(bytes).substring(0, 10)}`;
  }
};

/**
 * Symmetric encryption functions
 */
const symmetric = {
  /**
   * AES encryption (placeholder implementation)
   * @param {String|Array} plaintext - Data to encrypt
   * @param {String|Array} key - Encryption key
   * @param {String} mode - Encryption mode (e.g., 'cbc', 'gcm')
   * @returns {Object} - Encrypted data and IV
   */
  aesEncrypt(plaintext, key, mode = 'cbc') {
    // This is a placeholder. In a real implementation, we would use a proper AES algorithm
    const plaintextBytes = typeof plaintext === 'string' ? stringToBytes(plaintext) : plaintext;
    const keyBytes = typeof key === 'string' ? stringToBytes(key) : key;

    // Generate a random IV
    const iv = Array(16).fill().map(() => Math.floor(Math.random() * 256));

    // In a real implementation, we would perform actual AES encryption
    // For now, we'll return a placeholder
    const ciphertext = plaintextBytes.map((byte, i) => byte ^ keyBytes[i % keyBytes.length] ^ iv[i % iv.length]);

    return {
      ciphertext,
      iv,
      mode
    };
  },

  /**
   * AES decryption (placeholder implementation)
   * @param {Array} ciphertext - Encrypted data
   * @param {String|Array} key - Decryption key
   * @param {Array} iv - Initialization vector
   * @param {String} mode - Decryption mode (e.g., 'cbc', 'gcm')
   * @returns {Array} - Decrypted data
   */
  aesDecrypt(ciphertext, key, iv, mode = 'cbc') {
    // This is a placeholder. In a real implementation, we would use a proper AES algorithm
    const keyBytes = typeof key === 'string' ? stringToBytes(key) : key;

    // In a real implementation, we would perform actual AES decryption
    // For now, we'll return a placeholder
    const plaintext = ciphertext.map((byte, i) => byte ^ keyBytes[i % keyBytes.length] ^ iv[i % iv.length]);

    return plaintext;
  }
};

/**
 * Asymmetric encryption functions
 */
const asymmetric = {
  /**
   * Generate RSA key pair (placeholder implementation)
   * @param {Number} bits - Key size in bits
   * @returns {Object} - Public and private keys
   */
  generateRsaKeyPair(bits = 2048) {
    // This is a placeholder. In a real implementation, we would generate actual RSA keys
    return {
      publicKey: `rsa-public-key-placeholder-${bits}`,
      privateKey: `rsa-private-key-placeholder-${bits}`
    };
  },

  /**
   * RSA encryption (placeholder implementation)
   * @param {String|Array} plaintext - Data to encrypt
   * @param {String} publicKey - RSA public key
   * @returns {Array} - Encrypted data
   */
  rsaEncrypt(plaintext, publicKey) {
    // This is a placeholder. In a real implementation, we would use a proper RSA algorithm
    const plaintextBytes = typeof plaintext === 'string' ? stringToBytes(plaintext) : plaintext;

    // In a real implementation, we would perform actual RSA encryption
    // For now, we'll return a placeholder
    return plaintextBytes.map((byte) => (byte + 1) % 256);
  },

  /**
   * RSA decryption (placeholder implementation)
   * @param {Array} ciphertext - Encrypted data
   * @param {String} privateKey - RSA private key
   * @returns {Array} - Decrypted data
   */
  rsaDecrypt(ciphertext, privateKey) {
    // This is a placeholder. In a real implementation, we would use a proper RSA algorithm

    // In a real implementation, we would perform actual RSA decryption
    // For now, we'll return a placeholder
    return ciphertext.map((byte) => (byte - 1 + 256) % 256);
  }
};

/**
 * Digital signature functions
 */
const signature = {
  /**
   * Sign data with RSA (placeholder implementation)
   * @param {String|Array} data - Data to sign
   * @param {String} privateKey - RSA private key
   * @returns {Array} - Signature
   */
  rsaSign(data, privateKey) {
    // This is a placeholder. In a real implementation, we would use a proper RSA signing algorithm
    const dataBytes = typeof data === 'string' ? stringToBytes(data) : data;

    // In a real implementation, we would perform actual RSA signing
    // For now, we'll return a placeholder
    return hash.sha256(dataBytes + privateKey);
  },

  /**
   * Verify RSA signature (placeholder implementation)
   * @param {String|Array} data - Original data
   * @param {Array} signature - Signature to verify
   * @param {String} publicKey - RSA public key
   * @returns {Boolean} - True if signature is valid
   */
  rsaVerify(data, signature, publicKey) {
    // This is a placeholder. In a real implementation, we would use a proper RSA verification algorithm
    const dataBytes = typeof data === 'string' ? stringToBytes(data) : data;

    // In a real implementation, we would perform actual RSA verification
    // For now, we'll return a placeholder
    return signature === hash.sha256(dataBytes + publicKey.replace('public', 'private'));
  }
};

module.exports = {
  hash,
  symmetric,
  asymmetric,
  signature,
  utils: {
    stringToBytes,
    bytesToString,
    bytesToHex,
    hexToBytes
  }
};