Add hash bcrypt

[kishore-144]

🧩 Add bcrypt Algorithm (Custom Implementation)

Summary

This PR introduces a bcrypt algorithm reimplementation built entirely from scratch in Python — without relying on external bcrypt libraries. The goal is to provide an educational yet functional version of the real bcrypt algorithm that demonstrates its internal structure, including the EksBlowfish key setup, salted key expansion, and configurable cost factor.

Key Details

• Implements the core EksBlowfish logic (P-array, S-boxes, and Feistel network).

• Supports variable cost rounds (2^cost), simulating bcrypt’s computational scaling.

• Includes helper methods for hashing and verification (bcrypt_hash and bcrypt_check).

• Cleanly written for readability, with developer comments explaining each major step.

• No external dependencies — pure Python implementation.

Purpose

This PR aims to help developers understand how bcrypt works internally rather than using it as a black-box library. While it is not intended for production-grade security, it serves as a reference for studying password hashing and key expansion mechanisms.

Notes

-- Output format follows bcrypt-style structure for familiarity.

-- Future improvement: Optimize key schedule performance and integrate official test vectors for validation.

[algorithms-keeper]

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