"कळ जोडी" म्हणजे काय ?

The correct answer is Option B (A private key and its mathematically related public key).

Key Points:
• Asymmetric Cryptography Architecture: Digital signatures operate using asymmetric cryptosystems relying on paired cryptographic keys.
• Section 2(1)(x) of the Information Technology Act, 2000: Explicitly defines 'Key Pair' in an asymmetric cryptosystem.
• Statutory Definition: Under Section 2(1)(x), *'key pair', in an asymmetric cryptosystem, means a private key and its mathematically related public key, which are so related that the public key can verify a digital signature created by the private key*.
• Operational Mechanism: The Private Key is kept secure by the creator to sign documents, while the mathematically coupled Public Key is distributed to allow anyone to verify the document's authenticity and integrity.
• Key Result: Option 2 represents the exact legal definition of 'Key Pair'.
• Key Takeaway: Under Section 2(1)(x) of the IT Act, a 'Key Pair' is a private key and its mathematically related public key used in asymmetric cryptography.