Cryptography is often synonymous with security encryption.

Cryptography is also referred as encryption, where encryption is the process of converting readable (text) information into unintelligible format for transmitting in a secure way.

For a complete seminar on Cryptography, you may consider the following points:
Benaloh crypto system
Blum Blum Shub generator
Diffie-Hellman key exchange
Goldwasser-Micali crypto system
Okamoto-Uchiyama crypto system
Paillier crypto system
Rabin crypto system
RSA crypto system

Also refer to the following
SHA -- SHA-0,SHA-1,SHA-2,SHA-3

Suggested Reading on the related topic:

Cryonics cryptography
cryptography and Steganography
Elliptic curve cryptography (ECC)
Quantum Cryptography

External References
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