Some major techniques of Cryptography are listed below :
Steganography : One of the oldest techniques of cryptography, steganography involves hiding secret information or messages with no confidential status files in order to avoid detection. Decades ago, steganography was not as sophisticated as it is now. Earlier, invisible ink, slight variations, etc., were used to hide messages. But with the advent of technology, steganography has evolved as one of the commonly used techniques in cryptography.
Hashing : Hashing converts data to be hidden into a unique string. Irrespective of the type or form of data, hashing can be used to hide it. Once hashing is performed, it cannot be decrypted by using just keys.
Simple codes : A language is used to hide the meaning of the sentences written in a different language. The message is written in such a way that it is hard to decipher. In a majority of cases, niche alphabets are used to make the message more complex to read.
Symmetric encryption : It is mainly used for encrypting and decrypting electronic data through a secret key. Substitution ciphers form the base of symmetric encryption. However, nowadays, symmetric encryption is much more than just substitution ciphers. Symmetric encryption is largely used when the message to be encrypted is quite sizable.
Asymmetric encryption : This type of encryption uses two keys, public key, and private key, to encrypt and decrypt plaintext. Anyone with the secret key can decrypt the message. Hence, asymmetric encryption uses two corresponding keys to ensure secrecy.