# CRYPTOGRAPHY - Hashing

## Contents

## Hashing introduction

At a glance:
## Hashing types

Discussion
### Merkle-Damgaard

The Merkle-Damgaard construction is a method of building collision-resistant cryptographic hash functions from
collision-resistant one-way compression functions. This construction was used in the design of many popular hash algorithms
such as MD5, SHA-1 and SHA-2. It was described in Ralph Merkle's Ph.D. thesis in 1979. Ralph Merkle and Ivan Damgård
independently proved that the structure is sound:
that is, if an appropriate padding scheme is used and the compression function is collision-resistant,
then the hash function will also be collision-resistant.
### Other

At a glance:
## Algorithms

Discussion
## Standards

SHA-1, SHA-2, SHA-3 etc.
Refer also to crypto standards.
## Multihash

Multihash is a protocol for differentiating outputs from various well-established hash functions,
addressing size and encoding considerations.
It is useful to write applications that future-proof their use of hashes, and allow multiple hash functions to coexist.