_section: Hashing Algorithms @<hashing-algorithms>

Explain what hash functions are?


_subsection: Cryptographic Hash Functions @<cryptographic-hash-functions>

The [Cryptographic Hash Functions](link-wiki-cryptographichash)
are a specific family of hash functions.

_property: ethers.utils.id(text) => string<[[DataHexString]]<32>>  @<utils-id> @SRC<hash>
The Ethereum Identity function computes the [KECCAK256](link-wiki-sha3) hash of the //text// bytes.

_property:  ethers.utils.keccak256(aBytesLike) => string<[[DataHexString]]<32>>  @<utils-keccak256> @SRC<keccak256>
Returns the [KECCAK256](link-wiki-sha3) digest //aBytesLike//.

_property: ethers.utils.ripemd160(aBytesLike) => string<[[DataHexString]]<20>>  @<utils-ripemd160> @SRC<sha2>
Returns the [RIPEMD-160](link-wiki-ripemd) digest of //aBytesLike//.

_property: ethers.utils.sha256(aBytesLike) => string<[[DataHexString]]<32>>  @<utils-sha256> @SRC<sha2:function.sha256>
Returns the [SHA2-256](link-wiki-sha2) digest of //aBytesLike//.

_property: ethers.utils.sha512(aBytesLike) => string<[[DataHexString]]<64>>  @<utils-sha512> @SRC<sha2:function.sha512>
Returns the [SHA2-512](link-wiki-sha2) digest of //aBytesLike//.

_code: KECCAK256 @lang<javascript>

utils.keccak256([ 0x12, 0x34 ])
//!

utils.keccak256("0x")
//!

utils.keccak256("0x1234")
//!

// The value MUST be data, such as:
//  - an Array of numbers
//  - a data hex string (e.g. "0x1234")
//  - a Uint8Array

// Do NOT use UTF-8 strings that are not a DataHexstring
utils.keccak256("hello world")
//! error

// If needed, convert strings to bytes first:
utils.keccak256(utils.toUtf8Bytes("hello world"))
//!

// Or equivalently use the identity function:
utils.id("hello world")
//!

// Keep in mind that the string "0x1234" represents TWO
// bytes (i.e. [ 0x12, 0x34 ]. If you wish to compute the
// hash of the 6 characters "0x1234", convert it to UTF-8
// bytes first using utils.toUtf8Bytes.

// Consider the following examples:

// Hash of TWO (2) bytes:
utils.keccak256("0x1234")
//!

// Hash of TWO (2) bytes: (same result)
utils.keccak256([ 0x12, 0x34 ])
//!

const bytes = utils.toUtf8Bytes("0x1234");
// <hide>
bytes
// </hide>
//!

// Hash of SIX (6) characters (different than above)
utils.keccak256(bytes)
//!

// Hash of SIX (6) characters (same result)
utils.id("0x1234")
//!

_code: RIPEMD160  @lang<javascript>

utils.ripemd160("0x")
//!

utils.ripemd160("0x1234")
//!

_code: SHA-2  @lang<javascript>

utils.sha256("0x")
//!

utils.sha256("0x1234")
//!

utils.sha512("0x")
//!

utils.sha512("0x1234")
//!


_subsection: HMAC @<utils--hmac>

_property: ethers.utils.computeHmac(algorithm, key, data) => string<[[DataHexString]]>  @<utils-computeHmac> @SRC<sha2>
Returns the [HMAC](link-wiki-hmac) of //data// with //key//
using the [Algorithm](utils--hmac-supported-algorithm) //algorithm//.

_heading: **HMAC Supported Algorithms** @<utils--hmac-supported-algorithm> @SRC<sha2:enum.SupportedAlgorithm>

_property: ethers.utils.SupportedAlgorithm.sha256 => string
Use the [SHA2-256](link-wiki-sha2) hash algorithm.

_property: ethers.utils.SupportedAlgorithm.sha512 => string
Use the [SHA2-512](link-wiki-sha2) hash algorithm.

_code: HMAC  @lang<javascript>

const key = "0x0102";
const data = "0x1234";
utils.computeHmac("sha256", key, data)
//!


_subsection: Hashing Helpers @<utils--hashing-helpers>

_property: ethers.utils.hashMessage(message) => string<[[DataHexString]]<32>>  @<utils-hashMessage> @SRC<hash>
Computes the [[link-eip-191]] personal message digest of //message//. Personal messages are
converted to UTF-8 bytes and prefixed with ``\\x19Ethereum Signed Message:``
and the length of //message//.

_property: ethers.utils.namehash(name) => string<[[DataHexString]]<32>>  @<utils-namehash> @SRC<hash>
Returns the [ENS Namehash](link-namehash) of //name//.

_code: Hashing Messages  @lang<javascript>

// @TODO: include examples of hashMessage; it can be complex. :)


_code: Namehash  @lang<javascript>

utils.namehash("")
//!

utils.namehash("eth")
//!

utils.namehash("ricmoo.firefly.eth")
//!

utils.namehash("ricmoo.xyz")
//!


_subsection: Solidity Hashing Algorithms @<utils--solidity-hashing>

When using the Solidity ``abi.packEncoded(...)`` function, a non-standard
//tightly packed// version of encoding is used. These functions implement
the tightly packing algorithm.

_property: ethers.utils.solidityPack(types, values) => string<[[DataHexString]]>  @<utils-solidityPack> @SRC<solidity:pack>
Returns the non-standard encoded //values// packed according to
their respecive type in //types//.

_property: ethers.utils.solidityKeccak256(types, values) => string<[[DataHexString]]<32>>  @<utils-solidityKeccak256> @SRC<solidity:keccak256>
Returns the [KECCAK256](link-wiki-sha3) of the non-standard encoded //values// packed
according to their respective type in //types//.

_property: ethers.utils.soliditySha256(types, values) => string<[[DataHexString]]<32>>  @<utils-soliditySha256> @SRC<solidity:sha256>
Returns the [SHA2-256](link-wiki-sha2) of the non-standard encoded //values// packed
according to their respective type in //types//.

_code: Solidity Hashing  @lang<javascript>

utils.solidityPack([ "int16", "uint48" ], [ -1, 12 ])
//!

utils.solidityPack([ "string", "uint8" ], [ "Hello", 3 ])
//!

utils.solidityKeccak256([ "int16", "uint48" ], [ -1, 12 ])
//!

utils.soliditySha256([ "int16", "uint48" ], [ -1, 12 ])
//!