Hash

The Hash environment provides basic 1-way hash functions.

Algorithms

We support MD5, SHA1, SHA256, SHA384, and SHA512.

Function	Security (in bits) against collision attacks	Dangerous?
MD5	<= 18 (collisions found)	DANGEROUS
SHA1	< 63 (collisions found)	DANGEROUS
SHA256	128
SHA384	192
SHA512	256

API

There are two basic functions provided: hash and verify. For any message m, we have that verify(m, hash(m)) == true, and for any two messages m1and m2 where m1 != m2, verify(m1, hash(m2)) == false.

Both hash and verify are implemented in terms of String (provided you specify a Charset) and Chunk[Byte].

Usage

To use the hashing service, simply call the method hash with a type parameter specifying the algorithm you wish to use.

import java.nio.charset.StandardCharsets.US_ASCII
import zio.crypto.hash.{Hash, HashAlgorithm}
Hash.hash[HashAlgorithm.SHA256]("hello", US_ASCII)

However, we need to take special case when using algorithms marked DANGEROUS in the table above.

Secure

If you're using MD5 or SHA1, you need to explicitly not recognize that the function you're calling is unsecure. To do so, use the function zio.crypto.unsecure as follows:

import zio.crypto.unsecure
unsecure(implicit s => Hash.hash[HashAlgorithm.MD5]("hello", US_ASCII))

String Example

import java.nio.charset.StandardCharsets.US_ASCII
import zio.crypto.hash.{Hash, HashAlgorithm}

object Example extends zio.App {
  override def run(args: List[String]) = (for {
    digest <- Hash.hash[HashAlgorithm.SHA256](
      m = "hello",
      charset = US_ASCII
    )
    verified <- Hash.verify[HashAlgorithm.SHA256](
      m = "hello",
      digest = digest,
      charset = US_ASCII
    )
  } yield verified).exitCode
    .provideCustomLayer(Hash.live)
}

Byte Example

import zio.crypto.hash.{Hash, HashAlgorithm}
import zio.crypto.random.SecureRandom

object Example extends zio.App {
  override def run(args: List[String]) = (for {
    m <- SecureRandom.nextBytes(10)
    digest <- Hash.hash[HashAlgorithm.SHA256](
      m = m
    )
    verified <- Hash.verify[HashAlgorithm.SHA256](
      m = m,
      digest = digest
    )
  } yield verified).exitCode
    .provideCustomLayer(Hash.live ++ SecureRandom.live.orDie)
}