cryptohash/com.appmattus.crypto/Digest

Digest

Digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value.

A Digest object starts out initialized. The data is processed through it using the update methods. At any point reset can be called to reset the digest. Once all the data to be updated has been updated, one of the digest methods should be called to complete the hash computation.

The digest method can be called once for a given number of updates. After digest has been called, the Digest object is reset to its initialized state.

val digest = ...

digest.update(toChapter1)
val tc1 = digest.copy()
val toChapter1Digest = tc1.digest()
digest.update(toChapter2)
... etc.

Properties

blockLength

abstract val blockLength: Int

Return the "block length" for the hash function. This value is naturally defined for iterated hash functions (Merkle-Damgard). It is used in HMAC (that's what the HMAC specification names the "B" parameter).

digestLength

abstract val digestLength: Int

Get the natural hash function output length (in bytes).

Functions

copy

abstract fun copy(): D

Clone the current state. The returned object evolves independently of this object.

digest

abstract fun digest(): ByteArray

abstract fun digest(output: ByteArray, offset: Int, length: Int): Int

Completes the hash computation by performing final operations such as padding. The digest is reset after this call is made.

abstract fun digest(input: ByteArray): ByteArray

Performs a final update on the digest using the specified array of bytes, then completes the digest computation. That is, this method first calls update, passing the input array to the update method, then calls digest.

platform

open fun platform(): PlatformDigest<*>

A platform specific implementation of this Digest. For example, uses NSData instead of ByteArray on iOS.

reset

abstract fun reset()

Resets the digest for further use.

toString

abstract override fun toString(): String

Get the display name for this function (e.g. "SHA-1" for SHA-1).

update

abstract fun update(input: Byte)

Updates the digest using the specified byte.

abstract fun update(input: ByteArray)

Updates the digest using the specified array of bytes.

abstract fun update(input: ByteArray, offset: Int, length: Int)

Updates the digest using the specified array of bytes, starting at the specified offset.