Message Digests

Programmer Reference : Cryptography : Message Digests

Message Digests

Module Implementation: OpenSSLCryptoInterfaceMD

This module implements message digests, sometimes called hashes, to provide data-integrity to data.

Note: Internal classes are italicized and will only contain a short description.

See the class-side examples in the OpenSSLMessageDigestExamples class for additional usage detail.

Digests

OSSslDigest

This object wraps a specific message digest algorithm. It contains an API for one-shot digests.

Class methods: API

allDigestsCollect: aBlock

Answer a Collection that is created by iteratively evaluating the one argument block, aBlock using each element of the receiver as an argument.

Arguments:

aBlock - <Block> 1-arg

Answers:

< SequenceableCollection>

allDigestsDo: aBlock

Evaluate a one-arg block on all supported digests. The external library may only support a subset based on how it was compiled, so a check is performed to see if it is included in the list.

Arguments:

<Block> 1-arg block with digest <OSSslDigest> as param

allDigestsNames

Answer a sorted listing of all supported digest names. This will take the external library into account since what digests are available depend on compiler flags used.

Answers:

<SequenceableCollection> digest names

allDigestsSelect: aBlock

Answer a SequenceableCollection that is created by iteratively evaluating the one argument block, aBlock using an element of receiver and adding the element to the eturned <SequenceableCollection> only if aBlock evaluates to the Boolean true.

Arguments:

aBlock - <Block> 1-arg

Answers:

< SequenceableCollection>

Class methods: Creation

named: aDigestName

Answer the <OSSslDigest> associated with aDigestName. This performs a fast lookup, and if that fails then it queries OpenSSL. If OpenSSL is unable to locate it, it could be because the library was compiled in such a way that it left it out.

Arguments:

aDigestName- <String>

Answers:

<OSSslDigest> - digest object

<OpenSSLError> - error object

Class methods: Factory

The methods in this category all have the same name as the Digest algorithm and answer an OSSslDigest instance.
Note: OpenSSL may have been compiled without support for some of the factory algorithms, in this case error objects will be answered.
Example:

sha_256

Answer the Digest Object for the SHA_256 algorithm.

Answers:

Instance methods: Accessing

blockSize

Answer the block size of the message digest

Answers:

longName

Answer the longName <String> of this message digest

Answers:

<String> - long name

name

Answer the shortName <String> of this message digest

Answers:

<String> - short name

shortName

Answer the shortName <String> of this message digest

Answers:

<String> - short name

size

Answer the size of the message digest (i.e. size of hash).

Answers:

<Integer> - size

type

Answers the type of the passed message digest or context.

Answers:

<Integer> - type

Instance methods: API - Digest

digest: aByteObject

Compute and Answer the digest value <ByteArray> for aByteObject.

Arguments:

aByteObject - a collection of bytes THAT MUST KNOW ITS SIZE (i.e. String | ByteArray | OSStringZ)

Answers:

<ByteArray> - computed message digest

printableDigest: aByteObject

Compute and Answer the hex-formatted digest value <String> for aByteObject.

Arguments:

aByteObject - a collection of bytes THAT MUST KNOW ITS SIZE (i.e. String | ByteArray | OSStringZ)

Answers:

<String> computed message hex digest

Instance methods: Testing

isCtx

Test if this is a context object

Answers:

<Boolean> - false

OSSslDigestCtx

This is the context object that represents a particular session of a message digest computation. It contains an API for one-shot and streaming message digesting.

Class methods: Creation

createNew

Create a new EVP_MD_CTX instance and initialize it.

Answers:

< OSSslDigestCtx> - new instance

<OpenSSLError compatible error> - error object

createNewFromDigest: aDigest

Create a new EVP_MD_CTX instance

Arguments:

aDigest - < OSSslDigest > message digest algorithm object

Answers:

< OSSslDigestCtx > - new instance

<OpenSSLError compatible error> - error object

Instance methods: Duplication

duplicate

Answers a managed duplicate of this Digest Context.

Answers:

< OSSslDigestCtx> - new duplicate instance

Instance methods: High-Level API - Digest

digest: aByteObject

Compute and Answer the digest value <ByteArray> for aByteObject.

Arguments:

aByteObject - a collection of bytes THAT MUST KNOW ITS SIZE (i.e. String | ByteArray | OSStringZ)

Answers:

<ByteArray> - computed message digest

digest: aByteObject length: length

Compute and Answer the digest value <ByteArray> for length bytes from the data aByteObject.

Arguments:

aByteObject - byte object (i.e. ByteArray | EsString | OSObject)

length - length of the byte object

Answers:

<ByteArray> - computed message digest

printableDigest: aByteObject

Compute and Answer the hex-formatted digest value <String> for aByteObject.

Arguments:

aByteObject - a collection of bytes THAT MUST KNOW ITS SIZE (i.e. String | ByteArray | OSStringZ)

Answers:

<String> computed message hex digest

printableDigest: aByteObject length: length

Compute and Answer the printable digest value <String> for length bytes from the data aByteObject.

Arguments:

aByteObject - byte object (i.e. ByteArray | EsString | OSObject)

length - length of the byte object

Answers:

<String> printable digest in hex

Instance methods: Low-Level API - Digests

finish

Answers the digest value from the context After calling this...no more update: operations are allowed. You must call reset to reinit the state.

Answers:

<ByteArray> - computed digest

finishInto: aByteObject

Retrieves the digest value from the context and places it in aByteObject. Answers the number of data bytes actually written (length of the digest) This will be EVP_MAX_MD_SIZE at most.

aByteObject is allowed to be an OSObject, but be careful when using these. It is expected that aByteObject has AT LEAST the length of the digest as it's allocated size. To be safe, always allocate EVP_MAX_MD_SIZE worth of bytes. After calling this...no more update: operations are allowed. You must call reset reinit the state.

Arguments:

aByteObject - byte object (i.e. ByteArray | EsString | OSObject)

Answers:

<Integer> - number of bytes written

reset

Resets the Digest context to it's default state with the associated digest.

Answers:

< OSSslDigestsCtx> self

update: aByteObject

Update the digest from aByteObject.

Arguments:

aByteObject - a collection of bytes THAT MUST KNOW ITS SIZE (i.e. String | ByteArray | OSStringZ)

Answers:

<Integer> - 1 for success

update: aByteObject length: length

Update the digest from length number of bytes from aByteObject.

Arguments:

aByteObject - byte object (i.e. ByteArray | EsString | OSObject)

length - <Integer> length of aByteObject

Answers:

<Integer> - 1 for success

Instance methods: Testing

isCtx

Test if this is a context object

Answers:

<Boolean> - true

BIO

OSSslDigestBIO

OpenSSL BIO object that updates an internal hash value as data is read or written from it. Data that passes through it is unaltered. It can be chained together with other BIOs to create a high-performance crypto pipeline.

Class methods: Creation

createNewFromContext: anOSSslMessageDigestCtx

Create a new instance of the cipher BIO from the digest context.

Arguments:

anOSSslMessageDigestCtx - <OSSslDigestCtx>

Answers:

< OSSslDigestBIO> new instance

<OpenSSLError compatible error> - error object

createNewFromDigest: anOSSslMessageDigest

Create a new instance of the cipher BIO from the digest.

Arguments:

anOSSslMessageDigest - <OSSslDigest>

Answers:

< OSSslDigestBIO> new instance

<OpenSSLError compatible error> - error object

Instance methods: API

osDigestCtx

Answer the message digest context object associated with this BIO.

Answers:

< OSSslDigestCtx>

Instance methods: Conversion

asString

Answer the complete data within this bio as an ASCII String

which represents the printable HEX of the digest

Answers:

Extensions

ByteArray

asOpenSSLHexString

Answer the contents of aByteArray as an ASCII String which represents the printable HEX value.

Answers:

OSSslBIO

newDigestBIO: aMessageDigestOrCtx

Convenience Method for creating message digest BIOs

Answers:

< OSSslDigestBIO>

OSSslBIOMethod

messageDigest

Answer the Message Digest BIO-Method.

Answers:

< OSSslBIOMethod> digest bio method

Last modified date: 12/02/2016