chickadee » message-digest-primitive » make-message-digest-primitive

Create a message-digest-primitive object, defining a message digest algorithm.

The processing of a message digest is split into three phases: initialization, update, & finalization. These are represented by procedures: INIT, UPDATE | RAW-UPDATE, & FINAL, respectively.

CONTEXT-INFO

(or (CONTEXT-INFO -> context-object) positive-fixnum)

• (CONTEXT-INFO -> CONTEXT) ; returns the context-object, which should be unique. At least the object cannot be shared with another activated primitive.
• positive-fixnum : a memory-block of length CONTEXT-INFO bytes is allocated; the memory is automatically free'ed. The context-object here is a {pointer}} to a block of uninitialized memory.

DIGEST-SIZE

positive-fixnum

• The count of bytes in the result.

INIT

(CONTEXT -> void))

• sets up the CONTEXT.

UPDATE

#f or (CONTEXT SOURCE COUNT -> void))

• Must accumulate the SOURCE, beginning at 0, for COUNT bytes. Will be called zero or more times. SOURCE is usually a (or blob string) object.
• COUNT is the actual number of bytes in the SOURCE. Only the first COUNT bytes in the SOURCE are valid. COUNT is a positive-fixnum.
• when #f & RAW-UPDATE then an UPDATE is built, otherwise an error.

FINAL

(CONTEXT DESTINATION -> void)).

• Must build the message-digest result in the supplied result DESTINATION, which will have a byte-count of at least DIGEST-SIZE. DESTINATION is usually a (or blob string) object.

RAW-UPDATE

(CONTEXT POINTER COUNT -> void)).

• When UPDATE is #f RAW-UPDATE must be defined.
• Must accumulate the memory at POINTER, beginning at 0, for COUNT bytes. Will be called zero or more times.
• COUNT is the actual number of bytes in the SOURCE. Only the first COUNT bytes in the memory at POINTER are valid. COUNT is a positive-fixnum.

BLOCK-LENGTH

positive-fixnum ; default 4

• The primitive's accumulator length in bytes.

NAME

(or symbol string) ; default uninterned-symbol.

• Identifies the message digest algorithm. The suggested form is <algorithm>-primitive, 'md5-primitive for example.