---
name: "life_cycle-digest"
section: "7ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/life_cycle-digest"
---

# life\_cycle-digest(7ssl)

The digest algorithm life-cycle

## NAME

life\_cycle-digest - The digest algorithm life-cycle

## DESCRIPTION

All message digests (MDs) go through a number of stages in their life-cycle:

- start

  This state represents the MD before it has been allocated.  It is the starting state for any life-cycle transitions.

- newed

  This state represents the MD after it has been allocated.

- initialised

  This state represents the MD when it is set up and capable of processing input.

- updated

  This state represents the MD when it is set up and capable of processing additional input or generating output.

- finaled

  This state represents the MD when it has generated output. For an XOF digest, this state represents the MD when it has generated a single-shot output.

- squeezed

  For an XOF digest, this state represents the MD when it has generated output. It can be called multiple times to generate more output. The output length is variable for each call.

- freed

  This state is entered when the MD is freed.  It is the terminal state for all life-cycle transitions.

### State Transition Diagram

The usual life-cycle of a MD is illustrated:\
                                   \+--------------------+\
                                   \|       start        \|\
                                   \+--------------------+\
                                     \|                            EVP\_MD\_CTX\_reset\
                                     \| EVP\_MD\_CTX\_new           +-------------------------------------------------+\
                                     v                          v                                                 \|\
               EVP\_MD\_CTX\_reset    + - - - - - - - - - - - - - - - - - - - - - - +    EVP\_MD\_CTX\_reset            \|\
             \+-------------------\> '                   newed                     ' \<--------------------+         \|\
             \|                     + - - - - - - - - - - - - - - - - - - - - - - +                      \|         \|\
             \|                       \|                                                                  \|         \|\
             \|                       \| EVP\_DigestInit                                                   \|         \|\
             \|                       v                                                                  \|         \|\
             \|   EVP\_DigestInit    + - - - - - - - - - - - - - - - - - - - - - - +                      \|         \|\
        \+----+-------------------\> '                initialised                  ' \<+  EVP\_DigestInit   \|         \|\
        \|    \|                     + - - - - - - - - - - - - - - - - - - - - - - +  \|                   \|         \|\
        \|    \|                       \|                     ^                        \|                   \|         \|\
        \|    \|                       \| EVP\_DigestUpdate    \| EVP\_DigestInit         \|                   \|         \|\
        \|    \|                       v                     \|                        \|                   \|         \|\
        \|    \|                     +---------------------------------------------+  \|                   \|         \|\
        \|    +-------------------- \|                                             \|  \|                   \|         \|\
        \|                          \|                                             \|  \|                   \|         \|\
        \|      EVP\_DigestUpdate    \|                                             \|  \|                   \|         \|\
        \|    +-------------------- \|                                             \|  \|                   \|         \|\
        \|    \|                     \|                   updated                   \|  \|                   \|         \|\
        \|    +-------------------\> \|                                             \|  \|                   \|         \|\
        \|                          \|                                             \|  \|                   \|         \|\
        \|                          \|                                             \|  \|                   \|         \|\
   \+----+------------------------- \|                                             \| -+-------------------+----+    \|\
   \|    \|                          +---------------------------------------------+  \|                   \|    \|    \|\
   \|    \|                            \|                                              \|                   \|    \|    \|\
   \|    \|                            \| EVP\_DigestSqueeze        +-------------------+                   \|    \|    \|\
   \|    \|                            v                          \|                                       \|    \|    \|\
   \|    \|      EVP\_DigestSqueeze   +---------------------------------------------+                      \|    \|    \|\
   \|    \|    +-------------------- \|                                             \|                      \|    \|    \|\
   \|    \|    \|                     \|                  squeezed                   \|                      \|    \|    \|\
   \|    \|    +-------------------\> \|                                             \| ---------------------+    \|    \|\
   \|    \|                          +---------------------------------------------+                           \|    \|\
   \|    \|                                                       \|                                            \|    \|\
   \|    \|                                                       +---------------------------------------+    \|    \|\
   \|    \|                                                                                               \|    \|    \|\
   \|    \|                          +---------------------------------------------+  EVP\_DigestFinalXOF  \|    \|    \|\
   \|    +------------------------- \|             finaled                         \| \<--------------------+----+    \|\
   \|                               +---------------------------------------------+                      \|         \|\
   \|   EVP\_DigestFinal               ^                     \|    \|                                       \|         \|\
   \+---------------------------------+                     \|    \| EVP\_MD\_CTX\_free                       \|         \|\
                                                           \|    v                                       \|         \|\
                                                           \|  +------------------+  EVP\_MD\_CTX\_free     \|         \|\
                                                           \|  \|      freed       \| \<--------------------+         \|\
                                                           \|  +------------------+                                \|\
                                                           \|                                                      \|\
                                                           \+------------------------------------------------------+

### Formal State Transitions

This section defines all of the legal state transitions. This is the canonical list.\
  Function Call                --------------------- Current State -----------------------------------\
                               start   newed    initialised   updated     finaled     squeezed   freed\
  EVP\_MD\_CTX\_new               newed\
  EVP\_DigestInit                    initialised initialised initialised initialised  initialised\
  EVP\_DigestUpdate                                updated     updated\
  EVP\_DigestFinal                                             finaled\
  EVP\_DigestFinalXOF                                          finaled\
  EVP\_DigestSqueeze                                           squeezed                squeezed\
  EVP\_MD\_CTX\_free              freed   freed       freed       freed       freed\
  EVP\_MD\_CTX\_reset                     newed       newed       newed       newed\
  EVP\_MD\_CTX\_get\_params                newed    initialised   updated\
  EVP\_MD\_CTX\_set\_params                newed    initialised   updated\
  EVP\_MD\_CTX\_gettable\_params           newed    initialised   updated\
  EVP\_MD\_CTX\_settable\_params           newed    initialised   updated\
  EVP\_MD\_CTX\_copy\_ex                   newed    initialised   updated                 squeezed

## NOTES

At some point the EVP layer will begin enforcing the transitions described herein.

## SEE ALSO

**provider-digest**(7), **EVP\_DigestInit**(3)

## COPYRIGHT

Copyright 2021-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance with the License.  You can obtain a copy in the file LICENSE in the source distribution or at \<https://www.openssl.org/source/license.html\>.