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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
System Security Guide
The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
QNX Cryptography Library
The QNX cryptography library (qcrypto library) is a generic cryptographic shim layer that provides a consistent API to the various cryptographic primitives offered by third-party libraries.
QNX cryptography library reference
qcrypto.h
QNX cryptography library API.
qcrypto_padding_pkcs7_unpad()
Remove PKCS7 padding

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
  - Security Matrix
    The following table describes security problems and cyberattacks and the QNX OS security features that can mitigate them.
  - Security Features Overview
  - Security Features for Developers
  - Security Features for System Integrators
  - Security Policies
  - Fortified System Functions
  - QNX Cryptography Library
    The QNX cryptography library (qcrypto library) is a generic cryptographic shim layer that provides a consistent API to the various cryptographic primitives offered by third-party libraries.
    - Configuration file
      The qcrypto library configuration file allows the system integrator to define which cryptography providers are supported and available to the system.
    - Adding cryptographic primitives
      The libqcrypto_pluginS.a plugin library and qcrypto/qcrypto_plugin.h header file allow you to create a custom plugin to use with the qcrypto library.
    - Supported primitives
      The qcrypto library provides a consistent API to cryptographic primitives offered by third-party libraries.
    - QNX cryptography library reference
      - qcrypto.h
        QNX cryptography library API.
        Cipher actions
        Cipher padding modes
        RSA signing padding modes
        Signature operation types
        qcrypto_cipher_aad()
        Provide cipher additional authenticated data (AAD)
        qcrypto_cipher_action_t
        A structure to contain cipher actions
        qcrypto_cipher_args_t
        Cipher algorithm arguments
        qcrypto_cipher_blocksize()
        Retrieve the cipher blocksize
        qcrypto_cipher_decrypt()
        Decrypt a cipher
        qcrypto_cipher_encrypt()
        Encrypt a cipher
        qcrypto_cipher_final()
        Finalize a cipher
        qcrypto_cipher_get_tag()
        Retrieve a cipher tag
        qcrypto_cipher_init()
        Initialize a cipher
        qcrypto_cipher_ivsize()
        Retrieve the cipher initialization vector (IV) size
        qcrypto_cipher_keysize()
        Retrieve the cipher key size
        qcrypto_cipher_padding_t
        A structure to contain cipher padding modes
        qcrypto_cipher_request()
        Request a cipher
        qcrypto_cipher_supported()
        Query whether a cipher is supported
        qcrypto_cipher_tagsize()
        Retrieve the cipher tag size
        qcrypto_ctx_t
        An opaque handle to a cryptographic algorithm
        qcrypto_digest()
        Initialize, update, and finalize a digest
        qcrypto_digest_copy()
        Copy a digest state
        qcrypto_digest_final()
        Finalize a digest
        qcrypto_digest_init()
        Initialize a digest
        qcrypto_digest_request()
        Request a digest
        qcrypto_digest_supported()
        Query whether a digest is supported
        qcrypto_digest_update()
        Update the digest
        qcrypto_digestsize()
        Query the digest size
        qcrypto_kdf_args_t
        KDF arguments
        qcrypto_kdf_generate()
        Generate a symmetric key via KDF
        qcrypto_kdf_request()
        Request a KDF algorithm
        qcrypto_kdf_supported()
        Query whether a KDF is supported
        qcrypto_key_t
        An opaque handle to a cryptographic key
        qcrypto_init()
        Initialize a library
        qcrypto_mac_final()
        Finalize a MAC algorithm
        qcrypto_mac_init()
        Initialize a MAC algorithm
        qcrypto_mac_keysize()
        Retrieve the MAC key size
        qcrypto_mac_request()
        Request a MAC algorithm
        qcrypto_mac_supported()
        Query whether a MAC is supported
        qcrypto_mac_tagsize()
        MAC tag size
        qcrypto_mac_update()
        Update a MAC algorithm
        qcrypto_memclear()
        Set the cryptography safe memory to zero
        qcrypto_memcmp()
        Fixed-time memory comparison
        qcrypto_padding_iso7816_pad()
        Apply ISO 7816 padding
        qcrypto_padding_iso7816_size()
        Calculate ISO 7816 padding length
        qcrypto_padding_iso7816_unpad()
        Remove ISO 7816 padding
        qcrypto_padding_pkcs7_pad()
        Apply PKCS7 padding
        qcrypto_padding_pkcs7_size()
        Calculate PKCS7 padding length
        qcrypto_padding_pkcs7_unpad()
        Remove PKCS7 padding
        qcrypto_plugin_name()
        Retrieve the name of a plugin
        qcrypto_print_info()
        Print qcrypto library information
        qcrypto_release_ctx()
        Release an algorithm context handle
        qcrypto_rng_args_t
        RNG algorithm arguments
        qcrypto_rng_bytes()
        Retrieve RNG bytes
        qcrypto_rng_init()
        Initialize an RNG algorithm
        qcrypto_rng_request()
        Request an RNG algorithm
        qcrypto_rng_seed()
        Seed an RNG
        qcrypto_rng_supported()
        Query whether an RNG is supported
        qcrypto_rsa_pad_mode_t
        A structure to contain RSA signing padding modes
        qcrypto_set_config_path()
        Set the library configuration path
        qcrypto_signature_args_t
        Signature arguments
        qcrypto_signature_init()
        Initialize a signature
        qcrypto_signature_mode_t
        A structure to contain signature operation types
        qcrypto_signature_request()
        Request a signature
        qcrypto_signature_sign()
        Sign a signature
        qcrypto_signature_sign_nodgst()
        Sign a signature digest
        qcrypto_signature_sign_oneshot()
        Sign a signature using a single operation
        qcrypto_signature_sigsize()
        Retrieve the signature size
        qcrypto_signature_supported()
        Query whether a signature is supported
        qcrypto_signature_update()
        Update a signature digest
        qcrypto_signature_verify()
        Verify a signature
        qcrypto_signature_verify_nodgst()
        Verify a signature digest
        qcrypto_signature_verify_oneshot()
        Verify a signature in a single operation
        qcrypto_uninit()
        Un-initialize a library
      - qcrypto_dyn.h
        QNX cryptography library dynamic API.
      - qcrypto_error.h
        QNX cryptography library error handling API.
      - qcrypto_keys.h
        QNX cryptography library key handling API.
      - qcrypto_plugin.h
        QNX cryptography library plugin API.
  - The devcrypto service
    The devcrypto service is a legacy system driver interface and is mainly provided for backwards compatibility.
  - Pathtrust
    The pathtrust feature prevents processes from executing untrusted code. If a process is compromised, pathtrust mitigates the threat of the system being further compromised by an attacker using chained-together exploits.
  - PAM
    Systems that need authentication can use pluggable authentication module (PAM), a configurable standard library.
  - Using mkqnximage to Display Security Features
- Utilities & Libraries
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

qcrypto_padding_pkcs7_unpad()

QNX SDP8.0QNX OS System Security GuideAPIConfiguration

Remove PKCS7 padding

Synopsis:

#include <qcrypto/qcrypto.h>

int qcrypto_padding_pkcs7_unpad(uint8_t *data,
                                size_t *size)

Arguments:

data: The data buffer.
size: The combined size of the data buffer and the unpadded data.

Library:

libqcrypto

Description:

This function verifies the padding integrity and removes it from the input data by setting the unpadded length to size on success.

Returns:

QCRYPTO_R_EOK if successful or qcrypto_errno if an error occurred.

Page updated: March 05, 2025