krb5_k_decrypt -  Decrypt data using a key (operates on opaque key). 
=====================================================================

..

.. c:function:: krb5_error_code krb5_k_decrypt(krb5_context context, krb5_key key, krb5_keyusage usage, const krb5_data * cipher_state, const krb5_enc_data * input, krb5_data * output)

..


:param:

	          **[in]** **context** - Library context

	          **[in]** **key** - Encryption key

	          **[in]** **usage** - Key usage (see :data:`KRB5_KEYUSAGE` types)

	          **[inout]** **cipher_state** - Cipher state; specify NULL if not needed

	          **[in]** **input** - Encrypted data

	          **[out]** **output** - Decrypted data


..


:retval:
         -   0   Success; otherwise - Kerberos error codes


..







This function decrypts the data block *input* and stores the output into *output* . The actual decryption key will be derived from *key* and *usage* if key derivation is specified for the encryption type. If non-null, *cipher_state* specifies the beginning state for the decryption operation, and is updated with the state to be passed as input to the next operation.










..






.. note::

	 The caller must initialize *output* and allocate at least enough space for the result. The usual practice is to allocate an output buffer as long as the ciphertext, and let :c:func:`krb5_c_decrypt()` trim *output->length* . For some enctypes, the resulting *output->length* may include padding bytes.