Arguments

 

context

   type:      longword integer (signed)
   access:    write only
   mechanism: by reference
   Context area initialized when ENCRYPT$INIT completes execution.
   The context argument is the address of a longword of unspecified
   interpretation that is used to convey context between encryption
   operations.
 

input

   type:      char_string
   access:    read only
   mechanism: by descriptor
   Ciphertext record that ENCRYPT$DECRYPT is to decrypt. The input
   argument is the address of a descriptor pointing to a byte-
   aligned buffer containing the input record to the decryption
   operation.
 

output

   type:      char_string
   access:    write only
   mechanism: by descriptor
   Plaintext record that results when ENCRYPT$DECRYPT completes
   execution. The output argument is the address of a descriptor
   pointing to a byte-aligned padding buffer that will contain the
   output record from the decryption operation.

   If the descriptor is dynamic and insufficient space is allocated
   to contain the output record, storage will be allocated from
   dynamic memory. If insufficient space exists to contain the
   output of the operation, then an error status is returned.

   The ENCRYPT$DECRYPT routine adjusts the length of the output
   descriptor, if possible, to reflect the actual length of the
   output string. If the descriptor type is not DSC$K_DTYPE_VS
   (varying string), DSC$K_DTYPE_V (varying), or DSC$K_DTYPE_D
   (dynamic), the routine takes the actual output count from the
   output-length argument.

   The output buffer must be able to accommodate a padded block to
   an increment of the block length. For AES this is 16 bytes and
   for DES, eight bytes.
 

output-length

   type:      word integer
   access:    write only
   mechanism: by reference
   Optional argument.

   Number of bytes that ENCRYPT$DECRYPT wrote to the output buffer.
   The output-length argument is the address of a word containing
   the number of bytes written to the output buffer, including any
   bytes of pad characters generated by the selected algorithm to
   meet length requirements of the input buffer, if any. Output
   length does not count padding in the case of a fixed-length
   string.

   Some encryption algorithms have specific requirements for the
   length of the input and output strings. In particular, DESECB
   and DESCBC pad input data with from 1 to 7 bytes to form complete
   64-bit blocks for operation. The values of the pad characters are
   indeterminate.

   When you decrypt fewer than 8 bytes, present the full 8 bytes
   resulting from the ENCRYPT$ENCRYPT to ENCRYPT$DECRYPT. Retain the
   byte count of the input data in order to strip trailing pad bytes
   after a subsequent decryption operation. Note that the AES block
   mode algorithms (AESCBCxxx and AESECBxxx), pad the data to even
   16 byte block boundaries. For AES, one byte encrypts and decrypts
   to 16 bytes, 72 bytes to 80, and so forth. The AES padding
   character is a HEX number of bytes indicating the number of bytes
   padded, for example, the one byte encrypted pad would decrypt to
   15 characters of 0F following the one decrypted byte of data. For
   the 72 bytes of data, eight bytes of padding characters (08 08
   ... 08), would follow the 72 bytes of decrypted data. DESECB and
   DESCBC modes always pad with characters of zeros. The character
   stream modes (AESCFBxxx, AESOFBxxx, DESCFB), do not pad the data,
   so the output-length will match the actual number of data bytes.
 

p1

   type:      quadword[1](DES), quadword[2](AES)
   access:    read only
   mechanism: by reference
   Optional argument. The p1 argument is the address of a quadword
   initialization vector used to seed the two modes of the DES
   algorithm for which it is applicable (DESECB and DESCFB). (That
   is, the DES IV initialization vector is a quadword reference, to
   an eight byte value.)

   For AES, the optional P1 argument for the AES IV initialization
   vector is a reference to a 16 byte (two quadwords) value.

   If this argument is omitted, the initialization vector used is
   the residue of the previous use of the specified context block.
   ENCRYPT$INIT initializes the context block with an initialization
   vector of zero.