Standard preamble:
========================================================================
..
.... Set up some character translations and predefined strings. \*(-- will
give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
double quote, and \*(R" will give a right double quote. \*(C+ will
give a nicer C++. Capital omega is used to do unbreakable dashes and
therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
nothing in troff, for use with C<>.
.tr \(*W- . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\}
Escape single quotes in literal strings from groff's Unicode transform.
If the F register is >0, we'll generate index entries on stderr for
titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
entries marked with X<> in POD. Of course, you'll have to process the
output yourself in some meaningful fashion.
Avoid warning from groff about undefined register 'F'.
.. .nr rF 0 . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF
Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] .\} . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents . \" corrections for vroff . \" for low resolution devices (crt and lpr) \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} ========================================================================
Title "EVP_ENCODEINIT 3"
way too many mistakes in technical documents.
\fBEVP_ENCODE_CTX_new() allocates, initializes and returns a context to be used for the encode/decode functions.
\fBEVP_ENCODE_CTX_free() cleans up an encode/decode context ctx and frees up the space allocated to it.
Encoding of binary data is performed in blocks of 48 input bytes (or less for the final block). For each 48 byte input block encoded 64 bytes of base 64 data is output plus an additional newline character (i.e. 65 bytes in total). The final block (which may be less than 48 bytes) will output 4 bytes for every 3 bytes of input. If the data length is not divisible by 3 then a full 4 bytes is still output for the final 1 or 2 bytes of input. Similarly a newline character will also be output.
\fBEVP_EncodeInit() initialises ctx for the start of a new encoding operation.
\fBEVP_EncodeUpdate() encode inl bytes of data found in the buffer pointed to by \fBin. The output is stored in the buffer out and the number of bytes output is stored in *outl. It is the caller's responsibility to ensure that the buffer at out is sufficiently large to accommodate the output data. Only full blocks of data (48 bytes) will be immediately processed and output by this function. Any remainder is held in the ctx object and will be processed by a subsequent call to EVP_EncodeUpdate() or EVP_EncodeFinal(). To calculate the required size of the output buffer add together the value of inl with the amount of unprocessed data held in ctx and divide the result by 48 (ignore any remainder). This gives the number of blocks of data that will be processed. Ensure the output buffer contains 65 bytes of storage for each block, plus an additional byte for a \s-1NUL\s0 terminator. EVP_EncodeUpdate() may be called repeatedly to process large amounts of input data. In the event of an error \fBEVP_EncodeUpdate() will set *outl to 0 and return 0. On success 1 will be returned.
\fBEVP_EncodeFinal() must be called at the end of an encoding operation. It will process any partial block of data remaining in the ctx object. The output data will be stored in out and the length of the data written will be stored in *outl. It is the caller's responsibility to ensure that out is sufficiently large to accommodate the output data which will never be more than 65 bytes plus an additional \s-1NUL\s0 terminator (i.e. 66 bytes in total).
\fBEVP_ENCODE_CTX_copy() can be used to copy a context sctx to a context \fBdctx. dctx must be initialized before calling this function.
\fBEVP_ENCODE_CTX_num() will return the number of as yet unprocessed bytes still to be encoded or decoded that are pending in the ctx object.
\fBEVP_EncodeBlock() encodes a full block of input data in f and of length \fBn and stores it in t. For every 3 bytes of input provided 4 bytes of output data will be produced. If n is not divisible by 3 then the block is encoded as a final block of data and the output is padded such that it is always divisible by 4. Additionally a \s-1NUL\s0 terminator character will be added. For example if 16 bytes of input data is provided then 24 bytes of encoded data is created plus 1 byte for a \s-1NUL\s0 terminator (i.e. 25 bytes in total). The length of the data generated without the \s-1NUL\s0 terminator is returned from the function.
\fBEVP_DecodeInit() initialises ctx for the start of a new decoding operation.
\fBEVP_DecodeUpdate() decodes inl characters of data found in the buffer pointed to by in. The output is stored in the buffer out and the number of bytes output is stored in *outl. It is the caller's responsibility to ensure that the buffer at out is sufficiently large to accommodate the output data. This function will attempt to decode as much data as possible in 4 byte chunks. Any whitespace, newline or carriage return characters are ignored. Any partial chunk of unprocessed data (1, 2 or 3 bytes) that remains at the end will be held in the ctx object and processed by a subsequent call to EVP_DecodeUpdate(). If any illegal base 64 characters are encountered or if the base 64 padding character \*(L"=\*(R" is encountered in the middle of the data then the function returns \-1 to indicate an error. A return value of 0 or 1 indicates successful processing of the data. A return value of 0 additionally indicates that the last input data characters processed included the base 64 padding character \*(L"=\*(R" and therefore no more non-padding character data is expected to be processed. For every 4 valid base 64 bytes processed (ignoring whitespace, carriage returns and line feeds), 3 bytes of binary output data will be produced (or less at the end of the data where the padding character \*(L"=\*(R" has been used).
\fBEVP_DecodeFinal() must be called at the end of a decoding operation. If there is any unprocessed data still in ctx then the input data must not have been a multiple of 4 and therefore an error has occurred. The function will return -1 in this case. Otherwise the function returns 1 on success.
\fBEVP_DecodeBlock() will decode the block of n characters of base 64 data contained in f and store the result in t. Any leading whitespace will be trimmed as will any trailing whitespace, newlines, carriage returns or \s-1EOF\s0 characters. After such trimming the length of the data in f must be divisible by 4. For every 4 input bytes exactly 3 output bytes will be produced. The output will be padded with 0 bits if necessary to ensure that the output is always 3 bytes for every 4 input bytes. This function will return the length of the data decoded or -1 on error.
\fBEVP_ENCODE_CTX_num() returns the number of bytes pending encoding or decoding in \fBctx.
\fBEVP_EncodeUpdate() returns 0 on error or 1 on success.
\fBEVP_EncodeBlock() returns the number of bytes encoded excluding the \s-1NUL\s0 terminator.
\fBEVP_DecodeUpdate() returns -1 on error and 0 or 1 on success. If 0 is returned then no more non-padding base 64 characters are expected.
\fBEVP_DecodeFinal() returns -1 on error or 1 on success.
\fBEVP_DecodeBlock() returns the length of the data decoded or -1 on error.
Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.