man/man3/EVP_EncodeInit.3

98 bytes of binary data provided 4 bytes of base64 encoded data will be produced
109 Encoding of binary data is performed in blocks of 48 input bytes (or less for
111 For each 48 byte input block encoded 64 bytes of base64 data
112 is output plus an additional newline character (i.e. 65 bytes in total). The
113 final block (which may be less than 48 bytes) will output 4 bytes for every 3
114 bytes of input. If the data length is not divisible by 3 then a full 4 bytes is
115 still output for the final 1 or 2 bytes of input. Similarly a newline character
120 \&\fBEVP_EncodeUpdate()\fR encode \fBinl\fR bytes of data found in the buffer pointed to by
121 \&\fBin\fR. The output is stored in the buffer \fBout\fR and the number of bytes output
124 blocks of data (48 bytes) will be immediately processed and output by this
130 Ensure the output buffer contains 65 bytes of storage for each block, plus an
141 65 bytes plus an additional NUL terminator (i.e. 66 bytes in total).
146 \&\fBEVP_ENCODE_CTX_num()\fR will return the number of as yet unprocessed bytes still to
150 \&\fBn\fR and stores it in \fBt\fR. For every 3 bytes of input provided 4 bytes of
154 example if 16 bytes of input data is provided then 24 bytes of encoded data is
155 created plus 1 byte for a NUL terminator (i.e. 25 bytes in total). The length of
162 The output is stored in the buffer \fBout\fR and the number of bytes output is
176 end\-of\-input, subsequent bytes are not buffered, and the return value will be
179 input bytes.
188 A return value of 0 additionally indicates that the last 4 bytes processed
193 For every 4 valid base64 bytes processed (ignoring whitespace, carriage returns
194 and line feeds), 3 bytes of binary output data will be produced (except at the
211 For every 4 input bytes exactly 3 output bytes will be produced.
212 Padding bytes (\fB=\fR) (even if internal) are decoded to 6 zero bits, the caller
214 bytes at the tail of the returned output.
221 \&\fBEVP_ENCODE_CTX_num()\fR returns the number of bytes pending encoding or decoding in
226 \&\fBEVP_EncodeBlock()\fR returns the number of bytes encoded excluding the NUL
241 so now it produces the number of bytes specified in \fBoutl*\fR
242 and does not decode padding bytes (\fB=\fR) to 6 zero bits.