| | 1 | .\" -*-nroff-*- |
| | 2 | .TH base32 3 "28 September 2004" "Straylight/Edgeware" "mLib utilities library" |
| | 3 | .SH NAME |
| | 4 | base32 \- conversion to and from base32 encoding |
| | 5 | .\" @base32_encode |
| | 6 | .\" @base32_decode |
| | 7 | .\" @base32_init |
| | 8 | .SH SYNOPSIS |
| | 9 | .nf |
| | 10 | .B "#include <mLib/base32.h>" |
| | 11 | |
| | 12 | .BI "void base32_encode(base32_ctx *" ctx , |
| | 13 | .BI " const void *" p ", size_t " sz , |
| | 14 | .BI " dstr *" d ); |
| | 15 | .BI "void base32_decode(base32_ctx *" ctx , |
| | 16 | .BI " const void *" p ", size_t " sz , |
| | 17 | .BI " dstr *" d ); |
| | 18 | .BI "void base32_init(base32_ctx *" ctx ); |
| | 19 | .fi |
| | 20 | .SH DESCRIPTION |
| | 21 | The |
| | 22 | .B base32 |
| | 23 | functions perform base32 encoding and decoding of arbitrary binary |
| | 24 | strings. The base32 encoding is defined by RFC2938. |
| | 25 | .PP |
| | 26 | Before encoding or decoding a string, a |
| | 27 | .I context |
| | 28 | (of type |
| | 29 | .BR base32_ctx ) |
| | 30 | must be initialized, by passing it to |
| | 31 | .BR base32_init . |
| | 32 | The context contains data which must be retained between calls to encode |
| | 33 | or decode substrings. The |
| | 34 | .B base32_init |
| | 35 | function sets up initial values for the data, and sets up defaults for |
| | 36 | the output formatting settings (see below). |
| | 37 | .PP |
| | 38 | Encoding of a string is performed by the |
| | 39 | .B base32_encode |
| | 40 | function. It is passed a pointer to a context block |
| | 41 | .IR ctx , |
| | 42 | the input substring to encode passed by address |
| | 43 | .I p |
| | 44 | and length |
| | 45 | .IR sz , |
| | 46 | and a pointer to a dynamic string |
| | 47 | .I d |
| | 48 | in which to write its output (see |
| | 49 | .BR dstr (3) |
| | 50 | for details on dynamic strings). Once all the input data has been |
| | 51 | passed through |
| | 52 | .B base32_encode |
| | 53 | it is necessary to flush the final few bytes of output. This is |
| | 54 | achieved by passing |
| | 55 | .B base32_encode |
| | 56 | a null pointer as its source argument. It is an error to attempt to |
| | 57 | continue encoding after flushing output. |
| | 58 | .PP |
| | 59 | The output of the |
| | 60 | .B base32_encode |
| | 61 | function is formatted into lines using values from the context |
| | 62 | structure. The |
| | 63 | .B indent |
| | 64 | member is a pointer to a null-terminated string which is used to |
| | 65 | separate the output lines. The default indent string contains only a |
| | 66 | newline character. The |
| | 67 | .B maxline |
| | 68 | member gives the maximum length of line that |
| | 69 | .B base32_encode |
| | 70 | is allowed to produce. If this is not a multiple of 4, it is rounded |
| | 71 | up to the next highest multiple of four before use. A value of zero |
| | 72 | instructs |
| | 73 | .B base32_encode |
| | 74 | not to perform line splitting: the output will be a single (possibly |
| | 75 | very long) output line. The default maximum line length is 72 |
| | 76 | characters. You may set these parameters by direct assignment to the |
| | 77 | context structure once it has been initialized. |
| | 78 | .PP |
| | 79 | Decoding is performed similarly by the |
| | 80 | .B base32_decode |
| | 81 | function. The comments above about flushing output apply equally to |
| | 82 | decoding. |
| | 83 | .PP |
| | 84 | Decoding ignores all whitespace characters in the encoded string. It |
| | 85 | also ignores |
| | 86 | .RB ` = ' |
| | 87 | characters in the string and works out the final block length |
| | 88 | automatically based on the input size. |
| | 89 | .SH "SEE ALSO" |
| | 90 | .BR base64 (3), |
| | 91 | .BR dstr (3), |
| | 92 | .BR hex (3), |
| | 93 | .BR mLib (3). |
| | 94 | .SH AUTHOR |
| | 95 | Mark Wooding, <mdw@distorted.org.uk> |
~mdw / mLib / blame_incremental