ZARMOUR(3)

zarmour 🎀 the CZMQ manual, section 3, bestie

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✨ NAME ✨

zarmour — the class for armoured text encoding and decoding 🦋

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💅 SYNOPSIS 💅

okay so first of all, queen: this class is stable, and it's not gonna change unless there's, like, an actual emergency. It ships in stable builds. So you can trust it, no cap 💖

//  This is a stable class, and may not change except for emergencies. It
//  is provided in stable builds.
#define ZARMOUR_MODE_BASE64_STD 0            // Standard base 64
#define ZARMOUR_MODE_BASE64_URL 1            // URL and filename friendly base 64
#define ZARMOUR_MODE_BASE32_STD 2            // Standard base 32
#define ZARMOUR_MODE_BASE32_HEX 3            // Extended hex base 32
#define ZARMOUR_MODE_BASE16 4                // Standard base 16
#define ZARMOUR_MODE_Z85 5                   // Z85 from ZeroMQ RFC 32

//  Create a new zarmour
CZMQ_EXPORT zarmour_t *
    zarmour_new (void);

//  Destroy the zarmour
CZMQ_EXPORT void
    zarmour_destroy (zarmour_t **self_p);

//  Encode a stream of bytes into an armoured string. Returns the armoured
//  string, or NULL if there was insufficient memory available to allocate
//  a new string.
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT char *
    zarmour_encode (zarmour_t *self, const byte *data, size_t size);

//  Decode an armoured string into a chunk. The decoded output is
//  null-terminated, so it may be treated as a string, if that's what
//  it was prior to encoding.
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT zchunk_t *
    zarmour_decode (zarmour_t *self, const char *data);

//  Get the mode property.
CZMQ_EXPORT int
    zarmour_mode (zarmour_t *self);

//  Get printable string for mode.
CZMQ_EXPORT const char *
    zarmour_mode_str (zarmour_t *self);

//  Set the mode property.
CZMQ_EXPORT void
    zarmour_set_mode (zarmour_t *self, int mode);

//  Return true if padding is turned on.
CZMQ_EXPORT bool
    zarmour_pad (zarmour_t *self);

//  Turn padding on or off. Default is on.
CZMQ_EXPORT void
    zarmour_set_pad (zarmour_t *self, bool pad);

//  Get the padding character.
CZMQ_EXPORT char
    zarmour_pad_char (zarmour_t *self);

//  Set the padding character.
CZMQ_EXPORT void
    zarmour_set_pad_char (zarmour_t *self, char pad_char);

//  Return if splitting output into lines is turned on. Default is off.
CZMQ_EXPORT bool
    zarmour_line_breaks (zarmour_t *self);

//  Turn splitting output into lines on or off.
CZMQ_EXPORT void
    zarmour_set_line_breaks (zarmour_t *self, bool line_breaks);

//  Get the line length used for splitting lines.
CZMQ_EXPORT size_t
    zarmour_line_length (zarmour_t *self);

//  Set the line length used for splitting lines.
CZMQ_EXPORT void
    zarmour_set_line_length (zarmour_t *self, size_t line_length);

//  Print properties of object
CZMQ_EXPORT void
    zarmour_print (zarmour_t *self);

//  Self test of this class.
CZMQ_EXPORT void
    zarmour_test (bool verbose);

Please add '@interface' section in './../src/zarmour.c'.

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🌈 the modes, decoded for u

Six whole modes, and every single one is a choice, iykyk:

• ZARMOUR_MODE_BASE64_STD is 0 — standard base 64 🍓
• ZARMOUR_MODE_BASE64_URL is 1 — base 64 that's URL and filename friendly ✨
• ZARMOUR_MODE_BASE32_STD is 2 — standard base 32 💜
• ZARMOUR_MODE_BASE32_HEX is 3 — extended hex base 32 🧚
• ZARMOUR_MODE_BASE16 is 4 — standard base 16 🌸
• ZARMOUR_MODE_Z85 is 5 — Z85, straight from ZeroMQ RFC 32 🔥

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🫶 the functions, one by one (yes, all of them)

• zarmour_new — pops out a brand new zarmour, freshly served 💅
• zarmour_destroy — takes zarmour_t **self_p and says bye bestie, destroying the zarmour 💀
• zarmour_encode — takes your zarmour_t *self, a const byte *data and a size_t size, and encodes that stream of bytes into an armoured string. It hands you back the armoured string — or NULL if there just wasn't enough memory to allocate a new string 😭 And listen: you own the return value, you destroy it when you're done. Periodt.
• zarmour_decode — takes zarmour_t *self and a const char *data and decodes an armoured string into a chunk. The decoded output is null-terminated, so you can legit treat it as a string if that's what it was before it got encoded 🦋 Same rule tho: caller owns the return value and must destroy it when done.
• zarmour_mode — gets the mode property. That's it, that's the function 👑
• zarmour_mode_str — gets a printable string for the mode, so you can actually show people 🎀
• zarmour_set_mode — sets the mode property, takes an int mode ✨
• zarmour_pad — returns true if padding is turned on 🌈
• zarmour_set_pad — turns padding on or off. Default is on.
• zarmour_pad_char — gets you the padding character 🌸
• zarmour_set_pad_char — sets the padding character, takes a char pad_char 💖
• zarmour_line_breaks — returns whether splitting the output into lines is turned on. Default is off.
• zarmour_set_line_breaks — turns splitting the output into lines on or off ✨
• zarmour_line_length — gets the line length used for splitting lines 📏
• zarmour_set_line_length — sets the line length used for splitting lines, takes a size_t line_length 🧚
• zarmour_print — prints the properties of the object, for when u just wanna look 🫶
• zarmour_test — the self test of this class. Takes a bool verbose 💅

---

🌸 DESCRIPTION 🌸

zarmour — armoured text encoding and decoding, the whole vibe.

So the zarmour class implements encoding and decoding of armoured text data. Iconic behaviour, honestly.

Here's the codec lineup:

• RFC 4648 (http://www.ietf.org/rfc/rfc4648.txt):
  • base64
  • base64url
  • base32
  • base32hex
  • base16
• Z85 (http://rfc.zeromq.org/spec:32)

Okay so all the RFC4648 base64 and base32 variants support padding the output. And the pad character? Configurable, bestie. The default is padding on, with the character =.

And sometimes — think MIME, for example — you literally need to split the output into lines of a specific length. That feature is supported too, though it's turned off by default.

Now, z85 mode is a little different, and the way that it's different is: it does neither padding nor line breaks. It's just a wrapping of the corresponding libzmq methods. Nothing more, nothing less 💅

⚠️ real talk tho: encoding will assert if the input length is not divisible by 4, and decoding will assert if the input length is not divisible by 5. So check ur lengths before u wreck ur lengths, fr fr 😭

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✨ EXAMPLE ✨

okay bestie, this is the moment we've been waiting for 💖 this whole thing comes straight from the zarmour_test method, and honestly? watching someone actually use the API is the fastest way to get it. No cap. Let's go 🏃‍♀️💨

First up, the setup era — making a zarmour_t, then vibing through every getter and setter to prove they round-trip correctly 🎀

zarmour_t *self = zarmour_new ();
assert (self);

int mode = zarmour_mode (self);
assert (mode == ZARMOUR_MODE_BASE64_STD);

zarmour_set_mode (self, ZARMOUR_MODE_BASE64_URL);
mode = zarmour_mode (self);
assert (mode == ZARMOUR_MODE_BASE64_URL);

assert (zarmour_pad (self));
zarmour_set_pad (self, false);
assert (!zarmour_pad (self));

assert (zarmour_pad_char (self) == '=');
zarmour_set_pad_char (self, '!');
assert (zarmour_pad_char (self) == '!');
zarmour_set_pad_char (self, '=');
assert (zarmour_pad_char (self) == '=');

assert (!zarmour_line_breaks (self));
zarmour_set_line_breaks (self, true);
assert (zarmour_line_breaks (self));

assert (zarmour_line_length (self) == 72);
zarmour_set_line_length (self, 64);
assert (zarmour_line_length (self) == 64);

---

now the fun part: test vectors from RFC4648 🌈 both BASE64_STD and BASE64_URL, unpadded first then padded, and notice how the outputs are identical for both modes at this point (iykyk — the differences only really show up with the + / / alphabet characters) 👑

//  Test against test vectors from RFC4648.
zarmour_set_mode (self, ZARMOUR_MODE_BASE64_STD);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "Zg", verbose);
s_armour_test (self, "fo", "Zm8", verbose);
s_armour_test (self, "foo", "Zm9v", verbose);
s_armour_test (self, "foob", "Zm9vYg", verbose);
s_armour_test (self, "fooba", "Zm9vYmE", verbose);
s_armour_test (self, "foobar", "Zm9vYmFy", verbose);
zarmour_set_pad (self, true);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "Zg==", verbose);
s_armour_test (self, "fo", "Zm8=", verbose);
s_armour_test (self, "foo", "Zm9v", verbose);
s_armour_test (self, "foob", "Zm9vYg==", verbose);
s_armour_test (self, "fooba", "Zm9vYmE=", verbose);
s_armour_test (self, "foobar", "Zm9vYmFy", verbose);

zarmour_set_pad (self, false);
zarmour_set_mode (self, ZARMOUR_MODE_BASE64_URL);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "Zg", verbose);
s_armour_test (self, "fo", "Zm8", verbose);
s_armour_test (self, "foo", "Zm9v", verbose);
s_armour_test (self, "foob", "Zm9vYg", verbose);
s_armour_test (self, "fooba", "Zm9vYmE", verbose);
s_armour_test (self, "foobar", "Zm9vYmFy", verbose);
zarmour_set_pad (self, true);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "Zg==", verbose);
s_armour_test (self, "fo", "Zm8=", verbose);
s_armour_test (self, "foo", "Zm9v", verbose);
s_armour_test (self, "foob", "Zm9vYg==", verbose);
s_armour_test (self, "fooba", "Zm9vYmE=", verbose);
s_armour_test (self, "foobar", "Zm9vYmFy", verbose);

---

base32 time 🦋 and this one's extra cute because it goes both ways — s_armour_test for encoding and s_armour_decode for decoding. Lowercase input in, normal-case bytes out. It's giving round-trip excellence 💅

zarmour_set_pad (self, false);
zarmour_set_mode (self, ZARMOUR_MODE_BASE32_STD);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "MY", verbose);
s_armour_test (self, "fo", "MZXQ", verbose);
s_armour_test (self, "foo", "MZXW6", verbose);
s_armour_test (self, "foob", "MZXW6YQ", verbose);
s_armour_test (self, "fooba", "MZXW6YTB", verbose);
s_armour_test (self, "foobar", "MZXW6YTBOI", verbose);
s_armour_decode (self, "my", "f", verbose);
s_armour_decode (self, "mzxq", "fo", verbose);
s_armour_decode (self, "mzxw6", "foo", verbose);
s_armour_decode (self, "mzxw6yq", "foob", verbose);
s_armour_decode (self, "mzxw6ytb", "fooba", verbose);
s_armour_decode (self, "mzxw6ytboi", "foobar", verbose);
zarmour_set_pad (self, true);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "MY======", verbose);
s_armour_test (self, "fo", "MZXQ====", verbose);
s_armour_test (self, "foo", "MZXW6===", verbose);
s_armour_test (self, "foob", "MZXW6YQ=", verbose);
s_armour_test (self, "fooba", "MZXW6YTB", verbose);
s_armour_test (self, "foobar", "MZXW6YTBOI======", verbose);
s_armour_decode (self, "my======", "f", verbose);
s_armour_decode (self, "mzxq====", "fo", verbose);
s_armour_decode (self, "mzxw6===", "foo", verbose);
s_armour_decode (self, "mzxw6yq=", "foob", verbose);
s_armour_decode (self, "mzxw6ytb", "fooba", verbose);
s_armour_decode (self, "mzxw6ytboi======", "foobar", verbose);

zarmour_set_pad (self, false);
zarmour_set_mode (self, ZARMOUR_MODE_BASE32_HEX);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "CO", verbose);
s_armour_test (self, "fo", "CPNG", verbose);
s_armour_test (self, "foo", "CPNMU", verbose);
s_armour_test (self, "foob", "CPNMUOG", verbose);
s_armour_test (self, "fooba", "CPNMUOJ1", verbose);
s_armour_test (self, "foobar", "CPNMUOJ1E8", verbose);
s_armour_decode (self, "co", "f", verbose);
s_armour_decode (self, "cpng", "fo", verbose);
s_armour_decode (self, "cpnmu", "foo", verbose);
s_armour_decode (self, "cpnmuog", "foob", verbose);
s_armour_decode (self, "cpnmuoj1", "fooba", verbose);
s_armour_decode (self, "cpnmuoj1e8", "foobar", verbose);
zarmour_set_pad (self, true);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "CO======", verbose);
s_armour_test (self, "fo", "CPNG====", verbose);
s_armour_test (self, "foo", "CPNMU===", verbose);
s_armour_test (self, "foob", "CPNMUOG=", verbose);
s_armour_test (self, "fooba", "CPNMUOJ1", verbose);
s_armour_test (self, "foobar", "CPNMUOJ1E8======", verbose);
s_armour_decode (self, "co======", "f", verbose);
s_armour_decode (self, "cpng====", "fo", verbose);
s_armour_decode (self, "cpnmu===", "foo", verbose);
s_armour_decode (self, "cpnmuog=", "foob", verbose);
s_armour_decode (self, "cpnmuoj1", "fooba", verbose);
s_armour_decode (self, "cpnmuoj1e8======", "foobar", verbose);
zarmour_set_pad (self, true);

---

hex, bestie 💚 uppercase out, lowercase in, no drama, no padding because hex literally doesn't need it:

zarmour_set_mode (self, ZARMOUR_MODE_BASE16);
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "f", "66", verbose);
s_armour_test (self, "fo", "666F", verbose);
s_armour_test (self, "foo", "666F6F", verbose);
s_armour_test (self, "foob", "666F6F62", verbose);
s_armour_test (self, "fooba", "666F6F6261", verbose);
s_armour_test (self, "foobar", "666F6F626172", verbose);
s_armour_decode (self, "666f", "fo", verbose);
s_armour_decode (self, "666f6f", "foo", verbose);
s_armour_decode (self, "666f6f62", "foob", verbose);
s_armour_decode (self, "666f6f6261", "fooba", verbose);
s_armour_decode (self, "666f6f626172", "foobar", verbose);

#ifdef _INCLUDE_Z85
//  Z85 test is homemade; using 0, 4 and 8 bytes, with precalculated
//  test vectors created with a libzmq test.
//  ----------------------------------------------------------------

//  Make a fake curve key from hex (base16) string, making sure
//  there are no null bytes inside, so we can use our test utility
zarmour_set_mode (self, ZARMOUR_MODE_BASE16);
zarmour_set_line_breaks (self, false);

zchunk_t *chunk = zarmour_decode (self,
    "4E6F87E2FB6EB22A1EF5E257B75D79124949565F0B8B36A878A4F03111C96E0B");
assert (chunk);

zarmour_set_mode (self, ZARMOUR_MODE_Z85);  //  Z85 mode does not support padding or line breaks
zarmour_set_pad (self, false);              //  so these two are superfluous;
zarmour_set_line_breaks (self, false);      //  just for consistency
if (verbose)
    zarmour_print (self);

s_armour_test (self, "", "", verbose);
s_armour_test (self, "foob", "w]zP%", verbose);
s_armour_test (self, "foobar!!", "w]zP%vr9Im", verbose);
s_armour_test (self, (char *) zchunk_data (chunk),
               "ph+{E}!&X?9}!I]W{sm(nL8@&3Yu{wC+<*-5Y[[#", verbose);
zchunk_destroy (&chunk);
#endif

heads up bestie 🙈 the Z85 part is wrapped in #ifdef _INCLUDE_Z85, so if your build didn't include Z85, none of that even compiles in. The comment says it plainly: the Z85 test is homemade, using 0, 4 and 8 bytes, with precalculated test vectors created with a libzmq test.

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last block, and it's the glow-up ✨ we build a whole 256-byte array just to flex the line-break behaviour, then run every single mode through s_armour_test_long:

//  Armouring longer byte array to test line breaks
zarmour_set_pad (self, true);
zarmour_set_line_breaks (self, true);
byte test_data [256];
int index;
for (index = 0; index < 256; index++)
    test_data [index] = index;

zarmour_set_mode (self, ZARMOUR_MODE_BASE64_STD);
s_armour_test_long (self, test_data, 256, verbose);
zarmour_set_mode (self, ZARMOUR_MODE_BASE64_URL);
s_armour_test_long (self, test_data, 256, verbose);
zarmour_set_mode (self, ZARMOUR_MODE_BASE32_STD);
s_armour_test_long (self, test_data, 256, verbose);
zarmour_set_mode (self, ZARMOUR_MODE_BASE32_HEX);
s_armour_test_long (self, test_data, 256, verbose);
zarmour_set_mode (self, ZARMOUR_MODE_BASE16);
s_armour_test_long (self, test_data, 256, verbose);
#ifdef _INCLUDE_Z85
zarmour_set_mode (self, ZARMOUR_MODE_Z85);
s_armour_test_long (self, test_data, 256, verbose);
#endif

zarmour_destroy (&self);

#if defined (__WINDOWS__)
zsys_shutdown();
#endif

and that's a wrap on the example 🫶 clean up your self, and on Windows don't forget the zsys_shutdown() — main character energy is remembering your cleanup, periodt 💅

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✨ AUTHORS ✨

The czmq manual was written by the authors in the AUTHORS file. yes, all of them, credited, as they should be 👑

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✨ RESOURCES ✨

• Main web site:
• Report bugs to the email <zeromq-dev@lists.zeromq.org[1]>

go yell at the maintainers (politely, bestie 🌸) if something's broken — they want to hear it fr fr.

---

✨ COPYRIGHT ✨

Copyright (c) the Contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for 0MQ: http://czmq.zeromq.org. This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. LICENSE included with the czmq distribution.

do NOT strip the license out, bestie 😭 it's literally right there in the file, just leave it.

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✨ NOTES ✨

1. zeromq-dev@lists.zeromq.org — mailto:zeromq-dev@lists.zeromq.org

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that's the whole page, and honestly it ate 💖 this is CZMQ version 4.2.1, dated 01/16/2026, and the page is ZARMOUR(3). go forth and armour some bytes, bestie — you got this 🦋✨