



Network Working Group                                             Rayner
Internet-Draft                                               Independent
Intended status: Informational                            11 August 2025
Expires: 12 February 2026


     Proquints: Readable, Spellable, and Pronounceable Identifiers
                        draft-rayner-proquint-03

Abstract

   This document specifies "proquints" (PRO-nounceable QUINT-uplets), a
   human-friendly encoding that maps binary data to pronounceable
   identifiers using fixed consonant-vowel patterns.  The concept was
   originally described by Daniel Shawcross Wilkerson in 2009.  This
   document formalizes the format for archival and reference.

Status of This Memo

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   This Internet-Draft will expire on 12 February 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Format  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Encoding  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Decoding  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   6.  Encoding and Decoding Specification . . . . . . . . . . . . .   3
     6.1.  Letter Tables and Indices . . . . . . . . . . . . . . . .   4
     6.2.  Bit Layout  . . . . . . . . . . . . . . . . . . . . . . .   4
     6.3.  Encoding Algorithm (Pseudocode) . . . . . . . . . . . . .   5
     6.4.  Decoding Algorithm (Pseudocode) . . . . . . . . . . . . .   5
     6.5.  Normalization . . . . . . . . . . . . . . . . . . . . . .   6
     6.6.  Test Vectors  . . . . . . . . . . . . . . . . . . . . . .   7
     6.7.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Proquints encode binary data as alternating consonant-vowel letters
   grouped into five-letter syllables, yielding identifiers that are
   readable, spellable, and pronounceable.  The idea and specific letter
   tables were first described by Daniel Shawcross Wilkerson in 2009
   ([WILKERSON2009]).  This document does not claim originality for the
   concept; it reformulates and formalizes the description for archival
   purposes.

   While multiple schemes exist for encoding network addresses and other
   binary data, Proquints aim to provide a unique blend of human-
   reabability, accessibility, and long-term usability.  They reduce
   transcription errors, are friendlier for non-technical users, and
   offer mnemonic qualities that can help in educational or operational
   contexts.  Although they may not replace all existing
   representations, Proquints can serve as a complementary format that
   improves clarity in documentation, user interfaces, and spoken
   communication, particularly where accuracy and inclusivity matter.









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2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Format

   A proquint encodes data in 16-bit blocks.  Each block maps to a five-
   letter syllable of the form CVCVC (Consonant-Vowel-Consonant-Vowel-
   Consonant).

   The mapping tables are fixed:

   Consonants (indices 0..15):

   *  b d f g h j k l m n p r s t v z

   Vowels (indices 0..3):

   *  a i o u

4.  Encoding

   *  Split the input byte string into 16-bit words (big-endian).  If
      the number of bytes is odd, an implementation MAY pad a single
      zero byte to complete the final word; if padding is used,
      applications MUST define how the original length is recovered.

   *  For each 16-bit word, map bits 15-12 to the first consonant, bits
      11-10 to the first vowel, bits 9-6 to the second consonant, bits
      5-4 to the second vowel, and bits 3-0 to the final consonant.

   *  Concatenate syllables.  Hyphens MAY be inserted between syllables
      for readability; decoders MUST ignore hyphens.

5.  Decoding

   Decoders MUST reverse the mapping in Section 4.  Each five-letter
   syllable maps to one 16-bit value using the same tables and bit
   ordering.  Hyphens, if present, MUST be ignored.

6.  Encoding and Decoding Specification






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6.1.  Letter Tables and Indices

   Proquint encodes each 16-bit word as five letters in the pattern
   CVCVC (Consonant–Vowel–Consonant–Vowel–Consonant).  The mapping
   tables and indices are fixed and normative.

   Consonant table (index 0..15):

   Index  Hex  Bits  Consonant
   -----  ---  ----  ---------
     0     0   0000     b
     1     1   0001     d
     2     2   0010     f
     3     3   0011     g
     4     4   0100     h
     5     5   0101     j
     6     6   0110     k
     7     7   0111     l
     8     8   1000     m
     9     9   1001     n
    10     A   1010     p
    11     B   1011     r
    12     C   1100     s
    13     D   1101     t
    14     E   1110     v
    15     F   1111     z

   Vowel table (index 0..3):

   Index  Bits  Vowel
   -----  ----  -----
     0    00      a
     1    01      i
     2    10      o
     3    11      u

6.2.  Bit Layout

   Each 16-bit input value (bits 15..0, most significant bit first) MUST
   be mapped to letters in this order:

   bits 15..12 -> first consonant (C1)
   bits 11..10 -> first vowel     (V1)
   bits  9.. 6 -> second consonant(C2)
   bits  5.. 4 -> second vowel    (V2)
   bits  3.. 0 -> third consonant (C3)





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   Encoders MUST process input as an ordered sequence of 16-bit words
   formed from the input octet string in network byte order (big-
   endian): octet[i] contributes bits 15..8 and octet[i+1] contributes
   bits 7..0 of the word.  If the input contains an odd number of
   octets, encoders MAY pad a single zero octet to complete the final
   16-bit word; applications using padding MUST specify how the original
   length is recovered.

   Encoders MAY insert ASCII hyphens (0x2D) between syllables for
   readability.  Decoders MUST ignore hyphens.

6.3.  Encoding Algorithm (Pseudocode)

   Input: bytes[]  // octet string
   Output: string  // proquint

   consonants = "bdfghjklmnprstvz"   // length 16, index 0..15
   vowels     = "aiou"               // length 4,  index 0..3

   function encode(bytes):
     out = ""
     i = 0
     while i < len(bytes):
       hi = bytes[i]; i += 1
       if i < len(bytes): lo = bytes[i]; i += 1
       else:              lo = 0  // optional pad
       w = (hi << 8) | lo        // 16-bit word

       c1 = consonants[(w >> 12) & 0xF]
       v1 = vowels    [(w >> 10) & 0x3]
       c2 = consonants[(w >>  6) & 0xF]
       v2 = vowels    [(w >>  4) & 0x3]
       c3 = consonants[(w      ) & 0xF]

       syllable = c1 + v1 + c2 + v2 + c3
       out += syllable
       // optional readability: insert '-' between syllables
       // e.g., if not last: out += '-'

     return out

6.4.  Decoding Algorithm (Pseudocode)









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   Input: string pq  // CVCVC syllables, hyphens optional
   Output: bytes[]   // octet string

   consonants = "bdfghjklmnprstvz"
   vowels     = "aiou"

   function indexOf(ch, table):
     pos = table.find(ch)
     if pos < 0: error("invalid character")
     return pos

   function decode(pq):
     // remove hyphens; decoders MUST accept upper or lower case
     s = toLowercase(removeAll(pq, '-'))
     if len(s) % 5 != 0: error("length not multiple of 5")

     out = []
     for j in range(0, len(s), 5):
       c1 = indexOf(s[j+0], consonants)
       v1 = indexOf(s[j+1], vowels)
       c2 = indexOf(s[j+2], consonants)
       v2 = indexOf(s[j+3], vowels)
       c3 = indexOf(s[j+4], consonants)

       w = (c1 << 12) | (v1 << 10) | (c2 << 6) | (v2 << 4) | c3
       out.append( (w >> 8) & 0xFF )
       out.append(  w       & 0xFF )

     return out

   Decoders MUST accept input in either case (upper/lower) and MUST
   reject any character not in the defined consonant/vowel sets (after
   stripping hyphens).  If applications use padding on encode, they MUST
   specify how to remove any trailing zero octet introduced solely for
   padding.

6.5.  Normalization

   Encoders SHOULD produce lowercase output.  Decoders MUST treat input
   as case-insensitive and MUST ignore ASCII hyphens (0x2D).

   Encoders and decoders MUST use the tables and ordering defined in
   Section 6.1 and Section 6.2.  Substituting letters or re-ordering
   bits is not Proquint and will not interoperate.







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6.6.  Test Vectors

   The following vectors are derived directly from this specification
   and can be used to verify independent implementations.

   # Single-word (16-bit) values:
   0x0000 -> babab
   0xFFFF -> zvzuz
   0x1234 -> damuh
   0xF00D -> zabat
   0xBEEF -> ruroz

   # Two words (32-bit), big-endian byte order:
   bytes:  0x12 0x34 0xF0 0x0D
   words:  0x1234, 0xF00D
   pq:     damuh-zabat      (with hyphen)  or  damuhzabat (without)

   # Raw ASCII example ("F3r41OutL4w"),
   # UTF-8 bytes, zero-padded to even length:
   ASCII:  46 33 72 34 31 4F 75 74 4C 34 77
   Pad:                                      00
   Words:  0x4633 0x7234 0x314F 0x7574 0x4C34 0x7700
   PQ:     himug-lamud-kudaz-lijuh-hubuh-lisab  (hyphens optional)

   Implementations MUST reproduce these outputs exactly.

6.7.  Error Handling

   Decoders MUST fail input that: (1) contains characters outside the
   defined tables (after hyphen removal); (2) has length not divisible
   by 5 letters; or (3) violates the CVCVC pattern.  Error signaling is
   application-specific but MUST reject invalid input rather than
   attempt to guess.

7.  Security Considerations

   Proquint is a presentation encoding.  It provides no confidentiality,
   integrity, or authentication services.  It does not add or remove
   entropy, and it MUST NOT be used as a cryptographic transform.

8.  IANA Considerations

   This document has no IANA actions.








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9.  Acknowledgments

   The author thanks Daniel Shawcross Wilkerson for originating the
   proquint concept and publishing the initial specification in 2009
   ([WILKERSON2009]).

10.  References

10.1.  Normative References

   [BCP14]    Best Current Practice 14,
              <https://www.rfc-editor.org/info/bcp14>.
              At the time of writing, this BCP comprises the following:

              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

              Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

10.2.  Informative References

   [WILKERSON2009]
              Wilkerson, D.S., "Proquints: Identifiers that are
              Readable, Spellable, and Pronounceable", arXiv 0901.4016,
              January 2009, <https://arxiv.org/html/0901.4016>.

Author's Address

   Thomas Rayner
   Independent
   Email: thmsrynr@outlook.com
















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