| Internet-Draft | Updates to RFC2289 | September 2026 |
| Corbel | Expires 12 March 2027 | [Page] |
This document aims to submit a few updates to RFC 2289 [RFC2289], which describes a One-Time Password (OTP) System: an application programming interface to the new Secure Hash Algorithms (SHA256, SHA384, and SHA512), an algorithm for folding hashes to 64 bits, using alternate dictionaries, and automatic renewal of authentication parameters will be described.¶
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Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.¶
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When [RFC2289] was published in 1998, and became a Standards Track specification in 2000, it described a powerful One-Time Password system. Many things have changed since that time, notably the way hashes are computed: one distinct interface for each hash algorithm yesterday, only one today. We describe here that unique interface. As a consequence, folding hashes to 64 bits (the length of an OTP) requires a different technique, which is also described. Finally, we suggest a technique for automatically renewing authentication parameters between a user and an OTP authentication server. Understanding [RFC2289] is a requirement.¶
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 [BCP14] when, and only when, they appear in all capitals, as shown here.¶
In 1998, only three secure hash algorithms were commonly used: MD4 [RFC1320], MD5 [RFC1321], and SHA1 [NIST]. As the security of those algorithms became insufficient, three new secure hash algorithms appeared: SHA256, SHA384, and SHA512 [RFC6234]. MD4 is not used anymore. A common interface has been defined by OpenSSL [OSSL] for those five hash algorithms, in C [CLANG]:¶
EVP_MD_CTX * mdctx; unsigned int dlen; const EVP_MD * md; unsigned char digest[EVP_MAX_MD_SIZE+1]; /* algo is a string naming the desired hash. Case insensitive. Name is one of "md5", "sha1", "sha256", "sha384", and "sha512". */ md = EVP_get_digestbyname(algo); mdctx = EVP_MD_CTX_new(); /* Compute the hash. */ memset(digest, 0, sizeof digest); EVP_DigestInit_ex(mdctx, md, NULL); EVP_DigestUpdate(mdctx, data, sizeof(data)); EVP_DigestFinal_ex(mdctx, digest, &dlen); /* Free the memory used by the context. */ EVP_MD_CTX_free(mdctx);¶
The lengths of the hashes produced by MD5, SHA1, SHA256, SHA384, and SHA512 are, respectively, 128, 160, 256, 384, and 512 bits. Since the length of an OTP is 64 bits, it is necessary to fold the hashes.¶
The technique in C [CLANG] for folding MD5 hashes to 64 bits is taken as is from [RFC2289] (Appendix A):¶
/* The MD5 hash */ unsigned char result[16]; /* Fold the 128 bit result to 64 bits */ for (i = 0; i < 8; i++) result[i] ^= result[i+8];¶
The technique for folding SHA hashes to 64 bits is a generalization of the one presented in [RFC2289] for SHA1. It is designed to be compiled and to run on a 64-bit, Little Endian platform. This algorithm is written in C [CLANG].¶
/* dlen is the number of BYTES contained in the array pointed
to by d1. d2 is the array that receives the result of the
folding. */
void foldShaTo64(unsigned int dlen, unsigned char * d1,
unsigned char d2[8]) {
/* Size of the array pointed to by d1 in number of 32-bit
words. */
unsigned int dlen32 = dlen / 4;
/* Typecast digest d1 to an array of 32-bit words. */
unsigned int ld[dlen32];
unsigned int * pl = (unsigned int *)d1;
for (unsigned int i = 0; i < dlen32; i++) {
ld[i] = *(pl + i);
}
/* Actual folding to 64 bits. */
for (unsigned int i = 2; i < dlen32; i++) {
ld[i % 2] ^= ld[i];
}
/* Store the result as a Big Endian value in the output
array. */
int i, j;
for (i = 0, j = 0; j < 8; i++, j += 4) {
d2[j+0] = (unsigned char)((ld[i] >> 24) & 0xFF);
d2[j+1] = (unsigned char)((ld[i] >> 16) & 0xFF);
d2[j+2] = (unsigned char)((ld[i] >> 8) & 0xFF);
d2[j+3] = (unsigned char)((ld[i] ) & 0xFF);
}
}
¶
We now have the tools for producing 64-bits OTP from hashes computed by any of the five algorithms. Appendix A gives a series of inputs and correct outputs to check the behavior of an implementation of an OTP generator. [RFC2289] gives such information for MD5 and SHA1, while Appendix A here gives the information for the same inputs hashed by SHA256, SHA384, and SHA512 hash algorithms.¶
The conversion of a 64-bit OTP to a set of six words taken from the [RFC2289] Standard Dictionary is based upon the same process (compute a 2-bit checksum from the 64-bit OTP, stick those two bits at the end of the OTP thus producing a 66-bit value; this value is then splitted into six slices of 11 bits that allow to address six different words in a 2048-word dictionary).¶
[RFC2289] specifies a 2048 English word dictionary (Appendix D) that can be used by OTP generators for converting a raw OTP expressed in hexadecimal into a set of six different words taken from that dictionary. This feature is designed to ease authentication by human users.¶
[RFC2289] also specifies a way to use Alternate Dictionaries, that is dictionaries made of 2048 words taken from a language different than English, no word appearing in more than one dictionary. As stated in [RFC2289] Appendix B:¶
"An alternative dictionary of 2048 words may be created such that
each word W and position of the word in the dictionary N obey the
relationship: alg( W ) % 2048 == N where alg is the hash algorithm
used (e.g. MD4, MD5, SHA1). In addition, no words in the standard
dictionary may be chosen."
¶
Let's consider the [RFC2289] Standard Dictionary and the Alternate Dictionary defined in this document (Appendix B), made of 2048 French words, and let's apply the above algorithm to both lists of words, using the five hash algorithms. The results can be found in this document (Appendix C below).¶
For both lists, the collision rate varies roughly from 35% to 37%. This means that on 10 words taken from one of the lists, almost 4 of them share at least two equal (alg(W) % 2048) values. Concretely, every word W of a n-uplet that share the same (alg(W) % 2048) value will be written in the same slot of the 2048-word alternate dictionary, the last word of the n-uplet taking over the first ones. Finally, this technique leaves (n-1) empty slots or "holes" in the final alternate dictionary.¶
This MAY lead to a security weakness if an attacker gets to know the alternate dictionary computed, as shown above, from an initial list of 2048 words (none of them appears in the Standard Dictionary). The alternate dictionary is reduced by roughly 35% in size, eventually easing the task of guessing one or more words that will appear in the next OTP.¶
By design, OTP's cannot be used forever by the same user: when the sequence number, decreased at each successful authentication, reaches zero, the user can't authenticate anymore. A renewal of the user's parameters MUST occur, by providing the server with a new seed, a new sequence number, and the first matching OTP resulting from these new parameters. A different hash algorithm name MAY also be transmitted to the server.¶
The renewal MAY be done by hand, but it is much more efficient to use an automatic mechanism, that is, that does not require a human hand. This would be particularly useful in the field of the Internet of Objects (IoT), for example.¶
Since the channel between a client and a server is supposed unencrypted, the user cannot transmit his new authentication parameters in clear text. The user MUST encrypt them, by using an algorithm both parties have agreed on when the user's account has been created and provisioned in the server. Obviously, the key used to encrypt the new authentication parameters cannot be the current OTP.¶
So we say that, when the sequence number reaches the value 2, the user computes (normally) the OTP matching this sequence number, and computes also the following OTP, that is the OTP that matches the sequence number 1. That last OTP is then used to encrypt the new authentication parameters, which are thansmitted by the user to the server along with the OTP for sequence number 2. The new parameters MAY be encoded in Base 64 before being transmitted. The user and the server can now renew the authentication parameters, thus initiating a new authentication cycle.¶
This document does not create a new registry nor does it register any values in existing registries, and no IANA action is required.¶
This document is entirely about security. Note that the technique described above allows the user to update his authent parameters anytime, whatever the value of the sequence (superior or equal to 2). It is then possible to design the user client program so that it requests a renewal of its authentication parameters on a regular basis (every hour, every twelve hours,...). The client program can also choose a random number between 2 and the current sequence number, and require a renewal when the sequence number reaches the random number. These techniques would constitute a good protection against race attacks, because they prevent an attacker from accumulating data on the sequences of OTP's he may see.¶
This appendix provides a series of inputs and correct outputs for all three of the new OTP cryptographic hashes, specifically SHA256, SHA384, and SHA512. This document is intended to be used by developers for interoperability checks when creating generators or servers. Output is provided in both hexadecimal notation and the six-word encoding with the [RFC2289] Standard Dictionary.¶
Passphrase Seed Cnt Hex Six Word Format
========================================================================
This is a test. TeSt 0 6FF2 6FCA 1D41 2482
DATA HANG USER SAP EVE TOM
This is a test. TeSt 1 61A3 30FB 5460 EFE8
BUSY HAY SUP KYLE DO VEND
This is a test. TeSt 99 A759 47C5 CB99 C0FE
KLAN OVAL TURN HERO HUFF FERN
AbCdEfGhIjK alpha1 0 33B7 C6B4 7704 4BC2
PI MONK LENT TOOT WEB SODA
AbCdEfGhIjK alpha1 1 9D7B 7E17 5E8D 0112
HUSH SIGN FOWL MOAN RINK GARY
AbCdEfGhIjK alpha1 99 3CCC F2F5 054F 0E7C
SKY CLAY MOCK CAP TUNA SUB
OTP's are good correct 0 3ACF A072 7DE5 CAFA
SAW FAIL HUH WILL BOOM FAIR
OTP's are good correct 1 4013 9EB6 13CA 6C66
TEN HUNT LEST MAW KING PEP
OTP's are good correct 99 A194 AD13 0170 DF76
JILL KATE WED APT DEN MILL
¶
Passphrase Seed Cnt Hex Six Word Format
========================================================================
This is a test. TeSt 0 A25E 045C 7326 E83A
JOEL TROY GIL SWAY DALE IDA
This is a test. TeSt 1 0F19 0252 ACE0 9271
DOE OLIN HATH BLUE BUM ROW
This is a test. TeSt 99 BE65 531C A0CC E0D5
MOOD NAG OHIO TON REEK COOL
AbCdEfGhIjK alpha1 0 C542 1287 DBD0 6FFA
NONE EAT JOAN MARS BEN WONT
AbCdEfGhIjK alpha1 1 4A3D 9E8A C1CA DF58
AIRY TOGO JOIN FOAM LICE LEEK
AbCdEfGhIjK alpha1 99 8012 50DA 1475 F556
FILE HAIR RAT MOB BROW LATE
OTP's are good correct 0 3111 133B 8359 9CFA
OWL GALA REST BEE HOLT FAIL
OTP's are good correct 1 1D33 F015 80C0 F50D
IDA ISLE BAD ALP DON FROG
OTP's are good correct 99 F4D5 13BA 5694 3100
VICE KURD TOUR LEON UP FIND
¶
Passphrase Seed Cnt Hex Six Word Format
========================================================================
This is a test. TeSt 0 9A33 631B AA8E 1097
HONK HOST OBOE BEAU SOAK ALTO
This is a test. TeSt 1 72B2 58A6 8686 BC04
DIAL HALF MOT DAD COWL ANT
This is a test. TeSt 99 41B5 690A 77B8 C1CC
TOO LAVA TUM TREK GIST SWAN
AbCdEfGhIjK alpha1 0 40EA E6E7 F6DA 6A1F
TIP BETH MELT TONY KIND DUB
AbCdEfGhIjK alpha1 1 D53A DF93 1E55 FB53
RUTH SARA SUIT SKI BUFF LAMB
AbCdEfGhIjK alpha1 99 91DC 3DF2 5AE1 A17F
GWEN SOLD EYED MAGI HER MOVE
OTP's are good correct 0 0F78 A93E 448A AC9A
DOT NONE AVID GAME LASS ANNE
OTP's are good correct 1 208A CD3F 2C54 BB0E
JOB BERG AVON BITS ALUM FUNK
OTP's are good correct 99 16AF FE29 10EC AB94
GEM FIGS GEAR KEY OWNS OUTS
¶
This dictionary is made up of 2048 French words. None of these words appears in the [RFC2289] Standard Dictionary, and none of these words are composed solely of A to F letters (thus avoiding confusion with hexadecimal numbers). This French dictionary MAY be used as an alternate dictionary by a user, although 35% of its words share at least two equal (alg(W)%2048) values (see Appendix C below). But, once again, this list can be used straightforward as an alternate dictionary because, when receiving a set of six words from this list computed by the user willing to authenticate, the server just computes (alg(W)%2048) for each of the six words. It doesn't care about the number of words in the alternate dictionary that generate the same (alg(W)%2048) value, nor does it need to know the alternate dictionary at all (as stated in [RFC2289]). The syntax of the dictionary is that of the C language [CLANG].¶
char frdict[2048][5] =
{ "AAS", "ADO", "AGA", "AGE", "AGI", "AIE", "AIL", "AIS",
"AIT", "ALE", "ALU", "AME", "AMI", "ANE", "ANS", "API",
"ARA", "ARS", "ASA", "ASE", "AUX", "AXA", "AXE", "AYS",
"BAI", "BAL", "BAS", "BAU", "BEL", "BER", "BIC", "BIO",
"BIP", "BIS", "BLE", "BOA", "BOF", "BOL", "BOT", "BOX",
"BRU", "BUE", "CAS", "CEP", "CES", "CET", "CHU", "CIF",
"CIL", "CIS", "CLE", "COB", "COI", "COQ", "COR", "COU",
"CRE", "CRI", "CRU", "CUL", "DAL", "DAO", "DAW", "DER",
"DEY", "DIA", "DIS", "DIT", "DIX", "DOC", "DOL", "DOM",
"DOP", "DOS", "DRU", "DUC", "DUO", "DUR", "DUS", "DUT",
"EAU", "ECO", "ECU", "ELU", "EMU", "EON", "EPI", "ERE",
"ERG", "ERS", "ETA", "ETE", "EUE", "EUH", "EUS", "EUT",
"EUX", "EXO", "FAQ", "FAX", "FER", "FEU", "FEZ", "FIA",
"FIC", "FIE", "FIL", "FIS", "FLA", "FOB", "FOC", "FOI",
"FOL", "FOU", "FOX", "FUI", "FUS", "FUT", "GAI", "GAN",
"GAZ", "GEO", "GEX", "GIS", "GIT", "GLU", "GOI", "GON",
"GOS", "GOY", "GRE", "GUE", "GUI", "GUR", "HAI", "HEP",
"HEU", "HIA", "HIC", "HIE", "HOU", "HUA", "HUI", "HUN",
"IBN", "IBO", "ICI", "IDE", "IFS", "ILE", "ILS", "IPE",
"ISO", "IVE", "IXA", "IXE", "JAS", "JEU", "JUS", "KAN",
"KAS", "KEA", "KHI", "KIF", "KIL", "KIP", "KIR", "KOB",
"KOP", "KOT", "KRU", "KSI", "KWA", "KYU", "LAI", "LAO",
"LAS", "LEI", "LEK", "LEM", "LES", "LEU", "LEV", "LEZ",
"LIA", "LIS", "LOF", "LOI", "LUE", "LUI", "LUS", "LUT",
"LUX", "LYS", "MAI", "MAL", "MAS", "MAX", "MEC", "MEO",
"MER", "MES", "MIE", "MIL", "MIR", "MIS", "MIX", "MMM",
"MOA", "MOI", "MOL", "MON", "MOR", "MOU", "MOX", "MUA",
"MUE", "MUR", "MUS", "MUT", "MYE", "NEF", "NEM", "NEO",
"NES", "NEY", "NEZ", "NIA", "NID", "NIE", "NIF", "NOM",
"NOS", "NUA", "NUE", "NUI", "NUL", "NUS", "OBA", "OBI",
"OHE", "OHM", "OIE", "OKA", "OLA", "OLE", "ONC", "ONT",
"OPE", "ORS", "OSA", "OSE", "OST", "OTA", "OTE", "OUD",
"OUF", "OUH", "OUI", "OVE", "OXO", "OYE", "PAF", "PAS",
"PEC", "PEU", "PFF", "PHO", "PIC", "PIF", "PIS", "PIU",
"PLI", "PLU", "POU", "PRE", "PSI", "PST", "PSY", "PUA",
"PUE", "PUR", "PUS", "PUY", "QAT", "QIN", "QUE", "QUI",
"RAB", "RAC", "RAD", "RAI", "RAS", "RAZ", "REA", "REE",
"REG", "REM", "REZ", "RHE", "RHO", "RIA", "RIE", "RIF",
"RIS", "RIT", "RIZ", "ROC", "ROI", "ROM", "ROS", "RUA",
"RUS", "RUT", "RUZ", "SAI", "SAR", "SAS", "SAX", "SEL",
"SEP", "SES", "SIC", "SIL", "SIX", "SKA", "SOC", "SOI",
"SOL", "SOM", "SOT", "SOU", "SPI", "SUA", "SUC", "SUR",
"SUS", "SUT", "TAC", "TAF", "TAO", "TAS", "TAT", "TAU",
"TEC", "TEK", "TEL", "TEP", "TER", "TES", "TET", "TEX",
"TIF", "TIR", "TOC", "TOI", "TOT", "TRI", "TUA", "TUE",
"TUF", "TUS", "TUT", "UNE", "UNI", "UNS", "URE", "USA",
"UTE", "VAL", "VAR", "VAS", "VAU", "VER", "VES", "VIA",
"VIF", "VIL", "VIN", "VIS", "VIT", "VOL", "VOS", "VUE",
"VUS", "WAP", "WAX", "WUS", "YAK", "YEN", "YIN", "YOD",
"YUE", "ZEC", "ZEE", "ZEF", "ZEK", "ZEN", "ZIG", "ZIP",
"ZOB", "ZOE", "ZOO", "ZOU", "ZUP", "ZUT",
"ABAT", "ABER", "ABOI", "ABOT", "ABRI", "ABUS", "ACCU", "ACES",
"ACNE", "ACON", "ACRA", "ACTE", "ACTU", "ACUL", "ADAS", "ADAV",
"ADNE", "ADON", "ADOS", "AERA", "AERE", "AFAT", "AFIN", "AGAS",
"AGES", "AGHA", "AGIE", "AGIO", "AGIR", "AGIS", "AGIT", "AGUI",
"AHAN", "AIES", "AIGU", "AILE", "AILS", "AIMA", "AIME", "AINE",
"AIRA", "AIRE", "AIRS", "AISE", "AISY", "AJUT", "AKAN", "ALEA",
"ALEM", "ALES", "ALFA", "ALLA", "ALLE", "ALLO", "ALOI", "ALPE",
"ALUN", "ALUS", "ALYA", "AMAN", "AMAS", "AMER", "AMIE", "AMIS",
"AMMI", "AMUI", "ANAL", "ANAR", "ANAS", "ANEE", "ANEL", "ANES",
"ANGE", "ANIL", "ANIS", "ANON", "ANSE", "ANUS", "AOUT", "APAX",
"APEX", "APIS", "APRE", "APTE", "ARAC", "ARAK", "ARAS", "ARCS",
"ARDU", "AREC", "AREG", "ARES", "AREU", "ARIA", "ARMA", "ARME",
"AROL", "ARUM", "ASES", "ASIN", "ASPE", "ASPI", "ASSE", "ASTI",
"ATRE", "AUBE", "AUGE", "AULA", "AULX", "AUNA", "AUNE", "AVAL",
"AVEC", "AVEN", "AVEU", "AVEZ", "AXAI", "AXAS", "AXAT", "AXEE",
"AXEL", "AXER", "AXES", "AXEZ", "AXIS", "AYEZ", "AZUR", "BACS",
"BAES", "BAHT", "BAIE", "BAIN", "BAIS", "BALS", "BANC", "BANI",
"BANS", "BARS", "BASA", "BASI", "BATA", "BATI", "BATS", "BAUD",
"BAUX", "BAVA", "BAVE", "BAYA", "BAYE", "BEAI", "BEAS", "BECS",
"BEES", "BEEZ", "BEGU", "BEKE", "BELE", "BELS", "BENE", "BENI",
"BENS", "BERK", "BERS", "BETE", "BEUR", "BEYS", "BIBI", "BICS",
"BIEF", "BIGE", "BILA", "BINA", "BINE", "BINZ", "BIOS", "BIPA",
"BIPE", "BIPS", "BIRR", "BISA", "BISE", "BITA", "BITU", "BIWA",
"BLES", "BLET", "BLEU", "BLOG", "BOAS", "BOBO", "BOBS", "BOER",
"BOGE", "BOGS", "BOIS", "BOIT", "BOLS", "BOME", "BONI", "BONS",
"BOPS", "BORA", "BORD", "BORT", "BOTE", "BOTS", "BOUC", "BOUE",
"BOUH", "BOUM", "BOUR", "BOUS", "BOXA", "BOXE", "BOYS", "BRAI",
"BRAS", "BREF", "BREN", "BRIE", "BRIK", "BRIN", "BRIO", "BRIS",
"BROC", "BROL", "BROU", "BRRR", "BRUI", "BRUN", "BRUS", "BRUT",
"BUEE", "BUES", "BUGS", "BUIS", "BUNA", "BUNS", "BURE", "BUSA",
"BUSC", "BUSE", "BUTA", "BUTE", "BUTO", "BUTS", "CABS", "CADI",
"CAGE", "CAID", "CALA", "CALE", "CALO", "CALS", "CAMA", "CAMP",
"CANA", "CAPA", "CAPE", "CAPO", "CAPS", "CARI", "CARS", "CARY",
"CASA", "CATA", "CATI", "CAVA", "CAYE", "CECI", "CEDI", "CELA",
"CELE", "CENE", "CENS", "CEPE", "CEPS", "CERF", "CERS", "CEUX",
"CHAH", "CHAI", "CHAN", "CHAS", "CHEB", "CHER", "CHEZ", "CHIA",
"CHIE", "CHIP", "CHOC", "CHOP", "CHTI", "CHUE", "CHUS", "CHUT",
"CHVA", "CIAO", "CIEL", "CILS", "CIME", "CINE", "CINQ", "CIRA",
"CIRE", "CITA", "CIVE", "CLAC", "CLAP", "CLEF", "CLES", "CLIC",
"CLIM", "CLIN", "CLIP", "CLOS", "CLOU", "COBS", "COCU", "COEF",
"COIR", "COIS", "COIT", "COLO", "COLS", "CONE", "CONS", "COPS",
"COQS", "CORS", "COSY", "COTA", "COTE", "COTI", "COUD", "COUP",
"COUR", "COUS", "COUT", "CRAC", "CRAN", "CRAU", "CREA", "CREE",
"CRET", "CRIA", "CRIC", "CRIE", "CRIN", "CRIS", "CROC", "CRUE",
"CRUS", "CRUT", "CUBI", "CUCU", "CUIR", "CUIS", "CUIT", "CULA",
"CULE", "CULS", "CURA", "CUTI", "CUVA", "CUVE", "CYAN", "CYME",
"CYON", "CZAR", "DABS", "DAHU", "DAIL", "DAIM", "DAIS", "DAMA",
"DAME", "DAMS", "DANS", "DAOS", "DARD", "DARI", "DAUW", "DAWS",
"DEBS", "DECI", "DECO", "DECU", "DEFI", "DEJA", "DELA", "DEME",
"DEMI", "DEMO", "DENI", "DENT", "DERS", "DEUG", "DEUX", "DEYS",
"DIAM", "DIAS", "DIBI", "DICO", "DIEU", "DINA", "DIOL", "DIOT",
"DIRA", "DISE", "DITE", "DITO", "DITS", "DIVA", "DOCS", "DODO",
"DODU", "DOGE", "DOIS", "DOIT", "DOJO", "DOLA", "DOLO", "DOLS",
"DOMS", "DONA", "DONC", "DONF", "DONG", "DONS", "DONT", "DOPA",
"DOPE", "DOPS", "DORE", "DORS", "DORT", "DOSA", "DOTA", "DOTS",
"DOUA", "DOUE", "DOUM", "DOUX", "DRAP", "DROP", "DRUE", "DRUS",
"DRYS", "DUBS", "DUCE", "DUCS", "DUES", "DUIT", "DUOS", "DUPA",
"DUPE", "DURA", "DURE", "DURS", "DYKE", "DYNE", "EAUX", "EBAT",
"ECHA", "ECHE", "ECHU", "ECOS", "ECOT", "ECRU", "ECUS", "EDAM",
"EGAL", "EJET", "ELFE", "ELIA", "ELIE", "ELIS", "ELIT", "ELLE",
"ELUA", "ELUE", "ELUS", "ELUT", "EMBU", "EMET", "EMEU", "EMIA",
"EMIE", "EMIR", "EMIS", "EMOI", "EMOU", "EMUE", "EMUS", "EMUT",
"ENOL", "ENTA", "ENTE", "ENVI", "EONS", "EPAR", "EPEE", "EPIA",
"EPIE", "EPIS", "EPOI", "ERES", "ERGS", "ERRA", "ERRE", "ERSE",
"ESSE", "ESTE", "ETAI", "ETAL", "ETAT", "ETAU", "ETES", "ETOC",
"ETRE", "ETUI", "EUES", "EURO", "EVOE", "EWES", "EXAM", "EXIL",
"EXIT", "EXON", "EXOS", "EXPO", "EYRA", "FACS", "FADO", "FAFS",
"FAIM", "FAIS", "FAIT", "FAIX", "FANA", "FANE", "FANS", "FAON",
"FAQS", "FARD", "FARE", "FARO", "FARS", "FART", "FATS", "FAUT",
"FAUX", "FAXA", "FAXE", "FEAL", "FEES", "FELA", "FELE", "FERA",
"FERS", "FERU", "FETA", "FETE", "FETU", "FEUE", "FEUJ", "FEUS",
"FEUX", "FEVE", "FIAI", "FIAS", "FIAT", "FICS", "FIEE", "FIEL",
"FIER", "FIES", "FIEU", "FIEZ", "FIFI", "FIGE", "FILA", "FILO",
"FILS", "FINI", "FINN", "FINS", "FION", "FIQH", "FISC", "FIXA",
"FIXE", "FIZZ", "FLAC", "FLAN", "FLET", "FLIC", "FLIP", "FLOE",
"FLOP", "FLOT", "FLOU", "FLUA", "FLUO", "FLUX", "FOCS", "FOGS",
"FOHN", "FOIE", "FOIN", "FOIS", "FORA", "FORS", "FOUI", "FOUS",
"FOUT", "FOXE", "FRAC", "FRAI", "FRIC", "FRIS", "FRIT", "FROC",
"FUGU", "FUIE", "FUIR", "FUIS", "FUIT", "FUMA", "FUNE", "FUNS",
"FUSA", "FUTE", "FUTS", "GABA", "GADE", "GAGA", "GAGS", "GAIE",
"GAIS", "GALS", "GANS", "GANT", "GAPS", "GARA", "GARE", "GARI",
"GARS", "GATA", "GAVA", "GAYS", "GAZA", "GAZE", "GEAI", "GELA",
"GELE", "GELS", "GEMI", "GENA", "GENS", "GEOS", "GERA", "GERE",
"GIGA", "GINS", "GITA", "GITE", "GLAS", "GLEY", "GLIE", "GLUA",
"GLUI", "GLUS", "GNON", "GNOU", "GOBA", "GOBE", "GODA", "GODE",
"GOGE", "GOGO", "GOIM", "GOIS", "GOND", "GONS", "GORD", "GOTH",
"GOUM", "GOUR", "GOYM", "GOYS", "GRAM", "GRAS", "GRAU", "GREA",
"GREC", "GREE", "GRES", "GRIL", "GRIP", "GRIS", "GROG", "GROS",
"GRRR", "GRUE", "GUAI", "GUEA", "GUEE", "GUES", "GUET", "GUIB",
"GUIS", "GUNZ", "GURS", "GUSS", "GYMS", "HADJ", "HAIE", "HAIK",
"HAIS", "HAIT", "HAJE", "HAKA", "HALA", "HARO", "HASE", "HATA",
"HAUT", "HAVA", "HAVI", "HEIN", "HELA", "HELE", "HEME", "HEUR",
"HIAI", "HIAS", "HIAT", "HIEE", "HIER", "HIES", "HIEZ", "HIFI",
"HILE", "HITS", "HOAX", "HOCA", "HOIR", "HOLA", "HOMO", "HOPI",
"HORA", "HORS", "HOTE", "HOTS", "HOTU", "HOUA", "HOUE", "HOUP",
"HOUX", "HUAI", "HUAS", "HUAT", "HUBS", "HUEE", "HUER", "HUES",
"HUEZ", "HUIS", "HUIT", "HUMA", "HUME", "HUNE", "HUNS", "HURE",
"HUTU", "IBNS", "IBOS", "IDEE", "IDEM", "IDES", "IGNE", "IGUE",
"IKAT", "ILES", "ILET", "ILOT", "IMAM", "IMAN", "IMBU", "INDE",
"INDU", "INFO", "INNE", "INNU", "INOX", "INSU", "INTI", "INUK",
"IODA", "IODE", "IPES", "IRAI", "IRAS", "IRES", "IREZ", "ISBA",
"ISSA", "ISSU", "ITOU", "IULE", "IVES", "IVRE", "IWAN", "IXAI",
"IXAS", "IXAT", "IXEE", "IXER", "IXES", "IXEZ", "IXIA", "JABS",
"JACO", "JAIN", "JAIS", "JALE", "JAMS", "JANS", "JARD", "JARS",
"JASA", "JASE", "JASS", "JAZZ", "JEEP", "JETA", "JETE", "JETS",
"JEUN", "JEUX", "JEZE", "JOIE", "JOJO", "JOLI", "JONC", "JOTA",
"JOUA", "JOUE", "JOUG", "JOUI", "JOUR", "JUBE", "JUGE", "JUIF",
"JUIN", "JUMP", "JUPE", "JURA", "JURE", "JUTA", "KADI", "KAKI",
"KALI", "KAMI", "KANA", "KANS", "KAON", "KAPO", "KART", "KATA",
"KAVA", "KAWA", "KAWI", "KEAS", "KEPI", "KEUF", "KEUM", "KHAN",
"KHAT", "KHOL", "KIDS", "KIEF", "KIFA", "KIFE", "KIFS", "KIKI",
"KILO", "KILS", "KILT", "KINA", "KINE", "KIPS", "KIRS", "KITS",
"KIWI", "KOAN", "KOBS", "KOKA", "KOLA", "KOPS", "KORA", "KORE",
"KOTA", "KOTE", "KOTO", "KOTS", "KRAK", "KRUS", "KSAR", "KUNA",
"KURU", "KVAS", "KWAS", "KYAT", "KYUS", "LABO", "LACA", "LACS",
"LADS", "LAIC", "LAIE", "LAIS", "LAIT", "LAKH", "LALA", "LAMA",
"LAOS", "LAPA", "LAPE", "LAPS", "LARE", "LARI", "LATS", "LAVE",
"LAYA", "LAYE", "LEGE", "LEGO", "LEGS", "LEHM", "LEKS", "LEMS",
"LESA", "LESE", "LEUR", "LEUS", "LEVA", "LEVE", "LEVS", "LIAI",
"LIAS", "LIAT", "MAAR", "MACH", "MACS", "MAFE", "MAGE", "MAIA",
"MAIE", "MAIS", "MAJE", "MAKI", "MALM", "MALS", "MAMY", "MANS",
"MANX", "MAOS", "MARA", "MARI", "MASO", "MATA", "MATI", "MATS",
"MATU", "MAUX", "MAXI", "MAYA", "MAYE", "MAZA", "MAZE", "MECS",
"MEDE", "MEGA", "MEGI", "MELA", "MELE", "MELO", "MELS", "MEME",
"MENA", "MENE", "MENS", "MENT", "MEOS", "MERE", "MERL", "MERS",
"MESA", "META", "METS", "MEUF", "MEUH", "MEUS", "MEUT", "MEZE",
"MIAM", "MICA", "MIDI", "MIEL", "MIEN", "MIES", "MILS", "MIMA",
"MIME", "MINA", "MING", "MINS", "MIPS", "MIRA", "MIRO", "MIRS",
"MISA", "MISE", "MISO", "MITA", "MIXA", "MIXE", "MOAI", "MOAS",
"MOBS", "MOCO", "MOHO", "MOIE", "MOIS", "MOKA", "MOKO", "MOLY",
"MOME", "MONO", "MONS", "MORD", "MORS", "MOTO", "MOTS", "MOUD",
"MOUE", "MOUS", "MOUT", "MOXA", "MOYA", "MOYE", "MUAI", "MUAS",
"MUAT", "MUEE", "MUER", "MUES", "MUET", "MUEZ", "MUGE", "MUGI",
"MUGS", "MUID", "MUNI", "MUON", "MURA", "MURE", "MURI", "MURS",
"MUSA", "MUSC", "MUSE", "MUTA", "MYES", "NABI", "NAFE", "NAGA",
"NAGE", "NAGI", "NAIF", "NAIN", "NAIS", "NAIT", "NAJA", "NANA",
"NAOS", "NARD", "NASE", "NAYS", "NAZE", "NAZI", "NEEM", "NEES",
"NEFS", "NEMI", "NEMS", "NENE", "NEOS", "NEPE", "NERE", "NERF",
"NETS", "NEUF", "NEVE", "NEYS", "NIAI", "NIAS", "NIAT", "NIDA",
"NIDS", "NIEE", "NIER", "NIES", "NIET", "NIEZ", "NIFE", "NIFS",
"NITS", "NIVE", "NIXE", "NOCA", "NOCE", "NOIE", "NOIR", "NOIX",
"NOME", "NOMS", "NORD", "NORI", "NOTA", "NOUA", "NOUC", "NOUE",
"NOUS", "NOVE", "NOVI", "NOYA", "NOYE", "NUAI", "NUAS", "NUAT",
"NUEE", "NUER", "NUES", "NUEZ", "NUIS", "NUIT", "NULS", "OBAS",
"OBEI", "OBEL", "OBIS", "OBIT", "OBUS", "OCRA", "OCRE", "ODES",
"OEIL", "OEUF", "OGAM", "OGRE", "OHMS", "OIES", "OING", "OINS",
"OKAS", "OKRA", "OLAS", "OLIM", "OLLE", "OMET", "OMIS", "ONDE",
"ONYX", "ONZE", "OPEN", "OPES", "OPTA", "OPTE", "OPUS", "ORBE",
"ORDI", "ORDO", "OREE", "ORES", "ORGE", "ORIN", "ORLE", "ORME",
"ORNA", "ORNE", "ORYX", "OSAI", "OSAS", "OSAT", "OSEE", "OSER",
"OSES", "OSEZ", "OSSU", "OSTO", "OSTS", "OTAI", "OTAS", "OTAT",
"OTEE", "OTER", "OTES", "OTEZ", "OUAH", "OUDS", "OUED", "OUFS",
"OUIE", "OUIN", "OUIR", "OUIS", "OUPS", "OURS", "OUZO", "OVEE",
"OVES", "OVIN", "OVNI", "OXER", "OYAT", "OYES", "OYEZ", "PACA",
"PACK", "PACS", "PAFS", "PAGE", "PAGI", "PAIE", "PAIN", "PAIR",
"PAIS", "PAIT", "PAIX", "PALA", "PALE", "PALI", "PALS", "PALU",
"PAMA", "PAME", "PANA", "PANE", "PANS", "PAON", "PAPA", "PAPE",
"PAPI", "PAPY", "PARA", "PARC", "PARE", "PARI", "PARS", "PART",
"PARU", "PATE", "PATI", "PATS", "PAVA", "PAVE", "PAYA", "PAYE",
"PAYS", "PEAN", "PEAU", "PECS", "PEDE", "PELA", "PELE", "PEND",
"PENE", "PEON", "PEPE", "PEPS", "PERD", "PERE", "PERF", "PERI",
"PERM", "PERS", "PESA", "PESE", "PESO", "PETA", "PETE", "PETS",
"PEUH", "PEUL", "PEUR", "PEUT", "PEUX", "PEZE", "PFFT", "PFUT",
"PHOS", "PHOT", "PIAF", "PIAN", "PICA", "PICS", "PIED", "PIER",
"PIES", "PIEU", "PIFA", "PIFE", "PIFS", "PIGE", "PILA", "PILE",
"PILS", "PINE", "PINS", "PION", "PIPA", "PIPE", "PIPI", "PIPO",
"PIRE", "PISE", "PITA", "PITE", "PIVE", "PLAF", "PLAN", "PLAT",
"PLIA", "PLIE", "PLIS", "PLOC", "PLOT", "PLUS", "PLUT", "PNEU",
"POCO", "POGO", "POIL", "POIS", "POIX", "POLE", "POLI", "POLO",
"POLY", "POND", "PONT", "POOL", "POPE", "POPS", "PORC", "PORE",
"PORT", "POSA", "POSE", "POTE", "POTS", "POTU", "POUF", "POUH",
"POUM", "POUR", "POUX", "POYA", "PRAO", "PRES", "PRET", "PRIA",
"PRIE", "PRIS", "PRIT", "PRIX", "PROF", "PROS", "PROU", "PSYS",
"PUAI", "PUAS", "PUAT", "PUBS", "PUCE", "PUCK", "PUEE", "PUER",
"PUES", "PUEZ", "PUIS", "PUJA", "PULA", "PULL", "PUMA", "PUNA",
"PUNI", "PUNK", "PUNT", "PUPE", "PURE", "PURO", "PURS", "PUTE",
"PUTS", "PUTT", "PUYS", "QATS", "QING", "QINS", "QUAI", "QUEL",
"QUIA", "QUIZ", "QUOI", "RAAG", "RABE", "RABS", "RACA", "RADA",
"RADE", "RADS", "RAGA", "RAIA", "RAIE", "RAIS", "RAIT", "RAJA",
"RAKI", "RALA", "RALE", "RAMA", "RAME", "RAMI", "RAND", "RANG",
"RANI", "RANZ", "RAPA", "RAPE", "RAPS", "RAPT", "RASA", "RASE",
"RATA", "RATS", "RAVI", "RAYA", "RAYE", "REAC", "REAI", "REAS",
"REAT", "REBU", "RECU", "REDU", "REER", "REES", "REEZ", "REGI",
"REGS", "REIS", "RELU", "REMS", "RENE", "REPS", "REPU", "RETS",
"REVA", "REVE", "REVU", "RHES", "RHUM", "RIAD", "RIAL", "RIAS",
"RIDA", "RIEL", "RIEN", "RIES", "RIEZ", "RIFF", "RIFS", "RIMA",
"RIOS", "RIPA", "RIPE", "RIRA", "RIRE", "RISS", "RITS", "RIVA",
"RIVE", "RIXE", "ROBA", "ROBS", "ROCS", "RODA", "ROIS", "ROLE",
"ROMS", "ROND", "ROSI", "ROTA", "ROTE", "ROTI", "ROTS", "ROUA",
"ROUE", "ROUF", "ROUI", "ROUX", "RUAI", "RUAS", "RUAT", "RUEE",
"RUER", "RUES", "RUEZ", "RUGI", "RUMB", "RUNE", "RUPA", "RUPE",
"RUSA", "RUTS", "RYAD", "RYAL", "RYES", "SACS", "SADO", "SAGA",
"SAIE", "SAIN", "SAIS", "SAIT", "SAKE", "SAKI", "SALA", "SALI",
"SALS", "SAMU", "SANA", "SANS", "SAPA", "SAPE", "SARI", "SARS",
"SART", "SATE", "SATI", "SAUF", "SAUR", "SAUT", "SAXE", "SAXO",
"SCIA", "SCIE", "SEAU", "SECS", "SECU", "SEGA", "SEIN", "SELS",
"SEMA", "SEME", "SENE", "SENS", "SEPS", "SEPT", "SERA", "SERE",
"SERF", "SERS", "SERT", "SEUL", "SEVE", "SEVI", "SEXE", "SEXY",
"SHAH", "SHIT", "SIAL", "SIDA", "SIDI", "TAAL", "TACO", "TACS",
"TAEL", "TAFS", "TAGS", "TAIE", "TAIN", "TAIS", "TAIT", "TAKA",
"TALA", "TALC", "TANS", "TANT", "TAON", "TAOS", "TAPA", "TAPE",
"TAPI", "TARA", "TARD", "TARE", "TARI", "TARO", "TARS", "TAUX",
"TAXA", "TAXE", "TAXI", "TEST", "TOUS", "TRES", "TROP", "TRIO",
"TRUC", "TUBE", "UNIR", "VERS", "VERT", "VELO", "VITE", "VLAN",
"VOIR", "VOIX", "VOUS", "VRAI", "WOLF", "XENON", "YACK", "YEUX",
"YOGA", "ZINC"
};
¶
For a given dictionary (English or EN, French or FR), and a given hash algorithm (MD5, SHA1, SHA256, SHA384, or SHA512), this table shows the number (and ratio on 2048 words) of collisions - that is, the number of words that share at least two equal (alg(word) % 2048) values. The EN dictionary is the [RFC2289] standard, while the FR dictionary is made of 2048 French different words shown in Appendix B above. None of these words appears in the English [RFC2289] standard dictionary.¶
| lang/alg | MD5 | SHA1 | SHA256 | SHA384 | SHA512 |
| FR | 759 37,0% |
766 37,4% |
757 37,0% |
763 37,3% |
764 37,3% |
| EN | 727 35,5% |
722 35,3% |
730 35,6% |
762 37,2% |
755 36,9% |
These figures show that collision rate varies from 35,3% to 37,4%, which can be considered very high, whatever the dictionary, word distribution, and hash algorithm. They mean that, among 10 words randomly chosen in a source dictionary, almost 4 of them share 1 slot in the final (computed) alternate dictionary.¶