remove mean stuff, doesn't work properly

README.md

@@ -87,21 +87,6 @@ Of course we do not use RLE. We measure compression
 using the [Flate algorithm](
 https://en.m.wikipedia.org/wiki/Deflate).
 
-### Optional: arithmetic mean value
-
-This is simply the result of summing the all the printable ascii chars
-divided by password length. The ideal value would be ~80, because most
-normal  letters hang  out in  the upper  area between  32 (space)  and
-126(tilde). We  consider a password ok,  if its mean lies  around this
-area give or  take 5.  If the  mean departs more from  this value, the
-characters are consistently  high or low (e.g. more  numbers and upper
-case  letters or  only  lower case  letters). The  latter,  5, can  be
-tweaked. The larger the number, tha laxer the result.
-
-Please be  warned, that this  metric will in  most cases give  you bad
-results on otherwise good passwords,  such as diceware passwords. Only
-use it if you know what you're doing.
-
 ### Optional: dictionary check
 
 You can supply a dictionary of words of your
@@ -149,7 +134,6 @@ type Options struct {
 	CharDistribution float64     // minimum character distribution in percent, default 10%
 	Entropy          float64     // minimum entropy value in bits/char, default 3 bits/s
 	Dictionary       *Dictionary // lookup given dictionary, the caller has to provide it
-	MeanDeviation    float64     // minimum arithmetic mean deviation, by default disabled, standard 5
 }
 ```
 

lib.go

@@ -26,27 +26,18 @@ type Options struct {
 	CharDistribution float64     // minimum character distribution in percent, default 10%
 	Entropy          float64     // minimum entropy value in bits/char, default 3 bits/s
 	Dictionary       *Dictionary // lookup given dictionary, the caller has to provide it
-	MeanDeviation    float64     // minimum arithmetic mean deviation, by default disabled, standard 5
 }
 
 const (
-	MIN_COMPRESS         int     = 10
-	MIN_DIST             float64 = 10.0
-	MIN_ENTROPY          float64 = 3.0
-	MIN_DICT_LEN         int     = 5000
-	MAX_CHARS            int     = 95 // maximum printable US ASCII chars
-	LIMIT_MEAN_DEVIATION float64 = 20
+	MIN_COMPRESS int     = 10
+	MIN_DIST     float64 = 10.0
+	MIN_ENTROPY  float64 = 3.0
+	MIN_DICT_LEN int     = 5000
+	MAX_CHARS    int     = 95 // maximum printable US ASCII chars
 
 	//  we start  our ascii  arrays  at char(32),  so to  have max  95
 	// elements in the slice, we subtract 32 from each ascii code
 	ascii_base byte = 32
-
-	//  arithmetic  mean limits:  we work on  chr(32) til  chr(126) in
-	// ascii. The mean value, however, is not 63 as one would suppose,
-	// but  80, because most used  printable ascii chars exist  in the
-	// upper area  of the space. So,  we take 80 as  the middle ground
-	// and go beyond 5 up or down
-	mean_base float64 = 80
 )
 
 // Result stores the results of all validations.
@@ -56,7 +47,6 @@ type Result struct {
 	Compress         int     // actual compression rate in percent
 	CharDistribution float64 // actual character distribution in percent
 	Entropy          float64 // actual entropy value in bits/chars
-	Mean             float64 // actual arithmetic mean, close to 127.5 is best
 }
 
 // Validate  validates a given password.  You can  tune its  behavior
@@ -73,7 +63,6 @@ func Validate(passphrase string, opts ...Options) (Result, error) {
 		CharDistribution: MIN_DIST,
 		Entropy:          MIN_ENTROPY,
 		Dictionary:       nil,
-		MeanDeviation:    0,
 	}
 
 	if len(opts) == 1 {
@@ -133,16 +122,6 @@ func Validate(passphrase string, opts ...Options) (Result, error) {
 		}
 	}
 
-	if options.MeanDeviation > 0 {
-		mean := getArithmeticMean(passphrase)
-
-		if mean > (mean_base+options.MeanDeviation) || mean < (mean_base-options.MeanDeviation) {
-			result.Ok = false
-		}
-
-		result.Mean = mean
-	}
-
 	return result, nil
 }
 
@@ -263,27 +242,3 @@ func getDictMatch(passphrase string, dict *Dictionary) (bool, error) {
 
 	return false, nil
 }
-
-/*
-* Return  the arithmetic  mean value:
-
-	This is simply the result of summing the all the bytes (bits if the
-
--b  option  is specified)  in  the  file  and  dividing by  the  file
-length. If the  data are close to random, this  should be about 127.5
-(0.5 for -b option output). If  the mean departs from this value, the
-values are consistently high or low.
-
-	Working on US-ASCII space
-*/
-func getArithmeticMean(passphrase string) float64 {
-	sum := 0.0
-	count := 0.0
-
-	for _, char := range []byte(passphrase) {
-		sum += float64(char)
-		count++
-	}
-
-	return sum / count
-}

lib_test.go

@@ -171,59 +171,6 @@ var pass_dict_bad = []string{
 	`effected`, `ministry`,
 }
 
-var pass_mean_bad = []string{
-	`UT6RTLTNAK3JN2UVWJGXSLHKT4P3ECXJ`,
-	`L4HENABMJR0UZBFSFV0GPSXWZ4HEMOHO`,
-	`YTYPHSGR8XHP4C85T3YZFF4TG2OLMQVF`,
-	`TWAGHNVLMYR5RW67RNKUO8K3SPYAJID2`,
-	`MU0OCIE9ZUYBFLMSKWKCLTSWKZ6GBTLM`,
-	`GHBSLIVXCJCVUNTJBSPHXZUSE906QGZH`,
-	`PZWQMRNG8LDRTY9GVELRALXCO181O8AK`,
-	`KZYKWCUZWDG4OSREEKCKOA58JQMRUUBZ`,
-	`CKZWG3H6A2TJKJDPEFX2CESMPYTA7WBF`,
-	`RT8HGYUBUNUJMF0SLWKW8JISCRSG6L6M`,
-	`368WCV4PGAWE1MWZJWZU8JPEQILMEBHV`,
-	`W6HVUTBNAGJN4ABMWEKK5OHTIXUYTPDG`,
-	`GZXQAEWMNSKJDYVQRPYIQXJTPIDHMF9T`,
-	`AWTJNUFOTML7GC2OC04K74F30AO9A2VJ`,
-	`MTHJUGOHCTYNWICVVNEMETRYA2L2QHBE`,
-	`XHTUQVYNSBPTH8TWCRMMV6BILHV6KYOP`,
-	`MTNAROLNNZZBARVNKGGVLL8VR682GQUP`,
-	`3VDYD0CJGFQ1UQKTRQOUQ5FZ4PROITVQ`,
-	`JWOFUTKGTVG035HUFTTWHGLECAX5IYMX`,
-	`DVVMB6XXZPALLFMEFJRMSZUZIRU7CLNF`,
-	`QCNKZ82LGDHT97LGJKLEVUSU1MSX7FNH`,
-	`HWNZDPHHFIDO88FB4KMJSTBI35FEJUCN`,
-	`1MJ7DRGDQ9BETU5JJ3NPUEWVSLZB9WGP`,
-	`TCVC1RLXKIKGIVYGGWOEQXDRSHQJCJUA`,
-	`BYMT86DO8VNU0UF0FFOC3EPLMLANAYY5`,
-	`OPEBVIMRKAAGURO3BQAGFSZQ0MV9OBAJ`,
-	`BKZUICCERVRZCFPSMFZPY1UHPFEDJLUH`,
-	`ECWSDOGFI1PXHI2ZAP06O1CT8USL7HLM`,
-	`ZRNFW4CWXP5HHYBETZQFTNOL6AJ8ZMXZ`,
-	`UDV3CHYM4YJUFMIS9QCHWEO1DIZ7PH59`,
-	`KS7FYTZ12TAZ8J3MTZAPT7TGXMYNABGX`,
-	`BFNAM5SRZQGO9ENP1E14GGJR8HDZZUHS`,
-	`34IIW3TPK2IUDTYVSEGNHNR0RLI1TL7B`,
-	`7TMGYVOA4NRHSY6TF6MRHHFJ07GOW2YR`,
-	`SDS0RTQUPVAGDMNYXYCVJEV2MDT4IH5S`,
-	`IQMMSGHI5JNG5VIV5K6N11WCGGGCSBWP`,
-	`11LMWSI2YPRMOJ9MBIA4IPKFPOJPS71U`,
-	`CPMXAMBOTBQ6AHXJ1FRHWBWZUX8TENST`,
-	`LEHQVCBRSSHY482UU1MZJZGFHWKWE716`,
-	`KMCGTBIYSJXDURAX5F1QQQB3Y1UU2EF6`,
-	`VPPZ8UFNTXAANQWDIDIAQJACVZPQIQ94`,
-	`CQ3GOBWGX91FT1SVVLOLCDX54HWUYLKO`,
-	`DKRJ7CX5JCKHEKI2JKMVPCHRCT3IKKUK`,
-	`XILAMTWXXGAHHMEUPNXBP5HQEGKCFH8X`,
-	`OGJ7A3RNOCSGPPUXSPOING6AYUNZ8OSR`,
-	`LB1XL9YWUXX6Q7GJBDI0BISHG7V1PAXY`,
-	`YRUJYIOYDNYBUBQK0YY02WA45YNGTKMS`,
-	`UTPTMOILT9WI3O2ZPPASMHQYCJPO2HTT`,
-	`J6NXVXG5FN9CTWYEYQBLFVZSSALFDJEF`,
-	`CQC84VGBZMJ65I8XLRF2PBMK5X86BVMC`,
-}
-
 var pass_dictsub_bad = []string{
 	`regational`, `iminalizat`, `rconductiv`, `substantia`,
 	`oritativen`, `trocardiog`, `communicat`, `aracterist`,
@@ -272,10 +219,6 @@ var opts_invaliddict = valpass.Options{
 	Dictionary:       &valpass.Dictionary{Words: []string{"eins", "zwei", "drei"}},
 }
 
-var opts_mean = valpass.Options{
-	MeanDeviation: 15, // very lax in order to succeed!
-}
-
 var tests = []Test{
 	{
 		name:      "checkgood",
@@ -295,12 +238,6 @@ var tests = []Test{
 		opts:      opts_dictsub,
 		passwords: Passwordlist{pass_dictsub_bad},
 	},
-	{
-		name:      "checkgood-mean",
-		want:      true,
-		opts:      opts_mean,
-		passwords: Passwordlist{pass_random_good},
-	},
 	{
 		name:      "checkbad",
 		want:      false,