63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
// Package passgen generates random passwords.
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//
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// Example usage:
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//
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// p := passgen.New() // p is "6NX(W`GD]4:Tqk};Y@A-"
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//
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// Logic originally from dchest's uniuri library:
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// https://github.com/dchest/uniuri
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//
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// Functions read from crypto/rand random source, and panic if they fail to
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// read from it.
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package passgen
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import "crypto/rand"
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// DefLen is the default password length returned.
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const DefLen = 20
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// DefChars is the default set of characters used in the password.
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var DefChars = []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()- _=+,.?/:;{}[]`~")
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// New returns a random, unmemorable password of the default length with the
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// default set of characters.
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func New() string {
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return NewLenChars(DefLen, DefChars)
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}
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// NewLen returns a random, unmemorable password of the given length with the
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// default set of characters.
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func NewLen(length int) string {
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return NewLenChars(length, DefChars)
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}
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// NewLenChars returns a random, unmemorable password of the given length with
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// the given set of characters.
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func NewLenChars(length int, chars []byte) string {
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if length == 0 {
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return ""
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}
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clen := len(chars)
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maxrb := 255 - (256 % clen)
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b := make([]byte, length)
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r := make([]byte, length+(length/4)) // storage for random bytes.
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i := 0
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for {
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if _, err := rand.Read(r); err != nil {
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panic("passgen: error reading random bytes: " + err.Error())
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}
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for _, rb := range r {
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c := int(rb)
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if c > maxrb {
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// Skip this number to avoid modulo bias.
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continue
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}
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b[i] = chars[c%clen]
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i++
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if i == length {
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return string(b)
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}
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}
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}
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}
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