146 lines
4.0 KiB
Go
146 lines
4.0 KiB
Go
package random
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import (
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"crypto/rand"
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"fmt"
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"io"
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"math/big"
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)
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// NewCryptographical returns a random.Provider, specifically *random.Cryptographical.
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func NewCryptographical() *Cryptographical {
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return &Cryptographical{}
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}
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// Cryptographical is the production random.Provider which uses crypto/rand.
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type Cryptographical struct{}
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// Read implements the io.Reader interface.
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func (r *Cryptographical) Read(p []byte) (n int, err error) {
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return io.ReadFull(rand.Reader, p)
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}
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// BytesErr returns random data as bytes with the standard random.DefaultN length and can contain any byte values
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// (including unreadable byte values). If an error is returned from the random read this function returns it.
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func (r *Cryptographical) BytesErr() (data []byte, err error) {
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return r.BytesCustomErr(0, nil)
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}
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// Bytes returns random data as bytes with the standard random.DefaultN length and can contain any byte values
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// (including unreadable byte values). If an error is returned from the random read this function ignores it.
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func (r *Cryptographical) Bytes() (data []byte) {
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data, _ = r.BytesErr()
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return data
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}
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// BytesCustomErr returns random data as bytes with n length and can contain only byte values from the provided
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// values. If n is less than 1 then DefaultN is used instead. If an error is returned from the random read this function
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// returns it.
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func (r *Cryptographical) BytesCustomErr(n int, charset []byte) (data []byte, err error) {
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if n < 1 {
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n = DefaultN
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}
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data = make([]byte, n)
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if _, err = rand.Read(data); err != nil {
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return nil, err
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}
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t := len(charset)
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if t > 0 {
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for i := 0; i < n; i++ {
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data[i] = charset[data[i]%byte(t)]
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}
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}
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return data, nil
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}
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// StringCustomErr is an overload of BytesCustomWithErr which takes a characters string and returns a string.
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func (r *Cryptographical) StringCustomErr(n int, characters string) (data string, err error) {
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var d []byte
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if d, err = r.BytesCustomErr(n, []byte(characters)); err != nil {
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return "", err
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}
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return string(d), nil
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}
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// BytesCustom returns random data as bytes with n length and can contain only byte values from the provided values.
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// If n is less than 1 then DefaultN is used instead. If an error is returned from the random read this function
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// ignores it.
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func (r *Cryptographical) BytesCustom(n int, charset []byte) (data []byte) {
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data, _ = r.BytesCustomErr(n, charset)
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return data
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}
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// StringCustom is an overload of BytesCustom which takes a characters string and returns a string.
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func (r *Cryptographical) StringCustom(n int, characters string) (data string) {
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return string(r.BytesCustom(n, []byte(characters)))
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}
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// IntnErr returns a random int error combination with a maximum of n.
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func (r *Cryptographical) IntnErr(n int) (value int, err error) {
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if n <= 0 {
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return 0, fmt.Errorf("n must be more than 0")
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}
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max := big.NewInt(int64(n))
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var result *big.Int
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if result, err = r.IntErr(max); err != nil {
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return 0, err
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}
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value = int(result.Int64())
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if value < 0 {
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return 0, fmt.Errorf("generated number is too big for int")
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}
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return value, nil
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}
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// Intn returns a random int with a maximum of n.
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func (r *Cryptographical) Intn(n int) (value int) {
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value, _ = r.IntnErr(n)
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return value
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}
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// IntErr returns a random *big.Int error combination with a maximum of max.
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func (r *Cryptographical) IntErr(max *big.Int) (value *big.Int, err error) {
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if max == nil {
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return nil, fmt.Errorf("max is required")
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}
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if max.Sign() <= 0 {
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return nil, fmt.Errorf("max must be 1 or more")
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}
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return rand.Int(rand.Reader, max)
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}
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// Int returns a random *big.Int with a maximum of max.
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func (r *Cryptographical) Int(max *big.Int) (value *big.Int) {
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var err error
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if value, err = r.IntErr(max); err != nil {
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return big.NewInt(-1)
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}
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return value
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}
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// Prime returns a number of the given bit length that is prime with high probability. Prime will return error for any
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// error returned by rand.Read or if bits < 2.
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func (r *Cryptographical) Prime(bits int) (prime *big.Int, err error) {
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return rand.Prime(rand.Reader, bits)
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}
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