mirror of
https://github.com/emmansun/gmsm.git
synced 2025-04-22 02:06:18 +08:00
249 lines
7.5 KiB
Go
249 lines
7.5 KiB
Go
package drbg
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import (
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"crypto/cipher"
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"crypto/rand"
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"errors"
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"hash"
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"io"
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"time"
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"github.com/emmansun/gmsm/sm3"
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"github.com/emmansun/gmsm/sm4"
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)
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const DRBG_RESEED_COUNTER_INTERVAL_LEVEL_TEST uint64 = 8
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const DRBG_RESEED_COUNTER_INTERVAL_LEVEL2 uint64 = 1 << 10
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const DRBG_RESEED_COUNTER_INTERVAL_LEVEL1 uint64 = 1 << 20
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const DRBG_RESEED_TIME_INTERVAL_LEVEL_TEST = time.Duration(6) * time.Second
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const DRBG_RESEED_TIME_INTERVAL_LEVEL2 = time.Duration(60) * time.Second
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const DRBG_RESEED_TIME_INTERVAL_LEVEL1 = time.Duration(600) * time.Second
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const MAX_BYTES = 1 << 27
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const MAX_BYTES_PER_GENERATE = 1 << 11
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var ErrReseedRequired = errors.New("reseed reuqired")
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type SecurityLevel byte
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const (
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SECURITY_LEVEL_ONE SecurityLevel = 0x01
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SECURITY_LEVEL_TWO SecurityLevel = 0x02
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SECURITY_LEVEL_TEST SecurityLevel = 0x99
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)
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// DrbgPrng sample pseudo random number generator base on DRBG
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type DrbgPrng struct {
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entropySource io.Reader
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securityStrength int
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impl DRBG
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}
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// NewCtrDrbgPrng create pseudo random number generator base on CTR DRBG
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func NewCtrDrbgPrng(cipherProvider func(key []byte) (cipher.Block, error), keyLen int, entropySource io.Reader, securityStrength int, gm bool, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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prng := new(DrbgPrng)
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if entropySource != nil {
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prng.entropySource = entropySource
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} else {
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prng.entropySource = rand.Reader
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}
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prng.securityStrength = selectSecurityStrength(securityStrength)
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if gm && securityStrength < 32 {
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return nil, errors.New("invalid security strength")
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}
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// Get entropy input
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entropyInput := make([]byte, prng.securityStrength)
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err := prng.getEntropy(entropyInput)
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if err != nil {
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return nil, err
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}
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// Get nonce
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nonce := make([]byte, prng.securityStrength/2)
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err = prng.getEntropy(nonce)
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if err != nil {
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return nil, err
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}
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prng.impl, err = NewCtrDrbg(cipherProvider, keyLen, securityLevel, gm, entropyInput, nonce, personalization)
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if err != nil {
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return nil, err
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}
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return prng, nil
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}
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// NewNistCtrDrbgPrng create pseudo random number generator base on CTR DRBG which follows NIST standard
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func NewNistCtrDrbgPrng(cipherProvider func(key []byte) (cipher.Block, error), keyLen int, entropySource io.Reader, securityStrength int, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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return NewCtrDrbgPrng(cipherProvider, keyLen, entropySource, securityStrength, false, securityLevel, personalization)
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}
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// NewNistCtrDrbgPrng create pseudo random number generator base on CTR DRBG which follows GM/T 0105-2021 standard
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func NewGmCtrDrbgPrng(entropySource io.Reader, securityStrength int, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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return NewCtrDrbgPrng(sm4.NewCipher, 16, entropySource, securityStrength, true, securityLevel, personalization)
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}
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// NewHashDrbgPrng create pseudo random number generator base on HASH DRBG
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func NewHashDrbgPrng(md hash.Hash, entropySource io.Reader, securityStrength int, gm bool, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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prng := new(DrbgPrng)
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if entropySource != nil {
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prng.entropySource = entropySource
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} else {
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prng.entropySource = rand.Reader
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}
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prng.securityStrength = selectSecurityStrength(securityStrength)
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if gm && securityStrength < 32 {
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return nil, errors.New("invalid security strength")
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}
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// Get entropy input
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entropyInput := make([]byte, prng.securityStrength)
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err := prng.getEntropy(entropyInput)
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if err != nil {
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return nil, err
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}
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// Get nonce from entropy source here
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nonce := make([]byte, prng.securityStrength/2)
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err = prng.getEntropy(nonce)
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if err != nil {
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return nil, err
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}
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prng.impl, err = NewHashDrbg(md, securityLevel, gm, entropyInput, nonce, personalization)
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if err != nil {
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return nil, err
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}
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return prng, nil
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}
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// NewNistHashDrbgPrng create pseudo random number generator base on hash DRBG which follows NIST standard
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func NewNistHashDrbgPrng(md hash.Hash, entropySource io.Reader, securityStrength int, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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return NewHashDrbgPrng(md, entropySource, securityStrength, false, securityLevel, personalization)
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}
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// NewGmHashDrbgPrng create pseudo random number generator base on hash DRBG which follows GM/T 0105-2021 standard
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func NewGmHashDrbgPrng(entropySource io.Reader, securityStrength int, securityLevel SecurityLevel, personalization []byte) (*DrbgPrng, error) {
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return NewHashDrbgPrng(sm3.New(), entropySource, securityStrength, true, securityLevel, personalization)
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}
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func (prng *DrbgPrng) getEntropy(entropyInput []byte) error {
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n, err := prng.entropySource.Read(entropyInput)
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if err != nil {
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return err
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}
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if n != len(entropyInput) {
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return errors.New("fail to read enough entropy input")
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}
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return nil
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}
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func (prng *DrbgPrng) Read(data []byte) (int, error) {
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maxBytesPerRequest := prng.impl.MaxBytesPerRequest()
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total := 0
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for len(data) > 0 {
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b := data
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if len(data) > maxBytesPerRequest {
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b = data[:maxBytesPerRequest]
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}
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err := prng.impl.Generate(b, nil)
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if err == ErrReseedRequired {
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entropyInput := make([]byte, prng.securityStrength)
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err := prng.getEntropy(entropyInput)
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if err != nil {
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return 0, err
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}
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err = prng.impl.Reseed(entropyInput, nil)
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if err != nil {
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return 0, err
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}
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} else if err != nil {
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return 0, err
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}
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total += len(b)
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data = data[len(b):]
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}
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return total, nil
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}
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// DRBG interface for both hash and ctr drbg implementations
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type DRBG interface {
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// check internal state, return if reseed required
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NeedReseed() bool
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// reseed process
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Reseed(entropy, additional []byte) error
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// generate requrested bytes to b
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Generate(b, additional []byte) error
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// MaxBytesPerRequest return max bytes per request
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MaxBytesPerRequest() int
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}
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type BaseDrbg struct {
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v []byte
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seedLength int
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reseedTime time.Time
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reseedIntervalInTime time.Duration
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reseedCounter uint64
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reseedIntervalInCounter uint64
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securityLevel SecurityLevel
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gm bool
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}
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func (hd *BaseDrbg) NeedReseed() bool {
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return (hd.reseedCounter > hd.reseedIntervalInCounter) || (hd.gm && time.Since(hd.reseedTime) > hd.reseedIntervalInTime)
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}
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func (hd *BaseDrbg) setSecurityLevel(securityLevel SecurityLevel) {
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hd.securityLevel = securityLevel
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switch securityLevel {
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case SECURITY_LEVEL_TWO:
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hd.reseedIntervalInCounter = DRBG_RESEED_COUNTER_INTERVAL_LEVEL2
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hd.reseedIntervalInTime = DRBG_RESEED_TIME_INTERVAL_LEVEL2
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case SECURITY_LEVEL_TEST:
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hd.reseedIntervalInCounter = DRBG_RESEED_COUNTER_INTERVAL_LEVEL_TEST
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hd.reseedIntervalInTime = DRBG_RESEED_TIME_INTERVAL_LEVEL_TEST
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default:
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hd.reseedIntervalInCounter = DRBG_RESEED_COUNTER_INTERVAL_LEVEL1
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hd.reseedIntervalInTime = DRBG_RESEED_TIME_INTERVAL_LEVEL1
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}
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}
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func selectSecurityStrength(requested int) int {
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switch {
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case requested <= 14:
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return 14
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case requested <= 16:
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return 16
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case requested <= 24:
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return 24
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case requested <= 32:
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return 32
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default:
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return requested
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}
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}
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func add(left, right []byte, len int) {
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var temp uint16 = 0
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for i := len - 1; i >= 0; i-- {
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temp += uint16(left[i]) + uint16(right[i])
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right[i] = byte(temp & 0xff)
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temp >>= 8
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}
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}
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func addOne(data []byte, len int) {
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var temp uint16 = 1
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for i := len - 1; i >= 0; i-- {
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temp += uint16(data[i])
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data[i] = byte(temp & 0xff)
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temp >>= 8
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}
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}
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