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rmcp_plus.go
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rmcp_plus.go
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package virtualbmc
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/rand"
"crypto/sha1"
"encoding/binary"
"encoding/hex"
"errors"
"io"
)
const (
payloadTypeRMCPPlusOpenSessionRequest = 0x10
payloadTypeRMCPPlusOpenSessionResponse = 0x11
payloadTypeRAKPMessage1 = 0x12
payloadTypeRAKPMessage2 = 0x13
payloadTypeRAKPMessage3 = 0x14
payloadTypeRAKPMessage4 = 0x15
)
type maximumPrivilegeLevel uint8
// 0x01: Callback, 0x02: User, 0x03: Operator. 0x04: Administrator, 0x05: OEM
// We only use Administrator
const maximumPrivilegeLevelAdministrator maximumPrivilegeLevel = 0x04
type rmcpStatus uint8
const (
rmcpPlusStatusNoErrors rmcpStatus = 0x00
)
type authenticationAlgorithm uint8
// 0x00: RKAP-SHA1, 0x01: RKAP-HMAC-SHA1, 0x02: RKAP-HMAC-MD5, 0x03: RKAP-HMAC-SHA256
// We only support RKAP-HMAC-SHA1 which is default authentication algorithm
const authenticationAlgorithmRKAPHMACSHA1 authenticationAlgorithm = 0x01
type integrityAlgorithm uint8
// 0x01: HMAC-SHA1-196, 0x02: HMAC-MD5-128, 0x03: MD5-128, 0x04: HMAC-SHA-256-128
// We only support HMAC-SHA1-196 which is default integrity algorithm
const integrityAlgorithmHMACSHA1196 integrityAlgorithm = 0x01
type confidentialityAlgorithm uint8
// 0x01: AES-CBC-128, 0x02: XRC-4128, 0x03: XRC-440
// We only support AES-CBC-128 which is default confidentiality algorithm
const confidentialityAlgorithmAESCBC128 confidentialityAlgorithm = 0x01
const authenticationPayloadTypeAuthenticationAlgorithm = 0x00
const integrityPayloadTypeIntegrityAlgorithm = 0x01
const confidentialityPayloadTypeConfidentialityAlgorithm = 0x02
// rmcpPlus represents RMCP+
type rmcpPlus struct {
header *rmcpPlusSessionHeader
session *rmcpPlusSessionHolder
bmcUser *bmcUserHolder
}
// rmcpPlusSessionHeader represents RMCP+ RMCPPlusSession Header
type rmcpPlusSessionHeader struct {
AuthenticationType authenticationType
// encrypted(1b) + authenticated(1b) + payloadType(6b)
PayloadType uint8
SessionId uint32
SessionSequenceNumber uint32
IpmiPayloadLen uint16
}
// openSessionRequestPayload represents Open RMCPPlusSession Request payload
type openSessionRequestPayload struct {
MessageTag uint8
RequestedMaximumPrivilegeLevel maximumPrivilegeLevel
Reserved2 [2]byte
RemoteConsoleSessionId uint32
AuthenticationPayloadType uint8
Reserved3 [2]byte
AuthenticationPayloadLength uint8
AuthenticationPayloadAlgorithm authenticationAlgorithm
Reserved5 [3]byte
IntegrityPayloadType uint8
Reserved6 [2]byte
IntegrityPayloadLength uint8
IntegrityPayloadAlgorithm integrityAlgorithm
Reserved8 [3]byte
ConfidentialityPayloadType uint8
Reserved9 [2]byte
ConfidentialityPayloadLength uint8
ConfidentialityPayloadAlgorithm confidentialityAlgorithm
Reserved11 [3]byte
}
// openSessionResponsePayload represents Open RMCPPlusSession Response payload
type openSessionResponsePayload struct {
MessageTag uint8
RmcpPlusStatusCode rmcpStatus
MaximumPrivilegeLevel maximumPrivilegeLevel
Reserved2 [1]byte
RemoteConsoleSessionId uint32
ManagedSystemSessionId uint32
AuthenticationPayloadType uint8
Reserved3 [2]byte
AuthenticationPayloadLength uint8
AuthenticationPayloadAlgorithm authenticationAlgorithm
Reserved5 [3]byte
IntegrityPayloadType uint8
Reserved6 [2]byte
IntegrityPayloadLength uint8
IntegrityPayloadAlgorithm integrityAlgorithm
Reserved8 [3]byte
ConfidentialityPayloadType uint8
Reserved9 [2]byte
ConfidentialityPayloadLength uint8
ConfidentialityPayloadAlgorithm confidentialityAlgorithm
Reserved11 [3]byte
}
// rakpMessage1Request represents RAKP Message1 request
type rakpMessage1Request struct {
MessageTag uint8
Reserved1 [3]byte
ManagedSystemSessionId uint32
RemoteConsoleRandomNumber [16]byte
// reserved2(3b) + name_only_lookup(1b) + requested_maximum_privilege_level(4b)
RequestedMaximumPrivilegeLevelAndNameOnlyLookup uint8
Reserved3 [2]byte
UserNameLength uint8
UserName [20]byte
}
// rakpMessage2Response represents RAKP Message2 response
type rakpMessage2Response struct {
MessageTag uint8
RmcpPlusStatusCode rmcpStatus
Reserved1 [2]byte
RemoteConsoleSessionId uint32
ManagedSystemRandomNumber [16]byte
ManagedSystemGuid [16]byte
KeyExchangeAuthenticationCode [20]byte
}
// rakpMessage3Request represents RAKP Message3 request
type rakpMessage3Request struct {
MessageTag uint8
RmcpPlusStatusCode rmcpStatus
Reserved1 [2]byte
ManagedSystemSessionId uint32
KeyExchangeAuthenticationCode [20]byte
}
// rakpMessage4Response represents RAKP Message4 response
type rakpMessage4Response struct {
MessageTag uint8
RmcpPlusStatusCode rmcpStatus
Reserved1 [2]byte
RemoteConsoleSessionId uint32
IntegrityCheckValue [12]byte
}
// ipmiSessionTrailer represents ipmi RMCPPlusSession Trailer added to the end of the encrypted packet
type ipmiSessionTrailer struct {
IntegrityPad [2]byte
PadLength uint8
NextHeader uint8
}
func newRMCPPlus(buf io.Reader, authType authenticationType, session *rmcpPlusSessionHolder, bmcUser *bmcUserHolder) (*rmcpPlus, error) {
header, err := deserializeRMCPPlusSessionHeader(buf, authType)
if err != nil {
return nil, err
}
return &rmcpPlus{
header: header,
session: session,
bmcUser: bmcUser,
}, nil
}
// handle handles RMCP+ format request
func (r *rmcpPlus) handle(buf io.Reader, machine Machine) ([]byte, error) {
payloadType := r.header.PayloadType & 0x3f
authenticated := (r.header.PayloadType & 0x40) >> 6
encrypted := (r.header.PayloadType & 0x80) >> 7
if authenticated == 1 && encrypted == 1 {
return r.handleEncryptedRequest(buf, machine)
}
switch payloadType {
case payloadTypeRMCPPlusOpenSessionRequest:
return r.handleOpenSessionRequest(buf)
case payloadTypeRAKPMessage1:
return r.handleRAKPMessage1Request(buf)
case payloadTypeRAKPMessage3:
return r.handleRAKPMessage3Request(buf)
}
return nil, errors.New("unsupported payload type")
}
func deserializeRMCPPlusSessionHeader(buf io.Reader, authType authenticationType) (*rmcpPlusSessionHeader, error) {
header := &rmcpPlusSessionHeader{}
header.AuthenticationType = authType
if err := binary.Read(buf, binary.LittleEndian, &header.PayloadType); err != nil {
return nil, err
}
if err := binary.Read(buf, binary.LittleEndian, &header.SessionId); err != nil {
return nil, err
}
if err := binary.Read(buf, binary.LittleEndian, &header.SessionSequenceNumber); err != nil {
return nil, err
}
if err := binary.Read(buf, binary.LittleEndian, &header.IpmiPayloadLen); err != nil {
return nil, err
}
return header, nil
}
func (r *rmcpPlus) handleOpenSessionRequest(buf io.Reader) ([]byte, error) {
payload, err := deserializeOpenSessionRequestPayload(buf)
if err != nil {
return nil, err
}
// Serialize RMCP+ session header
obuf := bytes.Buffer{}
rmcpPlus := &rmcpPlusSessionHeader{
AuthenticationType: authTypeRMCPPlus,
PayloadType: payloadTypeRMCPPlusOpenSessionResponse,
SessionId: 0,
SessionSequenceNumber: 0,
IpmiPayloadLen: 36,
}
if err := binary.Write(&obuf, binary.LittleEndian, rmcpPlus); err != nil {
return nil, err
}
// Serialize Open RMCPPlusSession Response Payload
session, err := r.session.getNewRMCPPlusSession(payload.RemoteConsoleSessionId)
if err != nil {
return nil, err
}
response := &openSessionResponsePayload{
MessageTag: payload.MessageTag,
RmcpPlusStatusCode: rmcpPlusStatusNoErrors,
MaximumPrivilegeLevel: maximumPrivilegeLevelAdministrator,
Reserved2: [1]byte{},
RemoteConsoleSessionId: payload.RemoteConsoleSessionId,
ManagedSystemSessionId: session.ManagedSystemSessionId,
AuthenticationPayloadType: authenticationPayloadTypeAuthenticationAlgorithm,
Reserved3: [2]byte{},
AuthenticationPayloadLength: 0x08,
AuthenticationPayloadAlgorithm: authenticationAlgorithmRKAPHMACSHA1,
Reserved5: [3]byte{},
IntegrityPayloadType: integrityPayloadTypeIntegrityAlgorithm,
Reserved6: [2]byte{},
IntegrityPayloadLength: 0x08,
IntegrityPayloadAlgorithm: integrityAlgorithmHMACSHA1196,
Reserved8: [3]byte{},
ConfidentialityPayloadType: confidentialityPayloadTypeConfidentialityAlgorithm,
Reserved9: [2]byte{},
ConfidentialityPayloadLength: 0x08,
ConfidentialityPayloadAlgorithm: confidentialityAlgorithmAESCBC128,
Reserved11: [3]byte{},
}
if err := binary.Write(&obuf, binary.LittleEndian, response); err != nil {
return nil, err
}
return obuf.Bytes(), nil
}
func deserializeOpenSessionRequestPayload(buf io.Reader) (*openSessionRequestPayload, error) {
payload := &openSessionRequestPayload{}
if err := binary.Read(buf, binary.LittleEndian, payload); err != nil {
return nil, err
}
return payload, nil
}
func (r *rmcpPlus) handleRAKPMessage1Request(buf io.Reader) ([]byte, error) {
payload, err := deserializeRAKPMessage1RequestPayload(buf)
if err != nil {
return nil, err
}
// Check if the session has been activated
session, ok := r.session.getRMCPPlusSession(payload.ManagedSystemSessionId)
if !ok {
return nil, errors.New("session hasn't been activated")
}
// Serialize RMCP+ session header
obuf := bytes.Buffer{}
rmcpPlus := &rmcpPlusSessionHeader{
AuthenticationType: authTypeRMCPPlus,
PayloadType: payloadTypeRAKPMessage2,
SessionId: 0,
SessionSequenceNumber: 0,
IpmiPayloadLen: 60,
}
if err := binary.Write(&obuf, binary.LittleEndian, rmcpPlus); err != nil {
return nil, err
}
userName := payload.UserName[:payload.UserNameLength]
user, ok := r.bmcUser.getBMCUser(string(userName))
if !ok {
return nil, errors.New("user not found")
}
managedSystemRandomNumber, err := generateRandomNumber()
if err != nil {
return nil, err
}
managedSystemGuid, err := generateRandomNumber()
if err != nil {
return nil, err
}
session.RemoteConsoleRandomNumber = payload.RemoteConsoleRandomNumber
session.ManagedSystemRandomNumber = managedSystemRandomNumber
session.ManagedSystemGuid = managedSystemGuid
session.RequestedPrivilegeLevel = payload.RequestedMaximumPrivilegeLevelAndNameOnlyLookup
session.UserNameLength = payload.UserNameLength
session.UserName = userName
// Generate Authentication Code with specified Authentication algorithm
authCode, err := generateAuthCode(session.RemoteConsoleSessionId, session.ManagedSystemSessionId, payload.RemoteConsoleRandomNumber, managedSystemRandomNumber,
managedSystemGuid, payload.RequestedMaximumPrivilegeLevelAndNameOnlyLookup, payload.UserNameLength, userName, user.Password)
if err != nil {
return nil, err
}
// Serialize RAKP Message2 Payload
fixedAuthCode := [20]byte{}
copy(fixedAuthCode[:], authCode)
response := &rakpMessage2Response{
MessageTag: payload.MessageTag,
RmcpPlusStatusCode: rmcpPlusStatusNoErrors,
Reserved1: [2]byte{},
RemoteConsoleSessionId: session.RemoteConsoleSessionId,
ManagedSystemRandomNumber: managedSystemRandomNumber,
ManagedSystemGuid: managedSystemGuid,
KeyExchangeAuthenticationCode: fixedAuthCode,
}
if err := binary.Write(&obuf, binary.LittleEndian, response); err != nil {
return nil, err
}
return obuf.Bytes(), nil
}
func deserializeRAKPMessage1RequestPayload(buf io.Reader) (*rakpMessage1Request, error) {
payload := &rakpMessage1Request{}
if err := binary.Read(buf, binary.LittleEndian, payload); err != nil {
return nil, err
}
return payload, nil
}
func generateAuthCode(remoteConsoleSessionId, managedSystemSessionId uint32, remoteConsoleRandomNumber, managedSystemRandomNumber, managedSystemGuid [16]byte,
requestedPrivilegeLevel, usernameLength uint8, userName []byte, password string) ([]byte, error) {
buf := bytes.Buffer{}
if err := binary.Write(&buf, binary.LittleEndian, remoteConsoleSessionId); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, managedSystemSessionId); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, remoteConsoleRandomNumber); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, managedSystemRandomNumber); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, managedSystemGuid); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, requestedPrivilegeLevel); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, usernameLength); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, userName); err != nil {
return nil, err
}
mac := hmac.New(sha1.New, []byte(password))
mac.Write(buf.Bytes())
return mac.Sum(nil), nil
}
func (r *rmcpPlus) handleRAKPMessage3Request(buf io.Reader) ([]byte, error) {
payload, err := deserializeRAKPMessage3RequestPayload(buf)
if err != nil {
return nil, err
}
session, ok := r.session.getRMCPPlusSession(payload.ManagedSystemSessionId)
if !ok {
return nil, errors.New("session hasn't been activated")
}
user, ok := r.bmcUser.getBMCUser(string(session.UserName))
if !ok {
return nil, errors.New("user not found")
}
ok, err = validateAuthCode(payload.KeyExchangeAuthenticationCode, session, user.Password)
if err != nil {
return nil, err
}
if !ok {
return nil, errors.New("authentication failed")
}
// Serialize RMCP+ session header
obuf := bytes.Buffer{}
rmcpPlus := &rmcpPlusSessionHeader{
AuthenticationType: authTypeRMCPPlus,
PayloadType: payloadTypeRAKPMessage4,
SessionId: 0,
SessionSequenceNumber: 0,
IpmiPayloadLen: 20,
}
if err := binary.Write(&obuf, binary.LittleEndian, rmcpPlus); err != nil {
return nil, err
}
sik, err := generateSessionIntegrityKey(session, user.Password)
if err != nil {
return nil, err
}
session.SessionIntegrityKey = sik
session.IntegrityKey = generateK1(sik)
session.ConfidentialityKey = generateK2(sik)
checkValue, err := generateSessionIntegrityCheckValue(session, sik)
if err != nil {
return nil, err
}
// Serialize RAKP Message4 Payload
fixedCheckValue := [12]byte{}
copy(fixedCheckValue[:], checkValue)
response := &rakpMessage4Response{
MessageTag: payload.MessageTag,
RmcpPlusStatusCode: rmcpPlusStatusNoErrors,
Reserved1: [2]byte{},
RemoteConsoleSessionId: session.RemoteConsoleSessionId,
IntegrityCheckValue: fixedCheckValue,
}
if err := binary.Write(&obuf, binary.LittleEndian, response); err != nil {
return nil, err
}
return obuf.Bytes(), nil
}
func deserializeRAKPMessage3RequestPayload(buf io.Reader) (*rakpMessage3Request, error) {
payload := &rakpMessage3Request{}
if err := binary.Read(buf, binary.LittleEndian, payload); err != nil {
return nil, err
}
return payload, nil
}
func validateAuthCode(authCode [20]byte, session *rmcpPlusSession, password string) (bool, error) {
buf := bytes.Buffer{}
if err := binary.Write(&buf, binary.LittleEndian, session.ManagedSystemRandomNumber); err != nil {
return false, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.RemoteConsoleSessionId); err != nil {
return false, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.RequestedPrivilegeLevel); err != nil {
return false, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.UserNameLength); err != nil {
return false, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.UserName); err != nil {
return false, err
}
mac := hmac.New(sha1.New, []byte(password))
mac.Write(buf.Bytes())
code := mac.Sum(nil)
return bytes.Equal(authCode[:], code[:]), nil
}
func generateSessionIntegrityKey(session *rmcpPlusSession, password string) ([]byte, error) {
buf := bytes.Buffer{}
if err := binary.Write(&buf, binary.LittleEndian, session.RemoteConsoleRandomNumber); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.ManagedSystemRandomNumber); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.RequestedPrivilegeLevel); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.UserNameLength); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.UserName); err != nil {
return nil, err
}
mac := hmac.New(sha1.New, []byte(password))
mac.Write(buf.Bytes())
return mac.Sum(nil), nil
}
func generateK1(sessionIntegrityKey []byte) []byte {
return generateAdditionalKeyingMaterials(sessionIntegrityKey, 0x01)
}
func generateK2(sessionIntegrityKey []byte) []byte {
return generateAdditionalKeyingMaterials(sessionIntegrityKey, 0x02)
}
func generateAdditionalKeyingMaterials(sessionIntegrityKey []byte, b byte) []byte {
mac := hmac.New(sha1.New, sessionIntegrityKey)
var cons []byte
for i := 0; i < sha1.Size; i++ {
cons = append(cons, b)
}
mac.Write(cons)
return mac.Sum(nil)
}
func generateSessionIntegrityCheckValue(session *rmcpPlusSession, sessionIntegrityKey []byte) ([]byte, error) {
buf := bytes.Buffer{}
if err := binary.Write(&buf, binary.LittleEndian, session.RemoteConsoleRandomNumber); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.ManagedSystemSessionId); err != nil {
return nil, err
}
if err := binary.Write(&buf, binary.LittleEndian, session.ManagedSystemGuid); err != nil {
return nil, err
}
mac := hmac.New(sha1.New, sessionIntegrityKey)
mac.Write(buf.Bytes())
// HMAC-SHA1-96
return mac.Sum(nil)[:12], nil
}
func (r *rmcpPlus) handleEncryptedRequest(buf io.Reader, machine Machine) ([]byte, error) {
session, ok := r.session.getRMCPPlusSession(r.header.SessionId)
if !ok {
return nil, errors.New("session hasn't been activated")
}
_, ok = r.bmcUser.getBMCUser(string(session.UserName))
if !ok {
return nil, errors.New("user not found")
}
payload := make([]byte, r.header.IpmiPayloadLen)
if err := binary.Read(buf, binary.LittleEndian, payload); err != nil {
return nil, err
}
plain, err := decryptByCBCMode(session.ConfidentialityKey, payload)
if err != nil {
return nil, err
}
ipmi, err := newIPMI(bytes.NewBuffer(plain), len(plain), machine, r.session)
if err != nil {
return nil, err
}
ipmiResponse, err := ipmi.handle()
if err != nil {
return nil, err
}
ciphered, err := encryptByCBCMode(session.ConfidentialityKey, ipmiResponse)
if err != nil {
return nil, err
}
// Serialize RMCP+ session header
obuf := bytes.Buffer{}
rmcpPlus := &rmcpPlusSessionHeader{
AuthenticationType: authTypeRMCPPlus,
PayloadType: 0xc0, // payload_type.encrypted(1b) + payload_type.authenticated(1b) + payload_type(6b) (11000000)
SessionId: session.RemoteConsoleSessionId,
SessionSequenceNumber: r.header.SessionSequenceNumber,
IpmiPayloadLen: uint16(len(ciphered)),
}
if err := binary.Write(&obuf, binary.LittleEndian, rmcpPlus); err != nil {
return nil, err
}
if err := binary.Write(&obuf, binary.LittleEndian, ciphered); err != nil {
return nil, err
}
// IntegrityPad is fixed at size 2 since we only support HMAC-SHA1-96
trailer := &ipmiSessionTrailer{
IntegrityPad: [2]byte{0xff, 0xff},
PadLength: 0x02,
NextHeader: 0x07,
}
if err := binary.Write(&obuf, binary.LittleEndian, trailer); err != nil {
return nil, err
}
ret := obuf.Bytes()
// Generate Integrity data using fields from RMCP+ header up to and including the field that immediately precedes the AuthCode itself
authCode, err := generateIntegrityData(ret, session.IntegrityKey)
if err != nil {
return nil, err
}
ret = append(ret, authCode...)
return ret, nil
}
func generateIntegrityData(data, integrityKey []byte) ([]byte, error) {
mac := hmac.New(sha1.New, integrityKey)
mac.Write(data)
// HMAC-SHA1-96
return mac.Sum(nil)[:12], nil
}
func decryptByCBCMode(key []byte, payload []byte) ([]byte, error) {
if len(payload) < aes.BlockSize {
return nil, errors.New("payload must be longer that block size")
} else if len(payload)%aes.BlockSize != 0 {
return nil, errors.New("payload must be multiple of block size")
}
block, err := aes.NewCipher(key[:aes.BlockSize])
if err != nil {
return nil, err
}
iv := payload[:aes.BlockSize]
payload = payload[aes.BlockSize:]
plain := make([]byte, len(payload))
cbc := cipher.NewCBCDecrypter(block, iv)
cbc.CryptBlocks(plain, payload)
padLength := plain[len(plain)-1]
return plain[:aes.BlockSize-(padLength+1)], nil
}
func encryptByCBCMode(key []byte, plain []byte) ([]byte, error) {
block, err := aes.NewCipher(key[:aes.BlockSize])
if err != nil {
return nil, err
}
paddedPlaintext := padPKCS7(plain)
iv, err := generateRandomNumber()
if err != nil {
return nil, err
}
cbc := cipher.NewCBCEncrypter(block, iv[:])
ciphered := make([]byte, aes.BlockSize)
cbc.CryptBlocks(ciphered, paddedPlaintext)
return append(iv[:], ciphered...), nil
}
func padPKCS7(data []byte) []byte {
padSize := aes.BlockSize - (len(data) % aes.BlockSize)
pad := make([]byte, padSize)
for i := range pad {
pad[i] = byte(i + 1)
}
pad[padSize-1] = byte(padSize - 1)
return append(data, pad...)
}
const randomNumberSize = 16
func generateRandomNumber() ([randomNumberSize]byte, error) {
b := make([]byte, randomNumberSize)
_, err := rand.Read(b)
if err != nil {
return [randomNumberSize]byte{}, err
}
encoded := make([]byte, hex.EncodedLen(randomNumberSize))
hex.Encode(
encoded, b)
fixedBytes := [randomNumberSize]byte{}
copy(fixedBytes[:],
encoded)
return fixedBytes, nil
}