51 lines
1.8 KiB
Go
51 lines
1.8 KiB
Go
package rfc3962
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import (
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"encoding/binary"
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"encoding/hex"
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"errors"
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"github.com/jcmturner/gofork/x/crypto/pbkdf2"
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"github.com/jcmturner/gokrb5/v8/crypto/etype"
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)
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const (
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s2kParamsZero = 4294967296
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)
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// StringToKey returns a key derived from the string provided according to the definition in RFC 3961.
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func StringToKey(secret, salt, s2kparams string, e etype.EType) ([]byte, error) {
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i, err := S2KparamsToItertions(s2kparams)
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if err != nil {
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return nil, err
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}
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return StringToKeyIter(secret, salt, i, e)
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}
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// StringToPBKDF2 generates an encryption key from a pass phrase and salt string using the PBKDF2 function from PKCS #5 v2.0
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func StringToPBKDF2(secret, salt string, iterations int64, e etype.EType) []byte {
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return pbkdf2.Key64([]byte(secret), []byte(salt), iterations, int64(e.GetKeyByteSize()), e.GetHashFunc())
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}
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// StringToKeyIter returns a key derived from the string provided according to the definition in RFC 3961.
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func StringToKeyIter(secret, salt string, iterations int64, e etype.EType) ([]byte, error) {
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tkey := e.RandomToKey(StringToPBKDF2(secret, salt, iterations, e))
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return e.DeriveKey(tkey, []byte("kerberos"))
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}
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// S2KparamsToItertions converts the string representation of iterations to an integer
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func S2KparamsToItertions(s2kparams string) (int64, error) {
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//The s2kparams string should be hex string representing 4 bytes
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//The 4 bytes represent a number in big endian order
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//If the value is zero then the number of iterations should be 4,294,967,296 (2^32)
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var i uint32
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if len(s2kparams) != 8 {
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return int64(s2kParamsZero), errors.New("invalid s2kparams length")
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}
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b, err := hex.DecodeString(s2kparams)
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if err != nil {
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return int64(s2kParamsZero), errors.New("invalid s2kparams, cannot decode string to bytes")
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}
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i = binary.BigEndian.Uint32(b)
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return int64(i), nil
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}
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