Takahiro Suzuki | d7bf820 | 2020-12-17 20:21:59 +0900 | [diff] [blame^] | 1 | package rfc3962 |
| 2 | |
| 3 | import ( |
| 4 | "encoding/binary" |
| 5 | "encoding/hex" |
| 6 | "errors" |
| 7 | |
| 8 | "github.com/jcmturner/gofork/x/crypto/pbkdf2" |
| 9 | "gopkg.in/jcmturner/gokrb5.v7/crypto/etype" |
| 10 | ) |
| 11 | |
| 12 | const ( |
| 13 | s2kParamsZero = 4294967296 |
| 14 | ) |
| 15 | |
| 16 | // StringToKey returns a key derived from the string provided according to the definition in RFC 3961. |
| 17 | func StringToKey(secret, salt, s2kparams string, e etype.EType) ([]byte, error) { |
| 18 | i, err := S2KparamsToItertions(s2kparams) |
| 19 | if err != nil { |
| 20 | return nil, err |
| 21 | } |
| 22 | return StringToKeyIter(secret, salt, i, e) |
| 23 | } |
| 24 | |
| 25 | // StringToPBKDF2 generates an encryption key from a pass phrase and salt string using the PBKDF2 function from PKCS #5 v2.0 |
| 26 | func StringToPBKDF2(secret, salt string, iterations int64, e etype.EType) []byte { |
| 27 | return pbkdf2.Key64([]byte(secret), []byte(salt), iterations, int64(e.GetKeyByteSize()), e.GetHashFunc()) |
| 28 | } |
| 29 | |
| 30 | // StringToKeyIter returns a key derived from the string provided according to the definition in RFC 3961. |
| 31 | func StringToKeyIter(secret, salt string, iterations int64, e etype.EType) ([]byte, error) { |
| 32 | tkey := e.RandomToKey(StringToPBKDF2(secret, salt, iterations, e)) |
| 33 | return e.DeriveKey(tkey, []byte("kerberos")) |
| 34 | } |
| 35 | |
| 36 | // S2KparamsToItertions converts the string representation of iterations to an integer |
| 37 | func S2KparamsToItertions(s2kparams string) (int64, error) { |
| 38 | //process s2kparams string |
| 39 | //The parameter string is four octets indicating an unsigned |
| 40 | //number in big-endian order. This is the number of iterations to be |
| 41 | //performed. If the value is 00 00 00 00, the number of iterations to |
| 42 | //be performed is 4,294,967,296 (2**32). |
| 43 | var i uint32 |
| 44 | if len(s2kparams) != 8 { |
| 45 | return int64(s2kParamsZero), errors.New("invalid s2kparams length") |
| 46 | } |
| 47 | b, err := hex.DecodeString(s2kparams) |
| 48 | if err != nil { |
| 49 | return int64(s2kParamsZero), errors.New("invalid s2kparams, cannot decode string to bytes") |
| 50 | } |
| 51 | i = binary.BigEndian.Uint32(b) |
| 52 | //buf := bytes.NewBuffer(b) |
| 53 | //err = binary.Read(buf, binary.BigEndian, &i) |
| 54 | if err != nil { |
| 55 | return int64(s2kParamsZero), errors.New("invalid s2kparams, cannot convert to big endian int32") |
| 56 | } |
| 57 | return int64(i), nil |
| 58 | } |