| khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 1 | package rfc4757 |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "encoding/hex" |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | |
| 10 | "golang.org/x/crypto/md4" |
| 11 | ) |
| 12 | |
| 13 | // StringToKey returns a key derived from the string provided according to the definition in RFC 4757. |
| 14 | func StringToKey(secret string) ([]byte, error) { |
| 15 | b := make([]byte, len(secret)*2, len(secret)*2) |
| 16 | for i, r := range secret { |
| 17 | u := fmt.Sprintf("%04x", r) |
| 18 | c, err := hex.DecodeString(u) |
| 19 | if err != nil { |
| 20 | return []byte{}, errors.New("character could not be encoded") |
| 21 | } |
| 22 | // Swap round the two bytes to make little endian as we put into byte slice |
| 23 | b[2*i] = c[1] |
| 24 | b[2*i+1] = c[0] |
| 25 | } |
| 26 | r := bytes.NewReader(b) |
| 27 | h := md4.New() |
| 28 | _, err := io.Copy(h, r) |
| 29 | if err != nil { |
| 30 | return []byte{}, err |
| 31 | } |
| 32 | return h.Sum(nil), nil |
| 33 | } |
| 34 | |
| 35 | func deriveKeys(key, checksum []byte, usage uint32, export bool) (k1, k2, k3 []byte) { |
| 36 | k1 = key |
| 37 | k2 = HMAC(k1, UsageToMSMsgType(usage)) |
| 38 | k3 = HMAC(k2, checksum) |
| 39 | return |
| 40 | } |