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keytransform.go
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keytransform.go
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package libsodium
import (
"encoding/base64"
"encoding/hex"
"fmt"
"strings"
)
const KeyTransformBase64 = "base64"
const KeyTransformHex = "hex"
const KeyTransformNone = "none"
type keyTransformRegEntry struct {
typ string
fun func(userInput string) ([]byte, error)
}
var keyTransformReg = []keyTransformRegEntry{
{typ: KeyTransformBase64, fun: keyTransformBase64},
{typ: KeyTransformHex, fun: keyTransformHex},
{typ: KeyTransformNone, fun: keyTransformNone},
}
func keyTransform(userInput string, transformType string, expectedLen int) ([]byte, error) {
for _, entry := range keyTransformReg {
if entry.typ == transformType {
decoded, err := entry.fun(userInput)
if err != nil {
return nil, err
}
if len(decoded) != expectedLen {
return nil, fmt.Errorf("key must be exactly %d bytes (got %d bytes)", expectedLen, len(decoded))
}
return decoded, nil
}
}
// unknown transform
var builder strings.Builder
for idx, entry := range keyTransformReg {
if idx > 0 {
if idx+1 == len(keyTransformReg) {
builder.WriteString(" or ")
} else {
builder.WriteString(", ")
}
}
builder.WriteString(entry.typ)
}
return nil, fmt.Errorf("unknown key transform '%s' (must be %s)", transformType, builder.String())
}
func keyTransformBase64(userInput string) ([]byte, error) {
decoded, err := base64.StdEncoding.DecodeString(userInput)
if err != nil {
return nil, fmt.Errorf("while base64 decoding key: %v", err)
}
return decoded, nil
}
func keyTransformHex(userInput string) ([]byte, error) {
decoded, err := hex.DecodeString(userInput)
if err != nil {
return nil, fmt.Errorf("while hex decoding key: %v", err)
}
return decoded, nil
}
// Mimics the behavior of older versions of wal-g.
func keyTransformNone(userInput string) ([]byte, error) {
if len(userInput) < minimalKeyLength {
return nil, newErrShortKey(len(userInput))
}
if len(userInput) > libsodiumKeybytes {
return []byte(userInput[:libsodiumKeybytes]), nil
}
if len(userInput) < libsodiumKeybytes {
buf := make([]byte, libsodiumKeybytes)
copy(buf[:libsodiumKeybytes], userInput)
return buf, nil
}
return []byte(userInput), nil
}