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decoder.go
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decoder.go
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package bcrypt
import (
"fmt"
"strconv"
"github.com/go-crypt/x/bcrypt"
"github.com/go-crypt/crypt/algorithm"
"github.com/go-crypt/crypt/internal/encoding"
)
// RegisterDecoder the decoder with the algorithm.DecoderRegister.
func RegisterDecoder(r algorithm.DecoderRegister) (err error) {
if err = RegisterDecoderStandard(r); err != nil {
return err
}
if err = RegisterDecoderSHA256(r); err != nil {
return err
}
return nil
}
// RegisterDecoderStandard registers specifically the standard decoder variant with the algorithm.DecoderRegister.
func RegisterDecoderStandard(r algorithm.DecoderRegister) (err error) {
decodefunc := DecodeVariant(VariantStandard)
if err = r.RegisterDecodeFunc(VariantStandard.Prefix(), decodefunc); err != nil {
return err
}
if err = r.RegisterDecodeFunc(AlgIdentifierVerA, decodefunc); err != nil {
return err
}
if err = r.RegisterDecodeFunc(AlgIdentifierVerX, decodefunc); err != nil {
return err
}
if err = r.RegisterDecodeFunc(AlgIdentifierVerY, decodefunc); err != nil {
return err
}
if err = r.RegisterDecodeFunc(AlgIdentifierUnversioned, decodefunc); err != nil {
return err
}
return nil
}
// RegisterDecoderSHA256 registers specifically the sha256 decoder variant with the algorithm.DecoderRegister.
func RegisterDecoderSHA256(r algorithm.DecoderRegister) (err error) {
if err = r.RegisterDecodeFunc(VariantSHA256.Prefix(), DecodeVariant(VariantSHA256)); err != nil {
return err
}
return nil
}
// Decode the encoded digest into a algorithm.Digest.
func Decode(encodedDigest string) (digest algorithm.Digest, err error) {
return DecodeVariant(VariantNone)(encodedDigest)
}
// DecodeVariant the encoded digest into a algorithm.Digest provided it matches the provided bcrypt.Variant. If
// bcrypt.VariantNone is used all variants can be decoded.
func DecodeVariant(v Variant) func(encodedDigest string) (digest algorithm.Digest, err error) {
return func(encodedDigest string) (digest algorithm.Digest, err error) {
var (
parts []string
variant Variant
)
if variant, parts, err = decoderParts(encodedDigest); err != nil {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, err)
}
if v != VariantNone && v != variant {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, fmt.Errorf("the '%s' variant cannot be decoded only the '%s' variant can be", variant.String(), v.String()))
}
if digest, err = decode(variant, parts); err != nil {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, err)
}
return digest, nil
}
}
func decoderParts(encodedDigest string) (variant Variant, parts []string, err error) {
parts = encoding.Split(encodedDigest, -1)
if len(parts) < 4 {
return VariantNone, nil, algorithm.ErrEncodedHashInvalidFormat
}
variant = NewVariant(parts[1])
if variant == VariantNone {
return variant, nil, fmt.Errorf("%w: identifier '%s' is not an encoded %s digest", algorithm.ErrEncodedHashInvalidIdentifier, parts[1], AlgName)
}
return variant, parts[2:], nil
}
func decode(variant Variant, parts []string) (digest algorithm.Digest, err error) {
countParts := len(parts)
var (
salt, key []byte
)
decoded := &Digest{
variant: variant,
}
switch decoded.variant {
case VariantStandard:
if countParts != 2 {
return nil, algorithm.ErrEncodedHashInvalidFormat
}
if decoded.iterations, err = strconv.Atoi(parts[0]); err != nil {
return nil, fmt.Errorf("%w: iterations could not be parsed: %v", algorithm.ErrEncodedHashInvalidOptionValue, err)
}
switch n, i := len(parts[1]), bcrypt.EncodedSaltSize+bcrypt.EncodedHashSize; n {
case i:
break
case 0:
return nil, fmt.Errorf("%w: key is expected to be %d bytes but it was empty", algorithm.ErrEncodedHashKeyEncoding, i)
default:
return nil, fmt.Errorf("%w: key is expected to be %d bytes but it has %d bytes", algorithm.ErrEncodedHashKeyEncoding, i, n)
}
salt, key = bcrypt.DecodeSecret([]byte(parts[1]))
case VariantSHA256:
if countParts != 3 {
return nil, algorithm.ErrEncodedHashInvalidFormat
}
salt, key = []byte(parts[1]), []byte(parts[2])
switch n := len(salt); n {
case bcrypt.EncodedSaltSize:
break
case 0:
return nil, fmt.Errorf("%w: salt is expected to be %d bytes but it was empty", algorithm.ErrEncodedHashSaltEncoding, bcrypt.EncodedSaltSize)
default:
return nil, fmt.Errorf("%w: salt is expected to be %d bytes but it has %d bytes", algorithm.ErrEncodedHashSaltEncoding, bcrypt.EncodedSaltSize, n)
}
switch n := len(key); n {
case bcrypt.EncodedHashSize:
break
case 0:
return nil, fmt.Errorf("%w: key is expected to be %d bytes but it was empty", algorithm.ErrEncodedHashKeyEncoding, bcrypt.EncodedHashSize)
default:
return nil, fmt.Errorf("%w: key is expected to be %d bytes but it has %d bytes", algorithm.ErrEncodedHashKeyEncoding, bcrypt.EncodedHashSize, n)
}
var params []encoding.Parameter
if params, err = encoding.DecodeParameterStr(parts[0]); err != nil {
return nil, err
}
for _, param := range params {
switch param.Key {
case oV, oT:
break
case oR:
decoded.iterations, err = param.Int()
default:
return nil, fmt.Errorf("%w: option '%s' with value '%s' is unknown", algorithm.ErrEncodedHashInvalidOptionKey, param.Key, param.Value)
}
if err != nil {
return nil, fmt.Errorf("%w: option '%s' has invalid value '%s': %v", algorithm.ErrEncodedHashInvalidOptionValue, param.Key, param.Value, err)
}
}
}
if decoded.salt, err = bcrypt.Base64Decode(salt); err != nil {
return nil, fmt.Errorf("%w: %v", algorithm.ErrEncodedHashSaltEncoding, err)
}
if len(key) == 0 {
return nil, fmt.Errorf("%w: key has 0 bytes", algorithm.ErrEncodedHashKeyEncoding)
}
decoded.key = key
return decoded, nil
}