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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,182 @@ | ||
package paseto | ||
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import ( | ||
"crypto/aes" | ||
"crypto/cipher" | ||
"crypto/hmac" | ||
"crypto/rand" | ||
"crypto/sha512" | ||
"crypto/subtle" | ||
"errors" | ||
"fmt" | ||
"io" | ||
"strings" | ||
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"golang.org/x/crypto/hkdf" | ||
) | ||
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const ( | ||
v3locHeader = "v3.local." | ||
v3locNonce = 32 | ||
v3locKey = 32 | ||
v3locMac = 48 | ||
v3locKDF = 48 | ||
) | ||
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func V3Encrypt(key []byte, payload, footer any, implicit string, randBytes []byte) (string, error) { | ||
payloadBytes, err := toBytes(payload) | ||
if err != nil { | ||
return "", fmt.Errorf("encode payload: %w", err) | ||
} | ||
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footerBytes, err := toBytes(footer) | ||
if err != nil { | ||
return "", fmt.Errorf("encode footer: %w", err) | ||
} | ||
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// step 0. | ||
m := payloadBytes | ||
k := key | ||
f := footerBytes | ||
i := []byte(implicit) | ||
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// step 1. | ||
if subtle.ConstantTimeEq(int32(len(k)), v3locKey) != 1 { | ||
return "", errors.New("bad key") | ||
} | ||
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// step 2. | ||
h := []byte(v3locHeader) | ||
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// step 3. | ||
n := randBytes | ||
if n == nil { | ||
n = make([]byte, v3locNonce) | ||
if _, err := io.ReadFull(rand.Reader, n); err != nil { | ||
return "", fmt.Errorf("read from crypto/rand.Reader: %w", err) | ||
} | ||
} | ||
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// step 4. | ||
ek, n2, ak, err := v3locSplitKey(key, n) | ||
if err != nil { | ||
return "", fmt.Errorf("create enc and auth keys: %w", err) | ||
} | ||
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// step 5. | ||
block, err := aes.NewCipher(ek) | ||
if err != nil { | ||
return "", fmt.Errorf("create aes cipher: %w", err) | ||
} | ||
c := make([]byte, len(m)) | ||
ciph := cipher.NewCTR(block, n2) | ||
ciph.XORKeyStream(c, m) | ||
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// step 6. | ||
preAuth := pae(h, n, c, f, i) | ||
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// step 7. | ||
hasher := hmac.New(sha512.New384, ak) | ||
hasher.Write(preAuth) | ||
t := hasher.Sum(nil) | ||
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// step 7. | ||
body := make([]byte, 0, len(n)+len(c)+len(t)) | ||
body = append(body, n...) | ||
body = append(body, c...) | ||
body = append(body, t...) | ||
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return buildToken(h, body, f), nil | ||
} | ||
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func V3Decrypt(token string, key []byte, payload, footer any, implicit string) error { | ||
// step 0. | ||
m := token | ||
k := key | ||
i := []byte(implicit) | ||
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// step 1. | ||
if subtle.ConstantTimeEq(int32(len(k)), v3locKey) != 1 { | ||
return errors.New("bad key") | ||
} | ||
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// step 2. | ||
// TODO: ? | ||
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// step 3. | ||
if !strings.HasPrefix(token, v3locHeader) { | ||
return ErrIncorrectTokenFormat | ||
} | ||
h := []byte(v3locHeader) | ||
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// step 4. | ||
body, footerBytes, err := splitToken(m, v3locHeader) | ||
if err != nil { | ||
return fmt.Errorf("decode token: %w", err) | ||
} | ||
if len(body) < v3locNonce { | ||
return ErrIncorrectTokenFormat | ||
} | ||
n, c, t, f := body[:v3locNonce], body[v3locNonce:len(body)-32], body[len(body)-32:], footerBytes | ||
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// step 5. | ||
ek, n2, ak, err := v3locSplitKey(key, n) | ||
if err != nil { | ||
return fmt.Errorf("create enc and auth keys: %w", err) | ||
} | ||
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// step 6. | ||
preAuth := pae(h, n, c, f, i) | ||
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// step 7. | ||
hasher := hmac.New(sha512.New384, ak) | ||
hasher.Write(preAuth) | ||
t2 := hasher.Sum(nil) | ||
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// step 8. | ||
if !hmac.Equal(t, t2) { | ||
return ErrInvalidTokenAuth | ||
} | ||
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// step 9. | ||
block, err := aes.NewCipher(ek) | ||
if err != nil { | ||
return fmt.Errorf("create aes cipher: %w", err) | ||
} | ||
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p := make([]byte, len(c)) | ||
ciph := cipher.NewCTR(block, n2) | ||
ciph.XORKeyStream(p, c) | ||
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// step 7. | ||
if payload != nil { | ||
if err := fromBytes(p, payload); err != nil { | ||
return fmt.Errorf("decode payload: %w", err) | ||
} | ||
} | ||
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if footer != nil { | ||
if err := fromBytes(f, footer); err != nil { | ||
return fmt.Errorf("decode footer: %w", err) | ||
} | ||
} | ||
return nil | ||
} | ||
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func v3locSplitKey(key, n []byte) (ek, ak, n2 []byte, err error) { | ||
eKDF := hkdf.New(sha512.New384, key, nil, append([]byte("paseto-encryption-key"), n...)) | ||
aKDF := hkdf.New(sha512.New384, key, nil, append([]byte("paseto-auth-key-for-aead"), n...)) | ||
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tmp := make([]byte, v3locKDF) | ||
if _, err := io.ReadFull(eKDF, tmp); err != nil { | ||
return nil, nil, nil, fmt.Errorf("unable to generate encryption key from seed: %w", err) | ||
} | ||
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ek, n2 = tmp[:v3locKey], tmp[v3locKey:] | ||
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ak = make([]byte, v3locKDF) | ||
if _, err := io.ReadFull(aKDF, ak); err != nil { | ||
return nil, nil, nil, fmt.Errorf("unable to generate authentication key from seed: %w", err) | ||
} | ||
return ek, n2, ak, nil | ||
} |
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@@ -0,0 +1,52 @@ | ||
package paseto | ||
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import ( | ||
"encoding/hex" | ||
"strings" | ||
"testing" | ||
) | ||
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func TestV3Loc_Encrypt(t *testing.T) { | ||
t.Skip() | ||
testCases := loadGoldenFile("testdata/v3.json") | ||
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for _, tc := range testCases.Tests { | ||
if tc.Key == "" || !strings.HasPrefix(tc.Token, v3locHeader) { | ||
continue | ||
} | ||
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t.Run(tc.Name, func(t *testing.T) { | ||
key := mustHex(tc.Key) | ||
payload := mustJSON(tc.Payload) | ||
footer := mustJSON(tc.Footer) | ||
imp := tc.ImplicitAssertion | ||
nonce := mustHex(tc.Nonce) | ||
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token, err := V3Encrypt(key, payload, footer, imp, nonce) | ||
if err != nil { | ||
t.Fatal(err) | ||
} | ||
mustEqual(t, token, tc.Token) | ||
}) | ||
} | ||
} | ||
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func TestV3Loc_Decrypt(t *testing.T) { | ||
t.Skip() | ||
testCases := loadGoldenFile("testdata/v3.json") | ||
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for _, tc := range testCases.Tests { | ||
if tc.Key == "" || !strings.HasPrefix(tc.Token, v3locHeader) { | ||
continue | ||
} | ||
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t.Run(tc.Name, func(t *testing.T) { | ||
imp := tc.ImplicitAssertion | ||
key := must(hex.DecodeString(tc.Key)) | ||
var payload, footer any | ||
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err := V3Decrypt(tc.Token, key, payload, footer, imp) | ||
mustOk(t, err) | ||
}) | ||
} | ||
} |