Fix bug in second hash calculation #141
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -5,6 +5,7 @@ import ( | |
| "crypto/aes" | ||
| "crypto/cipher" | ||
| "crypto/sha256" | ||
| "encoding/binary" | ||
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| "github.com/libp2p/go-libp2p/core/peer" | ||
| "github.com/multiformats/go-multihash" | ||
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@@ -13,30 +14,39 @@ import ( | |
| const ( | ||
| // nonceLen defines length of the nonce to use for AESGCM encryption | ||
| nonceLen = 12 | ||
| ) | ||
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| var ( | ||
| // secondHashPrefix is a prefix that a mulithash is prepended with when calculating a second hash | ||
| secondHashPrefix = []byte("CR_DOUBLEHASH\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00") | ||
| // deriveKeyPrefix is a prefix that a multihash is prepended with when deriving an encryption key | ||
| deriveKeyPrefix = []byte("CR_ENCRYPTIONKEY\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00") | ||
| // noncePrefix is a prefix that a multihash is prepended with when calculating a nonce | ||
| noncePrefix = []byte("CR_NONCE\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00") | ||
| ) | ||
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| // SecondSHA returns SHA256 over the payload | ||
| func SHA256(payload, dest []byte) []byte { | ||
| return sha256Multiple(dest, payload) | ||
| } | ||
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| func sha256Multiple(dest []byte, payloads ...[]byte) []byte { | ||
| h := sha256.New() | ||
| for _, payload := range payloads { | ||
| h.Write(payload) | ||
| } | ||
| return h.Sum(dest) | ||
| } | ||
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| // SecondMultihash calculates SHA256 over the multihash and wraps it into another multihash with DBL_SHA256 codec | ||
| func SecondMultihash(mh multihash.Multihash) (multihash.Multihash, error) { | ||
| digest := SHA256(append(secondHashPrefix, mh...), nil) | ||
| return multihash.Encode(digest, multihash.DBL_SHA2_256) | ||
| } | ||
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| // deriveKey derives encryptioin key from the passphrase using SHA256 | ||
| func deriveKey(passphrase []byte) []byte { | ||
| return SHA256(append(deriveKeyPrefix, passphrase...), nil) | ||
| } | ||
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| // DecryptAES decrypts AES payload using the nonce and the passphrase | ||
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@@ -62,9 +72,11 @@ func EncryptAES(payload, passphrase []byte) ([]byte, []byte, error) { | |
| derivedKey := deriveKey([]byte(passphrase)) | ||
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| // Create initialization vector (nonse) to be used during encryption | ||
| // Nonce is derived from the passphrase concatenated with the payload so that the encrypted payloads | ||
| // for the same multihash can be compared to each other without having to decrypt them, as it's not possible. | ||
| payloadLen := make([]byte, 8) | ||
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There was a problem hiding this comment. Concerning the payloadLen, the exact format isn't defined yet in ipfs/specs#373. Would it make more sense to use a constant byte array (e.g I think that I am more in favor of an unsigned varint format for the payload len, as it gives more agility. WDYT? There was a problem hiding this comment.
These values are hashed over, so Does that make sense? There was a problem hiding this comment. Alright, all good! 👍🏻 |
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| binary.LittleEndian.PutUint64(payloadLen, uint64(len(payload))) | ||
| nonce := sha256Multiple(nil, noncePrefix, payloadLen, payload, passphrase)[:nonceLen] | ||
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| // Create cypher and seal the data | ||
| block, err := aes.NewCipher(derivedKey) | ||
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There was a problem hiding this comment. The format for Encrypted PeerID/Metadata was recently updated in the DHT Spec. The format should be [ The encryption varint for There was a problem hiding this comment. Great point! As IPNI doesn't have anything stored after There was a problem hiding this comment. Perfect, just wanted to make sure we are on the same page 😄 |
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@@ -83,13 +95,13 @@ func EncryptAES(payload, passphrase []byte) ([]byte, []byte, error) { | |
| } | ||
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| // DecryptValueKey decrypts the value key using the passphrase | ||
| func DecryptValueKey(valKey, mh multihash.Multihash) ([]byte, error) { | ||
| return DecryptAES(valKey[:nonceLen], valKey[nonceLen:], mh) | ||
| } | ||
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| // EncryptValueKey encrypts raw value key using the passpharse | ||
| func EncryptValueKey(valKey, mh multihash.Multihash) ([]byte, error) { | ||
| nonce, encValKey, err := EncryptAES(valKey, mh) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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@@ -98,13 +110,13 @@ func EncryptValueKey(valKey, passphrase []byte) ([]byte, error) { | |
| } | ||
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| // DecryptMetadata decrypts metdata using the provided passphrase | ||
| func DecryptMetadata(encMetadata, valueKey []byte) ([]byte, error) { | ||
| return DecryptAES(encMetadata[:nonceLen], encMetadata[nonceLen:], valueKey) | ||
| } | ||
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| // EncryptMetadata encrypts metadata using the provided passphrase | ||
| func EncryptMetadata(metadata, valueKey []byte) ([]byte, error) { | ||
| nonce, encValKey, err := EncryptAES(metadata, valueKey) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| package dhash | ||
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| import ( | ||
| "bytes" | ||
| "crypto/sha256" | ||
| "math/rand" | ||
| "testing" | ||
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| "github.com/ipni/go-indexer-core/store/test" | ||
| "github.com/multiformats/go-multihash" | ||
| "github.com/stretchr/testify/require" | ||
| ) | ||
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| func TestSalt(t *testing.T) { | ||
| salt_len := 64 | ||
| require.Equal(t, len(secondHashPrefix), salt_len) | ||
| require.Equal(t, len(deriveKeyPrefix), salt_len) | ||
| require.Equal(t, len(noncePrefix), salt_len) | ||
| } | ||
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| func TestEncryptSameValueWithTheSameMultihashShouldProduceTheSameOutput(t *testing.T) { | ||
| rng := rand.New(rand.NewSource(1413)) | ||
| payload := make([]byte, 256) | ||
| _, err := rng.Read(payload) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| passphrase := make([]byte, 32) | ||
| _, err = rng.Read(passphrase) | ||
| require.NoError(t, err) | ||
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| nonce1, encrypted1, err := EncryptAES(payload, passphrase) | ||
| require.NoError(t, err) | ||
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| nonce2, encrypted2, err := EncryptAES(payload, passphrase) | ||
| require.NoError(t, err) | ||
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| require.True(t, bytes.Equal(nonce1, nonce2)) | ||
| require.True(t, bytes.Equal(encrypted1, encrypted2)) | ||
| } | ||
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| func TestCanDecryptEncryptedValue(t *testing.T) { | ||
| rng := rand.New(rand.NewSource(1413)) | ||
| payload := make([]byte, 256) | ||
| _, err := rng.Read(payload) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| passphrase := make([]byte, 32) | ||
| _, err = rng.Read(passphrase) | ||
| require.NoError(t, err) | ||
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| nonce, encrypted, err := EncryptAES(payload, passphrase) | ||
| require.NoError(t, err) | ||
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| decrypted, err := DecryptAES(nonce, encrypted, passphrase) | ||
| require.NoError(t, err) | ||
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| require.True(t, bytes.Equal(payload, decrypted)) | ||
| } | ||
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| func TestSecondMultihash(t *testing.T) { | ||
| mh := test.RandomMultihashes(1)[0] | ||
| smh, err := SecondMultihash(mh) | ||
| require.NoError(t, err) | ||
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| h := sha256.New() | ||
| h.Write(append(secondHashPrefix, mh...)) | ||
| digest := h.Sum(nil) | ||
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| decoded, err := multihash.Decode(smh) | ||
| require.NoError(t, err) | ||
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| require.Equal(t, uint64(multihash.DBL_SHA2_256), decoded.Code) | ||
| require.Equal(t, digest, decoded.Digest) | ||
| } | ||
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