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refactor(crypto): refactor crypto for download api
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,47 @@ | ||
| package m115 | ||
|
|
||
| import ( | ||
| "crypto/rand" | ||
| "encoding/base64" | ||
| "io" | ||
| ) | ||
|
|
||
| type Key [16]byte | ||
|
|
||
| func GenerateKey() Key { | ||
| key := Key{} | ||
| _, _ = io.ReadFull(rand.Reader, key[:]) | ||
| return key | ||
| } | ||
|
|
||
| func Encode(input []byte, key Key) (output string) { | ||
| // Prepare buffer | ||
| buf := make([]byte, 16+len(input)) | ||
| // Copy key and data to buffer | ||
| copy(buf, key[:]) | ||
| copy(buf[16:], input) | ||
| // XOR encode | ||
| xorTransform(buf[16:], xorDeriveKey(key[:], 4)) | ||
| reverseBytes(buf[16:]) | ||
| xorTransform(buf[16:], xorClientKey) | ||
| // Encrypt and encode | ||
| output = base64.StdEncoding.EncodeToString(rsaEncrypt(buf)) | ||
| return | ||
| } | ||
|
|
||
| func Decode(input string, key Key) (output []byte, err error) { | ||
| // Base64 decode | ||
| data, err := base64.StdEncoding.DecodeString(input) | ||
| if err != nil { | ||
| return | ||
| } | ||
| // RSA decrypt | ||
| data = rsaDecrypt(data) | ||
| // XOR decode | ||
| output = make([]byte, len(data)-16) | ||
| copy(output, data[16:]) | ||
| xorTransform(output, xorDeriveKey(data[:16], 12)) | ||
| reverseBytes(output) | ||
| xorTransform(output, xorDeriveKey(key[:], 4)) | ||
| return | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| package m115 | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "crypto/rand" | ||
| "io" | ||
| "math/big" | ||
| ) | ||
|
|
||
| var ( | ||
| _N, _ = big.NewInt(0).SetString( | ||
| "8686980c0f5a24c4b9d43020cd2c22703ff3f450756529058b1cf88f09b86021"+ | ||
| "36477198a6e2683149659bd122c33592fdb5ad47944ad1ea4d36c6b172aad633"+ | ||
| "8c3bb6ac6227502d010993ac967d1aef00f0c8e038de2e4d3bc2ec368af2e9f1"+ | ||
| "0a6f1eda4f7262f136420c07c331b871bf139f74f3010e3c4fe57df3afb71683", 16) | ||
| _E, _ = big.NewInt(0).SetString("10001", 16) | ||
|
|
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| _KeyLength = _N.BitLen() / 8 | ||
| ) | ||
|
|
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| func rsaEncrypt(input []byte) []byte { | ||
| buf := &bytes.Buffer{} | ||
| for remainSize := len(input); remainSize > 0; { | ||
| sliceSize := _KeyLength - 11 | ||
| if sliceSize > remainSize { | ||
| sliceSize = remainSize | ||
| } | ||
| rsaEncryptSlice(input[:sliceSize], buf) | ||
|
|
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| input = input[sliceSize:] | ||
| remainSize -= sliceSize | ||
| } | ||
| return buf.Bytes() | ||
| } | ||
|
|
||
| func rsaEncryptSlice(input []byte, w io.Writer) { | ||
| // Padding | ||
| padSize := _KeyLength - len(input) - 3 | ||
| padData := make([]byte, padSize) | ||
| _, _ = rand.Read(padData) | ||
| // Prepare message | ||
| buf := make([]byte, _KeyLength) | ||
| buf[0], buf[1] = 0, 2 | ||
| for i, b := range padData { | ||
| buf[2+i] = b%0xff + 0x01 | ||
| } | ||
| buf[padSize+2] = 0 | ||
| copy(buf[padSize+3:], input) | ||
| msg := big.NewInt(0).SetBytes(buf) | ||
| // RSA Encrypt | ||
| ret := big.NewInt(0).Exp(msg, _E, _N).Bytes() | ||
| // Fill zeros at beginning | ||
| if fillSize := _KeyLength - len(ret); fillSize > 0 { | ||
| zeros := make([]byte, fillSize) | ||
| _, _ = w.Write(zeros) | ||
| } | ||
| _, _ = w.Write(ret) | ||
| } | ||
|
|
||
| func rsaDecrypt(input []byte) []byte { | ||
| buf := &bytes.Buffer{} | ||
| for remainSize := len(input); remainSize > 0; { | ||
| sliceSize := _KeyLength | ||
| if sliceSize > remainSize { | ||
| sliceSize = remainSize | ||
| } | ||
| rsaDecryptSlice(input[:sliceSize], buf) | ||
|
|
||
| input = input[sliceSize:] | ||
| remainSize -= sliceSize | ||
| } | ||
| return buf.Bytes() | ||
| } | ||
|
|
||
| func rsaDecryptSlice(input []byte, w io.Writer) { | ||
| // RSA Decrypt | ||
| msg := big.NewInt(0).SetBytes(input) | ||
| ret := big.NewInt(0).Exp(msg, _E, _N).Bytes() | ||
| // Un-padding | ||
| for i, b := range ret { | ||
| // Find the beginning of plaintext | ||
| if b == 0 && i != 0 { | ||
| _, _ = w.Write(ret[i+1:]) | ||
| break | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,8 @@ | ||
| package m115 | ||
|
|
||
| // reverseBytes reverses data in place. | ||
| func reverseBytes(data []byte) { | ||
| for i, j := 0, len(data)-1; i < j; i, j = i+1, j-1 { | ||
| data[i], data[j] = data[j], data[i] | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,52 @@ | ||
| package m115 | ||
|
|
||
| var ( | ||
| // Pre-calculated key data | ||
| xorKeySeed = []byte{ | ||
| 0xf0, 0xe5, 0x69, 0xae, 0xbf, 0xdc, 0xbf, 0x8a, | ||
| 0x1a, 0x45, 0xe8, 0xbe, 0x7d, 0xa6, 0x73, 0xb8, | ||
| 0xde, 0x8f, 0xe7, 0xc4, 0x45, 0xda, 0x86, 0xc4, | ||
| 0x9b, 0x64, 0x8b, 0x14, 0x6a, 0xb4, 0xf1, 0xaa, | ||
| 0x38, 0x01, 0x35, 0x9e, 0x26, 0x69, 0x2c, 0x86, | ||
| 0x00, 0x6b, 0x4f, 0xa5, 0x36, 0x34, 0x62, 0xa6, | ||
| 0x2a, 0x96, 0x68, 0x18, 0xf2, 0x4a, 0xfd, 0xbd, | ||
| 0x6b, 0x97, 0x8f, 0x4d, 0x8f, 0x89, 0x13, 0xb7, | ||
| 0x6c, 0x8e, 0x93, 0xed, 0x0e, 0x0d, 0x48, 0x3e, | ||
| 0xd7, 0x2f, 0x88, 0xd8, 0xfe, 0xfe, 0x7e, 0x86, | ||
| 0x50, 0x95, 0x4f, 0xd1, 0xeb, 0x83, 0x26, 0x34, | ||
| 0xdb, 0x66, 0x7b, 0x9c, 0x7e, 0x9d, 0x7a, 0x81, | ||
| 0x32, 0xea, 0xb6, 0x33, 0xde, 0x3a, 0xa9, 0x59, | ||
| 0x34, 0x66, 0x3b, 0xaa, 0xba, 0x81, 0x60, 0x48, | ||
| 0xb9, 0xd5, 0x81, 0x9c, 0xf8, 0x6c, 0x84, 0x77, | ||
| 0xff, 0x54, 0x78, 0x26, 0x5f, 0xbe, 0xe8, 0x1e, | ||
| 0x36, 0x9f, 0x34, 0x80, 0x5c, 0x45, 0x2c, 0x9b, | ||
| 0x76, 0xd5, 0x1b, 0x8f, 0xcc, 0xc3, 0xb8, 0xf5, | ||
| } | ||
|
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| xorClientKey = []byte{ | ||
| 0x78, 0x06, 0xad, 0x4c, 0x33, 0x86, 0x5d, 0x18, | ||
| 0x4c, 0x01, 0x3f, 0x46, | ||
| } | ||
| ) | ||
|
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| func xorDeriveKey(seed []byte, size int) []byte { | ||
| key := make([]byte, size) | ||
| for i := 0; i < size; i++ { | ||
| key[i] = (seed[i] + xorKeySeed[size*i]) & 0xff | ||
| key[i] ^= xorKeySeed[size*(size-i-1)] | ||
| } | ||
| return key | ||
| } | ||
|
|
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| func xorTransform(data []byte, key []byte) { | ||
| dataSize, keySize := len(data), len(key) | ||
| mod := dataSize % 4 | ||
| if mod > 0 { | ||
| for i := 0; i < mod; i++ { | ||
| data[i] ^= key[i%keySize] | ||
| } | ||
| } | ||
| for i := mod; i < dataSize; i++ { | ||
| data[i] ^= key[(i-mod)%keySize] | ||
| } | ||
| } |
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