333 lines
8.5 KiB
Go
333 lines
8.5 KiB
Go
package util
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/hmac"
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"crypto/md5"
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"crypto/sha256"
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"encoding/base64"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"strings"
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)
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// 微信签名算法方式
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const (
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SignTypeMD5 = `MD5`
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SignTypeHMACSHA256 = `HMAC-SHA256`
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)
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// EncryptMsg 加密消息
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func EncryptMsg(random, rawXMLMsg []byte, appID, aesKey string) (encrtptMsg []byte, err error) {
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defer func() {
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if e := recover(); e != nil {
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err = fmt.Errorf("panic error: err=%v", e)
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return
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}
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}()
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var key []byte
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key, err = aesKeyDecode(aesKey)
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if err != nil {
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panic(err)
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}
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ciphertext := AESEncryptMsg(random, rawXMLMsg, appID, key)
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encrtptMsg = []byte(base64.StdEncoding.EncodeToString(ciphertext))
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return
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}
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// AESEncryptMsg ciphertext = AES_Encrypt[random(16B) + msg_len(4B) + rawXMLMsg + appId]
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// 参考：github.com/chanxuehong/wechat.v2
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func AESEncryptMsg(random, rawXMLMsg []byte, appID string, aesKey []byte) (ciphertext []byte) {
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const (
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BlockSize = 32 // PKCS#7
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BlockMask = BlockSize - 1 // BLOCK_SIZE 为 2^n 时, 可以用 mask 获取针对 BLOCK_SIZE 的余数
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)
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appIDOffset := 20 + len(rawXMLMsg)
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contentLen := appIDOffset + len(appID)
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amountToPad := BlockSize - contentLen&BlockMask
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plaintextLen := contentLen + amountToPad
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plaintext := make([]byte, plaintextLen)
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// 拼接
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copy(plaintext[:16], random)
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encodeNetworkByteOrder(plaintext[16:20], uint32(len(rawXMLMsg)))
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copy(plaintext[20:], rawXMLMsg)
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copy(plaintext[appIDOffset:], appID)
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// PKCS#7 补位
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for i := contentLen; i < plaintextLen; i++ {
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plaintext[i] = byte(amountToPad)
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}
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// 加密
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block, err := aes.NewCipher(aesKey)
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if err != nil {
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panic(err)
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}
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mode := cipher.NewCBCEncrypter(block, aesKey[:16])
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mode.CryptBlocks(plaintext, plaintext)
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ciphertext = plaintext
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return
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}
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// DecryptMsg 消息解密
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func DecryptMsg(appID, encryptedMsg, aesKey string) (random, rawMsgXMLBytes []byte, err error) {
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defer func() {
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if e := recover(); e != nil {
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err = fmt.Errorf("panic error: err=%v", e)
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return
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}
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}()
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var encryptedMsgBytes, key, getAppIDBytes []byte
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encryptedMsgBytes, err = base64.StdEncoding.DecodeString(encryptedMsg)
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if err != nil {
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return
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}
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key, err = aesKeyDecode(aesKey)
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if err != nil {
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panic(err)
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}
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random, rawMsgXMLBytes, getAppIDBytes, err = AESDecryptMsg(encryptedMsgBytes, key)
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if err != nil {
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err = fmt.Errorf("消息解密失败,%v", err)
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return
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}
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if appID != string(getAppIDBytes) {
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err = fmt.Errorf("消息解密校验APPID失败")
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return
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}
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return
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}
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func aesKeyDecode(encodedAESKey string) (key []byte, err error) {
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if len(encodedAESKey) != 43 {
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err = fmt.Errorf("the length of encodedAESKey must be equal to 43")
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return
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}
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key, err = base64.StdEncoding.DecodeString(encodedAESKey + "=")
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if err != nil {
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return
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}
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if len(key) != 32 {
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err = fmt.Errorf("encodingAESKey invalid")
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return
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}
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return
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}
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// AESDecryptMsg ciphertext = AES_Encrypt[random(16B) + msg_len(4B) + rawXMLMsg + appId]
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// 参考：github.com/chanxuehong/wechat.v2
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func AESDecryptMsg(ciphertext []byte, aesKey []byte) (random, rawXMLMsg, appID []byte, err error) {
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const (
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BlockSize = 32 // PKCS#7
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BlockMask = BlockSize - 1 // BLOCK_SIZE 为 2^n 时, 可以用 mask 获取针对 BLOCK_SIZE 的余数
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)
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if len(ciphertext) < BlockSize {
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err = fmt.Errorf("the length of ciphertext too short: %d", len(ciphertext))
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return
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}
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if len(ciphertext)&BlockMask != 0 {
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err = fmt.Errorf("ciphertext is not a multiple of the block size, the length is %d", len(ciphertext))
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return
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}
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plaintext := make([]byte, len(ciphertext)) // len(plaintext) >= BLOCK_SIZE
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// 解密
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block, err := aes.NewCipher(aesKey)
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if err != nil {
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panic(err)
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}
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mode := cipher.NewCBCDecrypter(block, aesKey[:16])
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mode.CryptBlocks(plaintext, ciphertext)
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// PKCS#7 去除补位
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amountToPad := int(plaintext[len(plaintext)-1])
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if amountToPad < 1 || amountToPad > BlockSize {
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err = fmt.Errorf("the amount to pad is incorrect: %d", amountToPad)
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return
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}
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plaintext = plaintext[:len(plaintext)-amountToPad]
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// 反拼接
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// len(plaintext) == 16+4+len(rawXMLMsg)+len(appId)
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if len(plaintext) <= 20 {
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err = fmt.Errorf("plaintext too short, the length is %d", len(plaintext))
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return
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}
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rawXMLMsgLen := int(decodeNetworkByteOrder(plaintext[16:20]))
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if rawXMLMsgLen < 0 {
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err = fmt.Errorf("incorrect msg length: %d", rawXMLMsgLen)
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return
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}
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appIDOffset := 20 + rawXMLMsgLen
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if len(plaintext) <= appIDOffset {
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err = fmt.Errorf("msg length too large: %d", rawXMLMsgLen)
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return
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}
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random = plaintext[:16:20]
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rawXMLMsg = plaintext[20:appIDOffset:appIDOffset]
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appID = plaintext[appIDOffset:]
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return
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}
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// 把整数 n 格式化成 4 字节的网络字节序
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func encodeNetworkByteOrder(orderBytes []byte, n uint32) {
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orderBytes[0] = byte(n >> 24)
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orderBytes[1] = byte(n >> 16)
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orderBytes[2] = byte(n >> 8)
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orderBytes[3] = byte(n)
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}
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// 从 4 字节的网络字节序里解析出整数
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func decodeNetworkByteOrder(orderBytes []byte) (n uint32) {
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return uint32(orderBytes[0])<<24 |
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uint32(orderBytes[1])<<16 |
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uint32(orderBytes[2])<<8 |
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uint32(orderBytes[3])
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}
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// CalculateSign 计算签名
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func CalculateSign(content, signType, key string) (string, error) {
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var h hash.Hash
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if signType == SignTypeHMACSHA256 {
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h = hmac.New(sha256.New, []byte(key))
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} else {
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h = md5.New()
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}
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if _, err := h.Write([]byte(content)); err != nil {
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return ``, err
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}
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return strings.ToUpper(hex.EncodeToString(h.Sum(nil))), nil
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}
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// ParamSign 计算所传参数的签名
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func ParamSign(p map[string]string, key string) (string, error) {
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bizKey := "&key=" + key
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str := OrderParam(p, bizKey)
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var signType string
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switch p["sign_type"] {
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case SignTypeMD5, SignTypeHMACSHA256:
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signType = p["sign_type"]
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case ``:
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signType = SignTypeMD5
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default:
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return ``, errors.New(`invalid sign_type`)
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}
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return CalculateSign(str, signType, key)
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}
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// ECB provides confidentiality by assigning a fixed ciphertext block to each plaintext block.
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// See NIST SP 800-38A, pp 08-09
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// reference: https://codereview.appspot.com/7860047/patch/23001/24001
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type ecb struct {
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b cipher.Block
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blockSize int
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}
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func newECB(b cipher.Block) *ecb {
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return &ecb{
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b: b,
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blockSize: b.BlockSize(),
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}
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}
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// ECBEncryptor -
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type ECBEncryptor ecb
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// NewECBEncryptor returns a BlockMode which encrypts in electronic code book mode, using the given Block.
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func NewECBEncryptor(b cipher.Block) cipher.BlockMode {
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return (*ECBEncryptor)(newECB(b))
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}
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// BlockSize implement BlockMode.BlockSize
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func (x *ECBEncryptor) BlockSize() int {
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return x.blockSize
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}
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// CryptBlocks implement BlockMode.CryptBlocks
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func (x *ECBEncryptor) CryptBlocks(dst, src []byte) {
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if len(src)%x.blockSize != 0 {
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panic("crypto/cipher: input not full blocks")
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}
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if len(dst) < len(src) {
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panic("crypto/cipher: output smaller than input")
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}
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for len(src) > 0 {
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x.b.Encrypt(dst, src[:x.blockSize])
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src = src[x.blockSize:]
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dst = dst[x.blockSize:]
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}
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}
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// ECBDecryptor -
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type ECBDecryptor ecb
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// NewECBDecryptor returns a BlockMode which decrypts in electronic code book mode, using the given Block.
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func NewECBDecryptor(b cipher.Block) cipher.BlockMode {
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return (*ECBDecryptor)(newECB(b))
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}
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// BlockSize implement BlockMode.BlockSize
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func (x *ECBDecryptor) BlockSize() int {
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return x.blockSize
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}
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// CryptBlocks implement BlockMode.CryptBlocks
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func (x *ECBDecryptor) CryptBlocks(dst, src []byte) {
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if len(src)%x.blockSize != 0 {
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panic("crypto/cipher: input not full blocks")
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}
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if len(dst) < len(src) {
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panic("crypto/cipher: output smaller than input")
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}
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for len(src) > 0 {
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x.b.Decrypt(dst, src[:x.blockSize])
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src = src[x.blockSize:]
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dst = dst[x.blockSize:]
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}
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}
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// AesECBDecrypt will decrypt data with PKCS5Padding
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func AesECBDecrypt(ciphertext []byte, aesKey []byte) ([]byte, error) {
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if len(ciphertext) < aes.BlockSize {
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return nil, errors.New("ciphertext too short")
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}
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// ECB mode always works in whole blocks.
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if len(ciphertext)%aes.BlockSize != 0 {
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return nil, errors.New("ciphertext is not a multiple of the block size")
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}
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block, err := aes.NewCipher(aesKey)
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if err != nil {
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return nil, err
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}
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NewECBDecryptor(block).CryptBlocks(ciphertext, ciphertext)
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return PKCS5UnPadding(ciphertext), nil
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}
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// PKCS5Padding -
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func PKCS5Padding(ciphertext []byte, blockSize int) []byte {
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padding := blockSize - len(ciphertext)%blockSize
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padText := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(ciphertext, padText...)
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}
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// PKCS5UnPadding -
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func PKCS5UnPadding(origData []byte) []byte {
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length := len(origData)
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unPadding := int(origData[length-1])
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return origData[:(length - unPadding)]
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}
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