66 lines
1.6 KiB
Go
66 lines
1.6 KiB
Go
package tpi
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import (
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"crypto/aes"
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"crypto/cipher"
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"encoding/base64"
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"errors"
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)
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func WeChat_Decrypt(sessionKey, encryptedData, iv string) (string, error) {
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aesKey, err := base64.StdEncoding.DecodeString(sessionKey)
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if err != nil {
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return "", err
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}
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cipherText, err := base64.StdEncoding.DecodeString(encryptedData)
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if err != nil {
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return "", err
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}
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ivBytes, err := base64.StdEncoding.DecodeString(iv)
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if err != nil {
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return "", err
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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 "", err
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}
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mode := cipher.NewCBCDecrypter(block, ivBytes)
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mode.CryptBlocks(cipherText, cipherText)
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cipherText, err = WeChat_Pkcs7Unpad(cipherText, block.BlockSize())
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if err != nil {
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return "", err
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}
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return string(cipherText), nil
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}
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// pkcs7Unpad returns slice of the original data without padding
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func WeChat_Pkcs7Unpad(data []byte, blockSize int) ([]byte, error) {
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var (
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// ErrInvalidBlockSize block size不合法
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ErrInvalidBlockSize = errors.New("invalid block size")
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// ErrInvalidPKCS7Data PKCS7数据不合法
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ErrInvalidPKCS7Data = errors.New("invalid PKCS7 data")
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// ErrInvalidPKCS7Padding 输入padding失败
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ErrInvalidPKCS7Padding = errors.New("invalid padding on input")
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)
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if blockSize <= 0 {
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return nil, ErrInvalidBlockSize
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}
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if len(data)%blockSize != 0 || len(data) == 0 {
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return nil, ErrInvalidPKCS7Data
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}
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c := data[len(data)-1]
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n := int(c)
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if n == 0 || n > len(data) {
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return nil, ErrInvalidPKCS7Padding
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}
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for i := 0; i < n; i++ {
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if data[len(data)-n+i] != c {
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return nil, ErrInvalidPKCS7Padding
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}
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}
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return data[:len(data)-n], nil
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}
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