<?php
$iv = "1234567890abcdef";
$key = "abcdef1234567890";
//使用OPENSSL_RAW_DATA,多一次转换,方便说明白通讯过程
echo base64_encode(openssl_encrypt("hello world", "AES-128-CBC", $key, OPENSSL_RAW_DATA, $iv));

结果

CtqXZg7SH5ACIK7gWwOu4w==

go解密部分

package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"fmt"
)
func main() {
    
originData , _ := base64.StdEncoding.DecodeString( "CtqXZg7SH5ACIK7gWwOu4w==" )
	iv := []byte("1234567890abcdef")
	keyByteString := "abcdef1234567890"
	cipherBlock, err := aes.NewCipher([]byte(keyByteString))
	if err != nil{
    
		fmt.Println(err)
	}
	cipher.NewCBCDecrypter(cipherBlock, iv).CryptBlocks(originData, originData)
	fmt.Println(string(PKCS5UnPadding(originData)))
}

//这个方法是直接找的网上的实现
func PKCS5UnPadding(src []byte) []byte {
    
	length := len(src)
	unpadding := int(src[length-1])
	if length - unpadding < 0 {
    
		return []byte("")
	}
	return src[:(length - unpadding)]
}

解密结果

hello world

Process finished with exit code 0

说明在AES-128-CBC的时候keyByteString是16个字符这个是固定的

再看下AES-256-CBC的时候

<?php
$iv = "1234567890abcdef";
$key = "abcdef12345678901234567890abcdef";

echo base64_encode(openssl_encrypt("hello world", "AES-256-CBC", $key, OPENSSL_RAW_DATA, $iv));

结果

RxpbfHR/FnUo5Mh9NRtudQ==

package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"fmt"
)
func main() {
    
originData , _ := base64.StdEncoding.DecodeString( "RxpbfHR/FnUo5Mh9NRtudQ==" )
	iv := []byte("1234567890abcdef")
	keyByteString := "abcdef12345678901234567890abcdef"
	cipherBlock, err := aes.NewCipher([]byte(keyByteString))
	if err != nil{
    
		fmt.Println(err)
	}
	cipher.NewCBCDecrypter(cipherBlock, iv).CryptBlocks(originData, originData)
	fmt.Println(string(PKCS5UnPadding(originData)))
}

//这个方法是直接找的网上的实现
func PKCS5UnPadding(src []byte) []byte {
    
	length := len(src)
	unpadding := int(src[length-1])
	if length - unpadding < 0 {
    
		return []byte("")
	}
	return src[:(length - unpadding)]
}

结果

hello world

Process finished with exit code 0

其中iv是固定16位,而keyByteString则变为了32位

以上这几种情况都比较简单,而比较坑的是啥呢,
1.php在key的长度不满足要求的时候也可以加密成功!
2.go则必须要求keyByteString的长度满足要求!!!
所以这几涉及到了key在php中到底是怎处理的
先看下php的源码

PHP_FUNCTION(openssl_decrypt)
{
    
	//省略无关代码
	//注意这里这里有对参数的初始化处理,那么我们就可以猜测这里有对key的处理
	if (php_openssl_cipher_init(cipher_type, cipher_ctx, &mode,
				&password, &password_len, &free_password,
				&iv, &iv_len, &free_iv, tag, tag_len, options, 0) == FAILURE ||
			php_openssl_cipher_update(cipher_type, cipher_ctx, &mode, &outbuf, &outlen,
				data, data_len, aad, aad_len, 0) == FAILURE) {
    
		RETVAL_FALSE;
	}
	//省略好多
}
//再来看php_openssl_cipher_init方法
static int php_openssl_cipher_init(const EVP_CIPHER *cipher_type,
		EVP_CIPHER_CTX *cipher_ctx, struct php_openssl_cipher_mode *mode,
		char **ppassword, size_t *ppassword_len, zend_bool *free_password,
		char **piv, size_t *piv_len, zend_bool *free_iv,
		char *tag, int tag_len, zend_long options, int enc)  /* {
    {
    { */
{
    
	//又省略好多
	/* check and set key */
	password_len = (int) *ppassword_len;
	key_len = EVP_CIPHER_key_length(cipher_type);
	//就是这里了这里PHP在key的长度不满足要求的长度时会自动重新填充一个新的key出来!而go中不支持这种操作!!!这就比较坑了,而解决的办法就是通过go实现key的填充
	if (key_len > password_len) {
    
		if ((OPENSSL_DONT_ZERO_PAD_KEY & options) && !EVP_CIPHER_CTX_set_key_length(cipher_ctx, password_len)) {
    
			php_openssl_store_errors();
			php_error_docref(NULL, E_WARNING, "Key length cannot be set for the cipher method");
			return FAILURE;
		}
		key = emalloc(key_len);
		memset(key, 0, key_len);
		memcpy(key, *ppassword, password_len);
		*ppassword = (char *) key;
		*ppassword_len = key_len;
		*free_password = 1;
	} 
	//省略好多
}

那么如何解决这个问题呢
直接看看代码吧

<?php
$iv = "1234567890abcdef";
$key = "abc";

echo base64_encode(openssl_encrypt("hello world", "AES-128-CBC", $key, OPENSSL_RAW_DATA, $iv));

结果

7s3/y57WmZt+f1Pz5KzXlg==

go 的解密处理方法

package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"fmt"
)
func main() {
    
	originData , _ := base64.StdEncoding.DecodeString( "7s3/y57WmZt+f1Pz5KzXlg==" )
	iv := []byte("1234567890abcdef")

	//key为abc
	key := "abc"
	//初始化一个空的字节数组,这里的16为AES-128-CBC的要求的key的长度
	keyByte := [16]byte{
    }
	//转换key为字节数组
	keyByteTemp := []byte(key)
	//依次赋值,这里的3为key的len
	for i := 0; i < 3; i++ {
    
		keyByte[i] = keyByteTemp[i]
	}
	fmt.Println(keyByteTemp,keyByte)
	//转换依次得到的keyByteString
	keyByteString := string(keyByte[:])

	//解密
	cipherBlock, err := aes.NewCipher([]byte(keyByteString))
	if err != nil{
    
		fmt.Println(err)
	}
	cipher.NewCBCDecrypter(cipherBlock, iv).CryptBlocks(originData, originData)
	fmt.Println(string(PKCS5UnPadding(originData)))
}

func PKCS5UnPadding(src []byte) []byte {
    
	length := len(src)
	unpadding := int(src[length-1])
	if length - unpadding < 0 {
    
		return []byte("")
	}
	return src[:(length - unpadding)]
}

结果

[97 98 99] [97 98 99 0 0 0 0 0 0 0 0 0 0 0 0 0]
hello world

Process finished with exit code 0

好了这里是针对AES-128-CBC的在key的长度不满足的情况做的处理
留给读者思考的问题
1.AES-256-CBC的key不满足长度的情况怎处理
2.在AES-128-CBC的情况iv不满足长度又要怎么处理呢