Last encoded character (before the paddings if any) is a valid base 64 alphabet but not a possible value. Expected the discarded bits to be zero. 异常 #1454
Description
简要描述
升级 commons-codec 至 1.13 版本后，加解密时出现 java.lang.IllegalArgumentException: Last encoded character (before the paddings if any) is a valid base 64 alphabet but not a possible value. Expected the discarded bits to be zero. 异常
问题原因
commons-codec 在 1.13 版本引入了 validateCharacter 方法,来验证在上下文中是否可以解码最后的尾随字符,微信生成的 EncodingAESKey 无法通过校验
/**
* Validates whether decoding the final trailing character is possible in the context
* of the set of possible base 64 values.
*
* <p>The character is valid if the lower bits within the provided mask are zero. This
* is used to test the final trailing base-64 digit is zero in the bits that will be discarded.
*
* @param emptyBitsMask The mask of the lower bits that should be empty
* @param context the context to be used
*
* @throws IllegalArgumentException if the bits being checked contain any non-zero value
*/
private static void validateCharacter(final int emptyBitsMask, final Context context) {
if ((context.ibitWorkArea & emptyBitsMask) != 0) {
throw new IllegalArgumentException(
"Last encoded character (before the paddings if any) is a valid base 64 alphabet but not a possible value. " +
"Expected the discarded bits to be zero.");
}
}解决方法
使用 commons-codec 加密 32 位字符(我是用的 UUID 生成 ID 后去除 -) 生成一个 EncodingAESKey 替换微信生成的 EncodingAESKey
Base64.encodeBase64String(UUID.randomUUID().toString().replaceAll("-","").getBytes());
commons-codec 加密 32 位字符串得到一个 44 位字符串,去除末尾等号得到 43 位EncodingAESKey