fwknop代码分析

Question

问题遇到的现象和发生背景

1.fwknop发送的SPA包的加密流程是什么样的
2.SPA Data Digest 是怎么生成的
3.HMAC 是怎么生成的
4.Final SPA Data 是怎么生成的

问题相关代码，请勿粘贴截图

printf("测试key:%x\n 测试_key_len:%d\n", key, key_len);
printf("测试hmac_key:%x\n 测试hmac_key_len:%d\n",hmac_key,hmac_key_len);

dump_ctx_to_buffer(ctx, dump_buf, sizeof(dump_buf));

运行结果及报错内容

测试key:6de9ba80
测试_key_len:32
测试hmac_key:6de9bb10
测试hmac_key_len:64
此时摘要类型为:SHA256
append_msg_to_buf:SPA Field Values:

Random Value: 1950431638355463
Username: root
Timestamp: 1658126031
FKO Version: 3.0.0
Message Type: 1 (Access msg)
Message String: 10.6.0.91,tcp/22
Nat Access:
Server Auth:
Client Timeout: 0
Digest Type: 3 (SHA256)
HMAC Type: 3 (SHA256)
Encryption Type: 1 (Rijndael)
Encryption Mode: 2 (CBC)
Encoded Data: 1950431638355463:cm9vdA:1658126031:3.0.0:1:MTAuNi4wLjkxLHRjcC8yMg
SPA Data Digest: b3CMkwIVnURz+Hf6B+bVCqEU4eDF0dVSURgO1Yg+m6E
HMAC: 4m95eGVJnc1NP0EIJ36h6Q3q83NcklRDRIX5b6N5QFI
Final SPA Data: +YylGvadvnTdkX9Vsl/syAHXbViBf/CgqATdCqGFsTO89AqIc+2Kk5Mj9vHdiY1919QA/+Kt5r68ngUK/5dL8zVLOj+wprZv8p9Vc+76/bOxf8gDT4McYyN178wPqsP7HkY6XDguTiL7vRPGh3E8J7au02U74WNk84m95eGVJnc1NP0EIJ36h6Q3q83NcklRDRIX5b6N5QFI

我的解答思路和尝试过的方法

KEY_BASE64
HMAC_KEY_BASE64

我想要达到的结果

网上相关文档很少啊，有没有资深钻研过啊