新手逆向ios，抓取icloud登录的一个字典X-Mme-Nas-Qualify，是如何加密的，已经找到了对应的函数，但是现在不懂怎么去进一步解读代码，从而得到加密的方式，希望有人给我解答一下或者指导一下方向，非常感谢，附上代码
void __cdecl __noreturn -[NSMutableURLRequest(AppleAccount) aa_signBodyData:withSigningSession:](id a1, SEL a2, id a3, id a4)
{
id v4; // x19
id v5; // x20
__int64 v6; // x21
__int64 v7; // x19
__int64 v8; // x0
__int64 v9; // x21
v4 = a4;
v5 = a1;
v6 = MEMORY[0x18F2C7424](a3, a2);
v7 = MEMORY[0x18F2C7298](v4, off_19D3C2B68, v6);
MEMORY0x18F2C7420;
MEMORY0x18F2C7430;
v8 = MEMORY0x18F2C7298;
v9 = MEMORY0x18F2C7430;
MEMORY[0x18F2C7298](v5, off_19D3C2318, v9, CFSTR(“X-Mme-Nas-Qualify”));
AALog(CFSTR(“X-Mme-Nas-Qualify: %@”));
}