c - OpenSSL AES_set_encrypt_key 因编译目标而异

Question

我从 AES_set_encrypt_key() 得到不同的结果，这取决于我编译的架构。据我了解， key 扩展是确定性的，这意味着其他地方出了问题。

我设置了一个简单的打印并与 diff 进行比较以轻松验证差异。

如果有人有任何想法，我将不胜感激

调试.sh:

#!/bin/bash

gcc -std=c99 -m32 bug.c -lssl -o test && ./test > m32.log && \
gcc -std=c99 -m64 bug.c -lssl -o test && ./test > m64.log && \
diff m32.log m64.log

bug.c:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/aes.h>

void
hexdump(FILE *f, const char *title, const unsigned char *s, int length)
{
    for(int n = 0; n < length ; ++n) {
        if((n%16) == 0)
            fprintf(f, "\n%s  %04x", title, n);
        fprintf(f, " %02x", s[n]);
    }
    fprintf(f, "\n");
}    

int main()
{
    char *key = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
    AES_KEY aes_key;

    if(AES_set_encrypt_key((unsigned char*) key, 128, &aes_key) != 0)
            return EXIT_FAILURE;

    hexdump(stdout, "AES_KEY", (unsigned char*) &aes_key, sizeof(AES_KEY));

    return EXIT_SUCCESS;
}

差异:

2,16c2,16
< AES_KEY  0000 65 72 6f 4c 70 69 20 6d 20 6d 75 73 6f 6c 6f 64
< AES_KEY  0010 26 da 3f e5 56 b3 1f 88 76 de 6a fb 19 b2 05 9f
< AES_KEY  0020 fd 0e 08 8c ab bd 17 04 dd 63 7d ff c4 d1 78 60
< AES_KEY  0030 2d 12 36 34 86 af 21 30 5b cc 5c cf 9f 1d 24 af
< AES_KEY  0040 54 c9 92 0a d2 66 b3 3a 89 aa ef f5 16 b7 cb 5a
< AES_KEY  0050 ea 8e 3b 05 38 e8 88 3f b1 42 67 ca a7 f5 ac 90
< AES_KEY  0060 8a d2 dd b4 b2 3a 55 8b 03 78 32 41 a4 8d 9e d1
< AES_KEY  0070 b4 9b 80 ff 06 a1 d5 74 05 d9 e7 35 a1 54 79 e4
< AES_KEY  0080 dd a9 a0 c9 db 08 75 bd de d1 92 88 7f 85 eb 6c
< AES_KEY  0090 8d 7b 37 3b 56 73 42 86 88 a2 d0 0e f7 27 3b 62
< AES_KEY  00a0 27 13 fb ef 71 60 b9 69 f9 c2 69 67 0e e5 52 05
< AES_KEY  00b0 88 fe 95 ff e5 2a 62 f7 00 00 00 00 f4 9f 04 08
< AES_KEY  00c0 98 fe 95 ff 44 84 04 08 90 ce 7d f7 f4 9f 04 08
< AES_KEY  00d0 c8 fe 95 ff 89 86 04 08 24 33 76 f7 f4 2f 76 f7
< AES_KEY  00e0 70 86 04 08 c8 fe 95 ff 65 b9 63 f7 90 ce 7d f7
---
> AES_KEY  0000 4c 6f 72 65 6d 20 69 70 73 75 6d 20 64 6f 6c 6f
> AES_KEY  0010 e5 3f da 26 88 1f b3 56 fb 6a de 76 9f 05 b2 19
> AES_KEY  0020 8c 08 0e fd 04 17 bd ab ff 7d 63 dd 60 78 d1 c4
> AES_KEY  0030 34 36 12 2d 30 21 af 86 cf 5c cc 5b af 24 1d 9f
> AES_KEY  0040 0a 92 c9 54 3a b3 66 d2 f5 ef aa 89 5a cb b7 16
> AES_KEY  0050 05 3b 8e ea 3f 88 e8 38 ca 67 42 b1 90 ac f5 a7
> AES_KEY  0060 b4 dd d2 8a 8b 55 3a b2 41 32 78 03 d1 9e 8d a4
> AES_KEY  0070 ff 80 9b b4 74 d5 a1 06 35 e7 d9 05 e4 79 54 a1
> AES_KEY  0080 c9 a0 a9 dd bd 75 08 db 88 92 d1 de 6c eb 85 7f
> AES_KEY  0090 3b 37 7b 8d 86 42 73 56 0e d0 a2 88 62 3b 27 f7
> AES_KEY  00a0 ef fb 13 27 69 b9 60 71 67 69 c2 f9 05 52 e5 0e
> AES_KEY  00b0 00 00 00 00 00 00 00 00 db 05 40 00 00 00 00 00
> AES_KEY  00c0 58 65 e0 e0 ff 7f 00 00 65 08 40 00 00 00 00 00
> AES_KEY  00d0 68 6b e6 0b e6 7f 00 00 20 08 40 00 00 00 00 00
> AES_KEY  00e0 00 00 00 00 00 00 00 00 30 06 40 00 00 00 00 00

gcc -Wl,-t -std=c99 -m32 bug.c -l ssl -o test

/usr/bin/ld: mode elf_i386
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib32/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib32/crti.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/32/crtbegin.o
/tmp/ccppFYUU.o
-lssl (/lib/../lib32/libssl.so)
-lgcc_s (/usr/lib/gcc/x86_64-linux-gnu/4.4.5/32/libgcc_s.so)
/lib32/libc.so.6 (//lib32/libc.so.6)
(//usr/lib32/libc_nonshared.a)elf-init.oS
/lib32/ld-linux.so.2 (//lib32/ld-linux.so.2)
-lgcc_s (/usr/lib/gcc/x86_64-linux-gnu/4.4.5/32/libgcc_s.so)
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/32/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib32/crtn.o

gcc -Wl,-t -std=c99 -m64 bug.c -l ssl -o test

/usr/bin/ld: mode elf_x86_64
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crti.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtbegin.o
/tmp/cclvw4XV.o
-lssl (/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/libssl.so)
-lgcc_s (/usr/lib/gcc/x86_64-linux-gnu/4.4.5/libgcc_s.so)
/lib/libc.so.6 (//lib/libc.so.6)
(//usr/lib/libc_nonshared.a)elf-init.oS
/lib/ld-linux-x86-64.so.2 (//lib/ld-linux-x86-64.so.2)
-lgcc_s (/usr/lib/gcc/x86_64-linux-gnu/4.4.5/libgcc_s.so)
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/4.4.5/../../../../lib/crtn.o

Answer 1

您正在比较 openssl 库中 key 的私有(private)二进制表示。此实现细节并不意味着跨平台一致。 OpenSSL使用优化的汇编函数进行加密和解密，这些优化的例程以不同的方式存储 key 。

aes.h 公共(public) header 包含注释注释:

/* This should be a hidden type, but EVP requires that the size be known */
struct aes_key_st {
#ifdef AES_LONG
    unsigned long rd_key[4 *(AES_MAXNR + 1)];
#else
    unsigned int rd_key[4 *(AES_MAXNR + 1)];
#endif
    int rounds;
};
typedef struct aes_key_st AES_KEY;

请自行查看(来自 openssl 源码压缩包的路径):

• crypto/aes/aes_misc.c:AES_set_encrypt_key 调用 private_AES_set_encrypt_key
• crypto/aes/asm/{.pl|.S}:private_AES_set_encrypt_key有很多实现

根据 cpu 类型，您可以在 32 位 386 兼容电脑上获得不同的结果事件。