在使用openSSL库时,我遇到了EVP_EncryptFinal_ex的问题。
具体地说,它每次失败都会导致致命错误./crypto/evp/evp_enc.c(348) OpenSSL internal error, assertion failed: b <= sizeof ctx -> buf
,而不依赖于算法(aes或des)。
这是我的代码。它尽可能简化。
procedure AESTest;
var
key : TBytes;
keyLen : Integer;
dataIn : string;
dataOut : TBytes;
inLen, outLen, resLen : integer;
// Context of an algorithm pointer
e_ctx : Pointer;
begin
// 256 bit key
keyLen := 32;
setlength(key, KeyLen);
RAND_bytes(@(key[0]), KeyLen);
// Input data to encrypt
dataIn := 'Simple data of 29 bits length';
inLen := length(dataIn);
// Init ctx
e_ctx := EVP_CIPHER_CTX_new();
EVP_CIPHER_CTX_init(e_ctx);
EVP_EncryptInit_ex(e_ctx, EVP_aes_256_cbc, nil, @key[0], nil);
// Prepare ouput buf in order to openSSL docs
outLen := inLen + EVP_CIPHER_CTX_block_size(e_ctx) - 1;
setlength(dataOut, outLen);
EVP_EncryptUpdate(e_ctx, @dataOut[0], outLen, @dataIn[1], inLen);
EVP_EncryptFinal_ex(e_ctx, @dataOut[outLen], resLen);
outLen := outLen + resLen;
setlength(dataOut, outLen);
// ... here goes decryption part but it does not matter now
end;
准确地说,使用了导入:
const
LIB_DLL_NAME = 'libeay32.dll';
type
PEVP_CIPHER_CTX : Pointer;
PEVP_CIPHER : Pointer;
function EVP_CIPHER_CTX_new : PEVP_CIPHER_CTX; cdecl; external LIB_DLL_NAME;
procedure EVP_CIPHER_CTX_init(a: PEVP_CIPHER_CTX); cdecl; external LIB_DLL_NAME;
function EVP_aes_256_cbc : PEVP_CIPHER_CTX; cdecl; external LIB_DLL_NAME;
function RAND_bytes(Arr : PByte; ArrLen : integer) : integer; cdecl; external LIB_DLL_NAME;
function EVP_CIPHER_CTX_block_size(ctx: PEVP_CIPHER_CTX): integer; cdecl; external LIB_DLL_NAME;
function EVP_EncryptInit_ex(ctx: PEVP_CIPHER_CTX; cipher_type: PEVP_CIPHER; Engine : Pointer; key: PByte; iv: PByte): integer; cdecl; external LIB_DLL_NAME;
function EVP_EncryptUpdate(ctx: PEVP_CIPHER_CTX; data_out: PByte; var outl: integer; data_in: PByte; inl: integer): integer; cdecl; external LIB_DLL_NAME;
function EVP_EncryptFinal_ex(ctx: PEVP_CIPHER_CTX; data_out: PByte; var outl: integer): integer; external LIB_DLL_NAME;
我实际上尝试阅读源代码(evp_enc.c)并找到了断言:
OPENSSL_assert(b <= sizeof ctx->buf);
此处b
是当前密码的块大小。这个断言是有道理的,但我仍然无法弄清楚它在我的代码中是如何失败的。
我试图在几天内解决这个问题,我会很感激任何建议。
更新: 以下是evp_enc.c的两行:
b=ctx->cipher->block_size;
OPENSSL_assert(b <= sizeof ctx->buf);
根据代码,b是当前密码的块大小,对于aes_256_cbc,它是16位长。
答案 0 :(得分:2)
问题出在你的函数EVP_EncryptFinal_ex
的声明中。您应该添加cdecl
指令(与所有其他函数一样)。
所以,新的声明将是:
function EVP_EncryptFinal_ex(ctx: PEVP_CIPHER_CTX; data_out: PByte; var outl: integer): integer; cdecl; external LIB_DLL_NAME;