EVP_CipherInit_ex because cipher->do_cipher is NULL

[Ambarish Mitra]

Hi all,

I am using the EVP API for encryption and decryption (Code snippet below).
The encrypion works fine, but the decryption fails in EVP_CipherInit_ex.
Both the codes are identical except that the said function uses 1 as the
last argument for encryption and 0 for decryption.

I am on Redhat Linux, OpenSSL 0.9.8h 28 May 2008, and g++ 3.3.2 compiler.
(C++ compiler)


The EVP_CipherInit_ex function returned 0 - indicating failure. Upon
investigation, I found out that the context cipher function pointer
"do_cipher" is NULL. I have no clue why this will be NULL. In encryption,
do_cipher is not NULL; only in decryption, this pointer is NULL.

Is there any way to resolve/fix this issue? Do I need to do anything else?

I could not find the definition of EVP_des_ede3_cbc() in the openssl
codebase.



        unsigned char initVector[8] =
{0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10};    //The init vector will be
derived from this
        unsigned char iv[EVP_MAX_IV_LENGTH], key[EVP_MAX_KEY_LENGTH];

        EVP_CIPHER_CTX ctx;

        unsigned char keyInput[24] =
{0x3F,0x6F,0x6B,0x69,0x20,0x5E,0x5F,0x45,0x65,0x54,0x5D,0x56,0x63,0x68,0x6E,
0x6F,0x14,0x32,0x2C,0x41,0x3F,0xD3,0x9B,0xA3};

        memcpy(iv,initVector,sizeof(iv));


        EVP_CIPHER_CTX_init(&ctx);


        int r2 = EVP_CipherInit_ex(&ctx, EVP_des_ede3_cbc(), NULL, keyInput,
iv, 0);
        fprintf(stderr, "cipher initEX ret =%d\n",r2);

          if (ctx.cipher->do_cipher == NULL)
                fprintf(stderr, "do_cipher is NULL!!\n");  // This prints,
meaning do_cipher is NULL!!

//
//.. CipherUpdate/Final follow. Not shown here.
//


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