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OpenSSL with C++, 3DES Decrypt

Posted on 2012-12-28

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Last Modified: 2013-01-08

Hello Experts,

I have to create code to decrypt using OpenSSL 3DES in C++.

I decrypted my encrypted string with OpenSSL command line like followings,

echo -en "\xca\x99\x19\x61\xd1\x21\x4f......." |
openssl des3 -d
-K e3c254b6ec976b4638f216c83de61504166d7.... -iv 4eed0d2f1c....

I have to create code those function in C++(DES_ncbc_encrypt()..etc).
I've already installed OpenSSL in my environment.

Windows 7 32bit, C++Builder

Please advice.

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Question by:NobMiwa

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3 Comments

LVL 64

Expert Comment

by:btan

ID: 387288422012-12-29

wondering if this help

http://stackoverflow.com/questions/8528995/openssl-c-3des-file-encryption-decryption-fail

Author Comment

by:NobMiwa

ID: 387291792012-12-29

Thank you for information.

I coded followings..

	unsigned char key[] = {0xe3,0xc2,0x54,0xb6,0xec,0x97,0x6b,0x46,0x38,0xf2,0x16,0xc8,0x3d,0xe6,0x15,0x04,0x16,0x6d,0x70,0x70,0xae,0x97,0xbf,0xb6};

	unsigned char iv[]  = {0x4e,0xed,0x0d,0x2f,0x1c,0x48,0xe0,0xf1};
	unsigned char encrypted[] = {0xca,0x99,0x19,0x61,0xd1,0x21,0x4f,0x77,0x3e,0x0d,0xd3,0xcc,0x07,0x9f,0x56,0x24};

	const EVP_CIPHER* cipherType = EVP_des_ede3_ecb();
	EVP_CIPHER_CTX ctx;
	EVP_CIPHER_CTX_init(&ctx);
	int rt = EVP_DecryptInit(&ctx, (const EVP_CIPHER*)cipherType, (const unsigned char*)key, (const unsigned char*)iv);

	int out_len;
	char ciphertext[2048] = {0};
	memset(ciphertext, 0x00, sizeof(ciphertext));

	rt = EVP_DecryptUpdate(&ctx, (unsigned char*)ciphertext, &out_len, (const unsigned char*)encrypted, 16);
	rt = EVP_DecryptFinal(&ctx, (unsigned char*)ciphertext, &out_len);

	rt = EVP_CIPHER_CTX_cleanup(&ctx);

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The answer must be "berobero", but I got 8 letters and was not the answer.

Please advice, if you have any idea..

LVL 64

Accepted Solution

by:btan

btan earned 1500 total points

ID: 387293312012-12-29

Was thinking an6thing to do with padding or the parameter to decrypt function

http://www.openssl.org/docs/crypto/EVP_EncryptInit.html

.

EVP_DecryptInit_ex(),EVP_DecryptUpdate() andEVP_DecryptFinal_ex() are the corresponding decryption operations.EVP_DecryptFinal() will return an error code if padding is enabled and the final block is not correctly formatted. The parameters and restrictions are identical to the encryption operations except that if padding is enabled the decrypted data buffer out passed toEVP_DecryptUpdate() should have sufficient room for (inl + cipher_block_size) bytes unless the cipher block size is 1 in which case inl bytes is sufficient.

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