Thread: Crypto API

  1. #1
    Registered User
    Join Date
    Feb 2009

    Crypto API

    Hi there,
    I am working on a homework that has to do with encryption. I want to be able to encrypt a string of characters. I have been reading about the Crypto API over the last few days, and I managed to get some code, but It doesn't work properly. This is just a test, once I know its working I will added it to the rest of my code. Here I am setting a password, encrypting a string, decrypting and then I expect to see the same string, but It doesn't work out.

            char me[5] = "nice";    // set the password
    	struct crypto_tfm *tfm;    // crypto pointer
    	struct scatterlist src, dst, dst2;
    	char str1[5] = "whic";
    	char str2[5];
    	char str3[5];
  = virt_to_page(str1);
    	src.offset = offset_in_page(str1);
    	src.length = 5;
  = virt_to_page(str2);
    	dst.offset = offset_in_page(str2);
    	dst.length = 5;
  = virt_to_page(str3);
    	dst2.offset = offset_in_page(str3);
    	dst2.length = 5;
    	tfm = crypto_alloc_tfm("blowfish", CRYPTO_TFM_MODE_ECB);   // initialize with blowfish
    	crypto_cipher_setkey(tfm, me, 4);    // set the key
    	crypto_cipher_encrypt(tfm, &dst, &src, 1); // (tfm, dest, source)
    	crypto_cipher_decrypt(tfm, &dst2, &dst, 1); // (tfm, dest, source)
    	*(str1+4) = '\0';
     	*(str2+4) = '\0';
     	*(str3+4) = '\0';
    Any suggestions on what I might be doing wrong?

    Thank you,


  2. #2
    Registered User
    Join Date
    Aug 2008
    tfm = crypto_alloc_tfm("blowfish", CRYPTO_TFM_MODE_ECB); // initialize with blowfish

    Havenīt tested this or nothing just throwing a couple of thoughts in the air.

    Is tfm really initialized with blowfish, maybe a check would be good?

    Isnīt the ECB automatically be used with blowfish, how about :

    Also is crypto_cipher_setkey(tfm, me, 4); returning succesfully value.?

    I know that you are testing things at this point, but ainīt it important to check is something being successfully initialized to see is everything going as planned.

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