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POReading and writing rsa keys to a pem file in C
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  1. POReading and writing rsa keys to a pem file in C
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    copied!<p>I am writing a C program to generate keys for RSA and write them to a file and then read from them. The homework requires me to generate the files in a openssl format. So, I chose PEM. Now, I have the following function for creating the file</p> <pre><code>rsa = RSA_new(); // These 3 keys are generated beforehand rsa-&gt;e = e; rsa-&gt;n = n; rsa-&gt;d = d; fp = fopen(pubkey_file, "w"); if(!PEM_write_RSAPublicKey(fp, rsa)) { printf("\n%s\n", "Error writing public key"); } fflush(fp); fclose(fp); fp = fopen(privkey_file, "w"); // pRsaKey = EVP_PKEY_new(); // EVP_PKEY_assign_RSA(pRsaKey, rsa); if(!PEM_write_RSAPrivateKey(fp, rsa, NULL, 0, 0, NULL, NULL)) // if (!PEM_write_PrivateKey(fp, pRsaKey, NULL, NULL, 0, 0, NULL)) { printf("\n%s\n", "Error writing private key"); } fflush(fp); fclose(fp); </code></pre> <p>And this is the function to read the files</p> <pre><code>rsa = RSA_new(); fp = fopen(pubkey_file, "r"); if(PEM_read_RSAPublicKey(fp, &amp;rsa, NULL, NULL) == NULL) { printf("\n%s\n", "Error Reading public key"); return; } fclose(fp); BN_bn2bin(rsa-&gt;n, (unsigned char *)modulus); BN_bn2bin(rsa-&gt;e, (unsigned char *)exp); printf("\n%s\n%s\n", exp, modulus); RSA_free(rsa); // pRsaKey = EVP_PKEY_new(); fp = fopen(privkey_file, "r"); if(fp) // if((PEM_read_PrivateKey(fp, &amp;pRsaKey, NULL, NULL)) == NULL) if((PEM_read_RSAPrivateKey(fp, &amp;rsa, NULL, NULL)) == NULL) { printf("\n%s\n", "Error Reading private key"); return; } // rsa = RSA_new(); // rsa = EVP_PKEY_get1_RSA(pRsaKey); fclose(fp); </code></pre> <p>The public key is written and read as required, but the provate key fails. I have tried writing using both the rsa and the evp(which is commented in the above code). But, both fail. I cannot get my head around why this is happening or try and find where to look to debug this issue. Can anyone please provide some pointers for this?</p>
 

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