Thanks Francesco, Anand for the tip.
I guess I need to supply the iv in hex format. Is it as simple as replacing
each ascii character of iv string with the equivalent hex value or something
else ?
I use the passphrase "As different as chalk and cheese" and iv "As dark as
pitch". What would my iv be in the format Openssl expects it to be ?
Thanks again,
Kunal
On Tue, May 25, 2010 at 6:32 PM, Anand Patel <anand.apa...@gmail.com> wrote:
> You need to use same iv and key for decryption.
> I believe the command is
> openssl enc -d -aes-256-cbc -K <key used to encrypt> -iv <iv used to
> encrypt> -in rgconf_encrypted -out rgconf_decrypted.
>
> -Anand
>
>
> On Tue, May 25, 2010 at 8:30 AM, ~ Kunal Sharma ~ <koolku...@gmail.com>wrote:
>
>> Friends,
>>
>> I'm trying to verify that my encryption and decryption routines work ok.
>> One way I do it is to encrypt the data and save it to a file. The I feed the
>> encrypted file to my decryption routine and write the decrypted data to
>> another file. I compare the original data and the contents of the decrypted
>> file and they are same. So the routines work fine in tandem.
>>
>> Another method I want to use it to encrypt the data and save it to a file.
>> Then I feed the encrypted file to Openssl command line to decrypt.
>>
>> I get my encrypted data in the file rgconf_encrypted. Then I run the
>> following command:
>>
>> openssl enc -d -aes-256-cbc -in rgconf_encrypted
>>
>> I enter the decryption password "As different as chalk and cheese" which I
>> used to encrypt the data. But I get the error "bad magic number".
>>
>> Am I missing something here ? I need to be able to use a simple phrase as
>> my encryption password so I can decrypt it on command line as well. Please
>> provide any pointers on what could be wrong here.
>>
>> Below is the code for my encryption routine.
>>
>> Thanks,
>> Kunal
>>
>> ++++++++++++++++++++++++++++++++++++++++++
>> int encrypt(void)
>> {
>> EVP_CIPHER_CTX ctx;
>> unsigned char ibuf[1024],obuf[1024];
>> int rfd, wfd,ilen,olen,tlen;
>>
>> unsigned char key32[] = "As different as chalk and cheese";
>> unsigned char iv[] = "As dark as pitch";
>> EVP_CIPHER_CTX_init(&ctx);
>> if(!EVP_CipherInit_ex(&ctx, EVP_aes_256_cbc(),NULL,key32,
>> iv,AES_ENCRYPT) ) {
>> console_printf("Couldnt initialize cipher\n");
>> return 1;
>> }
>> /* read the original contents that are stored in file /etc/rgconf */
>> if((rfd = open("/etc/rgconf",O_RDONLY) ) == -1) {
>> console_printf("Couldnt open input file\n");
>> return 1;
>> }
>>
>> /* open a file /et.rgconf_encrypted to store encrypted data */
>> if((wfd = creat("/etc/rgconf_encrypted",0644) ) == -1) {
>> console_printf("Couldn't open output file for writing\n");
>> return 1;
>> }
>> while((ilen = read(rfd,ibuf,1024) ) > 0) {
>> if(EVP_CipherUpdate(&ctx,obuf,&olen,ibuf,ilen)){
>> write(wfd,obuf,olen);
>> }
>> else {
>> console_printf("Encryption error\n");
>> return 1;
>> }
>> }
>> if(!EVP_CipherFinal_ex(&ctx,obuf+olen,&tlen)) {
>> console_printf("Trouble with padding the last block\n");
>> return 1;
>> }
>>
>> write(wfd,obuf+olen,tlen);
>> EVP_CIPHER_CTX_cleanup(&ctx);
>> close(rfd);
>> close(wfd);
>> console_printf("AES 256 CBC encryption complete\n");
>> return 0;
>> }
>> ++++++++++++++++++++++++++++++++++++++++++
>>
>>
>>
>>
>>
>
