ios - Using CommonCrypto with an IV but always returning nil -

i using commoncrypto cccryptorcreate decrypt message. using password , iv returns nil.

if use cccryptorcreate decrypt, don't use iv on during encryption on ruby side , don't use iv on obj-c decrypt side decryption works , can see message.

but if use iv on ruby , iv on obj-c side decryption ends nil message object.

i using encrypt in objective-c / decrypt in ruby using anything

obj-c method:

    - (nsdata *) decrypteddatausingalgorithm: (ccalgorithm) algorithm                                          key: (id) key      // data or string                         initializationvector: (id) iv       // data or string                                      options: (ccoptions) options                                        error: (cccryptorstatus *) error     {         cccryptorref cryptor = null;         cccryptorstatus status = kccsuccess;          nsparameterassert([key iskindofclass: [nsdata class]] || [key iskindofclass: [nsstring class]]);         nsparameterassert(iv == nil || [iv iskindofclass: [nsdata class]] || [iv iskindofclass: [nsstring class]]);          nsmutabledata * keydata, * ivdata;         if ( [key iskindofclass: [nsdata class]] )             keydata = (nsmutabledata *) [key mutablecopy];         else             keydata = [[key datausingencoding: nsutf8stringencoding] mutablecopy];          if ( [iv iskindofclass: [nsstring class]] )             ivdata = [[iv datausingencoding: nsutf8stringencoding] mutablecopy];         else             ivdata = (nsmutabledata *) [iv mutablecopy];    // data or nil          #if !__has_feature(objc_arc)             [keydata autorelease];             [ivdata autorelease];         #endif          // ensure correct lengths key , iv data, based on algorithms         fixkeylengths( algorithm, keydata, ivdata );          status = cccryptorcreate( kccdecrypt, algorithm, options,                                [keydata bytes], [keydata length], [ivdata bytes],                                &cryptor );          if ( status != kccsuccess )         {             if ( error != null )                 *error = status;             return ( nil );         }          nsdata * result = [self _runcryptor: cryptor result: &status];         if ( (result == nil) && (error != null) )             *error = status;          cccryptorrelease( cryptor );          return ( result );     }     === not work ==== nsdata * result = [self decrypteddatausingalgorithm: kccalgorithmaes128                                                 key: [[password datausingencoding:nsutf8stringencoding] sha256hash]                                initializationvector: [aniv datausingencoding:nsutf8stringencoding]                                             options: kccoptionpkcs7padding                                               error: &status];   === work === nsdata * result = [self decrypteddatausingalgorithm: kccalgorithmaes128                                                 key: [[password datausingencoding:nsutf8stringencoding] sha256hash]                                initializationvector: nil                                             options: kccoptionpkcs7padding                                               error: &status]; 

looks iv may different, ensure data bytes same , length correct.

you want cccrypt one-shot encryption.

from apple: cccrypt stateless, one-shot encrypt or decrypt operation. performs sequence of cccrytorcreate(), cccryptorupdate(), cccryptorfinal(), , cccryptorrelease().

since not using cccrypt have @ least add cccryptorfinal() example.

also note key , iv need correct size in bytes. using nsutf8stringencoding may not produce number of bytes expected if there characters require multiple byte encodings. note: "i" can encoded surrogate pair.

do not use password string without using pbkdf2 generate key.

consider using rncryptor unless know doing crypto.

here simple example code of one-shot encrypt/decrypy method
key , iv must required length.
encoding (base64, nsstring, etc) done outside of method.

+ (nsdata *)docipher:(nsdata *)datain                   iv:(nsdata *)iv                  key:(nsdata *)symmetrickey              context:(ccoperation)encryptordecrypt // kccencrypt or kccdecrypt                error:(nserror **)error {     cccryptorstatus ccstatus   = kccsuccess;     size_t          cryptbytes = 0;     nsmutabledata  *dataout    = [nsmutabledata datawithlength:datain.length + kccblocksizeaes128];      ccstatus = cccrypt( encryptordecrypt,                        kccalgorithmaes128,                        kccoptionpkcs7padding,                        symmetrickey.bytes,                         kcckeysizeaes128,                        iv.bytes,                        datain.bytes,                        datain.length,                        dataout.mutablebytes,                        dataout.length,                        &cryptbytes);      if (ccstatus == kccsuccess) {         dataout.length = cryptbytes;     }     else {         if (error) {             *error = [nserror errorwithdomain:@"kencryptionerror"                                          code:ccstatus                                      userinfo:nil];         }         dataout = nil;     }      return dataout; }