encryption - GCM-AEAD support for ubuntu system running linux kernel-3.10 -

i trying implement aead sample code encryption using gcm encryption. invalid argument error while setting key

static int init_aead(void)     {         printk("starting encryption\n");         struct crypto_aead *tfm = null;         struct aead_request *req;         struct tcrypt_result tresult;          struct scatterlist plaintext[1] ;         struct scatterlist ciphertext[1];         struct scatterlist gmactext[1];         unsigned char *plaindata = null;         unsigned char *cipherdata = null;         unsigned char *gmacdata = null;          const u8 *key =  kmalloc(16, gfp_kernel);          char *algo = "rfc4106(gcm(aes))";         unsigned char *ivp = null;         int ret, i, d;         unsigned int iv_len;         unsigned int keylen = 16;          /* allocating cipher handle aead */         tfm = crypto_alloc_aead(algo, 0, 0);         init_completion(&tresult.completion);         if(is_err(tfm)) {                      pr_err("alg: aead: failed load transform %s: %ld\n", algo,                             ptr_err(tfm));                 return ptr_err(tfm);         }          /* allocating request data structure used aead data structure */         req = aead_request_alloc(tfm, gfp_kernel);         if(is_err(req)) {             pr_err("couldn't allocate request handle %s:\n", algo);             return ptr_err(req);         }          /* allocting callback function used , when request completes */         aead_request_set_callback(req, crypto_tfm_req_may_backlog, aead_work_done,&tresult);          crypto_aead_clear_flags(tfm, ~0);          /* set key */         get_random_bytes((void*)key, keylen);       if((ret = crypto_aead_setkey(tfm, key, 16) != 0)) {             pr_err("return value setkey %d\n", ret);             pr_info("key not set\n");                 ret = -eagain;             return ret;         }          /* set authentication tag length */             if(crypto_aead_setauthsize(tfm, 16)) {             pr_info("tag size not authenticated\n");                 ret = -eagain;             return ret;         }          /* set iv size */         iv_len = crypto_aead_ivsize(tfm);         if (!(iv_len)){             pr_info("iv size not authenticated\n");                      ret = -eagain;                      return ret;              }           plaindata  = kmalloc(16, gfp_kernel);         cipherdata = kmalloc(16, gfp_kernel);         gmacdata   = kmalloc(16, gfp_kernel);         ivp        = kmalloc(iv_len, gfp_kernel);          if(!plaindata || !cipherdata || !gmacdata || !ivp) {             printk("memory not availaible\n");             ret = -enomem;             return ret;         }         (i = 0, d = 0; < 16; i++, d++)             plaindata[i] = d;          memset(cipherdata, 0, 16);         memset(gmacdata, 0, 16);          (i = 0,d=0xa8; < 16; i++, d++)             ivp[i] = d;          sg_init_one(&plaintext[0], plaindata, 16);         sg_init_one(&ciphertext[0], cipherdata, 16);         sg_init_one(&gmactext[0], gmacdata, 128);         aead_request_set_crypt(req, plaintext, ciphertext, 16, ivp);         aead_request_set_assoc(req, gmactext, 16);          ret = crypto_aead_encrypt(req);          if (ret)             printk("cipher call returns %d \n", ret);         else             printk("failure \n");         return 0;      }       module_init(init_aead);      module_exit(exit_aead);      module_license("gpl");      module_description("my code aead encryption test");      } 

on inserting module following output

starting encryption
return value setkey -22
key not set

according aead specification aead uses aes-128 encryption hence block size should 128 bit .

but system shows 1 byte block size support aead

name         : rfc4106(gcm(aes)) driver       : rfc4106-gcm-aesni module       : aesni_intel priority     : 400 refcnt       : 1 selftest     : passed type         : nivaead async        : yes blocksize    : 1 ivsize       : 8 maxauthsize  : 16 geniv        : seqiv 

does invalid argument error thrown becuase of block size. if , shall make work ?

the block size of aes indeed 128 bit. block size of gcm different matter though. gcm (galois-counter mode) - name suggests - build on top of ctr (counter) mode of operation, called sic (segmented integer counter) mode of operation. turns aes stream cipher. stream ciphers - definition - have block size of 1 byte (or, more precisely, 1 bit, bit level operations not supported api's).

block size has little key size displayed in call, , argument seem require bytes instead of bits (in key lengths defined).

the size of iv should 12 bytes (the default). otherwise additional calculations may needed gcm implementation (if exist @ all).