diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/crypto/api-aead.rst | 68 | ||||
| -rw-r--r-- | Documentation/crypto/api-akcipher.rst | 56 | ||||
| -rw-r--r-- | Documentation/crypto/api-digest.rst | 122 | ||||
| -rw-r--r-- | Documentation/crypto/api-rng.rst | 32 | ||||
| -rw-r--r-- | Documentation/crypto/api-samples.rst | 224 | ||||
| -rw-r--r-- | Documentation/crypto/api-skcipher.rst | 203 | ||||
| -rw-r--r-- | Documentation/crypto/api.rst | 24 | ||||
| -rw-r--r-- | Documentation/crypto/architecture.rst | 435 | ||||
| -rw-r--r-- | Documentation/crypto/devel-algos.rst | 247 | ||||
| -rw-r--r-- | Documentation/crypto/index.rst | 24 | ||||
| -rw-r--r-- | Documentation/crypto/intro.rst | 74 | ||||
| -rw-r--r-- | Documentation/crypto/userspace-if.rst | 387 | ||||
| -rw-r--r-- | Documentation/index.rst | 1 |
13 files changed, 1897 insertions, 0 deletions
diff --git a/Documentation/crypto/api-aead.rst b/Documentation/crypto/api-aead.rst new file mode 100644 index 000000000000..78a7ce48a331 --- /dev/null +++ b/Documentation/crypto/api-aead.rst @@ -0,0 +1,68 @@ +Authenticated Encryption With Associated Data (AEAD) Algorithm Definitions +-------------------------------------------------------------------------- + +.. kernel-doc:: include/crypto/aead.h + :doc: Authenticated Encryption With Associated Data (AEAD) Cipher API + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_alg + +Authenticated Encryption With Associated Data (AEAD) Cipher API +--------------------------------------------------------------- + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_alloc_aead + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_free_aead + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_ivsize + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_authsize + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_blocksize + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_setkey + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_setauthsize + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_encrypt + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_decrypt + +Asynchronous AEAD Request Handle +-------------------------------- + +.. kernel-doc:: include/crypto/aead.h + :doc: Asynchronous AEAD Request Handle + +.. kernel-doc:: include/crypto/aead.h + :functions: crypto_aead_reqsize + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_set_tfm + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_alloc + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_free + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_set_callback + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_set_crypt + +.. kernel-doc:: include/crypto/aead.h + :functions: aead_request_set_ad diff --git a/Documentation/crypto/api-akcipher.rst b/Documentation/crypto/api-akcipher.rst new file mode 100644 index 000000000000..305e616991c3 --- /dev/null +++ b/Documentation/crypto/api-akcipher.rst @@ -0,0 +1,56 @@ +Asymmetric Cipher Algorithm Definitions +--------------------------------------- + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_alg + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_request + +Asymmetric Cipher API +--------------------- + +.. kernel-doc:: include/crypto/akcipher.h + :doc: Generic Public Key API + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_alloc_akcipher + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_free_akcipher + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_set_pub_key + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_set_priv_key + +Asymmetric Cipher Request Handle +-------------------------------- + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_request_alloc + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_request_free + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_request_set_callback + +.. kernel-doc:: include/crypto/akcipher.h + :functions: akcipher_request_set_crypt + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_maxsize + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_encrypt + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_decrypt + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_sign + +.. kernel-doc:: include/crypto/akcipher.h + :functions: crypto_akcipher_verify diff --git a/Documentation/crypto/api-digest.rst b/Documentation/crypto/api-digest.rst new file mode 100644 index 000000000000..b5eaf0f6093e --- /dev/null +++ b/Documentation/crypto/api-digest.rst @@ -0,0 +1,122 @@ +Message Digest Algorithm Definitions +------------------------------------ + +.. kernel-doc:: include/crypto/hash.h + :doc: Message Digest Algorithm Definitions + +.. kernel-doc:: include/crypto/hash.h + :functions: hash_alg_common + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_alg + +.. kernel-doc:: include/crypto/hash.h + :functions: shash_alg + +Asynchronous Message Digest API +------------------------------- + +.. kernel-doc:: include/crypto/hash.h + :doc: Asynchronous Message Digest API + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_alloc_ahash + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_free_ahash + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_init + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_digestsize + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_reqtfm + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_reqsize + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_setkey + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_finup + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_final + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_digest + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_export + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_ahash_import + +Asynchronous Hash Request Handle +-------------------------------- + +.. kernel-doc:: include/crypto/hash.h + :doc: Asynchronous Hash Request Handle + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_request_set_tfm + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_request_alloc + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_request_free + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_request_set_callback + +.. kernel-doc:: include/crypto/hash.h + :functions: ahash_request_set_crypt + +Synchronous Message Digest API +------------------------------ + +.. kernel-doc:: include/crypto/hash.h + :doc: Synchronous Message Digest API + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_alloc_shash + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_free_shash + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_blocksize + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_digestsize + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_descsize + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_setkey + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_digest + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_export + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_import + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_init + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_update + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_final + +.. kernel-doc:: include/crypto/hash.h + :functions: crypto_shash_finup diff --git a/Documentation/crypto/api-rng.rst b/Documentation/crypto/api-rng.rst new file mode 100644 index 000000000000..0d7ee78c4f32 --- /dev/null +++ b/Documentation/crypto/api-rng.rst @@ -0,0 +1,32 @@ +Random Number Algorithm Definitions +----------------------------------- + +.. kernel-doc:: include/crypto/rng.h + :functions: rng_alg + +Crypto API Random Number API +---------------------------- + +.. kernel-doc:: include/crypto/rng.h + :doc: Random number generator API + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_alloc_rng + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_rng_alg + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_free_rng + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_rng_generate + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_rng_get_bytes + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_rng_reset + +.. kernel-doc:: include/crypto/rng.h + :functions: crypto_rng_seedsize diff --git a/Documentation/crypto/api-samples.rst b/Documentation/crypto/api-samples.rst new file mode 100644 index 000000000000..0a10819f6107 --- /dev/null +++ b/Documentation/crypto/api-samples.rst @@ -0,0 +1,224 @@ +Code Examples +============= + +Code Example For Symmetric Key Cipher Operation +----------------------------------------------- + +:: + + + struct tcrypt_result { + struct completion completion; + int err; + }; + + /* tie all data structures together */ + struct skcipher_def { + struct scatterlist sg; + struct crypto_skcipher *tfm; + struct skcipher_request *req; + struct tcrypt_result result; + }; + + /* Callback function */ + static void test_skcipher_cb(struct crypto_async_request *req, int error) + { + struct tcrypt_result *result = req->data; + + if (error == -EINPROGRESS) + return; + result->err = error; + complete(&result->completion); + pr_info("Encryption finished successfully\n"); + } + + /* Perform cipher operation */ + static unsigned int test_skcipher_encdec(struct skcipher_def *sk, + int enc) + { + int rc = 0; + + if (enc) + rc = crypto_skcipher_encrypt(sk->req); + else + rc = crypto_skcipher_decrypt(sk->req); + + switch (rc) { + case 0: + break; + case -EINPROGRESS: + case -EBUSY: + rc = wait_for_completion_interruptible( + &sk->result.completion); + if (!rc && !sk->result.err) { + reinit_completion(&sk->result.completion); + break; + } + default: + pr_info("skcipher encrypt returned with %d result %d\n", + rc, sk->result.err); + break; + } + init_completion(&sk->result.completion); + + return rc; + } + + /* Initialize and trigger cipher operation */ + static int test_skcipher(void) + { + struct skcipher_def sk; + struct crypto_skcipher *skcipher = NULL; + struct skcipher_request *req = NULL; + char *scratchpad = NULL; + char *ivdata = NULL; + unsigned char key[32]; + int ret = -EFAULT; + + skcipher = crypto_alloc_skcipher("cbc-aes-aesni", 0, 0); + if (IS_ERR(skcipher)) { + pr_info("could not allocate skcipher handle\n"); + return PTR_ERR(skcipher); + } + + req = skcipher_request_alloc(skcipher, GFP_KERNEL); + if (!req) { + pr_info("could not allocate skcipher request\n"); + ret = -ENOMEM; + goto out; + } + + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + test_skcipher_cb, + &sk.result); + + /* AES 256 with random key */ + get_random_bytes(&key, 32); + if (crypto_skcipher_setkey(skcipher, key, 32)) { + pr_info("key could not be set\n"); + ret = -EAGAIN; + goto out; + } + + /* IV will be random */ + ivdata = kmalloc(16, GFP_KERNEL); + if (!ivdata) { + pr_info("could not allocate ivdata\n"); + goto out; + } + get_random_bytes(ivdata, 16); + + /* Input data will be random */ + scratchpad = kmalloc(16, GFP_KERNEL); + if (!scratchpad) { + pr_info("could not allocate scratchpad\n"); + goto out; + } + get_random_bytes(scratchpad, 16); + + sk.tfm = skcipher; + sk.req = req; + + /* We encrypt one block */ + sg_init_one(&sk.sg, scratchpad, 16); + skcipher_request_set_crypt(req, &sk.sg, &sk.sg, 16, ivdata); + init_completion(&sk.result.completion); + + /* encrypt data */ + ret = test_skcipher_encdec(&sk, 1); + if (ret) + goto out; + + pr_info("Encryption triggered successfully\n"); + + out: + if (skcipher) + crypto_free_skcipher(skcipher); + if (req) + skcipher_request_free(req); + if (ivdata) + kfree(ivdata); + if (scratchpad) + kfree(scratchpad); + return ret; + } + + +Code Example For Use of Operational State Memory With SHASH +----------------------------------------------------------- + +:: + + + struct sdesc { + struct shash_desc shash; + char ctx[]; + }; + + static struct sdescinit_sdesc(struct crypto_shash *alg) + { + struct sdescsdesc; + int size; + + size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); + sdesc = kmalloc(size, GFP_KERNEL); + if (!sdesc) + return ERR_PTR(-ENOMEM); + sdesc->shash.tfm = alg; + sdesc->shash.flags = 0x0; + return sdesc; + } + + static int calc_hash(struct crypto_shashalg, + const unsigned chardata, unsigned int datalen, + unsigned chardigest) { + struct sdescsdesc; + int ret; + + sdesc = init_sdesc(alg); + if (IS_ERR(sdesc)) { + pr_info("trusted_key: can't alloc %s\n", hash_alg); + return PTR_ERR(sdesc); + } + + ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest); + kfree(sdesc); + return ret; + } + + +Code Example For Random Number Generator Usage +---------------------------------------------- + +:: + + + static int get_random_numbers(u8 *buf, unsigned int len) + { + struct crypto_rngrng = NULL; + chardrbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */ + int ret; + + if (!buf || !len) { + pr_debug("No output buffer provided\n"); + return -EINVAL; + } + + rng = crypto_alloc_rng(drbg, 0, 0); + if (IS_ERR(rng)) { + pr_debug("could not allocate RNG handle for %s\n", drbg); + return -PTR_ERR(rng); + } + + ret = crypto_rng_get_bytes(rng, buf, len); + if (ret < 0) + pr_debug("generation of random numbers failed\n"); + else if (ret == 0) + pr_debug("RNG returned no data"); + else + pr_debug("RNG returned %d bytes of data\n", ret); + + out: + crypto_free_rng(rng); + return ret; + } diff --git a/Documentation/crypto/api-skcipher.rst b/Documentation/crypto/api-skcipher.rst new file mode 100644 index 000000000000..eabd369482ce --- /dev/null +++ b/Documentation/crypto/api-skcipher.rst @@ -0,0 +1,203 @@ +Block Cipher Algorithm Definitions +---------------------------------- + +.. kernel-doc:: include/linux/crypto.h + :doc: Block Cipher Algorithm Definitions + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_alg + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_alg + +.. kernel-doc:: include/linux/crypto.h + :functions: blkcipher_alg + +.. kernel-doc:: include/linux/crypto.h + :functions: cipher_alg + +Symmetric Key Cipher API +------------------------ + +.. kernel-doc:: include/crypto/skcipher.h + :doc: Symmetric Key Cipher API + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_alloc_skcipher + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_free_skcipher + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_has_skcipher + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_ivsize + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_blocksize + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_setkey + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_reqtfm + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_encrypt + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_decrypt + +Symmetric Key Cipher Request Handle +----------------------------------- + +.. kernel-doc:: include/crypto/skcipher.h + :doc: Symmetric Key Cipher Request Handle + +.. kernel-doc:: include/crypto/skcipher.h + :functions: crypto_skcipher_reqsize + +.. kernel-doc:: include/crypto/skcipher.h + :functions: skcipher_request_set_tfm + +.. kernel-doc:: include/crypto/skcipher.h + :functions: skcipher_request_alloc + +.. kernel-doc:: include/crypto/skcipher.h + :functions: skcipher_request_free + +.. kernel-doc:: include/crypto/skcipher.h + :functions: skcipher_request_set_callback + +.. kernel-doc:: include/crypto/skcipher.h + :functions: skcipher_request_set_crypt + +Single Block Cipher API +----------------------- + +.. kernel-doc:: include/linux/crypto.h + :doc: Single Block Cipher API + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_alloc_cipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_free_cipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_has_cipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_cipher_blocksize + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_cipher_setkey + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_cipher_encrypt_one + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_cipher_decrypt_one + +Asynchronous Block Cipher API - Deprecated +------------------------------------------ + +.. kernel-doc:: include/linux/crypto.h + :doc: Asynchronous Block Cipher API + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_alloc_ablkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_free_ablkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_has_ablkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_ivsize + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_blocksize + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_setkey + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_reqtfm + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_encrypt + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_decrypt + +Asynchronous Cipher Request Handle - Deprecated +----------------------------------------------- + +.. kernel-doc:: include/linux/crypto.h + :doc: Asynchronous Cipher Request Handle + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_ablkcipher_reqsize + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_request_set_tfm + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_request_alloc + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_request_free + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_request_set_callback + +.. kernel-doc:: include/linux/crypto.h + :functions: ablkcipher_request_set_crypt + +Synchronous Block Cipher API - Deprecated +----------------------------------------- + +.. kernel-doc:: include/linux/crypto.h + :doc: Synchronous Block Cipher API + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_alloc_blkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_free_blkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_has_blkcipher + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_name + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_ivsize + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_blocksize + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_setkey + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_encrypt + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_encrypt_iv + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_decrypt + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_decrypt_iv + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_set_iv + +.. kernel-doc:: include/linux/crypto.h + :functions: crypto_blkcipher_get_iv diff --git a/Documentation/crypto/api.rst b/Documentation/crypto/api.rst new file mode 100644 index 000000000000..f2bbeb0fe9aa --- /dev/null +++ b/Documentation/crypto/api.rst @@ -0,0 +1,24 @@ +Programming Interface +===================== + +Please note that the kernel crypto API contains the AEAD givcrypt API +(crypto_aead_giv\* and aead_givcrypt\* function calls in +include/crypto/aead.h). This API is obsolete and will be removed in the +future. To obtain the functionality of an AEAD cipher with internal IV +generation, use the IV generator as a regular cipher. For example, +rfc4106(gcm(aes)) is the AEAD cipher with external IV generation and +seqniv(rfc4106(gcm(aes))) implies that the kernel crypto API generates +the IV. Different IV generators are available. + +.. class:: toc-title + + Table of contents + +.. toctree:: + :maxdepth: 2 + + api-skcipher + api-aead + api-digest + api-rng + api-akcipher diff --git a/Documentation/crypto/architecture.rst b/Documentation/crypto/architecture.rst new file mode 100644 index 000000000000..34e396bbc6e6 --- /dev/null +++ b/Documentation/crypto/architecture.rst @@ -0,0 +1,435 @@ +Kernel Crypto API Architecture +============================== + +Cipher algorithm types +---------------------- + +The kernel crypto API provides different API calls for the following +cipher types: + +- Symmetric ciphers + +- AEAD ciphers + +- Message digest, including keyed message digest + +- Random number generation + +- User space interface + +Ciphers And Templates +--------------------- + +The kernel crypto API provides implementations of single block ciphers +and message digests. In addition, the kernel crypto API provides +numerous "templates" that can be used in conjunction with the single +block ciphers and message digests. Templates include all types of block +chaining mode, the HMAC mechanism, etc. + +Single block ciphers and message digests can either be directly used by +a caller or invoked together with a template to form multi-block ciphers +or keyed message digests. + +A single block cipher may even be called with multiple templates. +However, templates cannot be used without a single cipher. + +See /proc/crypto and search for "name". For example: + +- aes + +- ecb(aes) + +- cmac(aes) + +- ccm(aes) + +- rfc4106(gcm(aes)) + +- sha1 + +- hmac(sha1) + +- authenc(hmac(sha1),cbc(aes)) + +In these examples, "aes" and "sha1" are the ciphers and all others are +the templates. + +Synchronous And Asynchronous Operation +-------------------------------------- + +The kernel crypto API provides synchronous and asynchronous API +operations. + +When using the synchronous API operation, the caller invokes a cipher +operation which is performed synchronously by the kernel crypto API. +That means, the caller waits until the cipher operation completes. +Therefore, the kernel crypto API calls work like regular function calls. +For synchronous operation, the set of API calls is small and +conceptually similar to any other crypto library. + +Asynchronous operation is provided by the kernel crypto API which +implies that the invocation of a cipher operation will complete almost +instantly. That invocation triggers the cipher operation but it does not +signal its completion. Before invoking a cipher operation, the caller +must provide a callback function the kernel crypto API can invoke to +signal the completion of the cipher operation. Furthermore, the caller +must ensure it can handle such asynchronous events by applying +appropriate locking around its data. The kernel crypto API does not +perform any special serialization operation to protect the caller's data +integrity. + +Crypto API Cipher References And Priority +----------------------------------------- + +A cipher is referenced by the caller with a string. That string has the +following semantics: + +:: + + template(single block cipher) + + +where "template" and "single block cipher" is the aforementioned +template and single block cipher, respectively. If applicable, +additional templates may enclose other templates, such as + +:: + + template1(template2(single block cipher))) + + +The kernel crypto API may provide multiple implementations of a template +or a single block cipher. For example, AES on newer Intel hardware has +the following implementations: AES-NI, assembler implementation, or +straight C. Now, when using the string "aes" with the kernel crypto API, +which cipher implementation is used? The answer to that question is the +priority number assigned to each cipher implementation by the kernel +crypto API. When a caller uses the string to refer to a cipher during +initialization of a cipher handle, the kernel crypto API looks up all +implementations providing an implementation with that name and selects +the implementation with the highest priority. + +Now, a caller may have the need to refer to a specific cipher +implementation and thus does not want to rely on the priority-based +selection. To accommodate this scenario, the kernel crypto API allows +the cipher implementation to register a unique name in addition to +common names. When using that unique name, a caller is therefore always +sure to refer to the intended cipher implementation. + +The list of available ciphers is given in /proc/crypto. However, that +list does not specify all possible permutations of templates and +ciphers. Each block listed in /proc/crypto may contain the following +information -- if one of the components listed as follows are not +applicable to a cipher, it is not displayed: + +- name: the generic name of the cipher that is subject to the + priority-based selection -- this name can be used by the cipher + allocation API calls (all names listed above are examples for such + generic names) + +- driver: the unique name of the cipher -- this name can be used by the + cipher allocation API calls + +- module: the kernel module providing the cipher implementation (or + "kernel" for statically linked ciphers) + +- priority: the priority value of the cipher implementation + +- refcnt: the reference count of the respective cipher (i.e. the number + of current consumers of this cipher) + +- selftest: specification whether the self test for the cipher passed + +- type: + + - skcipher for symmetric key ciphers + + - cipher for single block ciphers that may be used with an + additional template + + - shash for synchronous message digest + + - ahash for asynchronous message digest + + - aead for AEAD cipher type + + - compression for compression type transformations + + - rng for random number generator + + - givcipher for cipher with associated IV generator (see the geniv + entry below for the specification of the IV generator type used by + the cipher implementation) + +- blocksize: blocksize of cipher in bytes + +- keysize: key size in bytes + +- ivsize: IV size in bytes + +- seedsize: required size of seed data for random number generator + +- digestsize: output size of the message digest + +- geniv: IV generation type: + + - eseqiv for encrypted sequence number based IV generation + + - seqiv for sequence number based IV generation + + - chainiv for chain iv generation + + - <builtin> is a marker that the cipher implements IV generation and + handling as it is specific to the given cipher + +Key Sizes +--------- + +When allocating a cipher handle, the caller only specifies the cipher +type. Symmetric ciphers, however, typically support multiple key sizes +(e.g. AES-128 vs. AES-192 vs. AES-256). These key sizes are determined +with the length of the provided key. Thus, the kernel crypto API does +not provide a separate way to select the particular symmetric cipher key +size. + +Cipher Allocation Type And Masks +-------------------------------- + +The different cipher handle allocation functions allow the specification +of a type and mask flag. Both parameters have the following meaning (and +are therefore not covered in the subsequent sections). + +The type flag specifies the type of the cipher algorithm. The caller +usually provides a 0 when the caller wants the default handling. +Otherwise, the caller may provide the following selections which match +the aforementioned cipher types: + +- CRYPTO_ALG_TYPE_CIPHER Single block cipher + +- CRYPTO_ALG_TYPE_COMPRESS Compression + +- CRYPTO_ALG_TYPE_AEAD Authenticated Encryption with Associated Data + (MAC) + +- CRYPTO_ALG_TYPE_BLKCIPHER Synchronous multi-block cipher + +- CRYPTO_ALG_TYPE_ABLKCIPHER Asynchronous multi-block cipher + +- CRYPTO_ALG_TYPE_GIVCIPHER Asynchronous multi-block cipher packed + together with an IV generator (see geniv field in the /proc/crypto + listing for the known IV generators) + +- CRYPTO_ALG_TYPE_DIGEST Raw message digest + +- CRYPTO_ALG_TYPE_HASH Alias for CRYPTO_ALG_TYPE_DIGEST + +- CRYPTO_ALG_TYPE_SHASH Synchronous multi-block hash + +- CRYPTO_ALG_TYPE_AHASH Asynchronous multi-block hash + +- CRYPTO_ALG_TYPE_RNG Random Number Generation + +- CRYPTO_ALG_TYPE_AKCIPHER Asymmetric cipher + +- CRYPTO_ALG_TYPE_PCOMPRESS Enhanced version of + CRYPTO_ALG_TYPE_COMPRESS allowing for segmented compression / + decompression instead of performing the operation on one segment + only. CRYPTO_ALG_TYPE_PCOMPRESS is intended to replace + CRYPTO_ALG_TYPE_COMPRESS once existing consumers are converted. + +The mask flag restricts the type of cipher. The only allowed flag is +CRYPTO_ALG_ASYNC to restrict the cipher lookup function to +asynchronous ciphers. Usually, a caller provides a 0 for the mask flag. + +When the caller provides a mask and type specification, the caller +limits the search the kernel crypto API can perform for a suitable +cipher implementation for the given cipher name. That means, even when a +caller uses a cipher name that exists during its initialization call, +the kernel crypto API may not select it due to the used type and mask +field. + +Internal Structure of Kernel Crypto API +--------------------------------------- + +The kernel crypto API has an internal structure where a cipher +implementation may use many layers and indirections. This section shall +help to clarify how the kernel crypto API uses various components to +implement the complete cipher. + +The following subsections explain the internal structure based on +existing cipher implementations. The first section addresses the most +complex scenario where all other scenarios form a logical subset. + +Generic AEAD Cipher Structure +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The following ASCII art decomposes the kernel crypto API layers when +using the AEAD cipher with the automated IV generation. The shown +example is used by the IPSEC layer. + +For other use cases of AEAD ciphers, the ASCII art applies as well, but +the caller may not use the AEAD cipher with a separate IV generator. In +this case, the caller must generate the IV. + +The depicted example decomposes the AEAD cipher of GCM(AES) based on the +generic C implementations (gcm.c, aes-generic.c, ctr.c, ghash-generic.c, +seqiv.c). The generic implementation serves as an example showing the +complete logic of the kernel crypto API. + +It is possible that some streamlined cipher implementations (like +AES-NI) provide implementations merging aspects which in the view of the < |