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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
| commit | f4cdf7ca9a1fdcca413157df19753f388a5a224e (patch) | |
| tree | 60a31895b2446cd7fa27514e8c2843534a0de0da /Documentation/crypto/api-samples.rst | |
| download | linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip | |
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab:
- v4l2-core: added ISP statistics support and per-block validation
- v4l2-core: Allow unknown HDR10 white point and luminance
- New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor
- New codec: Milos: VPU v2.0 codec support
- isp driver: gained support for Dreamchip RPPX1 ISP framework
- vsp1 driver: gained support for RZ/T2H and RZ/N2H
- Novalake driver: gained CVS support for new NVL hardware
- dvb-core: fix feed leak on failed DMX_ADD_PID
- several driver fixes, cleanups and minor improvements
* tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits)
media: ipu-bridge: check all DMI entries when overriding sensor rotation
media: v4l2-async: avoid deleting unlinked ASC entry on link error
media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement
media: intel/ipu6: fix async notifier cleanup leak on parse error
media: staging/ipu7: fix async notifier UAF on probe error path
media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path
media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem()
media: rcar-isp: Fix VSPX reference leaks
media: rcar-isp: Release ISPCORE resources
media: i2c: imx415: Release runtime PM reference on VBLANK error
media: i2c: imx415: Return test pattern write errors
media: renesas: vsp1: Declare index variables in for loop statement
media: renesas: vsp1: Make reset control optional to support platforms without a reset line
media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs
media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs
media: nxp: imx8-isi: Add additional 32-bit RGB format support
media: nxp: imx8-isi: Add 16-bit raw Bayer format support
media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams
media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks
media: nxp: imx8-isi: Correct color map between V4L2 and ISI
...
Diffstat (limited to 'Documentation/crypto/api-samples.rst')
| -rw-r--r-- | Documentation/crypto/api-samples.rst | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/Documentation/crypto/api-samples.rst b/Documentation/crypto/api-samples.rst new file mode 100644 index 000000000..388bb7d7a --- /dev/null +++ b/Documentation/crypto/api-samples.rst @@ -0,0 +1,187 @@ +Code Examples +============= + +Code Example For Symmetric Key Cipher Operation +----------------------------------------------- + +This code encrypts some data with AES-256-XTS. For sake of example, +all inputs are random bytes, the encryption is done in-place, and it's +assumed the code is running in a context where it can sleep. + +:: + + static int test_skcipher(void) + { + struct crypto_skcipher *tfm = NULL; + struct skcipher_request *req = NULL; + u8 *data = NULL; + const size_t datasize = 512; /* data size in bytes */ + struct scatterlist sg; + DECLARE_CRYPTO_WAIT(wait); + u8 iv[16]; /* AES-256-XTS takes a 16-byte IV */ + u8 key[64]; /* AES-256-XTS takes a 64-byte key */ + int err; + + /* + * Allocate a tfm (a transformation object) and set the key. + * + * In real-world use, a tfm and key are typically used for many + * encryption/decryption operations. But in this example, we'll just do a + * single encryption operation with it (which is not very efficient). + */ + + tfm = crypto_alloc_skcipher("xts(aes)", 0, 0); + if (IS_ERR(tfm)) { + pr_err("Error allocating xts(aes) handle: %ld\n", PTR_ERR(tfm)); + return PTR_ERR(tfm); + } + + get_random_bytes(key, sizeof(key)); + err = crypto_skcipher_setkey(tfm, key, sizeof(key)); + if (err) { + pr_err("Error setting key: %d\n", err); + goto out; + } + + /* Allocate a request object */ + req = skcipher_request_alloc(tfm, GFP_KERNEL); + if (!req) { + err = -ENOMEM; + goto out; + } + + /* Prepare the input data */ + data = kmalloc(datasize, GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto out; + } + get_random_bytes(data, datasize); + + /* Initialize the IV */ + get_random_bytes(iv, sizeof(iv)); + + /* + * Encrypt the data in-place. + * + * For simplicity, in this example we wait for the request to complete + * before proceeding, even if the underlying implementation is asynchronous. + * + * To decrypt instead of encrypt, just change crypto_skcipher_encrypt() to + * crypto_skcipher_decrypt(). + */ + sg_init_one(&sg, data, datasize); + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + skcipher_request_set_crypt(req, &sg, &sg, datasize, iv); + err = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); + if (err) { + pr_err("Error encrypting data: %d\n", err); + goto out; + } + + pr_debug("Encryption was successful\n"); + out: + crypto_free_skcipher(tfm); + skcipher_request_free(req); + kfree(data); + return err; + } + + +Code Example For Use of Operational State Memory With SHASH +----------------------------------------------------------- + +:: + + + struct sdesc { + struct shash_desc shash; + char ctx[]; + }; + + static struct sdesc *init_sdesc(struct crypto_shash *alg) + { + struct sdesc *sdesc; + 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; + return sdesc; + } + + static int calc_hash(struct crypto_shash *alg, + const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct sdesc *sdesc; + int ret; + + sdesc = init_sdesc(alg); + if (IS_ERR(sdesc)) { + pr_info("can't alloc sdesc\n"); + return PTR_ERR(sdesc); + } + + ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest); + kfree(sdesc); + return ret; + } + + static int test_hash(const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct crypto_shash *alg; + char *hash_alg_name = "sha1-padlock-nano"; + int ret; + + alg = crypto_alloc_shash(hash_alg_name, 0, 0); + if (IS_ERR(alg)) { + pr_info("can't alloc alg %s\n", hash_alg_name); + return PTR_ERR(alg); + } + ret = calc_hash(alg, data, datalen, digest); + crypto_free_shash(alg); + return ret; + } + + +Code Example For Random Number Generator Usage +---------------------------------------------- + +:: + + + static int get_random_numbers(u8 *buf, unsigned int len) + { + struct crypto_rng *rng = NULL; + char *drbg = "stdrng"; + 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; + } |
