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Diffstat (limited to 'Documentation/crypto/userspace-if.rst')
| -rw-r--r-- | Documentation/crypto/userspace-if.rst | 39 |
1 files changed, 31 insertions, 8 deletions
diff --git a/Documentation/crypto/userspace-if.rst b/Documentation/crypto/userspace-if.rst index ff86befa61e0..f80f243e227e 100644 --- a/Documentation/crypto/userspace-if.rst +++ b/Documentation/crypto/userspace-if.rst @@ -23,7 +23,7 @@ user space, however. This includes the difference between synchronous and asynchronous invocations. The user space API call is fully synchronous. -[1] http://www.chronox.de/libkcapi.html +[1] https://www.chronox.de/libkcapi.html User Space API General Remarks ------------------------------ @@ -131,9 +131,9 @@ from the kernel crypto API. If the buffer is too small for the message digest, the flag MSG_TRUNC is set by the kernel. In order to set a message digest key, the calling application must use -the setsockopt() option of ALG_SET_KEY. If the key is not set the HMAC -operation is performed without the initial HMAC state change caused by -the key. +the setsockopt() option of ALG_SET_KEY or ALG_SET_KEY_BY_KEY_SERIAL. If the +key is not set the HMAC operation is performed without the initial HMAC state +change caused by the key. Symmetric Cipher API -------------------- @@ -296,15 +296,16 @@ follows: struct sockaddr_alg sa = { .salg_family = AF_ALG, - .salg_type = "rng", /* this selects the symmetric cipher */ - .salg_name = "drbg_nopr_sha256" /* this is the cipher name */ + .salg_type = "rng", /* this selects the random number generator */ + .salg_name = "drbg_nopr_sha256" /* this is the RNG name */ }; Depending on the RNG type, the RNG must be seeded. The seed is provided using the setsockopt interface to set the key. For example, the ansi_cprng requires a seed. The DRBGs do not require a seed, but may be -seeded. +seeded. The seed is also known as a *Personalization String* in NIST SP 800-90A +standard. Using the read()/recvmsg() system calls, random numbers can be obtained. The kernel generates at most 128 bytes in one call. If user space @@ -314,6 +315,16 @@ WARNING: The user space caller may invoke the initially mentioned accept system call multiple times. In this case, the returned file descriptors have the same state. +Following CAVP testing interfaces are enabled when kernel is built with +CRYPTO_USER_API_RNG_CAVP option: + +- the concatenation of *Entropy* and *Nonce* can be provided to the RNG via + ALG_SET_DRBG_ENTROPY setsockopt interface. Setting the entropy requires + CAP_SYS_ADMIN permission. + +- *Additional Data* can be provided using the send()/sendmsg() system calls, + but only after the entropy has been set. + Zero-Copy Interface ------------------- @@ -371,12 +382,24 @@ mentioned optname: - the RNG cipher type to provide the seed +- ALG_SET_KEY_BY_KEY_SERIAL -- Setting the key via keyring key_serial_t. + This operation behaves the same as ALG_SET_KEY. The decrypted + data is copied from a keyring key, and uses that data as the + key for symmetric encryption. + + The passed in key_serial_t must have the KEY_(POS|USR|GRP|OTH)_SEARCH + permission set, otherwise -EPERM is returned. Supports key types: user, + logon, encrypted, and trusted. + - ALG_SET_AEAD_AUTHSIZE -- Setting the authentication tag size for AEAD ciphers. For a encryption operation, the authentication tag of the given size will be generated. For a decryption operation, the provided ciphertext is assumed to contain an authentication tag of the given size (see section about AEAD memory layout below). +- ALG_SET_DRBG_ENTROPY -- Setting the entropy of the random number generator. + This option is applicable to RNG cipher type only. + User space API example ---------------------- @@ -384,4 +407,4 @@ Please see [1] for libkcapi which provides an easy-to-use wrapper around the aforementioned Netlink kernel interface. [1] also contains a test application that invokes all libkcapi API calls. -[1] http://www.chronox.de/libkcapi.html +[1] https://www.chronox.de/libkcapi.html |