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| -rw-r--r-- | Documentation/s390/crypto/crypto-API.txt | 83 |
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diff --git a/Documentation/s390/crypto/crypto-API.txt b/Documentation/s390/crypto/crypto-API.txt deleted file mode 100644 index 71ae6ca9f2c..00000000000 --- a/Documentation/s390/crypto/crypto-API.txt +++ /dev/null @@ -1,83 +0,0 @@ -crypto-API support for z990 Message Security Assist (MSA) instructions -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -AUTHOR: Thomas Spatzier (tspat@de.ibm.com) - - -1. Introduction crypto-API -~~~~~~~~~~~~~~~~~~~~~~~~~~ -See Documentation/crypto/api-intro.txt for an introduction/description of the -kernel crypto API. -According to api-intro.txt support for z990 crypto instructions has been added -in the algorithm api layer of the crypto API. Several files containing z990 -optimized implementations of crypto algorithms are placed in the -arch/s390/crypto directory. - - -2. Probing for availability of MSA -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -It should be possible to use Kernels with the z990 crypto implementations both -on machines with MSA available and on those without MSA (pre z990 or z990 -without MSA). Therefore a simple probing mechanism has been implemented: -In the init function of each crypto module the availability of MSA and of the -respective crypto algorithm in particular will be tested. If the algorithm is -available the module will load and register its algorithm with the crypto API. - -If the respective crypto algorithm is not available, the init function will -return -ENOSYS. In that case a fallback to the standard software implementation -of the crypto algorithm must be taken ( -> the standard crypto modules are -also built when compiling the kernel). - - -3. Ensuring z990 crypto module preference -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -If z990 crypto instructions are available the optimized modules should be -preferred instead of standard modules. - -3.1. compiled-in modules -~~~~~~~~~~~~~~~~~~~~~~~~ -For compiled-in modules it has to be ensured that the z990 modules are linked -before the standard crypto modules. Then, on system startup the init functions -of z990 crypto modules will be called first and query for availability of z990 -crypto instructions. If instruction is available, the z990 module will register -its crypto algorithm implementation -> the load of the standard module will fail -since the algorithm is already registered. -If z990 crypto instruction is not available the load of the z990 module will -fail -> the standard module will load and register its algorithm. - -3.2. dynamic modules -~~~~~~~~~~~~~~~~~~~~ -A system administrator has to take care of giving preference to z990 crypto -modules. If MSA is available appropriate lines have to be added to -/etc/modprobe.conf. - -Example: z990 crypto instruction for SHA1 algorithm is available - - add the following line to /etc/modprobe.conf (assuming the - z990 crypto modules for SHA1 is called sha1_z990): - - alias sha1 sha1_z990 - - -> when the sha1 algorithm is requested through the crypto API - (which has a module autoloader) the z990 module will be loaded. - -TBD: a userspace module probing mechanism - something like 'probe sha1 sha1_z990 sha1' in modprobe.conf - -> try module sha1_z990, if it fails to load standard module sha1 - the 'probe' statement is currently not supported in modprobe.conf - - -4. Currently implemented z990 crypto algorithms -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -The following crypto algorithms with z990 MSA support are currently implemented. -The name of each algorithm under which it is registered in crypto API and the -name of the respective module is given in square brackets. - -- SHA1 Digest Algorithm [sha1 -> sha1_z990] -- DES Encrypt/Decrypt Algorithm (64bit key) [des -> des_z990] -- Triple DES Encrypt/Decrypt Algorithm (128bit key) [des3_ede128 -> des_z990] -- Triple DES Encrypt/Decrypt Algorithm (192bit key) [des3_ede -> des_z990] - -In order to load, for example, the sha1_z990 module when the sha1 algorithm is -requested (see 3.2.) add 'alias sha1 sha1_z990' to /etc/modprobe.conf. - |