RSA provider use example

[Angus Robertson - Magenta Systems Ltd]

> I would like to see how the RSA* context parameter is filled in 
> and used, but I can't find an example using the RSA provider.

This is an example I just created by building a OSSL_PARAM array with
OSSL_PARAM_construct_xx and calling EVP_PKEY_get_params.  

I've been wondering if this is more efficient than getting the
parameters one at a time using multiple EVP_PKEY_get_xx_param which
also calls EVP_PKEY_get_params. 

I've removed trailing nulls from the unsigned integer fields where the
returned data size is always the buffer size.  

RSA Key Parameters:
Param Key: bits, type: Integer, len: 4 = 2048
Param Key: security-bits, type: Integer, len: 4 = 112
Param Key: max-size, type: Integer, len: 4 = 256
Param Key: e, type: UInteger, len: 1024 = 01000100
Param Key: n, type: UInteger, len: 1024 =
CBE73B4395545CA90A5CE459EEDE322D0F8EFCA775C641626CE156C82B4482F3AAEA048A
73AD41A55F95FA330C858473D2A5C9F1AE771D2B9FE41B43178CFDCBC952725AFD06DA27
6F1F5298B8DE5E08F9DED442B57798A01DE09746FDF3ED920385AADDAFD391139595F3F1
37BD4DADE7F43FBA65BFF9EC4CBCF1A7A7A43D53183CE057797A60B28F326569C3B56B06
F7FD4FF310DA44AC1FFC1E81FA2480CCA9265D14AA99B0956A7ECBDAE94151E95D73ED67
2AC2BC654DA516D3A9F5C5C9CFC51B41EFC05A232AA40700C64A2DBD3D0EBFFE33BC0157
8FFB6E8CE06B28D448E2E18C42982A1DD2C73BB7D8B0A8B79DE20128586283036C03FD26
497BEE92
Param Key: d, type: UInteger, len: 1024 =
91ED9788089647F342094199DDF8097801CD30866D19E854649D16B5585311DDDC015AEB
7885AF558084A88911D00FF9315A5C943136655B91F11886970A9508176C3F1325E0D4B4
E7C6D4B44FEE74B96F1C42E0C40367A6213D74D9391AB01825F68A5F3D2A78241B600089
B3FF68D9DA2BA7D14E6F96255AAEB0A2906C22AA85308EC17DD4372A622C908D2ECB0A9E
AA55773BE7C3C60D794D2E8628C71E95CB18A689BAB0385A20A5220521B71B1B5FB17A2D
E47C8AEE7088B594B41A0C2A84DE0283CC72C96145761F7CE66768B004991B6F1725DF19
951A12C70DFDDAF36FBE9A8D218E085E8E69B604FE9772617A5E0721937626F6339A4A74
5C5DAB06
Param Key: rsa-factor1, type: UInteger, len: 1024 =
8D2CBBDD31C6B7F88AFAC5F935DF5CED43D83D296B5B389B1CC2CE741C217594F64490D0
D904D433AEBC4572240B6BD4D5B0C69AC96FC561447D759E97DA80CF07B5D559EF777785
84445221EB20599FCD0B2236DCA7786DD7CAB1FB1AA9A6B8DE1AB80E74201CF27BEC1479
542945632114590E1FA160FFC4833B0E2122CCBE
Param Key: rsa-factor2, type: UInteger, len: 1024 =
B70BD9C4340422CD11A6443AF3B86E557B6EC0F4DA981CC25FB9DD7A8E548A794BC7775D
3EFC3EB91B242CA1C7925B8CE887B3817E3CE3B15F9C400E3710D29C62485413C76A8377
08E3708A7D9FDE29964F2C0893E74498B6330F9C15C7A235A60B37AFB4E397E3C16F4F5A
F146CC2674F98C4D4CC079B4310BE85FA2C124C5
Param Key: rsa-exponent1, type: UInteger, len: 1024 =
B9708BB779BA7984AB023E60FBD1263CBA4490D64ECFDE2C319FE29907F5F02B7570D181
2F3F3EEEECEFEA1A9A9FCD2D9C373D74BB76CF709B3BEAB0879F61157550621C60B6A9F5
2D4E83A9B5DAE6B859DED1A775797BDB720F06A0FD9FF9B7F3EBEFD58CEC73B580EA67F6
8BFF385923EB6C0D06B8ED3867D902B36136A20F
Param Key: rsa-exponent2, type: UInteger, len: 1024 =
152C82D495DD9CD6CF2327999B2B52C1F91BA352CDD2051CE8EE4D8EDE0D3C9B76B629AF
EE1DC90A52CD5CC9B6B1A481CF549D1720A7DB59C89B13ABAC1677A50CB8814EE7F671B2
1D42F48AC74448738030278126FF8ABF06AC566FCF1F081BB72F9511202D06EF30A941FE
36660B4E9C745E0A1E5D66F6898A32226A9FC6B9
Param Key: rsa-coefficient1, type: UInteger, len: 1024 =
0C7F4DBEBAAEC38C0E636872F33803584AF8B00E7FF4799054A4C4BF56DB145D6914A4D8
9AB5C8F05C2794AC723BA26EF9E7FED4D3DFB6D710222A21EFA030C9A5E7175E36D072E7
74E1BB760BEF735672E3113A8D3F11BD227312A49077EDE7EC22D210972F8F28C832836B
58D414535641469B9D79378A16ACA582EC54BA3E
Param Key: default-digest, type: String, len: 6 = SHA256
Total key parameters: 12

Angus