Seurity using stored procedures?

I wonder if it's possible to use stored procedures to create a layer that restricts read/write access for groups of tables and/or columns of tables. I'd like to give certain roles access to certain stored procedures.
Is this a realistic idea or are there big obstacles (functionality, performance etc.)?

Any help would be appreciated.

Hans.

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| You and me we're goin' nowhere slowly          + A N D R O O M     |

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