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Appendix A: System Functions
EncryptByKey
This one not only expects a symmetric key (instead of the other types of key), but it also expects that key
to already be “open” (using the OPEN SYMMETRIC KEY command) and a GUID to be available to reference
that key by. Other than that, it is fairly similar in use, with the data to be encrypted (either as a literal
string or a string coercible variable) fed in as a parameter and, in this case, a hash key optionally accepted
as an authenticator):
EncryptByKey({, ‘’|},
[, ‘’|])
Note that if you provide an add authenticator value (in the form of an int), that value must be supplied
when the string is decrypted, and you must also supply a hash value (which again will be needed at
decryption time).
EncryptByPassPhrase
This one encrypts data not by using a formal key, but by a passphrase. Other than accepting a passphrase
parameter instead of assuming an open key, EncryptByPassPhrase works almost exactly like
EncryptByKey:
EncryptByPassPhrase({‘’|},
{‘’|},
[, ‘’|])
As with EncryptByKey, if you provide an add authenticator value (in the form of an int), that value
must be supplied when the string is decrypted, and you must also supply a hash value.
Key_GUID
Fetches the GUID for a given symmetric key in the current database:
Key_ID
Key_GUID(‘’)
Fetches the GUID for a given symmetric key in the current database:
Key_ID(‘’)
SignByAsymKey
602
Adds an asymmetric key signature to a given plain text value:
SignByAsymKey(, [, ‘’])